EPIDEMIOLOGY Flashcards by Secret acc

______
• the study of the occurrence, distribution, and determinants of health and disease in populations and also deals with public health, the health of the population as a whole.

Epidemiology

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The ______ traces the spread of a disease to identify its origin and mode of transmission in a population.

epidemiologist

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A major job of the epidemiologist is to carry out ______—the observation, recognition, and reporting of diseases as they occur—and then analyze the data provided by local and national health authorities to reveal trends and signals of disease outbreaks.

disease surveillance

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The ______ of a particular disease is the number of new cases in a population in a given time period.

incidence

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The ______ of a given disease is the total number of new and existing disease cases in a population in a given time period.

prevalence

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Essentially a ______ measurement, disease ______ can be used to predict the risk of disease for an individual in a defined population within a specific time period.

rate, incidence

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By contrast, ______ measures the total disease burden in a population and can be thought of as a “snapshot” of the disease at a specific instant.

prevalence

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A disease is an ______ when it simultaneously infects an unusually high number of individuals in a population; a ______ is a widespread, usually global epidemic.

epidemic, pandemic

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By contrast, an ______ is one that is constantly present—typically in low numbers—in a population.

endemic disease

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An ______ implies that the pathogen may not be highly virulent or that the majority of individuals in the population may be immune, resulting in low but persistent numbers of cases.

endemic disease

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Individuals infected with a pathogen that causes an endemic disease are ______, a source of infectious agents from which susceptible individuals may be infected.

reservoirs of infection

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______ cases of a disease occur one at a time in geographically separated areas, suggesting that the cases are not related.

Sporadic

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A disease ______, on the other hand, is the appearance of a large num- ber of cases in a short time in an area previously experiencing only sporadic or endemic disease.

outbreak

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Diseased individuals that show no symptoms or only mild symptoms are said to have ______.

subclinical infections

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Subclinically infected individuals are frequently ______ of the particular pathogen, with the pathogen reproducing within them and being shed into the environment where it can infect others.

carriers

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Finally, the term ______, often used in ______, is a measure of the relative ability of a pathogen to cause disease.

virulence, epidemiological parlance

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Some pathogens are highly ______ while others are only weakly so.

virulent

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STAGES OF DISEASE 1

• A well-adapted pathogen lives in balance with its ______, taking what it needs for existence and causing only minimal harm.
• Such pathogens may cause ______ (long-term infections) in the host.
• When there is a ______ between host and pathogen, both host and pathogen survive. ______ is a good example of a chronic infection.
• On the other hand, a host whose ______ is compromised because of factors such as poor diet, age, and other stressors can be harmed or even killed; for example, a ______ can eventually kill the host.

host, chronic infections, balance, Tuberculosis, resistance, chronic tuberculosis infection

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The ______ and ______ of disease are also major indicators of the public health of a population.

incidence, prevalence

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STAGES OF DISEASE 2

• New pathogens occasionally emerge to which specific populations or even an entire species has not developed ______.
• Such emerging pathogens often cause ______, characterized by rapid and dramatic disease onset and a relatively quick return to health.
• ______ caused by a new strain of influenza virus would be an example of an acute infection, as would many other infectious diseases that show a rapid onset and recovery, such as various food infections and food poisonings, or even the common cold.

resistance, acute infections, Influenza

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STAGES OF DISEASE 3

• The progression of clinical symptoms for an acute infectious disease can be divided into stages, and the terms used to describe these stages are also part of the ______.

epidemiologist’s lexicon

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STAGES OF DISEASE 3

• The progression of clinical symptoms for an acute infectious disease can be divided into stages, and the terms used to describe these stages are also part of the epidemiologist’s lexicon:

Infection
Incubation period
Acute period
Decline period
Convalescent period

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STAGES OF DISEASE 3

• The progression of clinical symptoms for an acute infectious disease can be divided into stages, and the terms used to describe these stages are also part of the epidemiologist’s lexicon:

______: The organism invades, colonizes, and grows in the host.

Infection

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STAGES OF DISEASE 3

• The progression of clinical symptoms for an acute infectious disease can be divided into stages, and the terms used to describe these stages are also part of the epidemiologist’s lexicon:

______: Some time always passes between infection and the appearance of disease signs and symptoms.

Incubation period

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STAGES OF DISEASE 3 • The progression of clinical symptoms for an acute infectious disease can be divided into stages, and the terms used to describe these stages are also part of the epidemiologist’s lexicon: Incubation period • Some diseases, like ______, have very short incubation periods, measured in days; others, like ______, have longer ones, sometimes extending for years.

influenza, AIDS

STAGES OF DISEASE 3 • The progression of clinical symptoms for an acute infectious disease can be divided into stages, and the terms used to describe these stages are also part of the epidemiologist’s lexicon: Incubation period • The incubation period for a given disease is determined by the ______, the ______ and ______, and the ______.

inoculum size, virulence, life cycle of the pathogen, resistance of the host

STAGES OF DISEASE 3 • The progression of clinical symptoms for an acute infectious disease can be divided into stages, and the terms used to describe these stages are also part of the epidemiologist’s lexicon: Incubation period • At the ______ of the incubation period, the first signs and symptoms, for example, a mild cough and a feeling of general fatigue in the case of an ensuing cold, usually appear.

end

Acute period

STAGES OF DISEASE 3 • The progression of clinical symptoms for an acute infectious disease can be divided into stages, and the terms used to describe these stages are also part of the epidemiologist’s lexicon: ______: Disease signs and symptoms subside. As fever subsides, usually following a period of intense ______, a feeling of well-being develops. The decline period may be ______ (within one day), in which case decline occurs by ______, or it may be ______, extending over several days, in which case decline occurs by ______.

Decline period, sweating, rapid, crisis, slower, lysis

Convalescent period

STAGES OF DISEASE 3 • After the ______, the immune mechanisms of the host become increasingly important for complete recovery from the disease.

acute period

______ is the incidence of death in a population.

Mortality

______ diseases were the major causes of death worldwide in 1900, but they are now less prevalent in developed countries.

Infectious

______ “______” diseases such as ______ disease and ______ are now much more prevalent in developed regions and cause higher mortality than do infectious diseases. However, this could change rapidly if ______ measures were to break down.

Noninfectious, lifestyle, heart, cancer, public health

Worldwide, and especially in developing countries, ______ diseases are still major causes of mortality.

infectious

______ is the incidence of disease in a population and includes both fatal and nonfatal diseases.

Morbidity

______ statistics indicate the public health of a population more precisely than ______ statistics because many diseases have relatively low mortality. Put another way, the major causes of ______ are quite different from the major causes of ______.

Morbidity, mortality, illness, death

MORTALITY, MORBIDITY & DALY For example, high-morbidity infectious diseases include acute respiratory diseases such as the common cold and acute digestive disorders. However, seldom do these diseases cause death in populations living in developed countries. Thus, both of these diseases have ______ morbidity, but ______ mortality.

high, low

MORTALITY, MORBIDITY & DALY On the other hand, Ebola virus infects relatively few people worldwide every year, but the mortality in some outbreaks approaches 70% and averaged 40% in the West African Ebola outbreak of 2013–2015. Thus, Ebola has ______ morbidity, but ______ mortality.

low, high

Epidemiologists tend to focus on ______ and ______ statistics as a means of ranking the severity of pathogens and tracking disease trends. However, illness and death are not the only outcomes of an infectious disease. Lost among these statistics is the reduction in ______ and ______ due to a disease.

morbidity, mortality, life quality, productivity

The ______ is a quantitative measure of disease burden and is defined as the cumulative number of years lost due to an illness itself, a disability due to an illness (whether an infectious disease or not), or premature death.

disability-adjusted life year (DALY)

MORTALITY, MORBIDITY & DALY • The leading causes of ______ are not the leading causes of ______; about one-third of all disability years lost are due to ______ and ______ conditions. • But many infectious diseases cause ______ disability and thus such data are important measures of the overall burden of disease. • This is especially true of a series of neglected ______ diseases, a group of infectious diseases found mainly in tropical countries that are major ______ rather than ______. • These include in particular ______ infections such as ______, ______, and ______. • Hundreds of millions of people suffer from these infections world- wide, and although some ______, most do not.

death, disability, psychiatric, neurological chronic tropical, disablers, killers parasitic worm, hookworm, filariases, schistosomiasis die

MORTALITY, MORBIDITY & DALY • However, life quality and longevity of survivors is oftentimes greatly diminished, and ______ numbers attempt to quantify this often overlooked but nevertheless important aspect of epidemiological statistics. • With some of the epidemiologist’s common lingo in mind, we are now able to move on to consider how infectious diseases spread (or do not spread) in ______ populations.

