Evaluation of circumsporozoite antibody testing as a sero-epidemiological tool for the detection of Plasmodium falciparum infection in non-immune 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 investigated by use of a commercially available ELISA testkit. All specimens from patients with falciparum malaria were also tested for merozoite-antibodies by an indirect fluorescence antibody test (IFAT). Positive levels of merozoite-antibodies were detectable in 89.1% of the specimen in this panel during the period between days 8 and 90 after onset of symptoms and decreased steadily thereafter. The test results were positive for CS-antibodies in 36.4% of the specimens from patients with falciparum malaria during the first 7 days after onset of symptoms. This figure 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 specimens reacted positively to CS-antibody testing but negative in the IFAT. Therefore, the percentage of specimen detected by either IFAT or CS-ELISA 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 patients with vivax malaria while none of the sera from the malaria-negative control-group tested positive for CS-antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)