In regions with
drug-resistant
malaria, the ability to rapidly detect or predict treatment failure (TF) soon after a course of standard
therapy for
Plasmodium falciparum malaria would facilitate the prompt institution of second-line
therapy. We thus evaluated longitudinally the ability of the ICT
Malaria Pf/Pv immunochromatographic test to predict treatment outcome. Sixty-six Sumbanese Indonesians with uncomplicated
falciparum malaria were treated with
chloroquine and followed for 28 days by use of 1997 World Health Organization criteria for assessment of therapeutic efficacy of
antimalarial drugs. The ICT Pf/Pv testing could be compared with microscopy in approximately half of the patients on each day of follow-up. Although strongly positive
histidine rich
protein 2 (HRP2) line intensities (equal to or greater than the control band) in
convalescence were highly predictive of TF, any degree of positivity for the HRP2 and panmalarial
antigens in
convalescence was only moderately predictive of TE Positive predictive values of the HRP2 and panmalarial
antigens for TF were 76.9% and 87.0%, respectively, on Day 3, 82.4% and 87.5% on Day 7, and 78.9% and 78.9% on Day 14. Negative HRP2 and panmalarial
antigen results in
convalescence were even less predictive of an adequate clinical response, and false-negative HRP2 and panmalarial
antigen test results were found in one-sixth (6 of 37) of recrudescent
infections diagnosed by microscopy among patients with late treatment failure. To reliably predict treatment outcome with rapid
antigen tests, further development appears necessary to improve sensitivity for viable asexual parasites while avoiding detection of both gametocytes and persistent
antigen in
convalescence.