DALY susceptible

THE HOST COMMUNITY The colonization of a susceptible host population by a pathogen may lead to ______, ______, and an ______.

explosive infections, transmission to uninfected hosts, epidemic

THE HOST COMMUNITY As the host population develops resistance, however, the ______ of the pathogen is checked, and eventually a ______ is reached in which host and pathogen populations reach a state of ______.

spread, balance, equilibrium

THE HOST COMMUNITY In an extreme case, failure to reach equilibrium could result in ______ and eventual ______ of the ______ species.

death, extinction, host

THE HOST COMMUNITY If the pathogen has no other host, then the extinction of the host also results in extinction of the ______.

pathogen

THE HOST COMMUNITY The evolutionary success of a pathogen thus depends on its ability to establish an ______ with its ______ rather than destroy the host population altogether.

equilibrium, host

THE HOST COMMUNITY In most cases, the evolution of the ______ and the ______ affect one another; that is, the host and pathogen ______.

host, pathogen, coevolve

COEVOLUTION OF A HOST & A PATHOGEN 1 • A classic example of host and pathogen coevolution is a case where ______ was intentionally introduced to control an exploding wild ______ population in Australia. • The virus, spread by the bite of ______ and also from animal to animal by ______, is extremely ______ for rabbits and causes fatal infections in susceptible animals. • Within several ______, the infection had spread over a large area, rising to peak incidence in the ______ when the mosquito vectors were present, and then declining in the ______ as mosquitoes disappeared. • In this experiment, over ______% of the infected rabbits died during the first year, but within six years, wild rabbit mortality dropped to about ______%, indicating that the resistance of the wild rabbit population had ______ dramatically.

myxoma virus, rabbit, mosquitoes, direct contact, virulent months, summer, winter 95, 30, increased

COEVOLUTION OF A HOST & A PATHOGEN 2 • When virus isolated from these wild rabbits was used to infect ______ rabbits that had not previously been exposed to the virus, the virus could be seen to have lost ______ over the ______ period. • This was further confirmed by the resistance observed in ______ wild rabbits exposed to the virus. • Within three years, mortality of wild rabbits ______ by over ______% and maintained this ______ at a ______ level. • Thus, within just a few years, the rabbit population had evolved to reach an ______ with the ______.

laboratory, virulence, six-year newborn decreased, 80, resistance, constant equilibrium, pathogen

COEVOLUTION OF A HOST & A PATHOGEN 3 • For pathogens that do not exhibit host-to-host transmission, there is no selection for ______ to support ______, as was seen in the rabbit myxoma virus experiment. • An example of this is ______, a common soil bacterium that causes tetanus when accidently introduced into flesh through a penetrating wound. • ______ pathogens transmitted solely by the bite of ticks or other arthropods, such as in spotted fever ______ (______), are also under no evolutionary pressure to spare the human host. • As long as the vector is only a ______ of the pathogen and does not contract the disease itself, there is no selection for ______ of the pathogen and thus the pathogen can maintain a high level of ______.

decreased virulence, mutual coexistence Clostridium tetani Vector-borne, rickettsiosis, Rocky Mountain spotted fever carrier, weakened strains, virulence

HERD IMMUNITY • Spread of an infectious disease through a highly susceptible population is typically much different than through a population where many, or even just some, potential hosts are ______, either from a previous ______ with the same pathogen or by artificial means through ______.

immune, natural infection, vaccination

If a high enough proportion of the individuals in a population are immune to a pathogen, then the whole population can be protected, resulting in a collective level of resistance to infection called ______.

herd immunity

HERD IMMUNITY • The concept of herd immunity is easy to understand. In essence, what herd immunity amounts to is a breakage in the chain of ______ from one susceptible host to another because most hosts in the population are ______.

pathogen transmission, immune

HERD IMMUNITY • Herd immunity is not a ______ number, and the assessment of herd immunity is important for understanding the development of ______.

fixed, epidemics

HERD IMMUNITY • The more highly ______ a pathogen, or the ______ its period of ______, the ______ the proportion of immune individuals necessary to prevent epidemic disease spread.

infectious, longer, infectivity, greater

HERD IMMUNITY • For a highly infectious disease such as measles, ______–______% of the population must be immune to confer herd immunity.

90, 95,

HERD IMMUNITY • By contrast, a ______ proportion of immune individuals can prevent an epidemic of a less infectious agent or one with only a brief period of infectivity. • ______, which is less infectious than measles virus, exhibits this pattern. In the absence of immunity, even poorly infectious agents can be transmitted from person to person if susceptible hosts have ______ or ______ contact with an infected individual. • This is the case for the transmission of ______ among humans.

lower, Mumps virus, repeated, constant, H5N1 avian influenza

INFECTIOUS DISEASE TRANSMISSION & RESERVOIR • Epidemiologists follow the transmission of a disease by correlating ______, ______, ______, and ______ data with disease incidence. • Epidemiologists group infectious diseases by their ______.

geographic, climatic, social, demographic, mode of transmission

MODES OF DISEASE TRANSMISSION • Three major modes of infectious disease transmission are known and are summarized in Table 29.2. • These include diseases transmitted from ______; diseases transmitted by some ______ or ______, called a ______; and diseases transmitted by ______, that is, other organisms, especially those that access the ______, such as ticks and biting insects.

person to person, inanimate object, substance, vehicle, vectors, bloodstream

MODES OF DISEASE TRANSMISSION Each mechanism has three stages in common:

(1) escape from the host or reservoir, (2) travel, and (3) entry into a new host

MODES OF DISEASE TRANSMISSION • ______ disease transmission occurs when an infected host transmits a disease directly to a susceptible host without the assistance of an intermediate host or inanimate object.

Person-to-person

MODES OF DISEASE TRANSMISSION • Upper respiratory infections such as the ______ and ______ are most often transmitted person to person by droplets resulting from ______ or ______. • Many of these droplets, however, do not remain ______ for long, and so transmission requires ______, although not necessarily intimate, person-to-person contact.

common cold, influenza, sneezing, coughing airborne, close

MODES OF DISEASE TRANSMISSION • Some pathogens are extremely sensitive to environmental factors such as ______ and ______ and are unable to survive for significant periods of time away from the host. • These pathogens, transmitted only by intimate ______ contact such as exchange of ______ in ______, include those responsible for sexually transmitted diseases including ______ (______), ______ (______), and ______/______ (______; ______).

drying, heat person-to-person, body fluids, sexual intercourse, syphilis, Treponema pallidum, gonorrhea, Neisseria gonorrhoeae, HIV, AIDS, human immunodeficiency virus, acquired immunodeficiency syndrome

MODES OF DISEASE TRANSMISSION • Direct person-to-person contact is also how pathogens such as ______ (boils and pimples) and ______ (ringworm) are transmitted. • Some of these pathogens (______ is a good example) can spread by ______ transmission as well because when inoculated into a vehicle such as food, they grow ______ and produce ______.

staphylococci, fungi Staphylococcus aureus, vehicle, rapidly, poisonous toxins

MODES OF DISEASE TRANSMISSION • A marked ______ or ______ of a disease often signals a particular mode of transmission. • For example, ______ occurs in an annual cyclic pattern, causing epidemics propagated among schoolchildren and other populations of susceptible individuals.

