Precision mapping: An innovative tool and way forward to shrink the map, better target interventions, and accelerate toward the elimination of schistosomiasis

Spatial heterogeneity in mass drug administration from a longitudinal epidemiological study assessing transmission interruption of soil transmitted helminths in the Wolaita zone of southern Ethiopia (Geshiyaro Project)

OBJECTIVES

Deworming programmes of soil-transmitted helminths are generally monitored and evaluated by aggregating drug coverage and infection levels at a district level. However, heterogeneity in drug coverage at finer spatial scales means indicators may remain above thresholds for elimination as a public health problem or of transmission in some areas. This paper aims to highlight the misleading information that aggregating data at larger spatial scales can have for programme decision making.

METHODS

Drug coverage data from the Geshiyaro project were compared at two spatial scales with reference to the World Health Organisation's targets. District (woreda) and village (kebele) level were compared. The association between infection levels and drug coverage was analysed by fitting a weighted least-squares function to the mean intensity of infection (eggs per gram of faeces) against drug coverage.

RESULTS

The data show clearly that when the evaluation of coverage is aggregated to the district level, information on heterogeneity at a finer spatial scale is lost. Infection intensity decreases significantly (p = 0.0023) with increasing drug coverage.

CONCLUSION

Aggregating data at large spatial scales can result in prematurely ceasing deworming, prompting rapid infection bounce-back. There is a strong need to define context-specific spatial scales for monitoring and evaluating intervention programmes.

Enabling targeted mass drug administration for schistosomiasis in north-western Tanzania: Exploring the use of geostatistical modeling to inform planning at sub-district level

INTRODUCTION

Schistosomiasis is a parasitic disease in Tanzania affecting over 50% of the population. Current control strategies involve mass drug administration (MDA) campaigns at the district level, which have led to problems of over- and under-treatment in different areas. WHO guidelines have called for more targeted MDA to circumvent these problems, however a scarcity of prevalence data inhibits decision makers from prioritizing sub-district areas for MDA. This study demonstrated how geostatistics can be used to inform planning for targeted MDA.

METHODS

Geostatistical sub-district (ward-level) prevalence estimates were generated through combining a zero-inflated poisson model and kriging approach (regression kriging). To make predictions, the model used prevalence survey data collected in 2021 of 17,400 school children in six regions of Tanzania, along with several open source ecological and socio-demographic variables with known associations with schistosomiasis.

RESULTS

The model results show that regression kriging can be used to effectively predict the ward level parasite prevalence of the two species of Schistosoma endemic to the study area. Kriging was found to further improve the regression model fit, with an adjusted R-squared value of 0.51 and 0.32 for intestinal and urogenital schistosomiasis, respectively. Targeted treatment based on model predictions would represent a shift in treatment away from 193 wards estimated to be over-treated to 149 wards that would have been omitted from the district level MDA.

CONCLUSIONS

Geostatistical models can help to support NTD program efficiency and reduce disease transmission by facilitating WHO recommended targeted MDA treatment through provision of prevalence estimates where data is scarce.

High prevalence of soil-transmitted helminths and schistosomiasis among primary schoolchildren in Southwest Ethiopia: the need for health strategies alongside mass drug administration

BACKGROUND

Soil-transmitted helminths (STH) and schistosomiasis remain widely prevalent in Ethiopia. The aim of this study was to evaluate the prevalence of STH and schistosomiasis among schoolchildren in Gidi Bench district (Southern Nations, Nationalities, and People's Republic, Southwest Ethiopia) and the association with knowledge and health-related behaviors.

METHODS

A cross-sectional study was conducted. Stool samples, analyzed by the Kato-Katz technique and a knowledge, attitudes and practices questionnaire, were collected.

RESULTS

Out of 611 participants (mean age 12.8±3.1 y), 129 (21.1%) were infected with schistosomiasis and 382 (62.5%) had STH. More than 30% (n=195, 31.9%) were infected with a single intestinal parasite, while 138 (22.6%) and 47 (7.7%) were infected with two or three parasitic infections, respectively. Boys and those who did not participate in school clubs had higher infection rates (p=0.05). Lower parasitic infection was associated with using a latrine when available, washing hands and vegetables and wearing shoes regularly. Higher rates of infection were found among those who reported swimming and washing cloths and utensils in the river regularly.

CONCLUSIONS

Schistosomiasis and STH were highly prevalent among schoolchildren in Gidi Bench district. Infection rates were associated with gender, lack of knowledge on parasitic infections and unhealthy behaviors. Findings from this study may assist in decision making regarding disease prevalence and methods of control alongside mass drug administration.

Epidemiology of malaria, schistosomiasis, and geohelminthiasis amongst children 3-15 years of age during the dry season in Northern Cameroon

BACKGROUND

The double burden of malaria and helminthiasis in children poses an obvious public health challenge, particularly in terms of anemia morbidity. While both diseases frequently geographically overlap, most studies focus on mono-infection and general prevalence surveys without molecular analysis. The current study investigated the epidemiological determinants of malaria, schistosomiasis, and geohelminthiasis transmission among children in the North Region of Cameroon.

METHODOLOGY

School and pre-school children aged 3-15 year-of-age were enrolled from three communities in March 2021 using a community cross-sectional design. Capillary-blood samples were obtained, and each was examined for malaria parasites using rapid-diagnostic-test (RDT), microscopy, and PCR while hemoglobin level was measured using a hemoglobinometer. Stool samples were analyzed for Schistosoma mansoni, S. guineensis, and soil-transmitted-helminthiasis (STH) infections using the Kato Katz method, and urine samples were assessed for the presence of S. haematobium eggs (including hybrids) using the standard urine filtration technique.

RESULT

A malaria prevalence of 56% (277/495) was recorded by PCR as opposed to 31.5% (156/495) by microscopy and 37.8% (186/495) by RDT. Similarly, schistosomiasis was observed at prevalence levels of up to 13.3% (66/495) overall [S. haematobium (8.7%); S. mansoni (3.8%); mixed Sh/Sm (0.6%); mixed Sh/Sm/Sg (0.2%). Both infections were higher in males and the 3-9 year-of-age groups. A high frequency of PCR reported P. falciparum mono-infection of 81.9% (227/277) and mixed P. falciparum/P. malariae infection of 17.3% (48/277) was observed. Malaria-helminths co-infections were observed at 13.1% (65/495) with marked variation between P. falciparum/S. haematobium (50.8%, 33/65); P. falciparum/S. mansoni (16.9%, 11/65) and P. falciparum/Ascaris (9.2%, 6/65) (χ2 = 17.5, p = 0.00003). Anemia prevalence was 32.9% (163/495), categorically associated with P. falciparum (45.8%, 104/227), Pf/Sh (11.5%, 26/227), and Pf/Sm (3.9%, 9/227) polyparasitism.

