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30 Cards in this Set

  • Front
  • Back

Epidemiology

The study of the occurrence, distribution, & determinants of health & disease in a population

Epidemic

A disease occurring in a large number of people in a population at the same time

Pandemic

When a disease is widespread, usually worldwide

Endemic

When a disease is constantly present in a population, usually at low incidences

Incidence

The number of new cases of the disease in a given period of time

Prevalence

The total number of new & existing cases of the disease in a population in a given time

Outbreak

When a number of cases of a disease are reported in a short period of time

Subclinical infections

Diseased individuals who show no or mild symptoms

Carriers

Individuals with subclinical infections

Herd immunity

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




-If a high proportion on individuals are immune to infection, then the whole population will be protected




-Immunized people protect non-immunized people because the pathogen cannot be passed on, and the cycle of infectivity is broken

Diseases such as influenza tend to what?

Occur in cycles

Epidemiologists

Follow transmission of a disease by correlating geographic, climatic, social, & demographic data




-Used to identify possible modes of transmission




-For example, a disease limited to a tropical area may suggest something about its vector (e.g., malaria)

Direct host-to-host transmission

Infected individual transmits a disease directly to a susceptible host without the assistance of an intermediary (e.g., flu, common cold, STDs, ringworm)

Indirect host-to-host transmission

Occurs when transmission is facilitated by a living or nonliving agent

Vectors

Living agents that act as intermediaries in disease transmission

Fomites

Nonliving agents that act as intermediaries in disease transmission

Common-source epidemic

A classification of major epidemics, that usually arises from the contamination of food, where the disease shows a rapid rise to a peak incidence because a large number of individuals become ill within a relatively brief period of time




Ex. Cholera

Host-to-host epidemic

A classification of major epidemics, that shows a slow, progressive rise and a gradual decline




Ex. Influenza and Chicken pox

Reservoirs

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




-Some propagate in humans and animals (SARS bats)




-Non-living matter can be a reservoir (Ex. soil is a reservoir for Clostridium tetani, the cause of tetanus)





Common vehicles of infection disease include:

-Food




-Water




-Air

Controls directed against common vehicles

-Food laws lowered incidence of foodborne pathogens (even recently: gloves)




-Water purification reduced incidence of typhoid fever




-Airborne pathogens are difficult to control

What are the controls directed against the transmission of a pathogen?

-Immunization (Ex. Smallpox, Rubella, & Tetanus)




-Quarantine




-Surveillance: The observation, recognition, & reporting of diseases




-Pathogen eradication: The goal is to remove all of a pathogen from any reservoir (e.g. small pox (eradicatied), polio, & potentially rabies, leprosy, & others)

Emergent

Diseases that suddenly become prevalent

Re-emerging

Diseases that have become prevalent after having been under control

Emergence Factors

-Human demographics & behavior


-Technology & industry


-Economic development & land use


-International travel & commerce


-Microbial adaptation & change


-Breakdown of public health measures


-Abnormal natural occurences

What are the key elements in addressing emerging diseases?

-Recognition of the disease




-Intervention to prevent pathogen transmission



What are the methods in preventing the spread of emerging infections in regards to public health?

Methods include quarantine, immunization, drug treatment, & information

Acquired immunodeficiency syndrome (AIDS)

A viral disease that attacks the immune system




-First reported cases were in the U.S. in 1981




-At least 70 million people have been infected worldwide with HIV




-More than 25 million people have died from AIDS

Antigenic drift

Minor changes in influenza virus antigens due to gene mutation

Antigenic shift

Major change in influenza virus antigen due to gene reassortment




-Ex. 2009 Swine flu pandemic (H1N1)