seasonality, periodicity human influenza

MODES OF DISEASE TRANSMISSION • Cases of ______ are often high in schools or crowded offices because the virus is transmitted person to person by the ______; peak incidence occurs in ______ and early ______ when schools are in session and people are indoors much of the day.

influenza, respiratory route, midwinter, spring

MODES OF DISEASE TRANSMISSION • However, seasonality can also result from environmental factors such as ______ that influence the survival of the pathogen or its vector. • For example, ______—a viral disease transmitted by mosquitoes—shows a pattern opposite that of ______; the disease peaks during the ______ and ______ months but disappears in the ______, coinciding with the activity of its mosquito vector.

weather patterns California encephalitis, influenza, summer, fall, winter

MODES OF DISEASE TRANSMISSION • Diseases are often transmitted to humans by other ______ and by ______.

organisms, inanimate objects

MODES OF DISEASE TRANSMISSION • Living disease carriers are called ______, and ______ (______, ______, or ______) and ______ (______, ______, or ______) are common disease vectors.

vectors, arthropods, mites, ticks, fleas, vertebrates, dogs, cats, rodents

MODES OF DISEASE TRANSMISSION • ______ are often not definitive hosts for the pathogen but simply carry the pathogen from one host to another. • For instance, many arthropods obtain their nourishment by biting and sucking ______, and if the pathogen is present in the blood, the arthropod will ingest the pathogen and transmit it when ______ another individual. • In some cases viral pathogens multiply in the arthropod vector, which is then considered an ______. • Such is the case for ______ (in the ______) and the bacterium ______ (in the ______), the causative agent of ______ • Such replication leads to ______ pathogen abundance in the vector, and this ______ the probability that a subsequent bite will lead to infection.

Vectors blood, biting alternate host, West Nile virus, Culex mosquito, Yersinia pestis, rat flea, plague.S greater, increases

MODES OF DISEASE TRANSMISSION • ______ agents such as bedding, toys, books, and surgical instruments can also transmit disease.

Inanimate

MODES OF DISEASE TRANSMISSION • Inanimate objects that, when contaminated with a viable pathogen, can transfer the pathogen to a host are called ______.

fomites

MODES OF DISEASE TRANSMISSION • The term ______ is used to describe nonliving sources of pathogens that, upon entering the body, may transmit disease to large numbers of individuals; common disease vehicles are contaminated ______ or ______.

vehicle, food, water

MODES OF DISEASE TRANSMISSION • A key distinction here is that ______ are nonliving objects that are touched or handled by a limited number of individuals, whereas ______-source epidemics are typically traced to contaminated food or water—shared commodities consumed in large amounts by local or regional populations.

fomites, vehicle

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • As described earlier, a ______ is a pathogen-infected individual who has a subclinical infection and shows either no symptoms or only mild symptoms of the disease; ______ are thus potential sources of infection for others.

disease carrier, carriers

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • ______ may be in the incubation period of the disease, in which case the ______ state precedes the development of actual symptoms.

Carriers, carrier

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • Respiratory infections such as ______ and ______, for example, are often spread via carriers who are unaware of their infection and so are not taking any precautions against infecting others.

colds, influenza

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • The carrier state lasts only a short time for carriers who develop ______. • However, ______ usually appear healthy and may spread disease for extended periods of time. • Some examples here include carriers of ______, ______, ______, ______, and upper respiratory ______ infections

acute disease chronic carriers hepatitis B, typhoid fever, HIV/AIDS, tuberculosis, Staphylococcus aureus

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • ______ are sites at which infectious agents remain viable and from which individuals may become infected.

Disease reservoirs

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • Reservoirs may be either ______ or ______.

animate, inanimate

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • Some pathogens whose ______ are not in animals only incidentally infect humans and cause disease. • For example, some species of ______, common soil bacteria, occasionally infect humans, causing life-threatening diseases such as ______, ______, and ______. In these cases, the pathogen is not ______ on the host for survival, so ______ is not required.

reservoirs Clostridium, tetanus, botulism, gangrene, dependent, host–pathogen balance

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • For many pathogens (including many human pathogens) however, living organisms are the only ______. • In these cases, the ______ is essential for the life cycle of the infectious agent; maintenance of human pathogens of this kind requires ______ transmission. • Many viral and bacterial ______ pathogens and ______ transmitted pathogens fall into this category. When ______ are the main or only disease reservoir, infection control may be easy or not so easy. • With ______, for example, confirmed cases must be isolated and quarantined (Section 29.5). • However, for a disease like ______, where inapparent symptoms are common in females, tracking down and treating disease carriers can be difficult if not impossible.

reservoirs host, host-to-host respiratory, sexually, humans diphtheria gonorrhea

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • Some infectious diseases are caused by pathogens that reproduce in both ______ and ______.

humans, animals

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • A disease that primarily infects animals and is only occasionally transmitted to humans is called a ______; ______ is a good example. The ______ for rabies is wild mammals, primarily skunks, raccoons, foxes, and certain bats.

zoonosis, rabies, reservoir

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • Although person-to-person transmission of zoonoses is ______, control of zoonoses in humans is nearly ______ because of the frequent contact some humans have with wild animals and the fact that the animal reservoir can probably never be effectively ______.

rare, impossible, controlled

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • Certain other infectious diseases are caused by organisms such as ______ and ______ (______) that undergo complex life cycles including an obligate transfer from a nonhuman host to a human host back to the nonhuman host; the diseases ______ and ______ are good examples here.

protists, helminths, parasitic worms, malaria, schistosomiasis

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • In the case of malaria, the major reservoir other than humans is the mosquito ______, and some control of the disease can be achieved by ______ or ______ controls on the insect reservoir.

Anopheles gambiae, chemical, physical

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • In ______, by contrast, the reservoir is an aquatic snail and therefore although treatments for the disease are possible, ______ the reservoir is not an option.

schistosomiasis, eliminating

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • Major epidemics are usually classified as either ______ epidemics or ______ epidemics • The patterns of disease incidence observed in these two types of epidemics are contrasted in Figure 29.6.

common-source, host-to-host

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • A ______ results from an infection (or intoxication) of a large number of people from a contaminated source such as food or water that all infected individuals have ingested. • Such epidemics are often caused by a breakdown in the sanitation of a central ______ or ______ distribution system, but they can also be more local suchas the contaminated foodi the freezerrestaurant.

common-source epidemic, food, water

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • Foodborne and waterborne common-source epidemics are primarily ______ diseases; the pathogen leaves the body in ______ material, contaminates food or water supplies as a result of improper sanitation, and then enters the ______ tract of the recipient during ______ of the food.

intestinal, fecal, intestinal, ingestion

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • ______ disease outbreaks are characterized by a rapid rise to a peak incidence because a large number of individuals become ill within a relatively brief period of time.

Common-source

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • Moreover, assuming that epidemiological surveillance quickly identifies the disease vehicle, cases of a ______ disease declines fairly rapidly, as well.

common-source

DISEASE CARRIERS & DISEASE RESERVOOIRS & CONTROL • ______ is the classic example of a common-source epidemic as the disease is almost exclusively waterborne; if a sanitation breakdown occurs (or if sanitation is totally lacking, as is often the case in developing countries), the cholera bacterium can be shed from a carrier or an active infection into a water source used by many other people and quickly trigger an epidemic.

Cholera

BASIC REPRODUCTION NUMBER • In contrast to the common-source disease pattern, in a ______ epidemic the disease incidence shows a relatively slow, progressive rise and a gradual decline. • Cases continue to be reported over a period of time equivalent to several ______ periods of the disease.

host-to-host incubation

BASIC REPRODUCTION NUMBER • A ______ epidemic can be initiated by the introduction of a single infected individual into a susceptible population, with this individual infecting one or more people depending on the extent of herd immunity in that population.

host-to-host

BASIC REPRODUCTION NUMBER • In a ______ epidemic, the pathogen replicates in susceptible individuals, reaches a communicable stage, is transferred to other susceptible individuals, and again replicates and becomes communicable; such epidemics are often controlled by effective ______ due to previous infection or vaccination.

host-to-host, herd immunity

BASIC REPRODUCTION NUMBER • ______ and ______ are examples of diseases that can spread in host-to-host epidemics.

