Prevalence of afebrile parasitaemia due to Plasmodium falciparum & P. vivax in district Balaghat (Madhya Pradesh): Implication for malaria control

BACKGROUND & OBJECTIVES: Balaghat district in Central India is a highly malarious district where both Plasmodium falciparum and P. vivax are prevalent. In this district, the persistence of malaria was on an increase and not responsive to intervention measures even though there was no drug resistance. This study was undertaken by conducting mass screening to determine the prevalence of malaria among particularly vulnerable tribe of Balaghat, for developing evidence-based intervention measures for malaria control in hard to reach areas. METHODS: This prospective study was carried out during 2013-2014 by conducting mass survey of the population in 10 villages of Birsa community health centre (CHC) and 12 villages of Baihar CHC. Finger-pricked blood smears were collected from all consenting individuals with or without fever for microscopic examination. RESULTS: In the febrile group, the slide positivity rate (SPR) and slide falciparum rate (SFR) were 32.4 and 28.9 per cent, respectively, with 89.4 per cent P. falciparum, while in the afebrile individuals also, the SPR and SFR were high (29 and 26%, respectively), but these were significantly lower than that of febrile group. The gametocyte carriers were significantly higher (odds ratio 1.67, 95% confidence interval 1.25-2.25, P =0.0004) in afebrile patients when compared with febrile group. Vector incrimination showed the presence of four sporozoite-positive Anopheles culicifacies out of 1953 assayed. INTERPRETATION & CONCLUSIONS: Plasmodium falciparum malaria was high in young children (up to 8 years) as compared to the adult in both afebrile and febrile group in Balaghat district. High prevalence of gametocyte was observed in all age groups among the afebrile cases. The identification of afebrile malaria parasitaemia is an important challenge for the malaria elimination initiatives. A strong malaria surveillance system is fundamental to both programme design and implementation.