EPIDEMIOLOGY OF POLY-PARASITISM .3. EFFECTS ON DIAGNOSTIC CAPACITY OF IMMUNOLOGICAL TESTS

  • 1 January 1978
    • journal article
    • research article
    • Vol. 29  (2) , 145-155
Abstract
Some effects of the interaction between different types of parasitic infections on the diagnostic capacity of immunological tests for parasitic diseases are described. Examples include an analysis of reactions to tuberculin skin tests of individuals with and without skin manifestations of onchocerciasis; skin tests with Paragonimus westermani and Clonorchis sinensis antigens to detect double infections in patients harboring both trematodes; geographic evaluation of the sensitivity of the complement fixation (CF) test for schistosomiasis with Schistosoma mansoni antigen between different communities in Chad; reduced sensitivity of the CF test for schistosomiasis in patients with confirmed schistosomiasis who also have onchocerciasis; studies on the specificity of the slide flocculation (SF) test for schistosomiasis in relation to specified intestinal parasites and to the presence of antibodies to Echinococcus granulosus and Trichinella spiralis in villages of Afghanistan; and a study of association between polyparasitism and anticomplementary activity in the sera of population samples from the African savannah. There are large dissimilarities in test performance between communities with different disease spectra and nutritional status. Polyparasitism seems to interfere with immunodiagnostic tests both directly through cross-reactions with antigens and antibodies and indirectly through its effects on nutrition and on mechanisms affecting the complement system. Large scale screening for parasitic diseases with immunodiagnostic tests in areas in which the medical problems are not well known should be preceded by a small, well-planned pilot study in which the relative sensitivity and specificity of the test can be determined before its use in extensive population studies.

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