Influenza, chicken pox

BASIC REPRODUCTION NUMBER • The infectivity of a pathogen can be predicted using mathematical models that estimate the ______ (______) that the pathogen may trigger.

basic reproduction number, R0

BASIC REPRODUCTION NUMBER • The ______ is defined as the number of expected secondary transmissions from each single case of a disease in an entirely susceptible population, and Table 29.3 lists the R0 of selected infectious diseases.

BASIC REPRODUCTION NUMBER • R0 directly correlates with the ______ necessary to prevent spread of infection; the ______ the R0 value, the ______ the herd immunity required to stop infection.

herd immunity, higher, greater

BASIC REPRODUCTION NUMBER • Unfortunately, conditions are not always ______ and the mathematical models that predict R0 may not take into account such factors as numbers of recovered individuals, population density (close contact), length of contact time, populations of high-risk individuals, and other variables that may affect disease spread. As a result, R0 is a ______ construct and can only estimate ______.

ideal, theoretical, infectivity

BASIC REPRODUCTION NUMBER • Nevertheless, ______ is still useful as a gauge of the relative infectivity of a pathogen and helps to establish targets for immunization coverage to prevent spread of a particular infectious disease.

BASIC REPRODUCTION NUMBER • The ______, ______, calculated from studies of actual disease spread, is a more empirical term because it takes into account observed transmissions from infected to susceptible individuals.

observed reproduction number, R

BASIC REPRODUCTION NUMBER • Gathering the epidemiological data necessary to calculate an accurate ______ is often problematic, but for some diseases an ______ has been obtained.

R, empirical reproduction number

BASIC REPRODUCTION NUMBER • For example, or the ______ epidemic of 2003, the observed R was ______, matching its ______ value. • Public health officials, recognizing the potential for a serious epidemic, instiuted major infection controls including ______ of infected individuals and strict ______ protection for healthcare personnel. • These measures reduced the SARS R value to ______ and ended the threat of further disease spread.

SARS, 3.6, R0 isolation, barrier 0.7

______ refers to the health of the general population and to the activities of public health authorities in the control of disease.

Public health

The incidence and prevalence of many infectious diseases dropped dramatically during the ______, especially in developed countries, because of universal improvements in public health from advances in basic living conditions.

twentieth century

Access to safe ______ and ______, improved public ______, less ______ living conditions, and lighter ______ have all contributed immeasurably to disease control.

water, food, sewage treatment, crowded, workloads

Several historically important diseases, including ______, ______, ______, ______, and ______, have been controlled (and in the case of smallpox, even eliminated) by active, disease-specific public health measures.

smallpox, typhoid fever, diphtheria, brucellosis, poliomyelitis

Controls Directed against Common Vehicles and Major Reservoirs • Common vehicles for pathogen dispersal include ______, ______, and ______.

food, water, air

Controls Directed against Common Vehicles and Major Reservoirs • The control of ______ and ______ pathogens has seen the greatest successes through improved methods of preventing microbial contamination of food and water. • For example, water purification methods have dramatically reduced the incidence of ______, and laws controlling food purity, preparation, and storage coupled with strict monitoring of the food and water distribution network have greatly decreased the incidence of ______ disease.

foodborne, waterborne typhoid fever, common-source

Controls Directed against Common Vehicles and Major Reservoirs • However, in contrast to food and water, controlling transmission of ______ (______) pathogens is much more difficult. • Other than wearing personal protection such as face masks and avoiding individuals you know are infected, few effective measures of ______ control are possible except in specialized environments such as hospital operating rooms where chemical and physical agents can treat the rather small amount of circulating air.

respiratory, airborne airborne infection

Controls Directed against Common Vehicles and Major Reservoirs • When the disease reservoir is primarily ______ animals, infection of humans can be prevented if the disease is eliminated from the infected animal population by vaccinating herds and removing diseased individuals. • However, as we have seen, when the disease reservoir is a ______ animal, eradication is much more difficult. • Eradication of ______, for example, would require the immunization or destruction of all wild animal reservoirs, a virtually impossible task.

domestic wild rabies

Controls Directed against Common Vehicles and Major Reservoirs • When insect vectors are involved, effecive control can often be accomplished with ______. • However, the use of chemicals must be balanced with health and environmental concerns because in some cases, the elimination of one public health problem (the ______) simply creates another (______).

insecticides disease vector, toxic chemical exposure

Vehicles and Major Reservoirs • When humans are the disease reservoir—as, for example, in ______—______ and ______ can be difficult, especially, as mentioned previously in reference to gonorrhea, if there are asymptomatic carriers. • By contrast, certain diseases that are limited to humans and have no asymptomatic phase can be prevented through ______ or treatment with ______ or other drugs. • However, the disease can be eradicated only if those who have contracted the disease and all possible contacts are ______, ______, or if necessary, ______. • Such a strategy was successfully employed by the ______ to eradicate ______ worldwide and is currently being used to eradicate ______.

HIV/ AIDS, control, eradication immunization, antimicrobial immunized, treated, quarantined World Health Organization, smallpox, polio

IMMUNIZATION • Smallpox, diphtheria, tetanus, pertussis (whooping cough), measles, mumps, rubella, and poliomyelitis have been controlled primarily by ______.

immunization

IMMUNIZATION • ______, for example, is no longer considered even endemic in the United States.

Diphtheria

IMMUNIZATION • ______ are routinely administered in childhood for a number of other infectious diseases.

Vaccines

IMMUNIZATION • As we discussed in Section 29.4, ______% immunization is not necessary for effective disease control in a population because of ______, although the percentage needed to ensure disease control varies with the infectivity and virulence of the pathogen.

100, herd immunity

IMMUNIZATION • ______ epidemics offer an example of the power of herd immunity.

Measles

IMMUNIZATION • The occasional resurgence of the highly contagious ______ virus (R0 = ______) emphasizes the importance of maintaining appropriate immunization levels for a given pathogen.

measles, 18

IMMUNIZATION • Until ______, the year an effective measles vaccine was licensed, nearly every child in the United States acquired measles through ______ infections, resulting in over ______ annual cases. • However, after introduction of the vaccine, the number of annual measles infections ______ rapidly. • Case numbers reached a low of ______ by 1983. • However, by 1990, the percentage of children immunized against measles fell to ______%, and the number of new cases rose to ______. • A concerted effort to increase measles immunization levels to above ______% (about that needed for effective ______) virtually eliminated measles in the United States.

1963, natural, 300,000 decreased 1497 70, 27,786 90, herd immunity

ISOLATION, QUARANTINE & SURVEILLANCE • ______ and ______ are effective public health measures.

Isolation, quarantine

______ is the separation of persons who have an infectious disease from those who are healthy.

Isolation

______ is the separation and restriction of well persons who may have been exposed to an infectious disease to see if they develop the disease.

