Fine-scale maps of malaria incidence to inform risk stratification in Laos.

BACKGROUND: Malaria risk maps are crucial for controlling and eliminating malaria by identifying areas of varying transmission risk. In the Greater Mekong Subregion, these maps guide interventions and resource allocation. This article focuses on analysing changes in malaria transmission and developing fine-scale risk maps using five years of routine surveillance data in Laos (2017-2021). The study employed data from 1160 geolocated health facilities in Laos, along with high-resolution environmental data. METHODS: A Bayesian geostatistical framework incorporating population data and treatment-seeking propensity was developed. The models incorporated static and dynamic factors and accounted for spatial heterogeneity. RESULTS: Results showed a significant decline in malaria cases in Laos over the five-year period and a shift in transmission patterns. While the north became malaria-free, the south experienced ongoing transmission with sporadic outbreaks. CONCLUSION: The risk maps provided insights into changing transmission patterns and supported risk stratification. These risk maps are valuable tools for malaria control in Laos, aiding resource allocation, identifying intervention gaps, and raising public awareness. The study enhances understanding of malaria transmission dynamics and facilitates evidence-based decision-making for targeted interventions in high-risk areas.

Progress towards malaria elimination in the Greater Mekong Subregion: perspectives from the World Health Organization.

Malaria remains a global health challenge, disproportionately affecting vulnerable communities. Despite substantial progress, the emergence of anti-malarial drug resistance poses a constant threat. The Greater Mekong Subregion (GMS), which includes Cambodia, China's Yunnan province, Lao People's Democratic Republic, Myanmar, Thailand, and Viet Nam has been the epicentre for the emergence of resistance to successive generations of anti-malarial therapies. From the perspective of the World Health Organization (WHO), this article considers the collaborative efforts in the GMS, to contain Plasmodium falciparum artemisinin partial resistance and multi-drug resistance and to advance malaria elimination. The emergence of artemisinin partial resistance in the GMS necessitated urgent action and regional collaboration resulting in the Strategy for Malaria Elimination in the Greater Mekong Subregion (2015-2030), advocating for accelerated malaria elimination interventions tailored to country needs, co-ordinated and supported by the WHO Mekong malaria elimination programme. The strategy has delivered substantial reductions in malaria across all GMS countries, with a 77% reduction in malaria cases and a 97% reduction in malaria deaths across the GMS between 2012 and 2022. Notably, China was certified malaria-free by WHO in 2021. Countries' ownership and accountability have been pivotal, with each GMS country outlining its priorities in strategic and annual work plans. The development of strong networks for anti-malarial drug resistance surveillance and epidemiological surveillance was essential. Harmonization of policies and guidelines enhanced collaboration, ensuring that activities were driven by evidence. Challenges persist, particularly in Myanmar, where security concerns have limited recent progress, though an intensification and acceleration plan aims to regain momentum. Barriers to implementation can slow progress and continuing innovation is needed. Accessing mobile and migrant populations is key to addressing remaining transmission foci, requiring effective cross-border collaboration. In conclusion, the GMS has made significant progress towards malaria elimination, particularly in the east where several countries are close to P. falciparum elimination. New and persisting challenges require sustained efforts and continued close collaboration. The GMS countries have repeatedly risen to every obstacle presented, and now is the time to re-double efforts and achieve the 2030 goal of malaria elimination for the region.

Malaria risk stratification in Lao PDR guides program planning in an elimination setting.

Malaria in Lao People's Democratic Republic (Lao PDR) has declined rapidly over the last two decades, from 279,903 to 3926 (99%) cases between 2001 and 2021. Elimination of human malaria is an achievable goal and limited resources need to be targeted at remaining hotspots of transmission. In 2022, the Center of Malariology, Parasitology and Entomology (CMPE) conducted an epidemiological stratification exercise to assign districts and health facility catchment areas (HFCAs) in Lao PDR based on malaria risk. The stratification used reported malaria case numbers from 2019 to 2021, risk maps derived from predictive modelling, and feedback from malaria staff nationwide. Of 148 districts, 14 were deemed as burden reduction (high risk) districts and the remaining 134 as elimination (low risk) districts. Out of 1235 HFCAs, 88 (7%) were classified as highest risk, an improvement from 187 (15%) in the last stratification in 2019. Using the HFCA-level stratification, the updated stratification resulted in the at-risk population (total population in Strata 2, 3 and 4 HFCAs) declining from 3,210,191 to 2,366,068, a 26% decrease. CMPE are using the stratification results to strengthen targeting of resources. Updating national stratifications is a necessary exercise to assess progress in malaria control, reassign interventions to the highest risk populations in the country and ensure greatest impact of limited resources.

Health promoting schools in urban, semi-urban and rural Lao PDR.