CONCLUSION

Polyparasitism with malaria and helminth infections is common in school-aged children despite periodic long-lasting insecticide-treated nets (LLINs) distribution and regular school-based praziquantel (for schistosomiasis) and albendazole (for STH) campaigns. Co-existence of Plasmodium parasites and helminths infections notably Schistosoma species among children may concurrently lead to an increase in Plasmodium infection with an enhanced risk of anemia, highlighting the necessity of an integrated approach for disease control interventions.

Open-source environmental data as an alternative to snail surveys to assess schistosomiasis risk in areas approaching elimination

BACKGROUND

Although the presence of intermediate snails is a necessary condition for local schistosomiasis transmission to occur, using them as surveillance targets in areas approaching elimination is challenging because the patchy and dynamic quality of snail host habitats makes collecting and testing snails labor-intensive. Meanwhile, geospatial analyses that rely on remotely sensed data are becoming popular tools for identifying environmental conditions that contribute to pathogen emergence and persistence.

METHODS

In this study, we assessed whether open-source environmental data can be used to predict the presence of human Schistosoma japonicum infections among households with a similar or improved degree of accuracy compared to prediction models developed using data from comprehensive snail surveys. To do this, we used infection data collected from rural communities in Southwestern China in 2016 to develop and compare the predictive performance of two Random Forest machine learning models: one built using snail survey data, and one using open-source environmental data.

RESULTS

The environmental data models outperformed the snail data models in predicting household S. japonicum infection with an estimated accuracy and Cohen's kappa value of 0.89 and 0.49, respectively, in the environmental model, compared to an accuracy and kappa of 0.86 and 0.37 for the snail model. The Normalized Difference in Water Index (an indicator of surface water presence) within half to one kilometer of the home and the distance from the home to the nearest road were among the top performing predictors in our final model. Homes were more likely to have infected residents if they were further from roads, or nearer to waterways.

CONCLUSION

Our results suggest that in low-transmission environments, leveraging open-source environmental data can yield more accurate identification of pockets of human infection than using snail surveys. Furthermore, the variable importance measures from our models point to aspects of the local environment that may indicate increased risk of schistosomiasis. For example, households were more likely to have infected residents if they were further from roads or were surrounded by more surface water, highlighting areas to target in future surveillance and control efforts.

Precision and geographical prevalence mapping of schistosomiasis and soil-transmitted helminthiasis among school-aged children in selected districts of north-western Tanzania

BACKGROUND

The identification and mapping of at-risk populations at a lower administrative level than the district are prerequisites for the planning, resource allocation and design of impactful control intervention measures. Thus, the objective of the current study was to conduct sub-district precision mapping of soil-transmitted helminthiasis (STH) and schistosomiasis in 29 districts of north-western Tanzania using the current recommended World Health Organization criteria.

METHODS

A cross-sectional survey was conducted in 145 schools between March and May 2021. A urine filtration technique was used for the quantification of Schistosoma haematobium eggs, whereas quantification of Schistosoma mansoni and STH eggs was done using the Kato-Katz technique. Microhaematuria was examined using a urine dipstick.

RESULTS

The overall prevalences of any STH and schistosome infections were 9.3% [95% confidence interval (95%CI) 8.6-9.9] and 14.6% (95%CI 13.9-15.4), respectively. The overall prevalence of S. mansoni was 8.7% (95%CI 8.1-9.3), and 36.4%, 41.6%, and 21.9% of the children had low, moderate, and heavy infections, respectively. The overall prevalence of S. haematobium was 6.1% (95%CI 5.5-6.5), and 71.7% and 28.3% of the infected children had light and heavy intensity infections, respectively. The prevalence of microhaematuria was 7.3% (95%CI 6.7-7.8), with males having the highest prevalence (8.4%, P < 0.001). The prevalences of Trichuris trichiura, Ascaris lumbricoides and hookworm were, respectively, 1.3% (95%CI 0.1-1.5), 2.9% (95%CI 2.5-3.3) and 6.2% (95%CI 5.7-6.7). Most of the children infected with STH had light to moderate intensities of infection. The overall prevalence of co-infection with STH and schistosomiasis was 19.1%. The prevalence of schistosomiasis (P < 00.1) and STH (P < 0.001) varied significantly between schools and sub-districts. Schistosoma mansoni and S. haematobium were observed in 60 and 71 schools, respectively, whereas any STH was observed in 49 schools. In schools where schistosomiasis was observed, prevalence was < 10% in 90.8% of them, and ranged from ≥ 10% to < 50% in the other 9.2%. In schools where any STH was observed, the prevalence was < 10% in 87.7% of them.

CONCLUSIONS

The data reported here show that schistosomiasis and STH are widely distributed around Lake Victoria. In most of the schools where schistosomiasis and STH occurred the transmission thresholds were low. These data are important and need to be taken into consideration when decisions are made on the implementation of the next round of mass chemotherapies for schistosomiasis and STH in Tanzania.

Integrated survey of helminthic neglected tropical diseases and comparison of two mosquito sampling methods for lymphatic filariasis molecular xenomonitoring in the River Galana area, Kilifi County, coastal Kenya

A lymphatic filariasis (LF) endemic focus along the River Galana/ Sabaki in Kilifi County, coastal Kenya, provided a platform to conduct an integrated survey for three helminthic neglected tropical diseases (NTDs), namely soil-transmitted helminthiasis (STH), schistosomiasis (SCH) and LF. Additionally, the study compared the performance of two mosquito trapping methods for LF molecular xenomonitoring (MX). Cross-sectional surveys measuring STH, SCH and LF prevalence were conducted in four villages. Mosquitoes were trapped using the CDC light trap (CDC-LT) and the Ifakara A tent trap (Ifakara-TT) methods and stored in pools which were tested for Wuchereria bancrofti DNA using the real-time polymerase chain reaction assay. A total of 907 people (436 adults; 471 children) participated in the parasitological testing. Among the STH infections, Trichuris trichiura and hookworms were most prevalent among the children and adult populations, respectively. The schistosome worm eggs detected belonged to the species Schistosoma haematobium and the prevalence of the infection was generally higher among the children compared with the adult population. The prevalence of LF infection among the adult population ranged from 1.8% to 7.6% across all 4 villages (P < 0.05). A total of 3,652 mosquitoes, including Anopheles, Culex, Mansonia, and Aedes species were collected. One mosquito pool consisting of Anopheles mosquitoes tested positive for filarial DNA out of 1,055 pools that were tested. The CDC-LT caught significantly more mosquitoes compared with the Ifakara-TT (P < 0.001). This study demonstrated that integrated epidemiological surveys using standard parasitological and entomological methods can provide useful information on co-endemic parasitic diseases which could help direct interventions and surveillance activities.

