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Abstract Background Reactive case detection (RACD) for malaria control has been found effective in low transmission settings, but its impact and cost-effectiveness in moderate-to-high transmission settings are unknown. We conducted an economic evaluation alongside an empirical trial of a modified RACD strategy (1,7-mRCTR) in three moderate-to-high malaria transmission districts in Tanzania. Methods The costs and cost savings associated with the intervention relative to passive case detection alone were estimated in the study sites of Kilwa, Kibiti, and Rufiji districts in Tanzania from 2019–2021. Empirical cost data were collected using household surveys. The incremental costs of the intervention were calculated from under a societal perspective. Costs are reported in 2022 US dollars. Trial data and malaria registers from health facilities were used to calculate the number of malaria cases detected. We simulated unobserved and distal health effects of the intervention to assess cost-effectiveness in terms of incremental cost-effectiveness ratios (ICERs). Propagated uncertainty was assessed via second-order Monte Carlo simulation, including bootstrapping of empirical data distributions. Incremental costs per disability-adjusted life year (DALY) averted were compared to a willingness-to-pay threshold based on estimated opportunity costs of healthcare spending in Tanzania. Results The programmatic cost of the 1,7-mRCTR intervention was 5327 United States Dollars (USD) per 1000 population. The combination of reactive and passive case detection in the intervention arm resulted in an additional 445 malaria cases detected per 1000 compared to passive detection alone, yielding an incremental cost per additional case detected of 12.0 USD. Based on modelling results, for every percentage point decline in malaria prevalence, the intervention averted 95.2 cases and 0.04 deaths per 1000 population. On average, the 1,7-mRCTR intervention averted 19.1 DALYs per 1000 population. Compared to passive malaria detection, the ICERs for the 1,7-mRCTR intervention were 7.3 USD per case averted, 16,884 USD per death averted, and 163 USD per DALY averted. Conclusions Our analysis demonstrates that the 1,7-mRCTR intervention appears to be cost-effective under a willingness-to-pay threshold of 417 USD per DALY averted, showing that modified RACD strategies can provide value for money in moderate-to-high transmission settings. Graphical Abstract

Abstract Background Progress in malaria control has stalled in recent years and innovative surveillance and response approaches are needed to accelerate malaria control and elimination efforts in endemic areas of Africa. Building on a previous China-UK-Tanzania pilot study on malaria control, this study aimed to assess the impact of the 1,7-malaria Reactive Community-Based Testing and Response (1,7-mRCTR) approach implemented over two years in three districts of Tanzania. Methods The 1,7-mRCTR approach provides community-based malaria testing via rapid diagnostic tests and treatment in villages with the highest burden of malaria incidence based on surveillance data from health facilities. We used a difference-in-differences quasi-experimental design with linear probability models and two waves of cross-sectional household surveys to assess the impact of 1,7-mRCTR on malaria prevalence. We conducted sensitivity analyses to assess the robustness of our results, examined how intervention effects varied in subgroups, and explored alternative explanations for the observed results. Results Between October 2019 and September 2021, 244,771 community-based malaria rapid tests were completed in intervention areas, and each intervention village received an average of 3.85 rounds of 1-7mRCTR. Malaria prevalence declined from 27.4% at baseline to 11.7% at endline in the intervention areas and from 26.0% to 16.0% in the control areas. 1,7-mRCTR was associated with a 4.5-percentage-point decrease in malaria prevalence (95% confidence interval: − 0.067, − 0.023), equivalent to a 17% reduction from the baseline. In Rufiji, a district characterized by lower prevalence and where larviciding was additionally provided, 1,7-mRCTR was associated with a 63.9% decline in malaria prevalence. Conclusions The 1,7-mRCTR approach reduced malaria prevalence. Despite implementation interruptions due to the COVID-19 pandemic and supply chain challenges, the study provided novel evidence on the effectiveness of community-based reactive approaches in moderate- to high-endemicity areas and demonstrated the potential of South-South cooperation in tackling global health challenges. Graphical Abstract

BACKGROUND:The frequency and magnitude of dengue epidemics has increased dramatically throughout the tropics in the past 40 years due to unplanned urbanization, globalization and lack of effective mosquito control. The commercial capital of Tanzania, Dar es Salaam, is now experiencing regular dengue outbreaks. Three dengue serotypes have been detected in Dar es Salaam (DNV 1, 2 and 3). Without adequate vector monitoring and control, further outbreaks will certainly occur. METHODS/FINDINGS:A case series study followed 97 individuals with confirmed dengue fever (NS1 and/or IgM on rapid diagnostic test and/or PCR positive) to their households in Kinondoni, Dar es Salaam during the 2014 outbreak from a random sample of 202 confirmed cases at Mwananyamala Hospital. Kinondoni wards of Manzese, Mwananyamala, Tandale and Mabibo had the highest number of confirmed cases: 18, 13, 13 and 9 respectively. Individuals were interviewed by questionnaire on dengue prevention practices and houses were inspected for mosquito breeding sites to validate a Habitat Suitability Score (HSS). This is a tool devised to predict the productivity of any potential breeding habitats (PBHs) before the rains begin. There were 12 /312 positive Aedes breeding habitats. Drums/barrels, flowerpots and tyres were the most common breeding habitats. The HSS correctly identified 9/12 of Aedes breeding habitats. Larviciding is already conducted in urban Tanzania for malaria control and the HSS may be a useful means to train individuals on productive Aedes aegypti breeding sites should this program be extended to include dengue control. The population remains poorly informed about dengue transmission and prevention: 22% of respondents said dengue is spread from one person to another and 60% first heard about dengue when already sick. Less than 20% of respondents used personal protection and >80% thought bednets protected against dengue. Mobile phones were owned by almost all individuals followed up and have the potential of being the prime medium for dissemination of information on dengue prevention.

Abstract Background During the past six decades, remarkable success on malaria control has been made in China. The major experience could be shared with other malaria endemic countries including Tanzania with high malaria burden. Especially, China’s 1–3-7 model for malaria elimination is one of the most important refined experiences from many years’ efforts and key innovation measures for malaria elimination in China. Methods The China-UK-Tanzania pilot project on malaria control was implemented from April, 2015 to June, 2018, which was an operational research with two communities receiving the proposed interventions and two comparable communities serving as control sites. The World Health Organization “Test, Treat, Track” (WHO-T3) Initiative, which calls for every suspected case to receive a diagnostic test, every confirmed case to be treated, and for the disease to be tracked, was integrated with Chinese experiences on malaria control and elimination for exploration of a proper model tailored to the local settings. Application of China’s 1–3-7 model integrating with WHO-T3 initiative and local resources aiming at reducing the burden of malaria in terms of morbidity and mortality by 30% in the intervention communities in comparison with that at the baseline survey. Discussion The China-UK-Tanzania pilot project on malaria control was that at China's first pilot project on malaria control in Africa, exploring the feasibility of Chinese experiences by China-Africa collaboration, which is expected that the strategies and approaches used in this project could be potential for scaling up in Tanzania and African countries, and contribute to the acceleration of malaria control and elimination in Africa.