Quarantine

ISOLATION, QUARANTINE & SURVEILLANCE • The ______ of isolation or quarantine for a given disease varies and is typically the longest period of ______ for that disease. • To be effective, these measures must prevent infected or potentially infected individuals from contacting ______ susceptible individuals.

length, communicability uninfected

ISOLATION, QUARANTINE & SURVEILLANCE • By international agreement, six infectious diseases require isolation and quarantine: ______, ______, ______, ______, ______, and ______. • Each is a very serious, particularly ______ disease.

smallpox, cholera, plague, yellow fever, typhoid fever, relapsing fever communicable

ISOLATION, QUARANTINE & SURVEILLANCE • Spread of certain other highly contagious diseases such as Ebola hemorrhagic fever, SARS, H5N1 influenza, and meningitis may also be subject to ______ or ______ as outbreaks emerge in particular regions.

quarantine, isolation

ISOLATION, QUARANTINE & SURVEILLANCE • As mentioned earlier, ______ is a major job of the epidemiologist. Table 29.4 lists the infectious diseases currently under surveillance (referred to as reportable diseases) in the United States. • The ______ is the agency of the United States Public Health Service that tracks disease trends reported by physicians and other health professionals, provides the latest disease information, and forms public policy regarding disease prevention.

disease surveillance Centers for Disease Control and Prevention (CDC)

ISOLATION, QUARANTINE & SURVEILLANCE • The ______ operates a number of infectious disease surveillance programs and also carries out surveillance of major noninfectious diseases, such as ______, ______, and ______.

CDC, cancers, heart disease, stroke

ISOLATION, QUARANTINE & SURVEILLANCE • The overall practical goal of ______ is to formulate and implement plans for diagnosis and treatment of infections.

disease surveillance

PATHOGEN ERADICATION • Concerted disease eradication programs can sometimes completely eradicate an infectious disease and such was the case with naturally occurring ______, eradicated worldwide in ______.

smallpox, 1980

PATHOGEN ERADICATION • ______ was a viral disease with a virus reservoir consisting solely of the individuals with acute smallpox infections, and transmission was exclusively person-to-person through direct contact.

Smallpox

PATHOGEN ERADICATION • Although smallpox cannot be ______ once acquired, ______ practices have been very effective.

treated, immunization

PATHOGEN ERADICATION • The World Health Organization (WHO) implemented a ______ eradication plan in 1967.

smallpox

PATHOGEN ERADICATION • Because of the success of previous vaccination programs, ______ had already been confined to endemic status in parts of Africa, the Middle East, and the Indian subcontinent. • WHO field health workers proceeded to ______ everyone in these areas they could locate with the goal of providing either direct or herd immunity to the entire population. • Each subsequent outbreak or suspected outbreak was targeted by WHO teams that quickly traveled to the ______, ______ individuals with active disease, and ______ all contacts. • To break the chain of possible infection, they then ______ everyone who had contact with the contacts, and this aggressive vaccination policy eventually eliminated smallpox.

smallpox vaccinate outbreak site, quarantined, vaccinated immunized

PATHOGEN ERADICATION • Several other communicable diseases are candidates for global ______.

eradication

PATHOGEN ERADICATION • ______, like smallpox a viral disease with a human-only reservoir, is on its way to elimination using the same vaccination strategy used against smallpox; in 2014, a total of only ______ cases of polio were reported worldwide.

Poliomyelitis, 359

PATHOGEN ERADICATION • Diseases caused by parasites have also been targeted, including ______ (by treating active cases and destroying the insect vector) and ______ (by treating drinking water to prevent transmission of ______, the Guinea helminth parasite).

Chagas disease, dracunculiasis, Dracunculus medinensis

PATHOGEN ERADICATION • Eradication of certain ______ diseases is also on the horizon. • For example, ______ is a candidate because the disease is found only in humans and is readily treatable with antibiotics.

bacterial syphilis

PATHOGEN ERADICATION • ______, caused by the bacterium ______, could also be eradicated worldwide by application of the strict immunization protocols that have virtually eliminated diphtheria from North America.

Diphtheria, Corynebacterium diphtheriae

GLOBAL HEALTH COMPARISONS • The ______ has divided the world into six geographic regions for the purpose of collecting and reporting health information such as causes of morbidity and mortality. • These geographic regions are ______, the ______ (______, the ______, ______, and ______), the ______, ______, ______, and the ______.

World Health Organization (WHO) Africa, Americas, North America, Caribbean, Central America, South America, eastern Mediterranean, Europe, Southeast Asia, western Pacific

GLOBAL HEALTH COMPARISONS • Here we compare ______ data from a relatively developed region, the ______, to those from a developing region, ______, to emphasize the fact that infectious diseases are still major causes of morbidity and mortality in many regions of the world.

mortality, Americas, Africa

GLOBAL HEALTH COMPARISONS • ______ statistics in developed and developing countries are significantly different, as illustrated by a comparison of data from the ______ and from ______ in 2008 when the worldwide population was nearly ______. • Worldwide, ______ million individuals died, giving a mortality rate of ______ deaths per 1000 inhabitants per year, and ______ million (______%) of these deaths were attributable to infectious diseases. • There were ______ million people in the Americas in 2008 and there were ______ million deaths, or ______ deaths per 1000 persons per year. • In Africa, there were ______ million people in 2008 and ______ million deaths, or ______ deaths per 1000 persons per year. • These statistics clearly show differences in overall mortality between ______ and ______ countries, but a comparative examination of the causes of mortality is even more instructive.

Mortality, Americas, Africa, 6.8 billion 60.8, 8.8, 15.8, 26 924, 5.6, 6.1 837, 14.1, 16.8 developed, developing

INFECTIOUS DISEASE IN THE AMERICAS & AFRICA • Figure 29.9 indicates that ______ diseases caused the most deaths in Africa, whereas in the Americas, ______ diseases such as ______ and ______ disease were the leading causes of mortality.

infectious, noninfectious, cancer, cardiovascular

INFECTIOUS DISEASE IN THE AMERICAS & AFRICA • In Africa, there were about ______ million deaths due to infectious diseases and the life expectancy was ______ years of age.

6.6, 54

INFECTIOUS DISEASE IN THE AMERICAS & AFRICA • The African death toll due to infectious diseases was ______% of the total deaths in the world. In stark contrast, only ______ died of infectious disease in the Americas and the life expectancy was ______ years of age.

10, 672,000, 76

INFECTIOUS DISEASE IN THE AMERICAS & AFRICA • In developed countries, the ______ life expectancy is a direct consequence of the reduction in ______ from infection over the last century, and most of these gains are due to the advances in public health. • By contrast, lack of resources in developing countries limits access to adequate sanitation, safe food and water, immunizations, healthcare, and medicines, leading to increases in ______ diseases and, as a consequence, to dramatically ______ life expectancy.

increased, death rates infectious, shorter

INFECTIOUS DISEASE IN THE AMERICAS & AFRICA • Data for ______ (the most recent year for which complete morbidity and mortality statistics have been compiled by the WHO) show little change in these trends. • That is, the majority of deaths in sub-Saharan Africa continue to be due to ______ diseases or to perinatal, maternal, and nutritional causes, whereas in developed countries, ______ diseases continue to lead the way, with ______-related health issues such as ______ and lack of ______ rapidly emerging.

2012 infectious, lifestyle, obesity, type 2 diabetes, mobility

TRAVEL TO ENDEMIC AREAS • The high ______ of disease in many parts of the world is a concern for people traveling to such areas. • However, travelers can be ______ against many of the diseases that are endemic in foreign countries.

incidence immunized

TRAVEL TO ENDEMIC AREAS • Specific recommendations for immunization for those traveling abroad are updated ______ and published by the U.S. ______.

biannually, Centers for Disease Control and Prevention (CDC)

TRAVEL TO ENDEMIC AREAS • For many countries, ______ certificates for yellow fever are required for entry from areas with endemic yellow fever. • These areas include much of equatorial ______ and ______. • Most other nonstandard immunizations such as those for ______ and ______ are recommended only for people who are expected to be at high risk, such as veterinary healthcare providers.

immunization South America, Africa rabies, plague

TRAVEL TO ENDEMIC AREAS • The ______ summarizes current information for the potential for infectious disease transmission throughout the world, including diseases for which currently there are no effective immunizations (for example, HIV/AIDS, malaria, Ebola hemorrhagic fever, dengue fever, amebiasis, encephalitis, and typhus).