Fine-scale mapping of Schistosoma mansoni infections and infection intensities in sub-districts of Makenene in the Centre region of Cameroon

Background

Schistosomiasis control relies mainly on mass drug administration of Praziquantel (PZQ) to school aged children (SAC). Although precision mapping has recently guided decision making, the sub-districts and the epidemiological differences existing between bio-ecological settings in which infected children come from were not taken into consideration. This study was designed to fill this gap by using POC-CCA and KK to comparatively determine the prevalence and infection intensities of Schistosoma mansoni (S. mansoni) and to perform fine-scale mapping of S. mansoni infections and its infection intensities with the overarching goal of identifying sub-districts presenting high transmission risk where control operations must be boosted to achieve schistosomiasis elimination.

Methodology

During a cross- sectional study conducted in Makenene, 1773 stool and 2253 urine samples were collected from SAC of ten primary schools. S. mansoni infections were identified using the point of care circulating cathodic antigen (POC-CCA) and Kato-Katz (KK) test respectively on urine and stool samples. Geographical coordinates of houses of infected SAC were recorded using a global position system device. Schistosome infections and infection intensities were map using QGIS software.

Results

The prevalence of S. mansoni inferred from POC-CCA and KK were 51.3% and 7.3% respectively. Most infected SAC and those bearing heavy infections intensities were clustered in sub-districts of Baloua, Mock-sud and Carrière. Houses with heavily-infected SAC were close to risky biotopes.

Conclusion

This study confirms the low sensitivity of KK test compared to POC-CCA to accurately identify children with schistosome infection and bearing different schistosome burden. Fine-scale mapping of schistosome infections and infection intensities enabled to identify high transmission sub-districts where control measures must be boosted to reach schistosomiasis elimination.

Although some disparities in terms of prevalence and infection intensities have been acknowledged within and between schistosomiasis endemic areas, the current control measures did not take into consideration the disparities within endemic areas. To improve the control of schistosomiasis, a fine-scale mapping of schistosome infections and their intensities were undertaken using KK in comparison to POC-CCA to identify sub-districts with potential high transmission risk and where control operations must be boosted to achieve elimination. After the identification of schistosome infections by the point of care circulating cathodic antigen (POC-CCA) and Kato-Katz (KK) test, the geographical coordinates of each infected child’s house were recorded using a global position system device (GPS). QGIS software was used to create a map showing schistosome infections and their infection intensities. Our results showed that the majority of infected children and those bearing heavy infection intensities were clustering mostly in Baloua, Carrière and Mock-Sud sub-districts of Makenene while children with light and moderate infection intensity were widely distributed and far away from risky biotopes. The fine-scale mapping of schistosome infections and their infection intensities enable to identify hotspot transmission sites where control strategy must be boosted to achieve the elimination of intestinal schistosomiasis in Makenene.

Optimizing Implementation of Preventive Chemotherapy against Soil-Transmitted Helminthiasis and Intestinal Schistosomiasis Using High-Resolution Data: Field-Based Experiences from Côte d’Ivoire

Background: Despite efforts to control neglected tropical diseases (NTDs) using preventive chemotherapy (PC), soil-transmitted helminthiases and schistosomiasis remain widely prevalent in sub-Saharan Africa. The current PC regimen in endemic settings is defined based on health district-level prevalence. This work aims to highlight the need for high-resolution data when elimination, rather than morbidity control, is the targeted goal. Methodology: Cross-sectional parasitological surveys were conducted from July to August 2019 and from September to October 2019, respectively, across the entire Dabou and Jacqueville health districts in southern Côte d’Ivoire. From every village, 60 school-aged children (6–15 years) were randomly selected and invited to provide one fresh stool sample, whereof duplicate Kato–Katz thick smears were prepared and read by two independent technicians. Principal Findings: 4338 school-aged children from 77 villages were screened from the Dabou (n = 2174; 50.12%, 39 villages) and Jacqueville (n = 2164; 49.88%, 38 villages) health districts. The prevalence of any soil-transmitted helminth (STH) infection was 12.47% and 11.09% in the Dabou and Jacqueville health districts, respectively. Species-specific district-level prevalence remained below 10%, varying between 0.51% (hookworm in Jacqueville) and 9.06% (Trichuris trichiura in Dabou). However, when considering sub-districts or villages only, several STH infection hotspots (five sub-districts with ≥20% and four villages with more than 50% infected) were observed. Schistosoma mansoni infection was found in less than 1% of the examined children in each health district. Conclusions/Significance: We conclude that keeping health district-level prevalence as a reference for PC implementation leaves many high-risk sub-districts or villages requiring PC (≥20% prevalence) untreated. To avoid maintaining those high-risk villages as STH reservoirs by skipping control interventions and jeopardizing the successes already achieved in STH control through PC during the past two decades, precision mapping is required. Further investigation is needed to assess cost-efficient approaches to implement small-scale disease surveillance.

Prevalence Mapping of Schistosoma mansoni Among Pre-school Age Children in Rwanda

Schistosoma mansoni is endemic in Rwanda, and control programs have been implemented with a special focus on school-age children (SAC), ignoring pre-school age children (pre-SAC) for which the actual prevalence of the disease is not well established. This study consisted of a cross-sectional quantitative mapping of the distribution of Schistosoma mansoni and identification of associated risk factors among pre-SAC throughout the country. The study covered all the 17 districts of Rwanda endemic for Schistosoma mansoni, with a total sample of 4,675 children enrolled from 80 purposively selected villages. The parasitological assessment of children's urine and stool samples was conducted using CCA and Kato Katz methods, respectively, for infection detection. A standard questionnaire was used to collect data on the risk factors, and geospatial assessment was performed using tablets and GPS to record geographic coordinates for plotting locations on maps using ArcGIS software. The overall prevalence of S. mansoni infection across the surveyed areas was 24 and 0.8% by CCA and Kato-Katz, respectively. Infection was significantly associated with bathing children in open water bodies. Furthermore, pre-SAC looked after by siblings (sisters) were two times as much likely to be infected compared to those looked after by mothers. Schistosomiasis control interventions are needed for pre-SAC to limit their exposure to open water bodies with expectations of adapted chemotherapy to be availed. Community-based deworming campaigns may be the best way to ensure good treatment coverage of pre-SAC in Rwanda.