Health promoting school activities have been implemented in developing countries, but their experiences have not been fully shared. Our objective is to explore the differences of health promoting school status in urban, semi-urban and rural areas in Lao PDR. To accomplish this we evaluated 138 schools in three provinces using a checklist developed by the government school health taskforce. We interviewed first through fifth grade pupils, school principals, food vendors, community chiefs, and observed school environments. We found that urban and semi-urban schools had higher scores than rural schools in the areas of, "personal health and life skills," "healthy school environment," "health and nutrition services," and "common disease control and prevention." However, semi-urban and rural schools showed better results than urban schools for some questions within the "school and community partnerships" component. When the results of individual schools were examined, there was considerable variation. We found a tendency for higher scores in urban areas, which went down for semi-urban areas and further decreased for rural areas. However, we also found differences among schools within each study site. In conclusion, we found not only a large difference among urban, semi-urban and rural schools but also clear differences in health promoting school status among schools within each study site in Lao PDR. Based on the results, we recommend that each school adopt a tailored approach for the health promoting school programme based upon an analysis of its own scores.

Towards effective prevention and control of helminth neglected tropical diseases in the Western Pacific Region through multi-disease and multi-sectoral interventions.

Neglected tropical diseases (NTDs) cause serious health, social and economic burdens in the countries of the World Health Organization Western Pacific Region. Among the NTDs, helminth infections are particularly prominent with regard to the number of infected individuals and health impact. Co-endemicity is common among impoverished and marginalized populations. To achieve effective and sustainable control of helminth NTDs, a deeper understanding of the social-ecological systems governing their endemicity and strategies beyond preventive chemotherapy are required to tackle the multiple causes of infection and re-infection. We discuss the feasibility of implementing multi-disease, multi-sectoral intervention packages for helminth NTDs in the Western Pacific Region. After reviewing the main determinants for helminth NTD endemicity and current control strategies, key control activities that involve or concern other programmes within and beyond the health sector are discussed. A considerable number of activities that have an impact on more than one helminth NTD are identified in a variety of sectors, suggesting an untapped potential for synergies. We also highlight the challenges of multi-sectoral collaboration, particularly of involving non-health sectors. We conclude that multi-sectoral collaboration for helminth NTD control is feasible if the target diseases and sectors are carefully selected. To do so, an incentive analysis covering key stakeholders in the sectors is crucial, and the disease-control strategies need to be well understood. The benefits of multi-disease, multi-sectoral approaches could go beyond immediate health impacts by contributing to sustainable development, raising educational attainment, increasing productivity and reducing health inequities.

Coverage and costs of a school deworming programme in 2007 targeting all primary schools in Lao PDR.

Infections with soil-transmitted helminths (STHs) are among the commonest infections in Lao PDR. Recent investigation in this country showed that intestinal helminths currently infect the majority of school-aged children. The Lao Government has addressed the problem by organizing regular anthelminthic chemotherapy with mebendazole 500mg for school and pre-school children in conjunction with health education activities incorporated into the national school curriculum. The school deworming campaign in Lao PDR reached a national coverage rate of 95% at a cost of US$0.124/head for two rounds of deworming per year. The programme operates under the umbrella of the national school health programme. After 1 year (two rounds of deworming) the intervention reduced the prevalence of Ascaris lumbricoides from 60% to 20% and of Trichuris trichiura from 42% to 31%. Although infection was not eliminated by the deworming interventions, over 90% of those children who remain infected had a 'light' infection. The virtual absence of high and moderate intensity infection demonstrates the effectiveness of periodical deworming in reducing morbidity due to STHs. We expect that additional rounds of deworming will further reduce the STH prevalence in Lao PDR.

Large-scale preventive chemotherapy for the control of helminth infection in Western Pacific countries: six years later.

In 2001, Urbani and Palmer published a review of the epidemiological situation of helminthiases in the countries of the Western Pacific Region of the World Health Organization indicating the control needs in the region. Six years after this inspiring article, large-scale preventive chemotherapy for the control of helminthiasis has scaled up dramatically in the region. This paper analyzes the most recent published and unpublished country information on large-scale preventive chemotherapy and summarizes the progress made since 2000. Almost 39 million treatments were provided in 2006 in the region for the control of helminthiasis: nearly 14 million for the control of lymphatic filariasis, more than 22 million for the control of soil-transmitted helminthiasis, and over 2 million for the control of schistosomiasis. In general, control of these helminthiases is progressing well in the Mekong countries and Pacific Islands. In China, despite harboring the majority of the helminth infections of the region, the control activities have not reached the level of coverage of countries with much more limited financial resources. The control of food-borne trematodes is still limited, but pilot activities have been initiated in China, Lao People's Democratic Republic, and Vietnam.