COMPARATIVE PERFORMANCE OF THE PARASIGHT(R) F-TEST FOR DETECTION OF PLASMODIUM-FALCIPARUM IN MALARIA-IMMUNE AND NONIMMUNE POPULATIONS IN IRIAN-JAYA, INDONESIA

A comparison was made of the performance of the ParaSight(R) F test (F test) for detection of Plasmodium falciparum in blood from malaria-im mune (410 native Irianese) and nonimmune (369 new transmigrants) popul ations in Irian Jaya, Indonesia, where malaria is hyperendemic and all four species of human malaria occur. There were highly significant di fferences between populations in the sensitivity (Irianese, 60% versus transmigrants, 84%; P < 0.001) and specificity (Irianese, 97% versus transmigrants, 84%; P < 0.001) of the F test, The test had comparably high levels of sensitivity for irianese children aged less than or equ al to 10 years, both age groups of transmigrants (76-85%), but low sen sitivity for Irianese aged >10 years (40%), among whom only 7% of para sitaemias <120 per mu l and 69% of those> 120 per mu l were detected, Specificity was comparably high for transmigrant children aged less th an or equal to 10 years and both age groups of Irianese (93-98%), The low specificity for transmigrants aged > 10 years (79%) was due to a p reponderance of false positives, frequently identified by microscopy a s P. vivax. The results suggest that comparison based on microscopy un derestimated the performance of the ParaSight(R) F test and that malar ia immune status, irrespective of P, falciparum density, may influence the test's sensitivity.