Elimination of lymphatic filariasis as a public health problem in Malawi.

BACKGROUND: Lymphatic filariasis (LF) is a parasitic disease transmitted by mosquitoes, causing severe pain, disfiguring, and disabling clinical conditions such as lymphoedema and hydrocoele. LF is a global public health problem affecting 72 countries, primarily in Africa and Asia. Since 2000, the World Health Organization (WHO) has led the Global Programme to Eliminate Lymphatic Filariasis (GPELF) to support all endemic regions. This paper focuses on the achievements of the Malawi LF Elimination Programme between 2000 and 2020 to eliminate LF as a public health problem, making it the second sub-Saharan country to receive validation from the WHO. METHODOLOGY/PRINCIPAL FINDINGS: The Malawi LF Programme addressed the widespread prevalence of LF infection and disease across the country, using the recommended WHO GPELF strategies and operational research initiatives in collaboration with key national and international partners. First, to stop the spread of infection (i.e., interrupt transmission) and reduce the circulating filarial antigen prevalence from as high as 74.4% to below the critical threshold of 1-2% prevalence, mass drug administration (MDA) using a two-drug regime was implemented at high coverage rates (>65%) of the total population, with supplementary interventions from other programmes (e.g., malaria vector control). The decline in prevalence was monitored and confirmed over time using several impact assessment and post-treatment surveillance tools including the standard sentinel site, spot check, and transmission assessment surveys and alternative integrated, hotspot, and easy-access group surveys. Second, to alleviate suffering of the affected populations (i.e., control morbidity) the morbidity management and disability prevention (MMDP) package of care was implemented. Specifically, clinical case estimates were obtained via house-to-house patient searching activities; health personnel and patients were trained in self-care protocols for lymphoedema and/or referrals to hospitals for hydrocoele surgery; and the readiness and quality of treatment and services were assessed with new survey tools. CONCLUSIONS: Malawi's elimination of LF will ensure that future generations are not infected and suffer from the disfiguring and disabling disease. However, it will be critical that the Malawi LF Elimination programme remains vigilant, focussing on post-elimination surveillance and MMDP implementation and integration into routine health systems to support long-term sustainability and ongoing success. SUMMARY: Lymphatic filariasis, also known as elephantiasis, is a disabling, disfiguring, and painful disease caused by a parasite that infected mosquitoes transmit to millions of people worldwide. Since 2000, the Global Programme to Eliminate Lymphatic Filariasis (GPELF) has supported endemic countries such as Malawi in south-eastern Africa, to eliminate the disease as a public health problem. The Malawi National LF Elimination Programme has worked tirelessly over the past two decades to implement the GPELF recommended strategies to interrupt the transmission with a two-drug regime, and to alleviate suffering in patients with lymphoedema and/or hydrocoele through morbidity management and disability prevention. Additionally, the LF Programme has collaborated with national and international stakeholders to implement a range of supplementary operational research projects to address outstanding knowledge gaps and programmatic barriers. In 2020, the World Health Organisation validated that Malawi had successfully eliminated LF as a public health problem, making it the second country in sub-Saharan Africa to achieve this, which is remarkable given that Malawi previously had very high infection rates. The LF Programme now remains vigilant, putting its efforts towards post-elimination surveillance and the continued implementation of care for patients with chronic conditions. Malawi's elimination of LF will ensure that future generations are not affected by this devastating disease.

Mental health and neglected tropical diseases - the neglected dimension of burden: identifying the challenges and understanding the burden.

Mental health co-morbidity and the Neglected Tropical Diseases (NTDs) has been highlighted as a major component of the ill health. The impact of mental illness is considered to be significantly underestimated in the calculations of the overall Disability-Adjusted Life Years (DALYs). This commentary discusses the DALY burden of anxiety, depression and associated stigma of NTDs. The economic losses incurred as a result of mental health conditions is assessed, and the impact on caregivers and families. It recommends that mental health care is incorporated into NTDs programme planning and implementation. Priority research is the estimation of the NTD burden of depressive and anxiety disorders and neuropsychiatric conditions of NTDs and an evaluation of the economic costs of mental illness derived from NTDs causation.

