Interpretation of IHA titres for the study of malaria epidemiology.

The results of IHA test surveys of persons with malaria parasitaemia in Ethiopia and the Philippines suggest that the antibody response may be influenced by the frequency and intensity of the antigenic stimulations and also be age-dependent. Antibody frequency distribution curves from four different areas suggest that the shape of such curves can provide some information about the endemicity of malaria. Results of similar and of parasitological surveys in Bangladesh, Ethiopia, Haiti, and the Philippines were compared and related to available malaria surveillance information. The results indicate that a serologic population profile may provide an indication of the history and status of malaria. Technical aspects of the IHA test are reviewed; it may be desirable to use homologous antigens instead of a simian Plasmodium antigen. To obtain the most useful additional epidemiological information about a malaria situation, serologic data need to be age-related, and longitudinal surveys are usually more informative than a cross-sectional survey.