Pretreatment gametocyte carriage in symptomatic patients with Plasmodium falciparum and Plasmodium vivax infections on the Thai-Myanmar border.

Abstract

One hundred and twenty-six blood samples were collected from patients with signs and symptoms of malaria who attended malaria clinics. Malaria positive cases detected by microscopic examination were confirmed by species-specific nested-PCR in 97 (29 and 68 samples for P. falciparum and P. vivax, respectively). The proportion of P. vivax and P. falciparum-infected samples was 70.1: 29.9%. The density in P. falciparum positive samples [median (95%CI): 10,340 (5280-19,200) μ/l] was significantly higher than P. vivax positive samples [4508 (3240-6120) μ/l]. Sixteen out of twenty-nine (55.2%) and 36 out of 68 (52.9%) P. falciparum- and P. vivax-infected samples, respectively, were gametocyte-positive. Gametocyte density in the P. falciparum-infected[124 (69-253) /μl] was significantly higher than that of the P. vivax-infected [54 (45-70)/μl] samples. A significant correlation between gametocyte density and pretreatment parasitemia was only detected in P. falciparum-infected, but not P. vivax-infected samples. The observed high prevalence rates of pretreatment gametocyte carriage of both malaria species, which serves as a large malaria reservoir, particularly in P. falciparum infection, could have a significant impact on malaria control in the endemic populations.