Quantifying conflict zones as a challenge to certification of Guinea worm eradication in Africa: a new analytical approach.

OBJECTIVES: To quantify conflict events and access across countries that remain to be certified free of transmission of Dracunculus medinensis (Guinea worm disease) or require postcertification surveillance as part of the Guinea Worm Eradication Programme (GWEP). SETTING AND PARTICIPANTS: Populations living in Guinea worm affected areas across seven precertification countries and 13 postcertification sub-Saharan African countries. OUTCOME MEASURES: The number of conflict events and rates per 100 000 population, the main types of conflict and actors reported to be responsible for events were summarised and mapped across all countries. Chad and Mali were presented as case studies. Guinea worm information was based on GWEP reports. Conflict data were obtained from the Armed Conflict Location and Event Data Project. Maps were created using ArcGIS V.10.7 and access was measured as regional distance and time to cities. RESULTS: More than 980 000 conflict events were reported between 2000 and 2020, with a significant increase since 2018. The highest number and rates were reported in precertification Mali (n=2556; 13.0 per 100 000), South Sudan (n=2143; 19.4), Democratic Republic of Congo (n=7016; 8.1) and postcertification Nigeria (n=6903; 3.4), Central Africa Republic (n=1251; 26.4), Burkina Faso (n=2004; 9.7). Violence against civilians, protests and battles were most frequently reported with several different actors involved including Unidentified Armed Groups and Boko Haram. Chad and Mali had contracting epidemiological and conflict situations with affected regions up to 700 km from the capital or 10 hours to the nearest city. CONCLUSIONS: Understanding the spatial-temporal patterns of conflict events, identifying hotspots, the actors responsible and their sphere of influence is critical for the GWEP and other public health programmes to develop practical risk assessments, deliver essential health interventions, implement innovative surveillance, determine certification and meet the goals of eradication.

Are current preventive chemotherapy strategies for controlling and eliminating neglected tropical diseases cost-effective?

Neglected tropical diseases (NTDs) remain a significant cause of morbidity and mortality in many low-income and middle-income countries. Several NTDs, namely lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminthiases (STH) and trachoma, are predominantly controlled by preventive chemotherapy (or mass drug administration), following recommendations set by the WHO. Over one billion people are now treated for NTDs with this strategy per year. However, further investment and increased domestic healthcare spending are urgently needed to continue these programmes. Consequently, it is vital that the cost-effectiveness of preventive chemotherapy is understood. We analyse the current estimates on the cost per disability-adjusted life year (DALY) of the preventive chemotherapy strategies predominantly used for these diseases and identify key evidence gaps that require further research. Overall, the reported estimates show that preventive chemotherapy is generally cost-effective, supporting WHO recommendations. More specifically, the cost per DALY averted estimates relating to community-wide preventive chemotherapy for lymphatic filariasis and onchocerciasis were particularly favourable when compared with other public health interventions. Cost per DALY averted estimates of school-based preventive chemotherapy for schistosomiasis and STH were also generally favourable but more variable. Notably, the broader socioeconomic benefits are likely not being fully captured by the DALYs averted metric. No estimates of cost per DALY averted relating to community-wide mass antibiotic treatment for trachoma were found, highlighting the need for further research. These findings are important for informing global health policy and support the need for continuing NTD control and elimination efforts.

The history of the neglected tropical disease movement.

The history of the neglected tropical disease movement is seen through the lens of authors who worked during the last 4 decades in different roles and in different settings, from Western-based laboratories to clinical roles in endemic countries and in critical policy roles in the World Health Organization (WHO). The authors seek to identify key players from the introduction of the word 'neglected' by the late Kenneth Warren in his Rockefeller Foundation-supported Great Neglected Diseases of Mankind movement through to the more recent developments after the London Declaration of 2012. The role of the various actors-endemic countries, major pharmaceutical companies, the WHO, non-government development organizations, bilateral donors and academia-are discussed. The critical events and decisions are highlighted that were essential enabling factors in creating a viable and successful movement and with a resultant massive global public health and antipoverty impact. The importance of advocacy is emphasized in creating the momentum to establish a globally recognized public health 'brand' as a target in the United Nations Sustainable Development Goals.

