exam 1 Flashcards
changes brought about by Pasteur’s germ theoryni
antisepsis (the practice of using antiseptics to eliminate the microorganisms that cause disease) antibiotics immunization sanitation public health
impact of germ theory
reduced childhood mortality
life expectancy increased- elderly pop is 13% of US population
current top causes for dealth in US, and world wide threats
US:
1) Heart disease
2) cancer
3) stroke
4) pneumonia
worldwide: infections acocunt for 30-35% of all dealths
ex: TB infects 30% of world population
definiction of emerging infections
new, re-emerging or drug resistant infections whose incidence in humans has increased within the past two decades or whose incidence threatens to increase in the near future
factors leading to infectious disease emergence
- microbial adaptation and change
- human demographics and behavior
- international travel and commerce
- economic development and land use
- technology and industry
- breakdown of public health measures
- human susceptibility to infection
- climate and weather
- changing ecosystems
- poverty and social inequality
- war and famine
- lack of political will
- intent to harm
microbial adapatation and change mechanisms/reasons
a number of microbes utilize different genetic mechanisms
- genome sequencing shows lateral transfer is common
- high mutation rates in RNA viruses=rapid adaptation
- quick reproduction so rare mutations build up rapidly
antimicrobials for livestock growth enhancement and over prescription of antimicrobials by doctors for convenience
-evolve modifying enzymes and “drug pumps”
superbugs ex: streptococcus and penicillin staphylococcus and vancomycin tuberculosis and isoiazid malaria and choloroquinone
human demographics and behavior leading to emerging infections
-increases in human population
urbanization-more people in concentrated cities-often without adequate infrastructure
increases in the elderly population
increases in children in daycare, working women with kids= easy spread
fast paced lifestyles- which lead to increase in convenience items and more stress
high risk behavior- drug use and unprotected sex
international travel and commerce- easier and faster to travel the globe, transportation of products is rapid (fresh produce with diseases) and transport of livestock facilitates movements of viruses and arthropods (esp ticks)
increases in cruise ship travel
economic development and land use leading to emerging diseases
consumption of natural resources, deforestation and dam building
logging in the rainforest has exposed people to new viruses
new standing water from dam building, canalization and irrigation
reforestation in some parts of north american has caused the emergence of lyme disease in those arease
tech and industry relationship to emerging diseases
advances in technology are positive but medical technology has lead to people living longer but with weaker immune systems, blood tranfusions and organ transplants save lives but can cause infections
transportation technology- the ability to rapidly move people and goods
industrial changes- mass production of food so now we all get our water and food from same sources= easy to make many people sick from one source
industrial pollution increases incidence of TB
breakdown of public health worldwide and increase in emerging infectious diseases
world wide breakdown of public health measures like adequate sanitation, immunizations, tb control have increased EID
IMF and world bank reducing public sector investments led to nagative impacts such as immunization levels, nuitrition and medical supplies to drop
similar reduction in public health funding in US caused reduction in programs for disease prevention and surveillance
lack of diagnosis and treatment in many areas of the world
human susceptibility to infection
caused by:
impaired host immunity: AIDS and increases in the older population
genetic polymorphisms, malnutrition-host susceptibility is aggravated
climate and weather and emerging infectious diseases
global warming will continue to cause temps to increase
elevated rainfall
-is a breading habitat for mosquitos
-decreases in salinity can increase toxic bacteria
-increases vegitation increases rodents
-increase runoff into drinking reservoirs
hgiher ocean temps increase vibrio parahaemolyticus (Shellfish)
some soil pathogens are carried by dry dusty winds
changing ecosystems impact on infectious diseases
ecological changes can increase the risk of infection by altering human exposure or pathogen distribution
rainforest destruction- forests reduce while cropping increases humidity
urban development increases atmospheric particles and increases air temperatures
poverty and social inequality and EID
mortality from infectious diseases closely correlated with income- developing and former communist bloc communiites
factors: malnutrition, lack of clean water and sanitation, poor housing, ignorance of risky behaviors and lack of social agenices to teach these things, lack of transportation, lack of funds
population of the poorest is increasing the fastest
war and famine and EID
war refuges- 1% of global pop
war refugees are forced into new areas where they are exposed to new microbes from vectors and people
war and famine are closely linked
famine is also caused by social, economic and political forces. Weather and HIV/AIDS
Lack of political will and EID
a global commitment is rather vague
developing world diseases don’t matter to politicians