CDC

TRAVEL TO ENDEMIC AREAS • Travelers should take precautions such as avoiding insect and animal ______, drinking only water that has been properly treated to kill all ______, eating properly stored and prepared food (and avoiding fresh ______ foods), and undergoing antibiotic and chemotherapeutic programs for ______ or for suspected exposures. • Although these precautions do not guarantee that one will remain disease- free, adhering to them greatly reduces the risk of ______.

bites, microorganisms, uncooked, prophylaxis infection

EMERGING & REEMERGING DISEASES • The worldwide distribution of diseases can change ______ and ______.

dramatically, rapidly

EMERGING & REEMERGING DISEASES • Alterations in the ______, the ______, or the ______ population contribute to the spread of new diseases, with potential for high morbidity and mortality.

pathogen, environment, host

EMERGING & REEMERGING DISEASES • Diseases that suddenly become prevalent are called ______ and are not limited to “new” diseases; they also include ______, diseases that were previously under control but suddenly appear as a new epidemic.

emerging diseases, reemerging diseases

EMERGING & REEMERGING DISEASES • Examples of global emerging and reemerging disease are shown in Figure 29.10, and select diseases with high potential for emergence or reemergence are described in Table 29.5. • Occasionally, new diseases emerge very unexpectedly and for totally unknown reasons; for example, an emerging infection due to the unusual bacterium ______ in ______ (USA) in 2016 posed a real medical mystery.

Elizabethkingia, Wisconsin

EMERGING & REEMERGING DISEASES • ______ epidemic diseases are not a new phenomenon.

Emerging

EMERGING & REEMERGING DISEASES • Among the diseases that rapidly and sometimes catastrophically emerged in the past are ______ (caused by the bacterium ______) and ______. • For example, in the Middle Ages, up to ______ of all humans were killed by the periodic ______ epidemics that swept Europe, Asia, and Africa.

plague, Yersinia pestis, influenza one-third, plague

EMERGING & REEMERGING DISEASES • ______ caused a devastating worldwide pandemic in 1918–1919, claiming up to ______ million lives, and the pandemic ______ that emerged in 2009 killed up to a ______ million people in its first year. In the 1980s, ______ and ______ emerged as new diseases, and health officials worldwide are paying particular attention to the potential for rapid emergence of pandemic influenza developing from ______.

Influenza, 100, H1N1 influenza virus, half, HIV/AIDS, Lyme disease, H5N1 avian influenza

EMERGING & REEMERGING DISEASES • More recently, isolation of patients and extra protections for their caregivers was practiced during the ______ epidemic to prevent spread of this extremely dangerous viral disease.

West African Ebola hemorrhagic fever

EMERGENCE FACTORS • Many factors play into the emergence of new pathogens including human ______ and ______, ______, ______, ______, and other factors.

demographics, behavior, economic development, transportation, public health breakdowns

EMERGENCE FACTORS • The trend for human populations to reside in urban rather than rural areas facilitates ______. • For example, the high density of human hosts in cities has facilitated transmission of ______, a serious viral disease spread by mosquitoes.

disease transmission dengue fever

EMERGENCE FACTORS • ______ infects nearly 400,000 people yearly, primarily in ______ regions of ______ and ______ countries including far southern reaches of the United States.

Dengue, urban, tropical, subtropical

EMERGENCE FACTORS • Human ______ in large population centers also contributes to disease spread. • For example, sexually promiscuous practices in population centers contribute to the spread of ______ and ______.

behavior hepatitis, HIV/AIDS

EMERGENCE FACTORS • ______ development and changes in ______ use also promote disease spread. • For example, ______, the most common vectorborne disease in the United States, is on the rise largely due to residential reforestation and related changes in land use patterns. • These activities increase ______ habitat and thus contact between Lyme-infected ______ and ______, consequently increasing disease incidence.

Economic, land Lyme disease deer, deer ticks, humans

EMERGENCE FACTORS • ______, ______, and ______ methods have become increasingly important for quality assurance and economy in the food industry. • However, these same factors have increased the potential for ______ disease epidemics when sanitation measures fail. For example, a single U.S. meat-processing plant spread ______ O157:H7 to people in ______ states in 2009. • The contaminated food source, ______, was recalled and the epidemic was eventually stopped, but not before several people died.

Transportation, bulk processing, central distribution common-source foodborne, Escherichia coli, eight ground beef

EMERGENCE FACTORS • International ______ and ______ also affect the spread of pathogens. • For example, a single person showing symptoms from an Ebola infection on an international flight could infect many other passengers because of the ease with which the Ebola virus ______ ( Section 30.12). • If such a situation were not immediately recognized, the disease could rapidly spread to major ______ when healthy passengers who had contact with the diseased passenger and were now carrying the virus disembarked and continued their travels.

travel, commerce spreads population centers

EMERGENCE FACTORS • ______ and ______ can contribute to disease emergence. • For example, most RNA viruses, including ______, ______, and the ______ viruses, ______ rapidly. • These mutant RNA viruses present major epidemiological problems because their altered ______ often affect their ______, making ______ to old viral antigens ineffective for neutralizing the mutant viruses.

Pathogen adaptation, change influenza, HIV, hemorrhagic fever, mutate genomes, antigens, immunity

EMERGENCE FACTORS • ______ genetic mechanisms are also capable of enhancing virulence and promoting emergence of new epidemics.

Bacterial

EMERGENCE FACTORS • ______ are often carried by mobile genetic elements that can be transferred between and among members of the same species, and sometimes to other species and genera. • Such transfers can quickly generate emerging ______, and ______-resistant strains of ______ and ______ are good examples of this.

Virulence-enhancing factors pathogens, multidrug, Staphylococcus aureus, Pseudomonas aeruginosa

EMERGENCE FACTORS • A breakdown of ______ measures is sometimes responsible for the emergence or reemergence of diseases. • For instance, ______ (caused by ______) can be adequately controlled, even in endemic areas, by providing proper sewage disposal and water treatment. • In 2010 contaminated water supplies following a major earthquake triggered a ______ outbreak in ______ for the first time in over ______ years.

public health cholera, Vibrio cholerae cholera, Haiti, 100

EMERGENCE FACTORS • Inadequate public ______ programs can also lead to the resurgence of previously controlled diseases. • For example, ______, a vaccine-preventable childhood respiratory disease, has increased recently in Eastern Europe and in the United States partly because of inadequate ______ among adults and children.

vaccination pertussis, immunization

EMERGENCE FACTORS • Finally, ______ patterns can also upset the usual host–pathogen balance.

weather

EMERGENCE FACTORS • Disease vectors such as ______ have been moving ______ in response to ______.

mosquitoes, northward, climate change

EMERGENCE FACTORS • Even a single seasonal weather abnormality can have an effect, as evidenced by the 1993 ______ outbreak in the American Southwest. • A very mild winter coupled with record rainfall led to an explosive increase in ______ that can host ______. • This increased exposures for susceptible human hosts and led to the spread of this ______ infection.

hantavirus hemorrhagic fever rodents, hantavirus zoonotic

ADDRESSING EMERGING DISEASES • The keys for addressing emerging diseases are recognition of the ______ and ______ to prevent pathogen ______.

disease, intervention, transmission

ADDRESSING EMERGING DISEASES • ______ diseases have, at least at first, low incidence and are usually absent from the official notifiable disease list for the United States prepared by the ______.

Emerging, Centers for Disease Control and Prevention

ADDRESSING EMERGING DISEASES • ______ diseases are first recognized from their unique epidemic incidence, clusterings, and other epidemiological patterns, and clinical symptoms unrelated to known pathogens. • Such disease patterns trigger intensive public health ______ followed by specific interventions designed to control further outbreaks.