African regional progress and status of the programme to eliminate lymphatic filariasis: 2000-2020.

To eliminate lymphatic filariasis (LF) by 2020, the World Health Organization (WHO) has launched a campaign against the disease. Since the launch in 2000, significant progress has been made to achieve this ambitious goal. In this article we review the progress and status of the LF programme in Africa through the WHO neglected tropical diseases preventive chemotherapy databank, the Expanded Special Project for Elimination of Neglected Tropical Diseases (ESPEN) portal and other publications. In the African Region there are 35 countries endemic for LF. The Gambia was reclassified as not requiring preventive chemotherapy in 2015, while Togo and Malawi eliminated LF as a public health problem in 2017 and 2020, respectively. Cameroon discontinued mass drug administration (MDA) and transitioned to post-MDA surveillance to validate elimination. The trajectory of coverage continues to accelerate; treatment coverage increased from 0.1% in 2000 to 62.1% in 2018. Geographical coverage has also significantly increased, from 62.7% in 2015 to 78.5% in 2018. In 2019, 23 of 31 countries requiring MDA achieved 100% geographic coverage. Although much remains to be done, morbidity management and disability prevention services have steadily increased in recent years. Vector control interventions conducted by other programmes, particularly malaria vector control, have had a profound effect in stopping transmission in some endemic countries in the region. In conclusion, significant progress has been made in the LF programme in the region while we identify the key remaining challenges in achieving an Africa free of LF.

Podoconiosis: key priorities for research and implementation.

Podoconiosis is a non-infectious tropical lymphoedema causing swelling of the lower legs. Podoconiosis is associated with stigma, depression and reduced productivity, resulting in significant socio-economic impacts for affected individuals, families and communities. It is caused by barefoot exposure to soils and affects disadvantaged populations. Evidence from the past 5 y suggests that podoconiosis is amenable to public health interventions, e.g. footwear and hygiene-based morbidity management, which reduce acute clinical episodes. Although much has been learned in recent years, advances in care for these patients and worldwide control requires further reliable and relevant research. To develop a comprehensive global control strategy, the following key research priorities are important: better understanding of the global burden of podoconiosis through extended worldwide mapping, development of new point-of-care diagnostic methods and approaches to define the presence of the environmental characteristics that contribute to the development of the condition, improving treatment through an increased understanding of the pathogenesis of dermal changes over time, improved understanding of optimal ways of providing patient care at the national level, including research to optimize behavioural change strategies, determine the optimum package of care and integrate approaches to deliver robust surveillance, monitoring and evaluation of control programmes.

Cutaneous leishmaniasis and co-morbid major depressive disorder: A systematic review with burden estimates.

BACKGROUND: Major depressive disorder (MDD) associated with chronic neglected tropical diseases (NTDs) has been identified as a significant and overlooked contributor to overall disease burden. Cutaneous leishmaniasis (CL) is one of the most prevalent and stigmatising NTDs, with an incidence of around 1 million new cases of active CL infection annually. However, the characteristic residual scarring (inactive CL) following almost all cases of active CL has only recently been recognised as part of the CL disease spectrum due to its lasting psychosocial impact. METHODS AND FINDINGS: We performed a multi-language systematic review of the psychosocial impact of active and inactive CL. We estimated inactive CL (iCL) prevalence for the first time using reported WHO active CL (aCL) incidence data that were adjusted for life expectancy and underreporting. We then quantified the disability (YLD) burden of co-morbid MDD in CL using MDD disability weights at three severity levels. Overall, we identified 29 studies of CL psychological impact from 5 WHO regions, representing 11 of the 50 highest burden countries for CL. We conservatively calculated the disability burden of co-morbid MDD in CL to be 1.9 million YLDs, which equalled the overall (DALY) disease burden (assuming no excess mortality in depressed CL patients). Thus, upon inclusion of co-morbid MDD alone in both active and inactive CL, the DALY burden was seven times higher than the latest 2016 Global Burden of Disease study estimates, which notably omitted both psychological impact and inactive CL. CONCLUSIONS: Failure to include co-morbid MDD and the lasting sequelae of chronic NTDs, as exemplified by CL, leads to large underestimates of overall disease burden.

