EVALUATION OF 2 TESTS BASED ON THE DETECTION OF HISTIDINE-RICH PROTEIN-2 FOR THE DIAGNOSIS OF IMPORTED PLASMODIUM-FALCIPARUM MALARIA

The ParaSight(TM)-F dipstick test (Becton Dickinson, USA) and the ICT Malaria Pf(TM) test (ICT, Australia) both detect histidine rich protei n 2 (HRP-2), a water-soluble antigen expressed by Plasmodium falciparu m trophozoites. The present study compared the diagnostic performance of both tests in persons returning to Belgium from countries endemic f or malaria. During a period of 18 months both tests were performed on all patients returning from the tropics with a positive malaria blood film. Patients with fever without an obvious cause were used as contro ls. For the ParaSight(TM)-F test, considering P. falciparum trophozoit es only, sensitivity was 95% and specificity 90%. Considering trophozo ites of all species of Plasmodium, sensitivity was 71% and specificity 87%. Finally, considering patients with clinical malaria, the sensiti vity of the test was 72% and specificity 87%. For the ICT Malaria Pf(T M) test, sensitivity was 95% and specificity 89% for I? falciparum tro phozoites only, 71% and 86% for trophozoites of all species, and 72% a nd 87% for clinical malaria. Both tests gave highly comparable results . However, antigen detection assays cannot replace conventional micros copy in diagnosing imported malaria. Thick blood film examination is m ore sensitive and more specific, it allows estimation of parasitaemia and distinction between parasite growth stages, and it covers all spec ies. Moreover, with treated patients the use of antigen tests might le ad to problems in determining the efficacy of therapy.