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Flashcards in Exam 3 Deck (89):
1

Define Septicemic plague

Rapid spread of Y. pestis throughout the body

2

Define Pneumonic plague

occurs when Y. pestis reaches the lungs

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Lyme disease is spread by

Primarily through deer ticks. Transmitted to humans when tick has a blood meal

4

Symptoms of Lyme

Headache, backache, chills, fatigue
75% of cases include rash at bite site

5

Three types of Anthrax

cutaneous, gastrointestinal, respiratory

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Cutaneous Anthrax

infection through cut or abrasion of skin

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Gastrintestinal Anthrax

Ingestion of endospores

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Respiratory Anthrax

Inhalation of endospores, fatal if enters the blood stream

9

Anthrax Exotoxin

A subunit- responsible for toxic effect (lethal and edema factors)
B subunit- binds to target cell (Protective antigen)

10

Botulism (3 types)

Foodborne- Toxin only
Infant-ingested produce exotoxin
Wound- similar to infant involves growing cell and and toxin

11

Treatment of Botulism

Repeated washing out of intestinal tract
Administration of BIG-IV

12

Cholera

Infects through consumption of contaminated water.
Has an exotoxin (enterotoxin) that interferes with mucosal cell ion pumps.

13

E.coli

commensal organism in human intestines that provides a number of benefits.

14

enteroaggressive E.coli

-forms clumps adhering to epithelial cells
-Form biofilm, hard to remove, persistent diarhea
-toxins have not been identified

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diffusely adhering E. coli

-adheres in a uniform pattern to epithelial cells
-particular problem in immunologically naïve or malnourished children

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enteropathogenic E. coli

adheres in a uniform pattern to epithelial cells
particular problem in immunologically naïve or malnourished children

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enteroinvasive E. coli

-multiplies within intestinal epithelial cells
-may produce a cytotoxin and an enterotoxin
-Bloody diarrhea-dysentary

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enterohemorrhagic E. coli

-Starts in the gut, attaches to mucosal cells
-releases shiga toxins that has hemolytic activity
-Destroys blood vessels-bloody diarrhea

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Heliobacter pylori

responsible for ulcers

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Epidemiology

occurrence, distribution, and determinants of health and disease in a population. Identify cause and factors that increase person's risks, natural history and characteristics, evaluate preventative measures and guide policy decisions, trace origin and mode of transmision

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Agent

infectious or noninfectious
one or a complex

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Host

the infected, factors that affect exposure and disease occurrence, age sex race ethnicity immune status drugs/alcohol

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environment

external factors that affect likelihood of disease occurrence weather, population density, geography

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Chronic and acute infections

chronic: host and pathogen survive- well adapted pathogen, symbiotic
Acute: pathogen can be a selective force, rapid and explosion of infections

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carrier

individuals infected without symptoms or with mild symptoms

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endemic and epidemic

endemic: constant@ low incidence
epidemic: high incidence in specific population
worldwide epidemic: pandemic

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four steps of infection

infection
incubation
acute
decline

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incidence, prevalence, infectivity, pathogenicity, virulence, morbidity, mortality

incidence: # of new cases in a period of time (Rate)
Prevalence: total # of new and existing cases in a population in a given time
infectivity: ability to cause disease % exposed who become ill
pathogenicity: ability to induce disease
virulence: severity of diesase % of fatality
morbidity: incidence of disease
mortality: incidence of death

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pneumonia

-lung inflammation (alveoli/bronchioles fill with fluid)
-caused by bacteria (most serious), viruses, fungi
-most common = Streptococcus Pneumoniae

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Pneumococcal pneumonia

Some virulence factors:
-secrete adhesin that allow them to attach to epithelial cells of pharynx
-Capsule-avirulent strains non-capsulated
-Pneumolysin-binds cholesterol in ciliated epithelial cells' membrane
=> causes transmembrane pores and lysis
=> interferes with digestion of bacteria intracellularly in phagosomes

31

Diphtheria

-severe respiratory disease that typically infects children
-caused by Corynebacterium diphtheriae (forms irregular rods)
-preventable/treatable

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Corynebacterium diphtheriae

-Spreads by airborne droplets via the respiratory route
-Previous infection/immunization provides resistance
-Pathogenic strains lysogenized by bacteriophage produce a powerful exotoxin that causes:
=>Tissue death
=>The appearance of the pseudomembrane in the patient's throat

33

AB exotoxins

composed of two subunits:
*A subunit – responsible for toxic effect (Lethal and edema factor)
*B subunit – binds to target cell (Protective antigen)

34

Diphtheria (Diagnosis, Prevention, Treatment)

Diagnosis => C. diptheriae must be isolated from throat
Prevention => Vaccine
Treatment => antibiotics, surgery (if necessary to remove pseudomembrane); Diphtheria antitoxin available for acute cases

35

Three major functions of specific (adaptive) immunity:

