Define emerging diseases
New infectious disease that have not been recognized before as well as known infectious diseases with changing patterns
What are the six (plus 1) categories of changing conditions that lead to emerging diseases?
- Ecological change
- Changes in human demographics or behavior
- International travel and commerce
- Technology
- Microbial changes
- Break down in public health measures
- Unexplained emergence*
Describe ecological changes with examples
- Usually involves zoonotic diseases
- Korean hemorrhagic fever
- Rift Valley fever
- Lyme disease
What is Korean hemorrhagic fever and what ecological changes led to its emergence?
- High fever, internal bleeding caused by hantavirus from rodents
- Field mice flourish in rice fields
What is Rift Valley fever and what ecological changes led to its emergence?
- High fever, retinitis, and rarely hepatitis with hemorrhage
- Dams built along Senegal River in Mauritania, Africa increase the number of mosquitoes that carry viruses
What is Lyme disease and what ecological changes led to its emergence?
- Initially results in a rash, flu-like symptoms - weeks later, cardiac or neurologic problems
- Caused by bacterial spirochete transmitted via tick bite (deer tick)
- Emergence in forests near populated sites
Describe how changes in human behavior lead to infectious disease emergence
- Population movements - crowding of people into cities in poor nations; movement of people with HIV from villages in Africa to larger susceptible populations
- Unprotected sex or intravenous drug abuse shares body fluids amongst individuals
- Behaviors of misuse or overuse of antibiotics lead to resistant strains of bacteria
Describe how international travel and commerce lead to emerging infectious disease
- Movement of people
- Movement of plants, food, water, insects, and goods
- E.g. cholora - intestinal bacteria disease spread by contaminated water or food
Describe how new technology leads to the emergence of infectious disease
- Mass food processing combines large amounts of raw materials for widespread distribution
- Escherichia coli - meat used to make hamburger (ground beef) for fast food chain
Provide examples of how new technology has led to the emergence of infectious disease
- Salmonella poisoning in ice cream
- Transmission of bloodborne viruses (HIV hepatitis B and
C) during blood transfusions - Transmission of waterborne disease (legionnaires disease; pneumonia caused by Legionella pneumophilia) via Hotel water systems or air conditioning systems, whirlpools, humidifiers, shower heads
Describe how microbial changes lead to emerging infectious disease
- Mutations making microorganisms virulent or difficult to kill - most notably, influenza virus
- Development of drug resistance - antibiotic resistant strains
Describe how breakdowns in public health measures can lead to the emergence of infectious disease
- Production of safe drinking water - boil water notices due to temporary problems in water treatment plants
- Public Health vaccination programs
Give an example of an unexplained infectious disease emergence
- Ebola fever - mainly occurs in Africa subpopulations; rapidly victims die within days; the natural “reservoir” where the Ebola virus strains hide is unknown but attempts to identify the source are being made by culturing samples from animals, insects, and the environment
