Browsing by Author "Mwaiswelo, Richard"

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Agent-based simulation of seasonal malaria chemoprevention strategy in Southern Tanzania: comparing dihydroartemisinin-piperaquine with or without primaquine
(Springer Nature, 0026-02-13) Mfala, Celina; Nyambo, Devotha; Mwaiswelo, Richard; Tchuenche, Jean; Clemen, Thomas
Background The effect of seasonal malaria chemoprevention (SMC) strategy on malaria transmission using a single low dose of primaquine (SLDPQ) added to artemisinin-based combination therapy has not been established in Africa. An agent-based model and simulation (ABMS) was used to assess SMC effectiveness using dihydroartemisinin-piperaquine (DP) with and without SLDPQ in Masasi and Nanyumbu Districts, Tanzania. Methods ABMS was developed in AnyLogic platform using secondary data from a cluster-randomized DP-based SMC study conducted in the districts, to assess the effectiveness of DP with and without SLDPQ for control of malaria in under-five children. The model incorporated human, mosquito, transmission, intervention, and environment sub-models, and simulated three monthly rounds of SMC over a 180-day period. Environment temperature, an important factor in mosquito breeding was simulated in three scenarios, first using average field temperature, and then when it was increased or decreased by 10C from the average. Model outputs were compared with field results to evaluate external validity. Results Overall, 2275 participants, 1135 in the intervention and 1140 in the control arm were involved in the model. At baseline, malaria prevalence was 11.5% (130/1135) and 16.3% (186/1140) in the intervention and control arm, respectively. At the end of 125-day simulation period malaria prevalence declined to 4.1% (47/1135), and it rebounded to 7.1% (80/1135) at the end of 180-day simulation period after three rounds of DP alone administration. Addition of SLDPQ to DP led to a further declined of the prevalence to 1.4% (16/1135) and 3.9% (44/1135) at the end of 125-day and 180-day, respectively. In the DP alone, the increase in average temperature by 1˚C further decreased malaria prevalence to 2.6% (30/1135) and 5.0% (57/1135) at the end of 125-day and 180-day, respectively, whereas the decrease of temperature by 1 ˚C decreased the malaria prevalence to 3.2% (36/1135) and 4.2% (48/1135) at the end of 125-day and 180-day, respectively. Conclusions The ABMS has demonstrated that addition of SLDPQ to DP reduced malaria transmission significantly regardless of the increase or decrease of the average temperature by 1 ˚C. SLDPQ can be added to DP-SMC and scaled-out for the control of malaria in Tanzania.
Agent-based simulation of seasonal malaria chemoprevention strategy in Southern Tanzania: comparing dihydroartemisinin-piperaquine with or without primaquine
(Springer Nature, 2026-02-13) Mfala, Celina; Nyambo, Devotha; Mwaiswelo, Richard; Tchuenche, Jean; Clemen, Thomas
Background The effect of seasonal malaria chemoprevention (SMC) strategy on malaria transmission using a single low dose of primaquine (SLDPQ) added to artemisinin-based combination therapy has not been established in Africa. An agent-based model and simulation (ABMS) was used to assess SMC effectiveness using dihydroartemisinin-piperaquine (DP) with and without SLDPQ in Masasi and Nanyumbu Districts, Tanzania. Methods ABMS was developed in AnyLogic platform using secondary data from a cluster-randomized DP-based SMC study conducted in the districts, to assess the effectiveness of DP with and without SLDPQ for control of malaria in under-five children. The model incorporated human, mosquito, transmission, intervention, and environment sub-models, and simulated three monthly rounds of SMC over a 180-day period. Environment temperature, an important factor in mosquito breeding was simulated in three scenarios, first using average field temperature, and then when it was increased or decreased by 10C from the average. Model outputs were compared with field results to evaluate external validity. Results Overall, 2275 participants, 1135 in the intervention and 1140 in the control arm were involved in the model. At baseline, malaria prevalence was 11.5% (130/1135) and 16.3% (186/1140) in the intervention and control arm, respectively. At the end of 125-day simulation period malaria prevalence declined to 4.1% (47/1135), and it rebounded to 7.1% (80/1135) at the end of 180-day simulation period after three rounds of DP alone administration. Addition of SLDPQ to DP led to a further declined of the prevalence to 1.4% (16/1135) and 3.9% (44/1135) at the end of 125-day and 180-day, respectively. In the DP alone, the increase in average temperature by 1˚C further decreased malaria prevalence to 2.6% (30/1135) and 5.0% (57/1135) at the end of 125-day and 180-day, respectively, whereas the decrease of temperature by 1 ˚C decreased the malaria prevalence to 3.2% (36/1135) and 4.2% (48/1135) at the end of 125-day and 180-day, respectively. Conclusions The ABMS has demonstrated that addition of SLDPQ to DP reduced malaria transmission significantly regardless of the increase or decrease of the average temperature by 1 ˚C. SLDPQ can be added to DP-SMC and scaled-out for the control of malaria in Tanzania.
Developing an Agent-based Model for Evaluating the Effectiveness of Malaria Interventions in Nanyumbu and Masasi Districts, Tanzania
(creative common, 2024-11-28) Mfala, Celina; Nyambo, Devotha; Mwaiswelo, Richard; Mmbando, Bruno; Clemen, Thomas
Objective : Agent-based models and simulation (ABMS) can be utilized to understand the dynamism of transmission and the effect of interventions. We evaluated using ABMS, the efficacy of insecticide-treated bednets (ITNs) at different coverage levels and quality of houses for control of malaria in Masasi and Nanyumbu districts, Tanzania. Methods: The model was developed and simulated in Anylogic software with mosquitoes, humans, and the environment along with their attributes as agents. Using field data, buildings of different qualities were created to be human environment, and ITN use was assigned to respective human agents. Shapefiles were imported into the built-in global imaging system map in Anylogic for better placement of buildings using their coordinates, and coordinates of streams extracted from the study area map were used to allocate the aquatic environment of the mosquito agents. ITNs coverage scenarios of 16%, 40%, 64%, and 80% were simulated. The model was simulated for 90-day period and a model time-step was set to a day. The primary outcome was the prevalence of human agents with malaria infection at the end of the 90-day simulation period. Results: At the end of the 90-day simulation period and initial ITNs coverage of 16% (257/1607), the prevalence of malaria infection was 15.4% (248/1607). When the coverage was increased to 40%, 64%, and 80% malaria prevalence declined to 15.1% (242/1607), 14.1% (227/1607), and 13.9% (223/1607), respectively. ABMS clearly indicated that an increase in ITNs coverage was associated with a decline in the prevalence of infected humans and mosquito population in consistency with the field data. Novelty: This work is unique in a sense that it incorporated the data on house quality which has direct impact in malaria transmission.