Molecular monitoring of parasite resistance to artemisinin in Tanzania

Artemisinin-based combination therapies (ACTs) are recommended for use against uncomplicated malaria in areas of multi-drug resistant malaria; such as sub-Saharan Africa. However; their long-term usefulness in these high transmission areas remains unclear. It has been suggested that documentation of the S769N PfATPase6 mutations may indicate an emergence of artemisinin resistance of Plasmodium falciparum in the field. The present study assessed PfATPase6 mutations (S769N and A623E) in 615 asymptomatic P. falciparum infections in Tanzania but no mutant genotype was detected. This observation suggests that resistance to artemisinin has not yet been selected in Tanzania; supporting the Ministry of Healths decision to adopt artemether+lumefantrine as first-line malaria treatment. The findings recommend further studies to assess PfATPase6 mutations in sentinel sites and verify their usefulness in monitoring emergency of ACT resistance

Diagnosis of Plasmodium falciparum infection using ParaSight(R)-F test in blood and urine of Papua New Guinean children.

Rapid, simple, accurate and cheap methods are required for the diagnosis of malaria in endemic areas. The ParaSight(R)-F test, which is based on qualitative detection by monoclonal antibody of the Plasmodium falciparum (Pf) histidin-rich protein-II in the blood, showed promising results. As some antigens of Pf have been detected in the urine, we assessed the efficiency of the ParaSight(R)-F test in the whole blood and in the urine using microscopy and PCR as gold standards. One hundred and twelve children living in the East Sepik Province of Papua New Guinea (PNG) were recruited during a cross-sectional community survey. When using microscopy as reference, the ParaSight(R)-F test applied to whole blood had 84% sensitivity and 77% specificity. The semi-quantitative assessment showed that the intensity of the color on the wick correlated with parasite density. The ParaSight(R)-F test performed on urine had 81% sensitivity but only 26% specificity. Very similar results for blood and urine were obtained when using PCR as reference. The present evaluation of the ParaSight(R)-F test applied to blood compares well with findings in endemic areas of Africa or Asia, and confirms its usefulness to diagnose Pf infection in endemic areas of the South Pacific. Because of the lack of specificity, the ParaSight(R)-F test performed on urine cannot be recommended.