Environmental factors associated with the distribution of Loa loa vectors Chrysops spp. in Central and West Africa: seeing the forest for the trees.

BACKGROUND: Loiasis is caused by the filarial parasite Loa loa, which is widespread through Central and West Africa and largely confined the tropical equatorial rainforests. The tabanid flies Chrysops silacea and Chrysops dimidiata are the main vectors driving transmission. This study aimed to better define the spatial distribution and ecological niche of the two vectors to help define spatial-temporal risk and target appropriate, timely intervention strategies for filariasis control and elimination programmes. METHODS: Chrysops spp. distributions were determined by collating information from the published literature into a database, detailing the year, country, locality, latitude/longitude and species collected. Environmental factors including climate, elevation and tree canopy characteristics were summarised for each vector from data obtained from satellite modelled data or imagery, which were also used to identify areas with overt landcover changes. The presence of each Chrysops vector was predicted using a maximum entropy species distribution modelling (MaxEnt) method. RESULTS: A total of 313 location-specific data points from 59 published articles were identified across seven loiasis endemic countries. Of these, 186 sites were included in the climate and elevation analysis, and due to overt landcover changes, 83 sites included in tree canopy analysis and MaxEnt model. Overall, C. silacea and C. dimidiata were found to have similar ranges; annual mean temperature (24.6 °C and 24.1 °C, respectively), annual precipitation (1848.6 mm and 1868.8 mm), elevation (368.8 m and 400.6 m), tree canopy cover (61.4% and 66.9%) and tree canopy height (22.4 m and 25.1 m). MaxEnt models found tree canopy coverage was a significant environmental variable for both vectors. CONCLUSIONS: The Chrysops spp. database and large-scale environmental analysis provides insights into the spatial and ecological parameters of the L. loa vectors driving transmission. These may be used to further delineate loiasis risk, which will be important for implementing filariasis control and elimination programmes in the equatorial rainforest region of Central and West Africa.

Neglected Tropical Diseases and Mental Health: Progress, Partnerships, and Integration.

Neglected tropical diseases (NTDs) are increasingly recognised as major drivers of psychosocial morbidity in affected individuals and their caregivers. Nevertheless, there has remained a lack of prioritisation at the policy level of some of the most stigmatising and chronic NTDs, with subsequent under-representation within NTD programmes. In response, the Neglected Tropical Disease/Non-Governmental Organization/Network (NNN) has established a Mental Wellbeing and Stigma Task Group (MWS) to address these issues through a comprehensive research agenda. In our article, we highlight the progress in understanding the scope of the mental health impact of NTDs and the innovative practice emerging in this area. Finally, we examine opportunities for integration of mental and physical health for individuals with NTDs.

Innovative Surveillance Strategies to Support the Elimination of Filariasis in Africa.

Lymphatic filariasis (LF) and onchocerciasis are two neglected tropical diseases (NTDs) of public health significance targeted for global elimination. The World Health Organization (WHO) African Region is a priority region, with the highest collective burden of LF and onchocerciasis globally. Coendemic loiasis further complicates elimination due to the risk of adverse events associated with ivermectin treatment. A public health framework focusing on health-related data, systematic collection of data, and analysis and interpretation of data is used to highlight the range of innovative surveillance strategies required for filariasis elimination. The most recent and significant developments include: rapid point-of-care test (POCT) diagnostics; clinical assessment tools; new WHO guidelines; open-access online data portals; mHealth platforms; large-scale prevalence maps; and the optimisation of mathematical models.

Increasing evidence of low lymphatic filariasis prevalence in high risk Loa loa areas in Central and West Africa: a literature review.