need donors, healthcare professionals, country authorities and patients
intent to harm and EID
recognized as threat, even before 2001
countries- US versus Russia
The big 3
and diseases beyond the big 3
The big 3 Malaria TB HIV Diseases beyond the big 3 Respiratory infections Enteric infections STDs Vector-borne diseases
Emerging infectious diseases
Emerging infectious diseases are those whose incidence in humans has increased within the past two decades or whose incidence threatens to increase in the near future
May be due to:
Spread of a new agent
Recognition of a previously undetected agent
Finding that an established disease has an infectious origin
Reappearance of an agent after decline
Emerging Infectious Diseases
and CDC
Targets Surveillance and Response Applied Research Infrastructure and Training Prevention and Control
The Early Outcomes:
Raised awareness of public health deficiencies
We understood what needed to be done; however, minimal funding to do it
Addressing the EID Threat-2018
Increased awareness of EIDs
Increased public health workforce Improved surveillance systems State-of-art PHL diagnostic technologies Effective laboratory networks LRN, WCLN, PHL reference centers Much improved outbreak response More and improved vaccines
current EID threat
is global
high priority in high-income countries, top priority in low-income countries
definitive host
: Host in which the sexual stage of a parasite life cycle occurs
e.g. humans / Schistosoma
mosquitoes / malaria
intermediate host
Host in which asexual reproduction or development occurs
e.g. snails / Schistosoma
humans / malaria
incidental
accidental
): Is not an obligate part of the parasite life cycle
e.g. humans / Toxoplasma
often humans
Reservoir
Long-term hosts that maintain the natural cycle in the wild
- often are not really harmed be the carriage e. g. mice / Toxoplasma
Vector
A host species that transmits an infectious form of the parasite to another host species
e.g. mosquitoes / malaria
snails / Schistosoma
What makes an animal a good reservoir for human infectious diseases?
Commonly infected and carries the infection for a long time
Wide geographic range
Common contact with humans
Not sick, does not show signs of disease
A reservoir does not have to be a vector, but vector such as tick or mosquito can be a reservoir
ex: bats are a reservoir for Ebola
Geographic distribution
: the maximum global extent of a disease regardless of intensity
Prevalence
disease intensity in a given area (% susceptible population)
sporadic vs endemic vs epidemic
Colonization
: microbial infection where the infected person has no signs, symptoms, or damage of infection while still having the potential to infect others
Virulence
Virulence: severity or harmfulness of the pathogen
zoonoses
transmission of the infectious agent
to humans from an ongoing reservoir life cycle
in animals, without the permanent establishment
of a new life cycle in humans
ex: rabies, ebola, bird flu
just need good public health measures to control this
Species jumping
the infectious agent derives
from an ancient reservoir life cycle in animals,
but they have established a new life cycle in
humans that no longer involves the animals
Why it is important to understand the difference
between zoonoses and species jumping?
Prevention
Eradication
Virulence
Factors that Contribute to the Emergence of a New Zoonoses
Microbial/viral (e.g. mutations and evolution)
Individual host (lack of immune surveillance (AIDS)
Population host (e.g. transportation and urban crowding)
Environmental (e.g. ecological and climate influences)
Global human and livestock populations continue to grow
-this brings people and animals in closer contact
Advanced transportation makes long distance travel
possible in less than the incubation period
of most infectious agents
Massive ecological and environmental changes brought
about by humans
Zoonotic agents may be the choice for many
bioterrorist activities
Trypanosomiasis
Called Sleeping Sickness, vector is the tsetse fly
Classical example of an emerging infection, 1890-1930
-re-emerged in 60s,
Leading public health problem in Africa during that time,
colonialism brought it to new areas
Nearly eliminated by 1960 using population screening,
case treatment, chemoprophylaxis
Re-emerging infection in central Africa
-1960s was a time of turmoil and political upheaval because colonization was ending+ civil unrest due to the cold war
types of African trypanosomiasis
west african: humans are the reservoir, diseases is chronic (since we are the reservoir it takes a long time to kill us), mortalilty is 100%,
East Africans: reservoirs are antelopes and cattle- so direct zoonosis to humand, disease has rapid progression in humans since we arent the reservoir and pathogen doesnt care if it kills us, mortality is 100%
has waves of pasasitemia- same thing as plasmodium
10 days is about how long it takes adaptive immune response, so the pathogen changes its surface coat so immune repsonse can’t detect it, every 10 days, so can’t be detected= no way to make a vaccine
problems estimating t trypanosomiasis
60 million people at risk, but <2 million screened
No health facilities in many areas at risk
Conflict or insecurity in epidemic foci
Clinical diagnosis is difficult until late in disease
- intermittent fever - lymph node swelling - headaches and sleep disturbance - weight lose (they look like AIDS) - lab diagnosis is hard (antigenic variation)