The status of schistosomiasis japonica control in the Philippines: The need for an integrated approach to address a multidimensional problem

Schistosomiasis japonica remains a public health concern in many areas of the Philippines. Adequate and updated information is essential to enhance policy and service delivery toward control and elimination. Despite the efforts on schistosomiasis control in the Philippines, some challenges remain in these dimensions. An integrated surveillance system is recommended to determine the prevalence of infection in humans, animal reservoirs, and snail intermediate hosts, allowing the identification of high-priority areas for targeted interventions. This will entail the enhancement of laboratory diagnosis capacity through the use of more sensitive techniques, complemented by capacity building of concerned human and animal health professionals. Given the zoonotic nature of schistosomiasis japonica, adopting the One Health approach is essential to influence policies and interventions that may accelerate control and elimination. This can be achieved through the attainment of mass drug administration coverage targets and intensified case finding and management, robust implementation and integration of veterinary public health activities, the conduct of snail control measures, provision of safe water, sanitation, and hygiene services, and health promotion and education into the national schistosomiasis control and elimination program. This review aimed to describe the status of schistosomiasis japonica control in the Philippines in the context of human health, animal health, vector ecology and management, environmental health, and sociocultural dimensions.

Predictive Risk Mapping of Schistosomiasis in Madagascar Using Ecological Niche Modeling and Precision Mapping

Schistosomiasis is a neglected tropical disease (NTD) found throughout tropical and subtropical Africa. In Madagascar, the condition is widespread and endemic in 74% of all administrative districts in the country. Despite the significant burden of the disease, high-resolution risk maps have yet to be produced to guide national control programs. This study used an ecological niche modeling (ENM) and precision mapping approach to estimate environmental suitability and disease transmission risk. The results show that suitability for schistosomiasis is widespread and covers 264,781 km2 (102,232 sq miles). Covariates of significance to the model were the accessibility to cities, distance to water, enhanced vegetation index (EVI), annual mean temperature, land surface temperature (LST), clay content, and annual precipitation. Disease transmission risk is greatest in the central highlands, tropical east coast, arid-southwest, and northwest. An estimated 14.9 million people could be at risk of schistosomiasis; 11.4 million reside in rural areas, while 3.5 million are in urban areas. This study provides valuable insight into the geography of schistosomiasis in Madagascar and its potential risk to human populations. Because of the focal nature of the disease, these maps can inform national surveillance programs while improving understanding of areas in need of medical interventions.

GPS-based fine-scale mapping surveys for schistosomiasis assessment: a practical introduction and documentation of field implementation

BACKGROUND

Fine-scale mapping of schistosomiasis to guide micro-targeting of interventions will gain importance in elimination settings, where the heterogeneity of transmission is often pronounced. Novel mobile applications offer new opportunities for disease mapping. We provide a practical introduction and documentation of the strengths and shortcomings of GPS-based household identification and participant recruitment using tablet-based applications for fine-scale schistosomiasis mapping at sub-district level in a remote area in Pemba, Tanzania.

METHODS

A community-based household survey for urogenital schistosomiasis assessment was conducted from November 2020 until February 2021 in 20 small administrative areas in Pemba. For the survey, 1400 housing structures were prospectively and randomly selected from shapefile data. To identify pre-selected structures and collect survey-related data, field enumerators searched for the houses' geolocation using the mobile applications Open Data Kit (ODK) and MAPS.ME. The number of inhabited and uninhabited structures, the median distance between the pre-selected and recorded locations, and the dropout rates due to non-participation or non-submission of urine samples of sufficient volume for schistosomiasis testing was assessed.

RESULTS

Among the 1400 randomly selected housing structures, 1396 (99.7%) were identified by the enumerators. The median distance between the pre-selected and recorded structures was 5.4 m. A total of 1098 (78.7%) were residential houses. Among them, 99 (9.0%) were dropped due to continuous absence of residents and 40 (3.6%) households refused to participate. In 797 (83.1%) among the 959 participating households, all eligible household members or all but one provided a urine sample of sufficient volume.

CONCLUSIONS

The fine-scale mapping approach using a combination of ODK and an offline navigation application installed on tablet computers allows a very precise identification of housing structures. Dropouts due to non-residential housing structures, absence, non-participation and lack of urine need to be considered in survey designs. Our findings can guide the planning and implementation of future household-based mapping or longitudinal surveys and thus support micro-targeting and follow-up of interventions for schistosomiasis control and elimination in remote areas. Trial registration ISRCTN, ISCRCTN91431493. Registered 11 February 2020, https://www.isrctn.com/ISRCTN91431493.

Schistosoma mansoni infection risk for school-aged children clusters within households and is modified by distance to freshwater bodies

BACKGROUND

The interaction of socio-demographic and ecological factors with Schistosoma mansoni (S. mansoni) infection risk by age and the household clustering of infections between individuals are poorly understood.

METHODS

This study examined 1,832 individuals aged 5-90 years across 916 households in Mayuge District, Uganda. S. mansoni infection status and intensity were measured using Kato-Katz microscopy. Socio-demographic and ecological factors were examined as predictors of infection status and intensity using logistic and negative binomial regression models, respectively, with standard errors clustered by household. A subgroup analysis of children was conducted to examine the correlation of infection status between children and their caretakers.

FINDINGS

Infection varied within age groups based on the distance to Lake Victoria. Children aged 9-17 years and young adults aged 18-29 years who lived ≤0.50km from Lake Victoria were more likely to be infected compared to individuals of the same age who lived further away from the lake. Infections clustered within households. Children whose caretakers were heavily infected were 2.67 times more likely to be infected.

CONCLUSION

These findings demonstrate the focality of schistosome transmission and its dependence on socio-demographic, ecological and household factors. Future research should investigate the sampling of households within communities as a means of progressing towards precision mapping of S. mansoni infections.

