EVALUATION OF CIRCUMSPOROZOITE ANTIBODY TESTING AS A SEROEPIDEMIOLOGIC TOOL FOR THE DETECTION OF PLASMODIUM-FALCIPARUM INFECTION IN NONIMMUNE TRAVELERS

The objective of this investigation was to collect data concerning CS- antibody levels and duration of the immunological response to exposure of non-immune persons to a single malaria infection. For this purpose 156 specimens from 98 patients with confirmed falciparum malaria, 76 specimen derived from 64 patients with vivax malaria and sera from 32 patients who had not been previously to malarious areas were investiga ted by use of a commercially available ELISA testkit. All specimens fr om patients with falciparum malaria were also tested for merozoite-ant ibodies by an indirect fluorescence antibody test (IFAT). Positive lev els of merozoite-antibodies were detectable in 89.1% of the specimen i n this panel during the period between days 8 and 90 after onset of sy mptoms and decreased steadily thereafter. The test results were positi ve for CS-antibodies in 36.4% of the specimens from patients with falc iparum malaria during the first 7 days after onset of symptoms. This f igure increased to 55.8% during days 8-90 after onset and decreased to 38.9% in specimens which were tested later (91-1898 days). 11 specime ns reacted positively to CS-antibody testing but negative in the IFAT. Therefore, the percentage of specimen detected by either IFAT or CS-E LISA was at 51.9% during days 0 and 7 (p < 0.001), 95.3% during days 8 and 90 (p = 0.039) and 44.4% for testing performed later (p < 0.001). CS-antibodies could also be detected in 5.3% of specimen from patient s with vivax malaria while none of the sera from the malaria-negative control-group tested positive for CS-antibodies. Mie conclude that CS- antibody testing might prove valuable as an additional method for the determination of merozoite-antibodies in epidemiological surveys. Rega rdless its low sensitivity it might furthermore become a method for th e determination of the efficacy of malaria prevention measures since i t detects infection with parasites even without following clinical out break of malaria. It should not, however, be considered as a method on which a retrospective diagnosis of malaria could be based exclusively .