Exam 3 - Chapter 30

Epidemiology

Study of the occurrence, distribution, and determinants of health and disease in a population

Incidence

Number of new cases of the disease in a given period of time

Prevalence

Total number of new and existing cases in a population in a given time

Endemic disease

Disease that is constantly present, usually at low number in a population

Epidemic

Occurrence of a disease in unusually high numbers in a localized population

Pandemic

A widespread, usually worldwide epidemic

What does the yellow image represent?

Endemic disease

What does the blue image represent?

Epidemic disease

What does the pink image represent?

Pandemic disease

Mortality

Incidence of death in a population

Morbidity

Incidence of disease, including fatal and non fatal diseases

Disability-Adjusted Life Year (DALY)

Quantitatively measures disease burden in terms of lost years due to the disease, disability due to disease, and premature death

Direct host-to-host transmission

Infected individual transmits a disease directly to a susceptible host without the assistance of an intermediary

Examples of directly transmitted diseases

• 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 can transmit disease

Fomites

Nonliving agents that can transmit disease

Reservoirs

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

Carriers

Pathogen-infected individuals showing no signs of clinical disease

Zoonosis

Disease that primarily infects animals but is occasionally transmitted to humans

R₀

The average number of people who will contract a contagious disease from one person with that disease

What affect does herd immunity have on disease transmission

Decreases the R₀ of the disease in that population (blocks transmission to immune people)

Pathogen eradication

Remove all of a pathogen from any reservoir

Examples of pathgoen eradication

• Smallpox

• Polio

• Leprosy (potentially)

What impact did the introduction of a measles vaccine have?

Eliminated measles as a common childhood infection

Emergent

Diseases that suddenly become prevalent

Reemerging diseases

Diseases that have become prevalent after having been under control

Worldwide distribution of diseases…

changes rapidly

Emergence factors

• Human 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 natural occurrences

Biological weapons

Organisms or toxins that are:

• easy to produce and deliver

• safe for use by the offensive soldiers

• able to incapacitate or kill individuals under attack in a consistent and reproducible manner