Persistence of Plasmodium falciparum HRP-2 in successfully treated acute falciparum malaria

The potential for Plasmodium falciparum histidine-rich protein-2 (PfHRP-2) dipstick tests to predict antimalarial treatment failure was investigated i n a prospective study in Thailand of 38 patients admitted with severe malar ia and 54 hospitalized with uncomplicated P. falciparum infections. Of thes e, 40 had subsequent recrudescence of their infections. Overall, 89% of pat ients with severe malaria and 61% of patients with uncomplicated malaria ha d positive PfHRP-2 dipstick tests for >2 weeks following the start of treat ment. Persistence was correlated positively with admission parasite counts, PfHRP-2 intensity scores and disease severity. PfHRP-2 tests which remaine d positive for >2 weeks and PfHRP-2 reactive intensity scores on admission, at day 7 and day 14 did not predict treatment failure independent of admis sion parasitaemia. Freezing and thawing the blood samples did not significa ntly affect PfHRP-2 results tested by the dipstick technique. The PfHRP-2 d ipstick test provides a useful indicator of recent severe malaria, but does not predict the therapeutic response.