Towards global control of parasitic diseases in the Covid-19 era: One Health and the future of multisectoral global health governance

Human parasitic infections—including malaria, and many neglected tropical diseases (NTDs)—have long represented a Gordian knot in global public health: ancient, persistent, and exceedingly difficult to control. With the coronavirus disease (Covid-19) pandemic substantially interrupting control programmes worldwide, there are now mounting fears that decades of progress in controlling global parasitic infections will be undone. With Covid-19 moreover exposing deep vulnerabilities in the global health system, the current moment presents a watershed opportunity to plan future efforts to reduce the global morbidity and mortality associated with human parasitic infections. In this chapter, we first provide a brief epidemiologic overview of the progress that has been made towards the control of parasitic diseases between 1990 and 2019, contrasting these fragile gains with the anticipated losses as a result of Covid-19. We then argue that the complementary aspirations of the United Nations Sustainable Development Goals (SDGs) and the World Health Organization (WHO)’s 2030 targets for parasitic disease control may be achieved by aligning programme objectives within the One Health paradigm, recognizing the interdependence between humans, animals, and the environment. In so doing, we note that while the WHO remains the preeminent international institution to address some of these transdisciplinary concerns, its underlying challenges with funding, authority, and capacity are likely to reverberate if left unaddressed. To this end, we conclude by reimagining how models of multisectoral global health governance—combining the WHO's normative and technical leadership with greater support in allied policy-making areas—can help sustain future malaria and NTD elimination efforts.

Scoping review of Neglected Tropical Disease Interventions and Health Promotion: A framework for successful NTD interventions as evidenced by the literature

Background

Neglected Tropical Diseases (NTDs) affect more than one billion people globally. A Public Library of Science (PLOS) journal dedicated to NTDs lists almost forty NTDs, while the WHO prioritises twenty NTDs. A person can be affected by more than one disease at the same time from a range of infectious and non-infectious agents. Many of these diseases are preventable, and could be eliminated with various public health, health promotion and medical interventions. This scoping review aims to determine the extent of the body of literature on NTD interventions and health promotion activities, and to provide an overview of their focus while providing recommendations for best practice going forward. This scoping review includes both the identification of relevant articles through the snowball method and an electronic database using key search terms. A two-phased screening process was used to assess the relevance of studies identified in the search–an initial screening review followed by data characterization using the Critical Appraisal Skills Program (CASP). Studies were eligible for inclusion if they broadly described the characteristics, methods, and approaches of (1) NTD interventions and/or (2) community health promotion.

Principal findings

90 articles met the CASP criteria partially or fully and then underwent a qualitative synthesis to be included in the review. 75 articles specifically focus on NTD interventions and approaches to their control, treatment, and elimination, while 15 focus specifically on health promotion and provide a grounding in health promotion theories and perspectives. 29 of the articles provided a global perspective to control, treatment, or elimination of NTDs through policy briefs or literature reviews. 19 of the articles focused on providing strategies for NTDs more generally while 12 addressed multiple NTDs or their interaction with other infectious diseases. Of the 20 NTDs categorized by the WHO and the expanded NTD list identified by PLOS NTDs, several NTDs did not appear in the database search on NTD interventions and health promotion, including yaws, fascioliasis, and chromoblastomycosis.

Conclusions

Based on the literature we have identified the four core components of best practices including programmatic interventions, multi sectoral and multi-level interventions, adopting a social and ecological model and clearly defining ‘community.’ NTD interventions tend to centre on mass drug administration (MDA), particularly because NTDs were branded as such based on their being amenable to MDA. However, there remains a need for intervention approaches that also include multiple strategies that inform a larger multi-disease and multi-sectoral programme. Many NTD strategies include a focus on WASH and should also incorporate the social and ecological determinants of NTDs, suggesting a preventative and systems approach to health, not just a treatment-based approach. Developing strong communities and incorporating social rehabilitation at the sublocation level (e.g. hospital) could benefit several NTDs and infectious diseases through a multi-disease, multi-sectoral, and multi-lateral approach. Finally, it is important the ‘community’ is clearly defined in each intervention, and that community members are included in intervention activities and viewed as assets to interventions.

Neglected Tropical Diseases (NTDs) affect more than one billion people globally. A person can be affected by more than one disease at the same time. Many of these diseases are preventable, and could be eliminated with various public health, health promotion and medical interventions. This scoping review aims to determine the extent of the body of literature on NTD interventions and health promotion activities, and to provide an overview of their focus while providing recommendations for best practice going forward. Through a database search and by identifying appropriate literature 75 articles were identified that specifically focus on NTD interventions and approaches to their control, treatment, and elimination, while 15 focus specifically on health promotion and provide a grounding in health promotion theories and perspectives. Based on the literature we have identified the four core components of best practices including programmatic interventions, multi sectoral and multi-level interventions, adopting a social and ecological model and clearly defining ‘community.’

Achieving equity in UHC interventions: who is left behind by neglected tropical disease programmes in Cameroon?

Background: The UN's Sustainable Development Goals (SDGs) which pledge to leave no one behind for Universal health coverage (UHC) raise the importance of ensuring equitable health outcomes and healthcare delivery. As Neglected Tropical Diseases (NTDs) affect the most disadvantaged and hard to reach populations, they are considered a litmus test for Universal health coverage.Objective: Here, we assess the challenges of implementing Mass Drug Administrations (MDAs) for schistosomiasis prevention and control, in a context of expanded treatment where both community and school-based distribution were carried out, assessing which groups are missed and developing strategies to enhance equity.Methods: This is a qualitative study applying ethnographic observations, in-depth interviews (109) and focus group discussions (6) with key informants and other community members. Participants included community drug distributors, teachers, health workers, and implementing partners across four schistosomiasis endemic regions in Cameroon. Data collected were analysed thematically.Results: Programme implementation gaps have created circumstances where indigenous farmers (originally from the region) and migrating farmers (not originally from the region known as 'strangers' and 'farm hands'), women of reproductive age and school-aged children are continuously missed in MDA efforts in Cameroon. Key implementation challenges that limit access to MDA within this context include inadequate sensitization campaigns that don't sufficiently build trust with different groups; limits in CDD training around pregnancy and reproductive health; lack of alignment between distribution and community availability and the exclusion of existing formal and informal governance structures that have established trusting community relationships.Conclusion: Through identifying key populations missed in MDAs within specific contexts, we highlight how social inclusion and equity could be increased within the Cameroonian context. A main recommendation is to strengthen trust at the community level and work with established partnerships and local governance structures that can support sustainable solutions for more equitable MDA campaigns.

