Lecture 7: Drivers of Emerging Disease Flashcards
- Up to what percent of emerging diseases are zoonotic in origin?
- About what percent of all human pathogens are emerging?
- What fraction of new human pathogens are viruses?
- 75%
- 15%
- 2/3
What are the 5 stages through zoonotic diseases evolve to become primarily human pathogens?
- Stage 1: agent only in animals
- No transmission to humans - Stage 2: primary infection
- Transmission to humans only from animals - Stage 3: limited outbreak
- From animals or a few humans - Stage 4: long outbreak
- From animals or many humans - Stage 5: exclusive human agent
- Only from humans
True or false: the emergence of a pathogen has multiple drivers.
True
What is the most common factor in outbreaks of new diseases with high mortality rates? Why?
Ecological changes and agricultural development
- Humans and their animals come closer in proximity to reservoirs of new diseases or their vectors
What drives ecological changes and agricultural development?
- Increase in human population –> increase in demand for livestock or farming
- Economic opportunity
List the following for Argentine hemorrhagic fever:
1. Causative agent
2. Reservoir
3. Transmission
- Junin virus
- Drylands vesper mouse/corn mouse
- Contact with rodent body fluids or excrement
Explain how Argentine hemorrhagic fever spread to humans/how outbreaks occur.
- Grassland was converted to cornfields –> mice made homes in the cornfields
- Epidemics occur during the corn harvesting season in autumn
List the following for Japanese encephalitis:
1. Causative agent
2. Reservoir
3. Transmission
- Japanese encephalitis virus
- Waterbirds
- Bite from Culex mosquitos
Explain how Japanese encephalitis spread to humans/how outbreaks occur.
- Pigs serve as amplifying hosts and are associated with human outbreaks in rural agricultural areas
- Pig population increases as pork consumption increases
- Flooded rice fields attract waterbirds and serve as breeding ground for mosquitos
What is bushmeat and how are bushmeat activities linked to outbreaks?
- Meat derived from wild animals for human consumption (important source of protein for many developing countries)
- Greatest risk occurs when butchering animals
- HIV, monkeypox, rabis, Ebola outbreaks
- Lack of knowledge of risks and safety is the major driver
How do animal markets and factory farming contribute to outbreaks?
- Animals are living in cramped and unhygienic conditions
- Sick animals can easily transmit to nearby animals
- Different animals in contact with each other increases the risk for spillover events
List some changes in demographics that act as drivers of emerging disease.
- Human population increasing
- Migration from rural areas to urban areas
- War or disaster promotes migration
- People are living longer
List the following for the reemergence of malaria in the Amazon region of Brazil:
1. Causative agent
2. Reservoir
3. Transmission
- Plasmodium falciparum and P. vivax
- Humans
- By mosquitos
Explain how the reemergence of malaria in the Amazon region of Brazil occurred.
- Malaria was practically eradicated in the Amazon region by the 1950s
- 1960s: new highways were built that linked the Amazon region with other parts of the country
- 1970s: rise in agriculture settlements in the region
- 1980s: discovery of gold led to mass migration
- People with malaria brought the disease to the region
What changes in society/behaviors acted as drivers of emerging disease?
- Sexual revolution in 1960s-70s lead to rapid emergence of STIs
- Antibiotics –> people less scared of getting sick
- Intravenous drug use
- Unprotected sex, sex with multiple partners, not regularly testing, not taking preventative medication
Why do childcare settings propagate outbreaks?
Because children are in close contact with each other
- High risk of transmitting enteric infections, respiratory infections, and skin infections
- Family members get infected from the child
List the following for Kingella kingae
1. What it is
2. Transmission
3. Diseases it causes
- Gram-negative coccobacillus that largely colonizes the respiratory tract of children under the age of 4
- Person-to-person via respiratory secretions
- Bacteremia and skeletal infections
How does poor health contribute to emerging disease?
Poor health, underlying conditions, AIDS, immunosuppressants and cancer increases the susceptibility to infection
What has led to increased HAIs?
- Invasive medical procedures, surgery, indwelling medical devices, prosthetics can introduce pathogens
- Poor infection control measures can lead to the spread of microorganisms
- Over usage of antimicrobials lead to resistance bugs
1 in _____ hospital patients have a HAI and 1 in _____ nursing home residents have a HAI.
- 31
- 43
In 2015, how many HAI cases in acute care were reported? How many of those with a HAI died?
- 687,000 cases
- 72,000
How do HAIs spread?
List the following for fungal meningitis associated with methylprednisolone injections.
1. Causative agent
2. Reservoir
3. Explain how the outbreak happened.
- Exserohilum rostratum (mainly) and other contaminants
- Environment
- September 2012: outbreak of fungal meningitis, joint infections, and other infections in the U.S.
-14,000 methylprednisolone acetate (steroid) vials from the New England Compounding Center were contaminated with various environmental microbes
How do non-pathogenic bacteria become pathogenic?
Horizontal gene transfer
- Bacteria acquire new pathogenic genetic material
