Evaluating the impact of larviciding with Bti and community education and mobilization as supplementary integrated vector management interventions for malaria control in Kenya and Ethiopia.

BACKGROUND: Malaria prevention in Africa is mainly through the use of long-lasting insecticide treated nets (LLINs). The objective of the study was to assess the effect of supplementing LLINs with either larviciding with Bacillus thuringiensis israelensis (Bti) or community education and mobilization (CEM), or with both interventions in the context of integrated vector management (IVM). METHODS: The study involved a factorial, cluster-randomized, controlled trial conducted in Malindi and Nyabondo sites in Kenya and Tolay site in Ethiopia, to assess the impact of the following four intervention options on mosquitoes and malaria prevalence: LLINs only (arm 1); LLINs and Bti (arm 2); LLINs and CEM (arm 3); and, LLINs combined with Bti and CEM (arm 4). Between January 2013 and December 2015, CDC light traps were used to sample adult mosquitoes during the second, third and fourth quarter of each year in 10 houses in each of 16 villages at each of the three study sites. Larvae were sampled once a fortnight from potential mosquito-breeding habitats using standard plastic dippers. Cross-sectional malaria parasite prevalence surveys were conducted involving a total of 11,846 primary school children during the 3-year period, including 4800 children in Tolay, 3000 in Malindi and 4046 in Nyabondo study sites. RESULTS: Baseline relative indoor anopheline density was 0.11, 0.05 and 0.02 mosquitoes per house per night in Malindi, Tolay and Nyabondo sites, respectively. Nyabondo had the highest recorded overall average malaria prevalence among school children at 32.4%, followed by Malindi with 5.7% and Tolay 1.7%. There was no significant reduction in adult anopheline density at each of the three sites, which could be attributed to adding of the supplementary interventions to the usage of LLINs. Malaria prevalence was significantly reduced by 50% in Tolay when using LLINs coupled with application of Bti, community education and mobilization. The two other sites did not reveal significant reduction of prevalence as a result of combining LLINs with any of the other supplementary interventions. CONCLUSION: Combining LLINs with larviciding with Bti and CEM further reduced malaria infection in a low prevalence setting in Ethiopia, but not at sites with relatively higher prevalence in Kenya. More research is necessary at the selected sites in Kenya to periodically determine the suite of vector control interventions and broader disease management strategies, which when integrated would further reduce adult anopheline populations and malaria prevalence beyond what is achieved with LLINs.

Community based integrated vector management for malaria control: lessons from three years' experience (2016-2018) in Botor-Tolay district, southwestern Ethiopia.

BACKGROUND: Integrated vector management (IVM) remains a key strategy in the fight against vector-borne diseases including malaria. However, impacts of the strategy should be regularly monitored based on feedback obtained through research. The objective of this study was to assess the impact of IVM for malaria control in Botor-Tolay district, southwestern Ethiopia after three years (2016-2018) of IVM implementation. METHOD: Prior to the implementation of IVM, a survey of socio-demographic, malaria burden, and communities' perception towards malaria control was conducted in 200 households selected at random from 12 villages using standard questionnaire. Households were revisited after three years of project implementation for impact assessment. Compiled malaria case data was obtained from district health bureau for the three years period of the study while adult mosquito collection was conducted during each year using CDC light traps. Monthly larval mosquito collections were made each year using standard dipping method. Community education and mobilization (CEM) was made through different community-based structures. RESULTS: The proportion of respondents who sought treatment in health facilities showed a significant increase from 76% in 2015 to 90% in 2018(P < 0.001). An average of 6.3 working and 2.3 school days were lost per year in a household due to parents and children falling sick with malaria. Malaria costs in a household in Botor-Tolay averaged 13.3 and 4.5 USD per episode for medical treatment and transportation respectively. Significantly fewer adult mosquitoes were collected in 2018 (0.37/house/trap-night) as compared to 2015 (0.73/house/trap-night) (P < .001). Malaria cases significantly declined in 2018 (262) when compared to the record in 2015 (1162) (P < 0.001). Despite improved human behavioral changes towards mosquito and malaria control, there were many setbacks too. These include reluctance to seek treatment in a timely manner, low user compliance of LLINs and low net repairing habit. CONCLUSION: The coordinated implementation of community-based education, environmental management, larviciding together with main core vector control interventions in Botor-Tolay district in Southwestern Ethiopia have contributed to significant decline in malaria cases reported from health facilities. However, commitment to seeking treatment by people with clinical symptoms of malaria and to repair of damaged mosquito nets remained low.