Socio-demographic, not environmental, risk factors explain fine-scale spatial patterns of diarrhoeal disease in Ifanadiana, rural Madagascar

Precision health mapping is a technique that uses spatial relationships between socio-ecological variables and disease to map the spatial distribution of disease, particularly for diseases with strong environmental signatures, such as diarrhoeal disease (DD). While some studies use GPS-tagged location data, other precision health mapping efforts rely heavily on data collected at coarse-spatial scales and may not produce operationally relevant predictions at fine enough spatio-temporal scales to inform local health programmes. We use two fine-scale health datasets collected in a rural district of Madagascar to identify socio-ecological covariates associated with childhood DD. We constructed generalized linear mixed models including socio-demographic, climatic and landcover variables and estimated variable importance via multi-model inference. We find that socio-demographic variables, and not environmental variables, are strong predictors of the spatial distribution of disease risk at both individual and commune-level (cluster of villages) spatial scales. Climatic variables predicted strong seasonality in DD, with the highest incidence in colder, drier months, but did not explain spatial patterns. Interestingly, the occurrence of a national holiday was highly predictive of increased DD incidence, highlighting the need for including cultural factors in modelling efforts. Our findings suggest that precision health mapping efforts that do not include socio-demographic covariates may have reduced explanatory power at the local scale. More research is needed to better define the set of conditions under which the application of precision health mapping can be operationally useful to local public health professionals.

Piloting an integrated approach for estimation of environmental risk of Schistosoma haematobium infections in pre-school-aged children and their mothers at Barombi Kotto, Cameroon

Within schistosomiasis control, assessing environmental risk of currently non-treated demographic groups e.g. pre-school-aged children (PSAC) and their mothers is important. We conducted a pilot micro-epidemiological assessment at the crater lake of Barombi Kotto, Cameroon with GPS tracking and infection data from 12 PSAC-mother pairs (n = 24) overlaid against environmental sampling inclusive of snail, parasite and water-use information. Several high-risk locations or 'hotspots' with elevated water contact, increased intermediate snail host densities and detectable schistosome environmental DNA (eDNA) were identified. Exposure between PSAC and mother pairs was temporally and spatially associated, suggesting interventions which can benefit both groups simultaneously might be feasible. When attempting to interrupt parasite transmission in future, overlaid maps of snail, parasite and water contact data can guide fine-scale spatial targeting of environmental interventions.

Discovering, Defining, and Summarizing Persistent Hotspots in SCORE Studies

The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) conducted large field studies on schistosomiasis control and elimination in Africa. All of these studies, carried out in low-, moderate-, and high-prevalence areas, resulted in a reduction in prevalence and intensity of Schistosoma infection after repeated mass drug administration (MDA). However, in all studies, there were locations that experienced minimal or no decline or even increased in prevalence and/or intensity. These areas are termed persistent hotspots (PHS). In SCORE studies in medium- to high-prevalence areas, at least 30% of study villages were PHS. There was no consistent relationship between PHS and the type or frequency of intervention, adequacy of reported MDA coverage, and prevalence or intensity of infection at baseline. In a series of small studies, factors that differed between PHS and villages that responded to repeated MDA as expected included sources of water for personal use, sanitation, and hygiene. SCORE studies comparing PHS with villages that responded to MDA suggest the potential for PHS to be identified after a few years of MDA. However, additional studies in different social-ecological settings are needed to develop generalizable approaches that program managers can use to identify and address PHS. This is essential if goals for schistosomiasis control and elimination are to be achieved.

Contributions of the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) to Schistosomiasis Control and Elimination: Key Findings and Messages for Future Goals, Thresholds, and Operational Research

Herein, we summarize what we consider are major contributions resulting from the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) program, including its key findings and key messages from those findings. Briefly, SCORE's key findings are as follows: i) biennial mass drug administration (MDA) with praziquantel can control schistosomiasis to moderate levels of prevalence; ii) MDA alone will not achieve elimination; iii) to attain and sustain control throughout endemic areas, persistent hotspots need to be identified following a minimal number of years of annual MDA and controlled through adaptive strategies; iv) annual MDA is more effective than biennial MDA in high-prevalence areas; v) the current World Health Organization thresholds for decision-making based on the prevalence of heavy infections should be redefined; and vi) point-of-care circulating cathodic antigen urine assays are useful for Schistosoma mansoni mapping in low-to-moderate prevalence areas. The data and specimens collected and curated through SCORE efforts will continue to be critical resource for future research. Besides providing useful information for program managers and revision of guidelines for schistosomiasis control and elimination, SCORE research and outcomes have identified additional questions that need to be answered as the schistosomiasis community continues to implement effective, evidence-based programs. An overarching contribution of SCORE has been increased cohesiveness within the schistosomiasis field-oriented community, thereby fostering new and productive collaborations. Based on SCORE's findings and experiences, we propose new approaches, thresholds, targets, and goals for control and elimination of schistosomiasis, and recommend research and evaluation activities to achieve these targets and goals.

National mapping of soil-transmitted helminth and schistosome infections in Ethiopia

Background

An accurate understanding of the geographical distributions of both soil-transmitted helminths (STHs; Ascaris lumbricoides, Trichuris trichiura, and the hookworms Necator americanus and Ancylostoma duodenale) and schistosomes (SCH; Schistosoma mansoni and S. haematobium) is pivotal to be able to effectively design and implement mass drug administration (MDA) programmes. The objective of this study was to provide up-to-date data on the distribution of both STH and SCH in Ethiopia to inform the design of the national control program and to be able to efficiently achieve the 75% MDA coverage target set by the WHO.

Methods

Between 2013 and 2015, we assessed the distributions of STH and SCH infections in a nationwide survey covering 153,238 school-aged children (aged 5–15 years), from 625 woredas (districts), representing all nine Regional States and two City Administrations of Ethiopia. Nationwide disease maps were developed at the woreda level to enable recommendations on the design of the national MDA programme.

Results

The prevalence of any STH infection across the study population was 21.7%, with A. lumbricoides (12.8%) being the most prevalent STH, followed by hookworms (7.6%) and T. trichiura (5.9%). The prevalence for any SCH was 4.0% in areas where both SCH species were evaluated. Schistosoma mansoni was the most prevalent SCH (3.5 vs 0.3%). STHs were more prevalent in southwest Ethiopia, whereas SCH was found mostly in the west and northeast of the country. The prevalence of moderate-to-heavy intensity infections was 2.0% for STHs and 1.6% for SCH. For STH, a total of 251 woredas were classified as moderately (n = 178) or highly endemic (n = 73), and therefore qualify for an annual and biannual MDA program, respectively. For SCH, 67 woredas were classified as endemic and 8 as highly endemic, and hence they require every two years and annual MDA programme, respectively.

