| Winifrida Kidima | 2 Articles |
As many countries implement different programs aimed at eliminating malaria, attention should be given to asymptomatic carriers that may interrupt the progress. This was a community-based cross-sectional study conducted in Tanzania from December 2022 to July 2023 within 4 villages from each of the 3 regions, Geita and Kigoma, which are high malaria transmission, and Arusha, which is low transmission. Malaria was diagnosed in asymptomatic individuals aged 1 year and older using the malaria rapid diagnostic test and light microscope. A total of 2,365 of 3,489 (67.9%) participants were enrolled from high-transmission villages. The overall prevalence was 25.5% and 15.8% by malaria rapid diagnostic test and light microscope, respectively. Using the respective tools, the prevalence was significantly higher at 35.6% (confidence interval (CI)=23.6–49.9) and 23.1% (CI=16.2–35.1) in the high-transmission regions (Geita and Kigoma) compared with 2.9% (CI=1.1–3.5) and 1.1% (CI=0.7–1.8) in the low-transmission region (Arusha). Children younger than 15 years and males accounted for the greatest proportion of infections. In the study area, the prevalence of asymptomatic cases was higher than that of reported symptomatic cases in health facilities. We hypothesize that these parasite reservoirs may contribute to the persistence of malaria in the country. Therefore, to achieve comprehensive malaria control in the country, the surveillance and screening of asymptomatic malaria cases are vital.
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Malaria transmission remains high in rural Tanzania despite widespread use of insecticide-treated nets and indoor residual spraying. Outdoor biting and flexible host-feeding behavior of Anopheles mosquitoes reduce the effectiveness of these interventions. Livestock near households may influence vector behavior, but evidence from high-transmission rural settings is limited. A cross-sectional study was conducted from November 2022 to February 2023 in 5 villages of Misungwi District, involving 44 households (22 livestock-keeping and 22 non-livestock-keeping). Adult Anopheles mosquitoes were collected indoors and outdoors using Center for Disease Control light traps, identified morphologically and by PCR, and blood-meal sources were determined by ELISA. Host-feeding patterns were assessed using the human blood index, bovine blood index, and foraging ratios. A total of 611 female mosquitoes were collected, dominated by An. gambiae s.l. (96.1%) and An. funestus s.l. (3.9%). Livestock households had more mosquitoes (61.5%) and higher outdoor activity (67.3%), while non-livestock households had higher indoor collections (73.6%). Among 231 blood-fed mosquitoes, 150 (64.9%) were from livestock households and 81 (35.1%) from non-livestock households. In livestock households, 108 (72.0%) had animal blood only, 27 (18.0%) mixed blood, and 15 (10.0%) human blood only. In non-livestock households, 44 (54.3%) had human blood only, 24 (29.6%) mixed blood, and 13 (16.0%) animal blood only. An. arabiensis was opportunistic, while An. gambiae s.s. and An. funestus s.s. remained strongly anthropophilic. Livestock shifts feeding toward animals and increases outdoor activity but does not eliminate human feeding, highlighting the need for integrated malaria control strategies.
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