EPIDEMIOLOGY

Epidemiology is the study of the distribution of diseases in a particular community or dis-

trict. A variety as well as a large quantity of data needs to be gathered in order to try and

establish a pattern of distribution of parasitic infections. The data are best obtained

either directly in the field or from a source such as hospital or regional health clinic

records.

n 8.1 COLLECTION OF DATA

The type of data that have to be collected and collated when studying the distribution of

a parasitic infection is based on the following:

n The total population of a defined geographical area and distribution of population

within the area.

n Climatic factors, such as average temperatures, yearly rainfall, seasonal distribution of

rain and temperature, humidity etc.

n The local topography, such as soil types, vegetation, water distribution (rivers, dams,

lakes etc).

n The type of agricultural practices, soil husbandry, animal husbandry, fishing, forestry

etc.

n Non-agricultural occupations and the amount of travel involved.

n Housing, fresh water storage and supply, sanitation.

n Diet, origin of food supply, storage, seasonal changes etc.

Population data should include age and sex profiles of the community and pro-

vide continuity of the population from one generation to another. The medical history

of the population is important, if any particular disease is prevalent throughout the

district.

Ecological data should include the type of fauna, invertebrates — insects snails etc and

vertebrates, including domestic pets and agricultural animals.

Most epidemiological studies begin by acquiring data from the local health centre, clinic

or hospital. This only provides information with regard to those persons who are already

ill and seeking medical assistance — persons who are acutely or chronically ill. Such in-

formation helps to provide data about the true distribution or prevalence of a particular

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