Epidemiology Objectives and Communicable Disease Terms

Objectives of Epidemiology

Objectives of epidemiology. The study of the environment, human habitat, waste, excrement, water supplies, methods of health education programs for health promotion, occupational health, the fight against drug addiction, and planning and management of health services to improve and correct the errors identified. Furthermore, the study presents the epidemiology of disease in relation to: the factors that determine the occurrence of disease; distribution in the population by municipalities, nations, and geographical regions; frequency and time course (mortality, morbidity and consequences of disease). Finally, what epidemiological studies of community health purport to do is: get to a diagnosis of community health, evaluate methods of diagnosis and treatment, establish the probability and risk of occurrence of a disease, understand biological phenomena to investigate the causes that can trigger disease, and improve the functioning of health services.

Infection and Infestation

Infection — when referring to microbes. Infestation — when it involves structured parasites such as:

• Protozoa: Plasmodium (causes malaria), amoeba.
• Metazoa (metazoans): e.g., helminths, nematodes, cestodes — examples include Ascaris and Oxyurus.

Epidemic, Endemic, Endoepidemia, Pandemic

Epidemic: the appearance in a community or region of a number of cases of a disease that is too large or unexpected for the time and place.

Endemic: when there is a constant presence of a communicable disease in a given geographical area, as with brucellosis in some areas of Spain. It occurs in a geographical area or population group with prevalence and incidence rates relatively high compared with those seen in other areas or populations. A focal endemic refers to the onset or presence of several cases of the disease in a given geographical area. Examples: malaria, dengue, tuberculosis.

Endoepidemia: an endemic in which outbreaks appear from time to time that increase the incidence of the disease; it is a combination of endemic and epidemic characteristics.

Pandemic: an epidemic that transcends a country's borders and affects part or all of the world, such as influenza.

Phases of Communicable Diseases

Incubation Period

The interval between the entry of an agent into a host organism and the onset of symptoms of the disease. This period depends largely on the number of microorganisms entering the host and their ability to multiply.

Prodromal Period

The prodromal period is characterized by the appearance of nonspecific signs and clinical characteristics that precede the defining symptoms of the disease.

General Period

The general period is characterized by the onset of symptoms and signs that define the disease and, together with analytical data, can allow the diagnosis.