Recognize nonself
Respond to nonself (effector response)
Remember nonself (anamnestic response)

36

Modes of specific immunity

Humoral immunity: aka antibody mediated immunity, based on antibody activity

Cellular immunity: aka cell mediated immunity, based on specific T lymphocytes

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Antigens

Recognized as foreign
Invoke immune responses
Name comes from antibody generators

38

Antibody

Immunoglobulin
Glycoprotein made by activated B cells (plasma cells)
Serves as antigen receptor on B cell surface
Found in blood serum, tissue fluids, and mucosal surfaces of vertebrate animals
Can recognize and bind antigen that causes its production

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Consequences of antigen antibody binding

Precipitation
Opsonization
Neutralization
Complement fixation
Agglutination

40

Streptococcus pyogenes

Also called group A streptococci
Commonly found in low numbers in the upper respiratory tract of herby individuals
Infections of inner ear, mammary glands and skin
Causative agent of strep throat

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Impetigo

Contagious superficial skin infection

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Erysipelas

Acute streptococcal skin infection

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Scarlet fever

Certain group a streptococci strains carry a lysogenic bacteriophage that encodes exotoxins responsible for scarlet fever

If left untreated, it can lead to rheumatic fever

44

Rheumatic fever

Inflammations lead to damage of heart valves and muscle
Autoimmune where antigens of strep cross react with heart antigens
Heart failure and death possible

45

Acute glomerulonephritis

Inflammation of the glomeruli in the kidney
Edema and smoky or rust colored urine
Children more likely to develop post streptococcal glomerulonephritis

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S. Pyogenes virulence factors

M proteins interfering with opsonization and lysis
C5a peptidase
Hyaluronic acid capsule
Streptokinase
Pyrogenic toxins

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Staphylococcus

g+
S epidemis and aureus
Salt, heat, UV and desiccation resistant

48

MRSA

Treat with vancomycin

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Staphylococcus aureus virulence factors

Coagulase
Hyaluronidase
Lipase
B lactamase
Capsules
Protein A
Toxins- cytolytic, leukocidin, exfoliative, TSS

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S. Epidermis

Only has lipase and capsule
Increasing threat, nosocomial infections

51

Impetigo

Staph a invades through scratches, abrasions, cold sores or other wounds
Small, flattened red patches that appear on face and limbs
Oozing, pus filled vesicles on a red base
Vesicles break and form thick honey colored crust

52

Erysipelas

Impetigo can spread into surrounding lymph nodes
Pain and inflammation
Reddening of the skin on face, arms, or legs

Swollen local lymph nodes, pain, fever, chills, and leukocytosis are seen

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Foliculitis

Pimple, sty, furuncle, carbuncle
On surface, grow in follicle, spread to sebaceous gland
Can spread to hypodermis or neighboring hair follicles

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Staphylococcus scalded skin syndrome-SSSS

Reddening, wrinkling around skin
Usually around mouth and spreads over entire body
Within 2 days, outer epidermis peels off
Mortality rare
Mostly affects infants, children under 5, elderly and immuno compromised
Methicillin by IV

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Toxic shock syndrome

Manifests in healthy individuals
Caused by enterotoxin B release by staph A
Symptoms- high fever, low BP, malaise, stupor, coma
Red rash anywhere on body early in infection
Vomiting, diarrhea, renal failure, hepatic inflammation and others types of organ failure

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Necrotizing fasciitis

Flesh eating bacteria
Entered through skin wounds
Spreads fast alone muscle fascia
Group A streptococcus most common cause

57

Streptococcus agalactiae

Aka group B strep
Normal member of the vaginal microbiota in about 1/3 of women
Produces protective capsule that allows it to evade phagocytosis when it gets into blood
Causes neonatal bacteremia and pneumonia and is frequent cause of meningitis in newborns

58

Tuberculosis

Mycobacterium tuberculosis is transmitted by airborne droplets (aerosols); gram +

Symptoms: weakness, fatigue, weightloss, no appetite, chills, fever, chest pain, coughing up blood or sputum, chest pain, COUGH LASTS MORE THAN 3 WKS

59

Primary Infection with Tuberculosis

-usually immune response takes care of it, infection inapparent (surprise TB test!)
-Hypersensitizes the patient to the bacteria and alters the individual's response to subsequent exposures
-Hypersensitivity is measured by a diagnostic skin test (tuberculin test)

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Secondary Infection with Tuberculosis

chronic tuberculosis often results in a gradual spread of tubercular lesions in the lungs

61

Why is Tuberculosis difficult to treat?

slow growth (due to mycolic acid makes diffusion of nutrients into cell slow) and waxy cell coat; Only few antibiotics work and resistance is growing;Highly resistant strains developed in prisons and travel the world; hard to do correctly: DOTS

62

tuberculoid leprosy

non-progressive form of leprosy; in patients with strong cell mediated immunity => kills infected cells

