Endemic

Definition

In the medical sciences, the term endemic refers to an infectious disease that survives in a population without input from some external source.

Description

Endemic diseases are always present in an affected population, usually at relatively low, but constant, levels. For example, malaria is endemic to sub-Saharan Africa, where it is so common that humans have evolved a genetic factor (the sickle-cell trait) that protects against the disease. Endemic diseases are transmitted from person to person, either directly or by means of a vector, such as a mosquito. As long as there are enough humans with a disease to continue passing it on in a region, or as long as a vector is present in adequate numbers, the disease will persist—it will be endemic—in the population. The likelihood of a disease becoming endemic in a region is obviously a function of the density of human population in the area. The denser the population, the greater the number of interpersonal contacts, and the greater the likelihood the disease will be spread from person to person. Living conditions are also a factor, since unsanitary conditions promote the survival and breeding of vectors and the maintenance of an infectious disease.

The term endemic is also used to describe noninfective diseases and health conditions. For example, some people have described obesity as endemic in certain parts of the developed world, such as the United States. That term is appropriate because the factors that lead to obesity, such as an abundance of food and a relative lack of physical exercise, are now fundamental parts of American life; obesity is likely to continue as an endemic health problem unless significant efforts are made to either reduce or eliminate the contributing factors or to make individuals aware of their role in producing an unhealthy lifestyle.

Demographics

Some examples of endemic diseases and their incidence (number of new cases annually) or prevalence (total number of present cases) are as follows:

Public health role and response

KEY TERMS
Endemic—
A health condition surviving in a population at, usually, a relatively low but constant frequency.
Epidemic—
The occurrence of a large number of cases of a disease in an area where that disease is normally not present in high numbers.
Sickle cell trait—
A genetic factor that provides a person with a level of protective immunity against malaria.

An example of the success that public health programs have had with endemic diseases is tuberculosis. At one time, the disease was endemic in many developed countries, especially among the urban poor. During the nineteenth and early twentieth centuries, the disease was responsible for one out of four deaths in England and one in six deaths in France. When the cause of the disease was finally determined in 1882 by Robert Koch, public health workers gained the knowledge they needed to begin making inroads against the disease. As a consequence, the rate of tuberculosis in developed nations dropped dramatically in the twentieth and twenty-first centuries, although the disease is still endemic and widespread in most parts of the developing world.

See also Communicable diseases .

Resources

BOOKS

Cook, Gordon C., and Alimuddin Zumula, eds. Manson's Tropical Diseases: Expert Consult Basic, 22nd ed. Philadelphia: Saunders, 2008.

Guerrant, Richard L., David H. Walker, and Peter F. Weller. Tropical Infectious Diseases: Principles, Pathogens and Practice, 3rd ed. Philadelphia: Saunders, 2011.

Temesgen, Zelalem, ed. Mayo Clinic Infectious Diseases Board Review. New York: Oxford University Press, 2011.

PERIODICALS

Alshishtawy, Moeness Moustafa. “Vitamin D Deficiency: This Clandestine Endemic Disease Is Veiled No More.” Sultan Qaboos University Medical Journal 12, no. 2 (2012): 140–52.

Stout, J. E., et al. “Pedicure-associated Rapidly Growing Mycobacterial Infection: An Endemic Disease.” Clinical Infectious Diseases 53, no. 8 (2011): 787–92.

Zhou, J., et al. “Impact of Supplementary Immunization Activities in Measles-endemic Areas: A Case Study from Guangxi, China.” Journal of Infectious Diseases 204, Suppl. 1 (2011): S455–62.

WEBSITES

Department of International Development. “Decision Support for Endemic Disease Control in Sub-Saharan Africa: Private Sector Drivers for Technology Adoption by Resource-poor Farmers.” http://www.dfid.gov.uk/r4d/Project/3721/Default.aspx (accessed October 11, 2012).

Institute of Endemic Diseases. http://www.iend.org/ . Accessed on October 11, 2012.

Partners in Health. “The PIH Guide to Chronic Care Integration for Endemic Non-communicable Diseases.” http://www.pih.org/publications/entry/the-pih-guide-to-chronic-care-integration-for-endemic-ncd (accessed October 11, 2012).

ORGANIZATIONS

World Health Organization, Avenue Appia 20, 1211 Geneva 27, Switzerland, 2241 791 21 11, Fax: 2241 791 31 11, info@who.int, http://www.who.int .

David E. Newton, EdD

  This information is not a tool for self-diagnosis or a substitute for professional care.