Mass diagnostic test using Plasmodium falciparum and chimpanzee erythrocyte lysate

Abstract

A soluble antigen fluorescent antibody test was developed for the serologic diagnosis of human malaria by using Plasmodium falciparum-parasitized erythrocyte lysates from experimentally infected chimpanzees as antigen. A stable antigen fractionated by sequential elution with chromatography on DEAE Sephadex A-25 was reactive at high dilutions. Therefore, approximately 50,000 tests could be performed with the amount of antigen normally collected from one infected chimpanzee. The technic was evaluated with 581 human serum specimens from selected individuals. Reactions were observed in 269 of 270 specimens from malaria patients whereas 129 of 132 specimens from healthy controls gave negative results. Occasional cross-reactions were observed with sera from individuals with infections other than malaria. Most of these reactions were obtained with sera from individuals with leprosy, leishmaniasis, American trypanosomiasis or hookworm in areas which are endemic for malaria. The high degree of sensitivity, specificity and reproducibility of the test, the objectivity of mechanical reading, the availability of large amounts of P. faldparum antigen and the possibility of processing many specimens semiautomatically in a relatively short time suggest that this technic may be well suited as a screening procedure in investigating the sero-epidemiology of malaria and for the mass screening of potential blood donors.