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Leprosy (Hansen's disease)

caused by Mycobacterium leprae;

Transmission:
-Person to person
-inhalation of respiratory droplets
-breaks in the skin
-not very virulent
-passed only after years of intimate contact
-genetic component

64

Mycobacterium leprae

gram + bacillus, non-endospore forming, high G+C

Cell wall contains a large amount of mycolic acid
-results in slow growth
-protection from lysis after phagocytosis/growth within the phagolysosome
-resistance to gram staining, detergents, many common antimicrobial drugs, and desiccation

65

Meningitis

Inflammation of the meninges (membranes that line the central nervous system, especially the spinal cord and brain); can be caused by viral, bacterial (most serious), fungal and protist types

Circulation of cerebrospinal fluid can carry infective microbes throughout the cranial cavity and spinal column

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Neisseria meningitidis

Gram-negative, nonsporulating, obligately aerobic, oxidase-positive, encapsulated diplococcus

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Meningococcal meningitis

Often occurs in epidemics, typically affects older school-age children/young adults, transmission is typically via airborne routes, treatment is usually penicillin G, incidence has decreased due to widespread vaccination in susceptible populations

68

Rickettsias

small bacteria w/ strict intracellular existence in vertebrates; associated with bloodsucking arthropods; (1) typhus group, (2) spotted fever group, and (3) ehrlichiosis group; closely related to human mitochondria; contain minimal sets of genes

69

Typhus Group (Rickettsia)

Example: Rickettsia prowazekii
Transmitted by the body or head louse bite that gets contaminated with louse feces

Some Symptoms: Back pain, Delirium
High fever (40 °C or 104 °F), Joint pain, Low blood pressure, Photophobia (sensitivity to light), Rashes, Severe headaches, Severe muscle pains

70

Spotted fever group (Rickettsia)

Example: Rickettsia rickettsii
Transmitted by dog and wood ticks; Over 2000 people acquire the disease every year; Rickettsia grow in nucleus and cytoplasm

Symptoms include headache, fever, and rash

71

Ehrlichiosis group (Rickettsia)

Example: Ehrlichia chaffeensis
Emerging diseases are human granulocytic anaplasmosis (HGA) and human monocytic ehrlichiosis (HME), which are spread by tick bites

Flulike symptoms include fever, headache, malaise, and leukopenia or thrombocytopenia

72

Plague

caused by Yersinia pestis, a gram-negative organism;

initial spread by contact with flea-infested animals, followed by spread among people by airborne transmission (in body multiply in blood and lymph
survive and proliferate in phagocytic cells)

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What are the 3 ways the plague is spread?

1. the urban cycle and rat fleas
2. the sylvatic cycle (enzootic among rodents) and their fleas
3. by airborne transmission from an infected person leading to pneumonic plague

74

Plague pathogenesis

V and W antigens of cell wall inhibit phagocytosis

Murine toxin causes systemic shock, liver damage, and respiratory distress

Endotoxin is especially immunogenic

75

Evolutionary trade off between virulence and mode of transmission

need to be virulent enough to survive but not kill the host if it requires host to host transmission. If it does not require host to host transmission it can be very virulent

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herd immunity

resistance of a group to infection due to high immunity proportion of the group

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WWJD

Japan found that immunizing a high proportion of children would protect the community better than protecting other members.

78

Direct Host to host

individual transmits disease to another susceptible host (flu, common cold)

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Indirect host to host

Facilitated by a living or non living agent
living agents are called vectors
nonliving vectors are called fomites

80

2 classifications of major epidemics

Common source: contamination of water or food
Host to host: slow progressive rise and gradual decline not as acute

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Resevoirs

sites in which infectious agents remain viable and from which individuals can become infected

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zoonosis

any disease that generally infects animals but can transmit to humans (rabies)

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carriers

infected with no signs of disease but still infectious may be individuals still in the incubation period (typhoid mary is an example)

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Controls against reservoir

Immunization
Quarantine-restricts movement of an individual with an active infection
surveillance-observation, recognition, and reporting of disease

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Emergent and reemerging

-Diseases that suddenly become prevalent
-diseases that become prevalent after having been under control

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Emergence factors and addressing emergence

demographics and behavior
technology and industry
economic development and land use
international travel and commerce
microbial adaptation and change
breakdown of public health measures
abnormal occurrence
Addressing: recognition, intervention to prevent transmission, quarantine, immunization, drug treatment

87

Biological warfare and biological weapons

use of biological agents to kill a military or civilian population
Need to be easy to produce or deliver and be safe for use by offense (anthrax)

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bacillus anthracis 3 forms

a preferred agent for warfare and terrorism
endospores enhance ability to desseminate B anthracis in aerosols
1. cutaneous
2. gastrointestinal
3 pulmonary

89

Weaponized anthrax

particles are small and interspersed with fine particulates
vaccination available for people at risk
anthrax is treated with ciproflaxin