ANALYSIS ON THE BURDEN OF HELMINTHS-Plasmodium falciparum POLYPARASITISM, EFFECT ON ANAEMIA AND THE ROLE OF INTEGRATED SCHOOL BASED PARASITE CONTROL AND HEALTH EDUCATION IN ZIMBABWE.

Abstract

Introduction: Globally, 207 million; 2 billion and 243 million people are infected with schistosomiasis (SCH), soil transmitted helminths (STH) and Plasmodium falciparum (P.f) respectively. Many of the affected people are primary school age children. Clinical outcomes of these parasitic infections include anaemia, impaired cognition and malnutrition. Although these parasites have different mechanisms through which they cause anaemia, data is scarce on the extent of helminths –Plasmodium polyparasitism and their effect on anaemia. We determined the extent of helminths-Plasmodium co-infections, their effect on anaemia and the efficacy of combined school based treatment intervention on prevalence of co-infections and anaemia among primary schoolchildren in rural and farming areas in Zimbabwe. Overall objective: To determine the prevalence of single and helminths–Plasmodium co-infections among primary schoolchildren living in rural and commercial farming areas, the effect of co-infections on anaemia and the efficacy of combined school based treatment intervention on prevalence of co-infections and anemia. Settings: The study was conducted in Nyamaropa rural area, Shamva districts and Burma Valley commercial farming areas in Mutare district, Zimbabwe. Study design: The study was a longitudinal intervention trial, which involved treatment of infected children at baseline, 6, 12 and 33 months follow up surveys. Methodology: Enrolled participants were screened for anaemia; schistosomiasis; STHs and P. falciparum (P.f) using the Hemocue machine, urine filtration technique, a combination of the Kato Katz and formal ether concentration techniques and Giemsa staining respectively at each survey. Results: Helminths- Plasmodium co-infections were heterogeneously distributed and were observed in the commercial farming area only. Overall, the prevalence of Schistosoma haematobium in the rural and farming areas was 66.8% and 52.3%, respectively, that of S. mansoni was 12.4% and 22.7%.. P. f, hookworms, Ascaris lumbricoides and Trichuris trichiura occurred only in the farming area, with a prevalence of 27.9%, 23.7%, 2.1%, 2.3%, respectively. Hookworm and S. mansoni infections were associated with P. f (P < 0.001, OR = 2.48, 95% CI: 1.56-3.93 and P = 0.005, OR = 1.85, 95% CI: 1.20-2.87). Of the 475 children screened for all parasites and anaemia, received combined treatment at baseline and successfully followed up to 33 months post treatment survey, 11.2%; 10.9%; 1.3% and 5.1% had SCH + STHs; SCH + P. f; STH + P. f; SCH+ STH + P. f co-infections respectively at baseline. These co-infections declined to 6.3%; 2.1%; 0.4; 1.1%, respectively at 33 months follow up survey. Overall, anaemia declined from 45.7% at baseline to 15.4% at 33 months follow up survey after treatment intervention, p < 0.001. School health education increased the knowledge of grade 3 children about causes of helminths and P. falciparum Conclusions: There is heterogeneity in the distribution of helminths –Plasmodium co-infections in diverse communities. Co-infections have a multiplicative effect on anaemia. Biannual combined school based treatment intervention reduces the prevalence of helminths-Plasmodium co-infections and anaemia. Determination of the extent of helminths –Plasmodium co-infection should be prioritized in planning allocation of limited resources for control. The Government of Zimbabwe nationalized this PhD work. The work also contributed towards the national policy formulation for the control of schistosomiasis, STH and other neglected tropical diseases in Zimbabwe.