Chemoprophylaxis: The use of drugs or biologics taken by asymptomatic persons to reduce the risk of developing a disease (http://odphp.osophs.dhhs.gov/pubs/guidecps/text/ii_met~1.txt).

Communicable Disease: An infectious disease transmissible (as from person to person) by direct contact with an affected individual or the individual’s discharges or by indirect means (as by a vector).

Disease: As used in this report, refers to a situation in which infection has elicited signs and symptoms in the infected individual; the infection has become clinically apparent.

Emerging infections: Any infectious disease that has come to medical attention within the last two decades or for which there is a threat that its prevalence will increase in the near future (IOM, 1992). Many times, such diseases exist in nature as zoonoses and emerge as human pathogens only when humans come into contact with a formerly isolated animal population, such as monkeys in a rain forest that are no longer isolated because of deforestation. Drug-resistant organisms could also be included as the cause of emerging infections since they exist because of human influence. Some recent examples of agents responsible for emerging infections include human immunodeficiency virus, Ebola virus, and multidrugresistant Mycobacterium tuberculosis, and H1N1 influenza A.

Emerging infectious diseases: Infections that are rapidly increasing in incidence or geographic range.

Emigration: To leave one’s usual country of residence to settle in another.

Encephalitis: An acute inflammatory disease of the brain due to direct viral invasion or to hypersensitivity initiated by a virus or other foreign protein.

Endemic: Present in a community or common among a group of people; said of a disease prevailing continually in a region.

Enteric: Of, relating to, or affecting the intestines.

Enzootic: A disease of low morbidity that is constantly present in an animal community.

Epidemic: The condition in which a disease spreads rapidly through a community in which that disease is normally not present or is present at a low level.