Plasmodium falciparumincreases its investment in gametocytes in the wet season in asymptomatic individuals

Abstract

In many regions, malaria transmission is seasonal, but it is not well understood whether P. falciparum modulates its investment in transmission in response to seasonal vector abundance. In two sites in western Kenya (Chulaimbo and Homa Bay), we sampled 1116 asymptomatic individuals in the wet season, when vectors are abundant, and 1743 in the dry season. We screened for P. falciparum by qPCR, and gametocytes by pfs25 RT-qPCR. Parasite prevalence in Chulaimbo and Homa Bay was 27.1% and 9.4% in the dry season, and 48.2% and 7.8% in the wet season respectively. Mean parasite densities did not differ between seasons (P=0.562). A contrasting pattern of gametocyte carriage was observed. In the wet season, fewer infections harbored gametocytes (22.3% vs. 33.8%, P=0.009), but densities were 3-fold higher (P<0.001). Thus, in the wet season, among gametocyte positive individuals, higher proportion of all parasites were gametocytes, reflecting an increased investment in transmission.

Accuracy of diagnosis among clinical malaria patients: comparing microscopy, RDT and a highly sensitive quantitative PCR looking at the implications for submicroscopic infections

“…Submicroscopic infections have been reported in multiple studies in Ghana [ 59 , 60 ] however, its contribution to disease transmission and clinical manifestation is poorly understood and warrants further studies. New evidence suggests that submicroscopic infections disproportionally contribute to higher investment in gametocyte formation that may be picked up by vectors to sustain disease transmission [ 61 ]. This makes it even more important to understand the burden of subpatent infections in symptomatic people attending hospital to receive care.…”