Conclusions

The results confirm that Ethiopia is endemic for both STHs and SCH, posing a significant public health problem. Following the WHO recommendations on mass drug administration, 18 and 14 million school-aged children are in need of MDA for STHs and SCH, respectively, based on the number of SACs that live on the eligible geographical areas.

Spatial distribution of leptospirosis incidence in the Upper Yangtze and Pearl River Basin, China: Tools to support intervention and elimination

BACKGROUND

Since 2011 human leptospirosis incidence in China has remained steadily low with persistent pockets of notifications reported in communities within the Upper Yangtze River Basin (UYRB) and Pearl River Basin (PRB). To help guide health authorities within these residual areas to identify communities where interventions should be targeted, this study quantified the local effect of socioeconomic and environmental factors on the spatial distribution of leptospirosis incidence and developed predictive maps of leptospirosis incidence for UYRB and PRB.

METHODS

Data on all human leptospirosis cases reported during 2005-2016 across the UYRB and PRB regions were geolocated at the county-level and included in the analysis. Bayesian conditional autoregressive (CAR) models with zero-inflated Poisson link for leptospirosis incidence were developed after adjustment of environmental and socioeconomic factors such as precipitation, normalized difference vegetation index (NDVI), modified normalized difference water index (MNDWI), land surface temperature (LST), elevation, slope, land cover, crop production, livestock density, gross domestic product and population density.

RESULTS

The relationship of environmental and socioeconomic variables with human leptospirosis incidence varied between both regions. While across UYRB incidence of human leptospirosis was associated with MNDWI and elevation, in PRB human leptospirosis incidence was significantly associated with NDVI, livestock density and land cover. Precipitation was significantly and positively associated with the spatial variation of incidence of leptospirosis in both regions. After accounting for the effect of environmental and socioeconomic factors, the predicted distribution of residual high-incidence county is potentially more widespread both in the UYRB and PRB compared to the observed distribution. In the UYRB, the highest predicted incidence was found along the border of Chongqing and Guizhou towards Sichuan basin and northwest Yunnan. The highest predicted incidence was also identified in counties in the central and lower reaches of the PRB.

CONCLUSIONS

This study demonstrated significant geographical heterogeneity in leptospirosis incidence within UYRB and PRB, providing an evidence base for prioritising targeted interventions in counties identified with the highest predicted incidence. Furthermore, environmental drivers of leptospirosis incidence were highly specific to each of the regions, emphasizing the importance of localized control measures. The findings also suggested the need to expand interventional coverage and to support surveillance and diagnostic capacity on the predicted high-risk areas.

Identification of transmission foci of Schistosoma mansoni: narrowing the intervention target from district to transmission focus in Ethiopia

BACKGROUND

Schistosoma mansoni (S. mansoni) infection is a significant public health problem in Ethiopia, and has wide distribution in the country. The impact of the disease is particularly high on school-age children. Nationwide 385 endemic districts were identified, whereby control and elimination interventions are underway using school-based annual mass drug administration (MDA) with praziquantel. The national elimination program targets endemic districts as a whole. The aim of this study was to identify the transmission foci of Schistosoma mansoni and determine prevalence of soil-transmitted helminths (STHs) in Abeshge district.

METHODS

The study was conducted from April to May, 2019 among school-age children randomly selected from public elementary schools in Abeshge district, South-central Ethiopia. Demographic information and data on risk factors of S. mansoni infection were gathered using pre-tested questionnaire. Moreover, a stool sample was collected from each child and examined using Kato-Katz thick smear technique. The data were analyzed using STATA_MP version 12.

RESULTS

A total of 389 school-age children from five public elementary schools were included in the study. The overall prevalence of S. mansoni and STHs was 19.3% (75/389) and 35% (136/389), respectively. The prevalence of S. mansoni was 60.6% in Kulit Elementary school, while it was zero in Geraba. The prevalence of S. mansoni was significantly higher among males (AOR = 2.6, 95% CI 1.3-5.1), those with habit of swimming and/or bathing in rivers (AOR = 2.9, 95%CI 1.3-5.1) and involved in irrigation activities (AOR = 2.9, 95% CI 1.0-8.3). Overall, the prevalence of S. mansoni was significantly higher among school children attending Kulit Elementary School compared to those attending the remaining schools (AOR = 12.5, 95%CI 6.2-25.1).

CONCLUSION

A wide variation of S. mansoni prevalence was observed among the school children in the different schools. Control interventions better identify and target foci of S. mansoni transmission, instead of targeting the district homogenously.

Schistosomiasis Control: Leave No Age Group Behind

Despite accelerating progress towards schistosomiasis control in sub-Saharan Africa, several age groups have been eclipsed by current treatment and monitoring strategies that mainly focus on school-aged children. As schistosomiasis poses a threat to people of all ages, unfortunate gaps exist in current treatment coverage and associated monitoring efforts, preventing subsequent health benefits to preschool-aged children as well as certain adolescents and adults. Expanding access to younger ages through the forthcoming pediatric praziquantel formulation and improving treatment coverage in older ages is essential. This should occur alongside formal inclusion of these groups in large-scale monitoring and evaluation activities. Current omission of these age groups from treatment and monitoring exacerbates health inequities and has long-term consequences for sustainable schistosomiasis control.

Sensitive diagnostic tools and targeted drug administration strategies are needed to eliminate schistosomiasis

Although preventive chemotherapy has been instrumental in reducing schistosomiasis incidence worldwide, serious challenges remain. These problems include the omission of certain groups from campaigns of mass drug administration, the existence of persistent disease hotspots, and the risk of recrudescent infections. Central to these challenges is the fact that the diagnostic tools currently used to establish the burden of infection are not sensitive enough, especially in low-endemic settings, which results in underestimation of the true prevalence of active Schistosoma spp infections. This central issue necessitates that the current schistosomiasis control strategies recommended by WHO are re-evaluated and, possibly, adapted. More targeted interventions and novel approaches have been used to estimate the prevalence of schistosomiasis, such as establishing infection burden by use of precision mapping, which provides high resolution spatial information that delineates variations in prevalence within a defined geographical area. Such information is instrumental in guiding targeted intervention campaigns. However, the need for highly accurate diagnostic tools in such strategies is a crucial factor that is often neglected. The availability of highly sensitive diagnostic tests also opens up the possibility of applying strategies of sample pooling to reduce the cost of control programmes. To interrupt the transmission of, and eventually eliminate, schistosomiasis, better local targeting of preventive chemotherapy, in combination with highly sensitive diagnostic tools, is crucial.