In West and Central Africa, there is a need to establish the prevalence of Wuchereria bancrofti in areas that are co-endemic for Loa loa, in order to implement the appropriate strategies to scale-up interventions for the elimination of lymphatic filariasis (LF). Due to the risk of severe adverse events (SAEs) to ivermectin in individuals with high L. loa microfilaraemia, the current strategy recommended by the World Health Organization (WHO) is twice yearly mass drug administration (MDA) with albendazole, supplemented by vector control targeting the Anopheles vectors. Defining W. bancrofti prevalence in areas co-endemic with L. loa is complicated by the cross-reactivity of rapid diagnostic immunochromatographic card tests (ICT), widely used for LF mapping, in individuals with high L. loa microfilaraemia. This has probably resulted in the overestimation of LF prevalence, triggering the implementation of MDA strategies, which may be unnecessary and wasteful of the limited resources for elimination programme implementation. Here we review the literature and present historical evidence, which uniformly highlight low or no prevalence of W. bancrofti infection and/or clinical LF cases across five Central African countries, in more than 30 different geographical areas covering 280 individual sites and > 22,000 individuals tested within high risk L. loa areas. This highlights the very limited information available on LF prevalence in L. loa areas, and potentially has major policy implications, which could shift the focus towards revised mapping criteria to verify low or no W. bancrofti prevalence in high risk L. loa areas. In this situation, revising the current WHO strategy from MDA, to focus more on ensuring high and effective vector control, through insecticide treated/long-lasting impregnated bednets (ITNs/LLINs), integration of point-of-care test-and-treat options into health systems, and consolidating closer links with the malaria control programme may be a more effective and appropriate use of the limited resources and drug donations available for LF elimination.

Integrated risk mapping and landscape characterisation of lymphatic filariasis and loiasis in South West Nigeria.

Nigeria has the heaviest burden of lymphatic filariasis (LF) in sub-Saharan Africa, which is caused by the parasite Wuchereria bancrofti and transmitted by Anopheles mosquitoes. LF is targeted for elimination and the national programme is scaling up mass drug administration (MDA) across the country to interrupt transmission. However, in some regions the co-endemicity of the filarial parasite Loa loa (loiasis) is an impediment due to the risk of severe adverse events (SAEs) associated with the drug ivermectin. To better understand factors influencing LF elimination in loiasis areas, this study conducted a cross-sectional survey on the prevalence and co-distribution of the two infections, and the potential demographic, landscape, human movement, and intervention-related risk factors at a micro-level in the South West zone of Nigeria. In total, 870 participants from 10 communities on the fringe of a meso-endemic loiasis area of Osun State were selected. LF prevalence was measured by clinical assessment and using the rapid immunochromatographic test (ICT) to detect W. bancrofti antigen. Overall LF prevalence was low with ICT positivity ranging from 0 to 4.7%, with only 1 hydrocoele case identified. Males had significantly higher ICT positivity than females (3.2% vs 0.8%). Participants who did not sleep under a bed net had higher ICT positivity (4.0%) than those who did (1.3%). ICT positivity was also higher in communities with less tree coverage/canopy height (2.5-2.8%) than more forested areas with greater tree coverage/canopy height (0.9-1.0%). In comparison, loiasis was determined using the rapid assessment procedure for loiasis (RAPLOA), and found in all 10 communities with prevalence ranging from 1.4% to 11.2%. No significant difference was found by participants' age or sex. However, communities with predominately shrub land (10.4%) or forested land cover (6.2%) had higher prevalence than those with mosaic vegetation/croplands (2.5%). Satellite imagery showed denser forested areas in higher loiasis prevalence communities, and where low or no ICT positivity was found. Only one individual was found to be co-infected. GPS tracking of loiasis positive cases and controls also highlighted denser forested areas within higher loiasis risk communities and the sparser land cover in lower-risk communities. Mapping LF-loiasis distributions against landscape characteristics helped to highlight the micro-heterogeneity, identify potential SAE hotspots, and determine the safest and most appropriate treatment strategy.