Malaria and mosquito net utilisation among schoolchildren in villages with or without healthcare facilities at different altitudes in Iringa District, Tanzania.

LE Mboera, ML Kamugisha, SF Rumisha, WN Kisinza, KP Senkoro, AY Kitua

Abstract
Background: The endemicity of malaria in Tanzania is heterogenous, mainly associated with physical factors such as topography, climate and socio-economic status. The contributions of these factors in many regions of Tanzania have not been studied in detail. Objective: This study was carried out to determine the prevalence and transmission of malaria and mosquito nets coverage among schoolchildren in relation to altitude in villages with or without healthcare facilities in Iringa District, Tanzania.

Methods: A cross-sectional survey of schoolchildren was carried out in six villages in three altitude transects (965-2075 m). In each transect a village with and without a healthcare facility were selected. The villages included Idodi (965m), Makifu (985m), Tosamaganga (1561m) Mangalali (1520m) Lulanzi (1917) and Kilolo (2075m). For the purpose of this study, the villages were categorised as lowlands (Idodi and Makifu), intermediate (Tosamaganga and Mangalali) and highlands (Lulanzi and Kilolo. Healthcare facilities were available at Idodi, Tosamaganga and Kilolo. Each child was asked whether or not slept under a mosquito net during the previous night. Mosquitoes were collected using pyrethrum spray catch technique in ten houses in each study village.

Results: Blood smears from a total of 1643 schoolchildren (mean age = 5.9-12.3 years) were examined for malaria infection. Plasmodium falciparum accounted for 93.1% of the malaria parasites. The prevalence of P. falciparum among children in Idodi, Makifu, Mangalali, Tosamaganga, was 51.51%, 73.66%, 22.79%, and 14.83%, respectively. Malaria parasites were not found among children in the highland villages of Lulanzi and Kilolo). The prevalence of malaria parasitaemia, packed cell volume, geometric mean parasite density and spleen rates were higher in children living in villages without healthcare facilities (P<0.001). Of the children, 16.1% (264/1643) slept under a mosquito net during the previous night. About three quarters (253/344) of the schoolchildren who had malaria parasites were not using mosquito nets. Mosquito net coverage was higher in lowland villages, accounting for 61.7% (163/ 264) of the total net use in the district. The majority (75.5%) of the mosquito net users were from village with health facilities (P<0.001). A total of 228 mosquitoes were collected, with Anopheles gambiae s.l. accounting for the majority (53.5%). Overall, 8.7% of the An. gambiae s.l. were infected with malaria sporozoites. Higher sporozoite rates were observed in mosquitoes collected in the lowlands.

Conclusion: Communities living in areas without health facilities form the largest proportion of malaria-infected populations in Iringa district. Availability of healthcare service has an influence on mosquito net coverage. The results provide more evidence of the
existence of a relationship between altitude variability or accessibility to healthcare services, and the burden of malaria in rural communities of Tanzania.