Emerging surveillance

ADDRESSING EMERGING DISEASES • Methods such as ______, ______, ______, and ______ can be applied to contain outbreaks.

isolation, quarantine, immunization, drug treatment

ADDRESSING EMERGING DISEASES • For ______ and ______ diseases, the nonhuman host or vector must be identified to intervene in the life cycle of the pathogen and stop human infection.

vectorborne, zoonotic

ADDRESSING EMERGING DISEASES • International public health surveillance and intervention programs were instrumental in controlling the emergence of ______ (______), a disease that emerged rapidly, explosively, and unpredictably from a ______ source. • On the other hand, even a rapid and focused response was unsuccessful in containing the spread of pandemic (______) 2009 ______, as we will see in the next section.

severe acute respiratory syndrome, SARS, zoonotic H1N1, influenza

______ is a continuum of disease, starting with the infection of an individual with the human immunodeficiency virus (HIV). Eventually, infection results in ______ (______), a disease which if not treated cripples the immune system, leading to opportunistic infections that can be fatal.

HIV/AIDS, acquired immunodeficiency syndrome, AIDS

HIV/AIDS • The first reported cases of AIDS were diagnosed in the ______ in ______. • Since then, more than ______ million cases have been reported in the United States with over ______ deaths; worldwide, over ______ million AIDS deaths have occurred.

United States, 1981 1.2, 635,000, 25

HIV/AIDS • Epidemiological studies in the United States in the 1980s suggested a high AIDS prevalence among men who have ______ with men and among intravenous ______ abusers. Individuals receiving ______ or blood products were also at high risk. • Collectively, these epidemiological data indicated a ______, presumably transferred during ______ activity or by contaminated ______.

sex, drug, blood transmissible agent, sexual, blood

HIV/AIDS • Soon after the discovery of HIV in ______, laboratory tests were developed to detect ______ to the virus in blood. • With this tool in hand, surveys of HIV incidence and prevalence defined the spread of HIV and showed conclusively that body ______, primarily ______ and ______, were the vehicles for transmission of the virus.

1983, anti-bodies fluids, blood, semen

HIV/AIDS • The HIV/AIDS data showed that in the United States, the number of AIDS cases was ______ high in men who have ______ with men, but among women, ______ were the largest risk group.

disproportionately, sex, heterosexuals

HIV/AIDS • Further analyses of the epidemiological data showed that the new infection rate for African American men was ______ times that of ______ males, indicating that social and economic factors may also influence infection risk.

seven, Caucasian

HIV/AIDS • However, regardless of gender or racial specifics, AIDS epidemiology provided a clear picture of HIV ______: Virtually all who acquired HIV engaged in ______ or ______ drug use in which body fluids—______ or ______—were transferred and commonly had ______ or exchanged ______ with multiple partners.

transmission, sex, intravenous, semen, blood, sex, syringe needles

______ is primarily a waterborne infection that is normally kept in check by appropriate public health measures for water treatment.

Cholera

CHOLERA • ______ is caused by ingestion of contaminated water containing ______, a gram-negative, curved rod–shaped species of ______ that produces a powerful enterotoxin that triggers severe diarrhea.

Cholera, Vibrio cholerae, Proteobacteria

CHOLERA • ______ is endemic in Africa, Southeast Asia, the Indian subcontinent, and Central and South America. Epidemic cholera occurs frequently in areas where ______ is either inadequate, altogether absent, or suffers a major breakdown, for example, from a ______ or an ______.

Cholera, sewage treatment, flood, earthquake

CHOLERA • In 2014, the World Health Organization (WHO) reported over ______ cases of cholera that led to ______ deaths. • However, the WHO estimates that only ______–______% of cholera cases are actually reported because diarrheal diseases from various pathogens are so common (Table 29.1); thus total worldwide incidence of cholera likely exceeds ______ million cases per year.

190,000, 2231 5, 10, 1

CHOLERA • Epidemic cholera may develop into ______ when travelers from endemic areas carry the pathogen to new locations with susceptible populations and poor sanitation.

pandemics

CHOLERA • Since 1817, ______ has swept the world in ______ major, and nearly consecutive, pandemics. • All but one of these originated on the ______ sub-continent, where cholera is endemic.

cholera, seven Indian

CHOLERA • Two distinct pandemic strains of V. cholerae are recognized, known as the ______ and the ______ biotypes.

classic, El Tor

CHOLERA • The V. cholerae O1 ______ biotype started the seventh pandemic in ______ in ______, and its spread continues to the present day. • This pandemic has caused over ______ million cases of cholera and at least ______ deaths and continues to be a major cause of morbidity and mortality, especially in developing countries.

El Tor, Indonesia, 1961 5, 250,000

CHOLERA • In October 2010 ______ experienced its first cholera in over ______ years, and in just two years experienced nearly ______ cases and ______ deaths. • The outbreak began in the aftermath of the catastrophic 2010 ______. • There were likely two triggers of this cholera outbreak, the first being a classic scenario of poor ______ following a disaster and the second an accidental ______ from an outside source. • ______ is present in marine waters and as a result of the earthquake, it may have been washed into coastal freshwaters where it contaminated drinking water sources.

Haiti, 100, 600,000, 8000 earthquake sanitation, importation Vibrio cholerae

CHOLERA • But in addition, ______ aid workers that arrived from Nepal, where a recent cholera outbreak had occurred, are thought to have shed ______ into sanitation streams that found their way into Haitian drinking water sources; if true, this would have contributed to the Haitian epidemic. • ______ has since spread from Haiti to the Dominican Republic and other areas of the Caribbean, and to Mexico.

United Nations, V. cholerae Cholera

Pandemic (H1N1) 2009 and Future Influenza Pandemics • Human ______ pandemics occur every ______ to ______ years as a result of major genetic changes in the ______ virus genome that affect the virus’s immune status (______ and ______).

influenza, 10, 40, influenza A, antigenic drift, antigenic shift

Pandemic (H1N1) 2009 and Future Influenza Pandemics • The most devastating influenza pandemic of all time occurred in ______; this flu infected over half a ______ people worldwide and killed approximately ______ million people before it ran its course.

1918, billion, 50

Pandemic (H1N1) 2009 and Future Influenza Pandemics • The 1918 pandemic was caused by a strain of influenza termed ______.

H1N1

Pandemic (H1N1) 2009 and Future Influenza Pandemics • A more recent influenza pandemic began in March ______ with the outbreak of epidemics in Mexico. • The culprit virus, a strain designated ______, was a hybrid of the 1918 strain and a later strain that caused a pandemic in 1957; ______ contained genes from bird, swine, and human influenza viruses. • Such ______ viruses, as they are called, can be highly ______, as they tend to produce ______ to which humans have no prior exposure and thus no immunity; the only way to obtain immunity to such a virus is to become ______ or artificially ______.

2009 (H1N1) 2009, (H1N1) 2009 reassortant, virulent, antigens, infected, immunized

Pandemic (H1N1) 2009 and Future Influenza Pandemics • Without an effective ______ at the ready and with the rapidity with which influenza is spread, the stage was set for the reassortant ______ flu to reach pandemic proportions. • Within ______ months of its emergence, (H1N1) 2009 had spread to almost every country in the world, qualifying it as a true ______. • Although official numbers range widely, it is estimated that more than a ______ of the world’s population was infected in the pandemic.

vaccine, (H1N1) 2009 six, pandemic quarter

Pandemic (H1N1) 2009 and Future Influenza Pandemics • In the United States, about ______ million persons were infected, with mortality confirmed as due to (H1N1) 2009 numbering about ______ persons. By late 2010 the (H1N1) 2009 pandemic was fading, and today few cases are observed because antigens from this strain of virus are typically included in seasonal influenza ______.

60, 3400, vaccines

Pandemic (H1N1) 2009 and Future Influenza Pandemics • Could new influenza pandemics sweep the world? Perhaps the greatest threat to global stability would be another influenza pandemic that has the virulence and infectivity of the ______ pandemic. • Because epidemiological ______ is currently so extensive, this possibility is unlikely, but the risk can never be zero. In recent years public health officials worldwide have been following the emergence and reemergence of a potentially devastating strain of influenza virus designated influenza A ______, originally found in birds. • This virus first appeared in ______ in ______, jumping directly from chickens and ducks to humans.

