Detection of the infective Plasmodium falciparum gametocytes by RT-qPCR assay from a malaria-endemic region of Northeastern India

Abstract

The diagnosis of infectious reservoirs in malaria (gametocytes) is necessary, especially in low-density infections and asymptomatic malaria patients. The gametocyte stage is a surrogate marker for infection of P. falciparum malaria in healthy individuals. The early detection of infectious gametocytes and treatment will strengthen our efforts in curbing transmission. The nested PCR and real-time quantitative PCR (RT-qPCR) methods have been demonstrated for the diagnosis of infectious gametocyte reservoirs. In this study, RDT, blood smear microscopy, and nested-PCR were used for the detection of P. falciparum and P. vivax, and compared with RT-qPCR detection of Pfg27 gametocyte biomarker gene.In the present cross-sectional study, 356 human blood samples were collected from endemic areas of Kokrajhar Assam (asymptomatic and symptomatic malaria patients) for malaria diagnosis.A total of 8.42%(30/356) incidence of malaria was observed. Malaria patients were observed to be both symptomatic, 80%(24/30; 13Pf+11Pv), and asymptomatic, 20%(6 (4Pf +2Pv)). More than 64%(11/17) of Pf and 92.3%(12/13) of Pv infections were observed in children and the adolescent population (age <20 years) by RDT, microscopy, nested PCR, and RT-qPCR methods. The prevalence of Pf infection was 4.77%(17/356) by RT-qPCR method. Of 16 the Pf positive samples 81.25%(13/16) were symptomatic and 18.75%(3/16) were asymptomatic. One asymptomatic individual was found positive for Pf infection by the RT-qPCR method.The findings from this research study revealed that the routine microscopy and RDT methods are insufficient for detecting all asymptomatic malaria and gametocyte infectious reservoirs. The early detection of infectious P. falciparum gametocytes and the treatment of patients will be helpful in preventing the transmission of malaria.