Assessing expanded community wide treatment for schistosomiasis: Baseline infection status and self-reported risk factors in three communities from the Greater Accra region, Ghana

BACKGROUND

This paper reports on the baseline prevalence and associated risk factor findings of a pilot, longitudinal study exploring community-wide treatment of schistosomiasis and soil-transmitted helminthiasis, using albendazole plus praziquantel in the Greater Accra region of Ghana.

METHOD

From three communities, at least, 658 individuals were enrolled into the study via random household selection. Prevalence and intensity of schistosomiasis and STH infection were determined from stool and urine samples with a questionnaire being administered in order to explore other morbidities and risk factors. Factor analysis of household demographic variables was undertaken to generate a socioeconomic score; this was then further categorised into tertiles. Proportional-odds cumulative logit generalised estimating equation (GEE) models were used to investigate categorical ordinal intensity of infection associations with morbidity. Separately, logistic GEE models were used to investigate risk factor associations with infection prevalence.

RESULTS

Both Schistosoma haematobium and S. mansoni were prevalent in the three communities, with the prevalence of S. haematobium ranging from 3.3% (24/679; 95% CI = 1.9-4.7) to 19% (114/632; 95% CI = 15.8-22.2) and S. mansoni ranging from 30% (202/679; 95% CI = 26.5-33.5) to 78.3% (409/536; 95% CI = 74.7-81.9). The total prevalence of STH across all three sites was negligible at 1.3% (24/1847; 95% CI = 0.8-1.9) comprising mainly hookworm (10/1847). Multivariable statistical models indicated males to be 2.3 (95% CI = 1.7-3.3) times more likely to have a high intensity S. mansoni infection and 1.5 (95% CI = 1.1-2) times more likely to have a high intensity of S. haematobium infection compared to females. There was no significant difference in the likelihood of infection with S. mansoni between adults and school age children (SAC), however S. haematobium infections were found to be 2.5 (95% CI = 1.8-3.5) times more likely to occur in school age children than in adults. Multivariable statistical models (adjusted for age and sex) indicated an association between schistosomiasis and a number of self-reported morbidity indicators (notably diarrhoea and blood in stool and urine). Low socio-economic status was also associated with SCH infection (OR: 2; 95% CI = 1.3-3.2).

CONCLUSION

The communities targeted by this study showed a range of Schistosoma prevalence's of infection, from hypo-endemic through to meso-endemic and hyper-endemic. The prevalence of SCH across the different age groups in the study locations highlights the large number of individuals currently being left out of the standard morbidity control method of annual treatment of the SAC.

Zoonotic transmission of intestinal helminths in southeast Asia: Implications for control and elimination

Intestinal helminths are extremely widespread and highly prevalent infections of humans, particularly in rural and poor urban areas of low and middle-income countries. These parasites have chronic and often insidious effects on human health and child development including abdominal problems, anaemia, stunting and wasting. Certain animals play a fundamental role in the transmission of many intestinal helminths to humans. However, the contribution of zoonotic transmission to the overall burden of human intestinal helminth infection and the relative importance of different animal reservoirs remains incomplete. Moreover, control programmes and transmission models for intestinal helminths often do not consider the role of zoonotic reservoirs of infection. Such reservoirs will become increasingly important as control is scaled up and there is a move towards interruption and even elimination of parasite transmission. With a focus on southeast Asia, and the Philippines in particular, this review summarises the major zoonotic intestinal helminths, risk factors for infection and highlights knowledge gaps related to their epidemiology and transmission. Various methodologies are discussed, including parasite genomics, mathematical modelling and socio-economic analysis, that could be employed to improve understanding of intestinal helminth spread, reservoir attribution and the burden associated with infection, as well as assess effectiveness of interventions. For sustainable control and ultimately elimination of intestinal helminths, there is a need to move beyond scheduled mass deworming and to consider animal and environmental reservoirs. A One Health approach to control of intestinal helminths is proposed, integrating interventions targeting humans, animals and the environment, including improved access to water, hygiene and sanitation. This will require coordination and collaboration across different sectors to achieve best health outcomes for all.

Precision mapping of snail habitat provides a powerful indicator of human schistosomiasis transmission

Recently, the World Health Organization recognized that efforts to interrupt schistosomiasis transmission through mass drug administration have been ineffective in some regions; one of their new recommended strategies for global schistosomiasis control emphasizes targeting the freshwater snails that transmit schistosome parasites. We sought to identify robust indicators that would enable precision targeting of these snails. At the site of the world's largest recorded schistosomiasis epidemic-the Lower Senegal River Basin in Senegal-intensive sampling revealed positive relationships between intermediate host snails (abundance, density, and prevalence) and human urogenital schistosomiasis reinfection (prevalence and intensity in schoolchildren after drug administration). However, we also found that snail distributions were so patchy in space and time that obtaining useful data required effort that exceeds what is feasible in standard monitoring and control campaigns. Instead, we identified several environmental proxies that were more effective than snail variables for predicting human infection: the area covered by suitable snail habitat (i.e., floating, nonemergent vegetation), the percent cover by suitable snail habitat, and size of the water contact area. Unlike snail surveys, which require hundreds of person-hours per site to conduct, habitat coverage and site area can be quickly estimated with drone or satellite imagery. This, in turn, makes possible large-scale, high-resolution estimation of human urogenital schistosomiasis risk to support targeting of both mass drug administration and snail control efforts.

More medicines alone cannot ensure the treatment of neglected tropical diseases

Neglected tropical diseases afflict more than 1 billion of the world's poorest people. Pharmaceutical donations of preventive chemotherapy for neglected tropical diseases enable the largest en masse treatment campaigns globally with respect to the number of people targeted for treatment. However, the blanket distribution of medicines at no cost to individuals in need of treatment does not guarantee that those individuals are treated. In this Personal View, we aim to examine the next steps that need to be taken towards ensuring equitable treatment access, including health system integration and the role of endemic countries in ensuring medicines are delivered to patients. We argue that the expansion of medicine donation programmes and the development of new medicines are not the primary solutions to sustaining and expanding the growth of neglected tropical disease programmes. Treatment is often not verified by a medical professional, independent surveyor, or national programme officer. Additionally, access to medicines might not be equitable across at-risk populations, and treatment targets for disease control remain largely unmet within many endemic countries. To enable equitable access and efficient use of existing medicines, research is needed now on how best to integrate the treatment of neglected tropical diseases into local health systems. A comprehensive approach should be used, which combines mass drug administration with on-demand access to treatment. Increased commitment by endemic countries, when possible, around the ownership of treatment campaigns is essential to improve access to medicines for neglected tropical diseases.