1918 surveillance, H5N1 Hong Kong, 1997

Pandemic (H1N1) 2009 and Future Influenza Pandemics • Since then ______ has reemerged several times in small outbreaks, with the most recent occurring in Egypt, Indonesia, Cambodia, Bangladesh, and China.

H5N1

Pandemic (H1N1) 2009 and Future Influenza Pandemics • Through 2014, 638 cases of human ______ infection have been confirmed, resulting in ______ deaths, for a mortality rate of almost ______%. This high mortality rate underscores the dangerous aspects of this virus.

H5N1, 379, 60

Pandemic (H1N1) 2009 and Future Influenza Pandemics • Besides poultry and humans, ______ has also infected swine. • If a reassortant strain were to emerge from ______ that had the capacity to spread from person to person, such a virus could trigger an influenza ______ of unprecedented ______. • Because of this, plans are in place ______ and ______ to provide appropriate vaccines and support for potential pandemics initiated by this and other emergent influenza strains.

H5N1 pigs, pandemic, mortality nationally, internationally

PUBLIC HEALTH THREATS FROM MICROBIAL WEAPONS • As if avoiding the wrath of pathogenic microbes that can infect us naturally is not enough, humans have researched the use of certain pathogens as ______ to be ______ deployed on others.

weapons, intentionally

PUBLIC HEALTH THREATS FROM MICROBIAL WEAPONS • ______ is the use of microbial agents to incapacitate or kill a military or civilian population in an act of war or terrorism.

Biological (microbial) warfare

PUBLIC HEALTH THREATS FROM MICROBIAL WEAPONS • Although the use and development of ______ are forbidden by ______ law, microbial weapons have already seen use, and facilities for their production likely exist in ______ countries and perhaps also in avowed ______ groups. • Because of this, microbial weapons research continues in many peaceful nations so as to best understand the most serious threats and learn how to ______ them.

microbial weapons, international, rogue, terrorist counter

Characteristics of Microbial Weapons • Effective microbial weapons are pathogens, or in a few cases toxins, that are:

(1) relatively easy to produce and deliver, (2) safe for use by the offensive forces, and (3) able to incapacitate or kill people in a systematic and consistent manner.

Characteristics of Microbial Weapons • Although microbial weapons are potentially useful in the hands of conventional ______ forces, the greatest likelihood of microbial weapons use is by ______ because of the ready availability and low cost of producing and propagating many of the organisms.

military, terrorists

Characteristics of Microbial Weapons • Virtually all pathogenic ______ or ______ are potentially useful for biological warfare, and select agents that have significant potential for use as microbial weapons are listed in Table 29.6. • The most frequently mentioned candidates are ______ virus and ______, the bacterium that causes anthrax. • Both of these microbes can be easily ______, are ______ from person to person, and typically cause high ______. • Other agents have their advantages and disadvantages as microbial weapons and are categorized as to their potential risk from Category A to Category C in Table 29.6.

bacteria, viruses smallpox, Bacillus anthracis disseminated, transmissible, mortality

Characteristics of Microbial Weapons • The United States government, through the ______, has developed the ______ to monitor possession and use of potential bioterrorism agents.

Centers for Disease Control and Prevention, Select Agent Program surveillance system

Characteristics of Microbial Weapons • In addition, the ______ and the ______ have been upgraded to enhance their diagnostic capabilities and increase the reporting abilities of local and regional healthcare centers to rapidly identify bioterrorism events as well as emerging diseases.

CDC Laboratory Response Network, Health Alert Network

SMALLPOX & ANTHRAX • ______ virus has intimidating potential as a microbial weapon because it can be spread easily by ______ or by ______ spray, is highly ______, causes a high ______, severe ______, and the eventual formation of ______ skin blisters, and has a mortality rate of ______% or higher.

Smallpox, direct contact, aerosol, debilitating, fever, fatigue, pus-filled, 30

SMALLPOX & ANTHRAX • Although an extremely effective smallpox ______ is available, it has not been in use in the general population since smallpox was eradicated worldwide in ______.

vaccine, 1980

SMALLPOX & ANTHRAX • Moreover, the potential of smallpox virus being deployed as a military weapon is considered ______ because military personnel are routinely ______.

low, vaccinated

SMALLPOX & ANTHRAX • Nevertheless, preparations for a potential ______ attack on civilians in the United States have been made and would include ______ of key individuals such as those evaluating, caring for, or transporting smallpox patients; laboratory personnel handling clinical specimens from smallpox patients; and other persons as necessary who might come into contact with infectious materials from smallpox patients.

smallpox, immunization

SMALLPOX & ANTHRAX • ______ is the causative agent of anthrax, and its unique properties make it particularly attractive as a bioweapon. • Chief among these is that it is easily grown ______, producing distinctive ______ on ______ culture media, and it differentiates into highly resistant ______. • Once prepared, endospores can be ______ and stored indefinitely and then disseminated as a weapon by ______ or in ______ suspension.

Bacillus anthracis aerobically, colonies, enriched, endospores dried, aerosol, powdered

SMALLPOX & ANTHRAX • There are three clinical forms of anthrax:

Cutaneous anthrax gastrointestinal anthrax Inhalation anthrax (also called pulmonary anthrax)

SMALLPOX & ANTHRAX There are three clinical forms of anthrax. • ______ is contracted when abraded skin is contaminated by B. anthracis endospores; the organism grows and kills the skin, forming a necrotic tissue lesion called an ______.

Cutaneous anthrax, eschar

SMALLPOX & ANTHRAX There are three clinical forms of anthrax. • The most rare form—______—is contracted from consumption of endospore-contaminated plants or meat from animals infected with anthrax.

gastrointestinal anthrax

SMALLPOX & ANTHRAX There are three clinical forms of anthrax. • ______ (also called ______) is the deadliest form and is contracted when B. anthracis endospores are inhaled.

Inhalation anthrax, pulmonary anthrax

SMALLPOX & ANTHRAX • The symptoms of inhalation anthrax include ______ and ______, which makes this form of anthrax so dangerous.

pulmonary, cerebral hemorrhage

SMALLPOX & ANTHRAX • All forms of anthrax have the potential to become ______ infections; however, ______ anthrax is easily treatable with antibiotics and is fatal in only about ______% of untreated cases.

systemic, cutaneous, 20

SMALLPOX & ANTHRAX • Without treatment, ______ anthrax is fatal in about half those infected, whereas inhalation anthrax mortality approaches ______%.

gastrointestinal, 100

SMALLPOX & ANTHRAX • ______ anthrax is the form of the disease that makers of microbial weapons would aim for, as has already transpired in the United States.

Inhalation

SMALLPOX & ANTHRAX • At least ______ cases of anthrax leading to ______ deaths occurred in a ______ bioterrorism attack where dense ______ endospore preparations were mailed in envelopes to certain news outlets and government officials. • Of the 22 anthrax cases, ______ were inhalational and ______ cutaneous. • These weaponized anthrax strains were endospore preparations mixed within a fine ______ material that allowed the endospores to be spread by ______ currents. • Thus, opening an envelope containing endospores or releasing the powder–endospore mixture into a ______ system or other ______ could contaminate surrounding areas and personnel.

22, 5, 2001, B. anthracis 11, 11 particulate, air ventilation, air exchange

SMALLPOX & ANTHRAX • Vaccination for ______ is possible and is restricted to individuals who are considered at risk. • This includes agricultural ______ workers (livestock tenders and those working with animal products), ______ personnel working with anthrax, ______, and ______ personnel.

anthrax, animal, laboratory, veterinarians, military

SMALLPOX & ANTHRAX • As was discussed with smallpox, ______ is an unlikely military weapon but could be a very effective means of terrorizing a civilian population because the vast majority of the population is ______.

anthrax, unvaccinated

EPIDEMIOLOGY Flashcards

(237 cards)