Abstract
Malaria parasites are only transmitted by female mosquitoes of the genus Anopheles; hence, the disease's distribution is linked to that of the vector mosquitoes. As such, the goal of this study was to find out the spatial and temporal distribution of Anopheles mosquito adults in the research sites. This was a repeated cross-sectional ecological study that took place in Morogoro and Dodoma, Tanzania. Vacuum aspiration was used to collect mosquitoes both outside and inside human dwellings. All mosquito-related data was collected and entered into appropriate data collection forms. Female mosquitoes were recognized morphologically using Gillies and Coetzee morphological criteria, followed by PCR. In total, about 2742 Anopheles mosquitoes with an average collection of 18.21 ± 1.12 per day were collected outside human houses of which 1717 (10.51 ± 1.17) and 1025 (8.42 ± 1.41) were collected from Morogoro and Dodoma, respectively. Of the captured mosquitoes, 89.0%, 10.0%, and 1.0% were recognized as Anopheles arabiensis, Anopheles gambiae s.s., and Anopheles quadrianulatus, respectively. The distribution varied significantly with seasons, whereby 302 (4.72 ± 1.04) and 2440 (12.96 ± 1.52) mosquitoes were captured in the cold-dry and warm-wet season, respectively (p < 0.0001). Of the captured mosquitoes, 42.33%, 16.33%, 14.96%, and 4.27 were found on the ceiling, stored junks, verandas, and barks/tree, respectively. In malaria-endemic countries, vector control forms an important component of the malaria control efforts. This study found significant variation of Anopheles mosquito abundance in time and space with Anopheles arabiensis being the most predominant malaria vector. This signifies the need to introduce mosquito control methods that will target the less anthropophilic Anopheles arabiensis or the immature aquatic stages. The study further found that underbeds, store room/piled bags, and undisturbed curtains were the most preferred resting places by mosquitoes signifying to be the most effective strategic sites for spraying insecticides during the implementation of indoor residual spraying (IRS).
Highlights
Malaria is a major public health issue in Tanzania, with 93 percent of the population being at risk, the disease is the main national cause of outpatient visits and admissions in health care facilities, among children under the age of five and pregnant women [1]
The variation in the distribution of vector mosquitoes by location was observed to be statistically significant with respect to season (χ2 = 168:79, p = < 0:0001), whereby in dry-cold season (June-September), a total of 320 vector Anopheles mosquitoes were caught outside houses of which 36.47%, 22.43%, 16.11%, and 8.55% were collected from ceiling, stored junks, verandas, and inside unfinished buildings, respectively
Anopheles mosquito abundance may be used as a proxy of malaria transmission intensity and used to guide focused malaria control interventions in endemic areas as countries move towards malaria focal elimination
Summary
Malaria is a major public health issue in Tanzania, with 93 percent of the population being at risk, the disease is the main national cause of outpatient visits and admissions in health care facilities, among children under the age of five and pregnant women [1]. Region, country, or continent, climate and topography are significant factors of macro spatial-temporal Anopheles mosquito distribution [3,4,5,6]. The knowledge of BioMed Research International malaria transmission dynamics, the temporal and spatial distribution of Anopheles mosquito vector populations, is generally low due to Tanzania’s large geographic size and different ecoclimatic conditions. Understanding the temporal and spatial distribution of sympatric malaria vector species is important for effective vector control in malaria-endemic countries like Tanzania [2, 12]. This research intended, to investigate distribution in time and space of Anopheles mosquito adults so as to have a better understanding of the distribution of these important malaria vectors to be used in implementing different vector control measures that target adult mosquitoes
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