Cross-border collaboration for neglected tropical disease efforts-Lessons learned from onchocerciasis control and elimination in the Mano River Union (West Africa)

Neglected tropical diseases in Republic of Guinea: disease endemicity, case burden and the road towards the 2030 target

Neglected tropical diseases (NTDs) predominantly affect vulnerable and marginalized populations in tropical and subtropical areas and globally affect more than one billion people. In Guinea, the burden of NTDs is estimated to be >7.5 disability-adjusted life years per million inhabitants. Currently the Guinea NTDs master plan (2017-2020) has identified eight diseases as public health problems: onchocerciasis, lymphatic filariasis, trachoma, schistosomiasis and soil-transmitted helminthiasis, leprosy, human African trypanosomiasis and Buruli ulcer. In this review we discuss the past and the current case burden of the priority NTDs in Guinea, highlight the major milestones and discuss current and future areas of focus for achieving the 2030 target outlined by the World Health Organization.

Neglected tropical diseases activities in Africa in the COVID-19 era: the need for a "hybrid" approach in COVID-endemic times

With the coronavirus disease 2019 (COVID-19) pandemic showing no signs of abating, resuming neglected tropical disease (NTD) activities, particularly mass drug administration (MDA), is vital. Failure to resume activities will not only enhance the risk of NTD transmission, but will fail to leverage behaviour change messaging on the importance of hand and face washing and improved sanitation-a common strategy for several NTDs that also reduces the risk of COVID-19 spread. This so-called "hybrid approach" will demonstrate best practices for mitigating the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by incorporating physical distancing, use of masks, and frequent hand-washing in the delivery of medicines to endemic communities and support action against the transmission of the virus through water, sanitation and hygiene interventions promoted by NTD programmes. Unless MDA and morbidity management activities resume, achievement of NTD targets as projected in the WHO/NTD Roadmap (2021-2030) will be deferred, the aspirational goal of NTD programmes to enhance universal health coverage jeopardised and the call to 'leave no one behind' a hollow one. We outline what implementing this hybrid approach, which aims to strengthen health systems, and facilitate integration and cross-sector collaboration, can achieve based on work undertaken in several African countries.

Onchocerciasis Elimination: Progress and Challenges

Onchocerciasis is a parasitic infection caused by the filarial nematode Onchocerca volvulus and transmitted through the bites of black flies of the genus Similium that breed in rivers and streams. The impact of mass treatment with ivermectin and supplemented by vector control in some countries has changed the global scene of onchocerciasis. There has been reported progress made in elimination of onchocerciasis in central and southern American countries and in some localities in Africa. The target for elimination in the Americas has been set at 2022 while for 12 countries in Africa this is expected in 2030. This review was conducted to examine the current status of onchocerciasis elimination at the global level and report on progress made. Literature searches were made through PubMed, articles in English or English abstracts, reports and any other relevant articles related to the subject. The global burden of onchocerciasis is progressively reducing and is no longer a public health problem in some regions. However, programs are challenged with a range of issues: cross-border transmission, diagnostic tools, Loa loa co-endemicity, limited workforce in entomology and maintaining enthusiasm among community drug distributors. More concerted effort using appropriate tools is required to overcome the challenges.

The Galabat-Metema cross-border onchocerciasis focus: The first coordinated interruption of onchocerciasis transmission in Africa

Background

Onchocerciasis transmission across international borders is not uncommon, yet a coordinated cross border stops mass drug administration (MDA) decision has not been documented.

Methods/Principle findings

The Galabat-Metema focus involves neighboring districts on the border between Sudan and Ethiopia. Mass drug administration (MDA) was provided once and subsequently twice per year in this focus, with twice-per-year beginning in Ethiopia’s Metema subfocus in 2016 and in the Sudan’s Galabat subfocus in 2008. Ov16 ELISA-based serosurveys were conducted in 6072 children under 10 years of age in the Metema subfocus in 2014, and 3931 in the Galabat in 2015. Between 2014 and 2016, a total of 27,583 vector Simulium damnosum flies from Metema and 9,148 flies from Galabat were tested by pool screen PCR for Onchocerca volvulus O-150 DNA. Only 8 children were Ov16 seropositive (all in the Metema subfocus); all were negative by skin snip PCR. The upper limit of the 95% confidence interval (UCL) for Ov16 seropositive was <0.1% for the overall focus and 0.14 positive fly heads per 2000 (UCL = 0.39/2000). However, an entomological ‘hotspot’ was detected on the Wudi Gemzu river in Metema district. The hotspot was confirmed when 4 more positive fly pools were found on repeat testing in 2017 (1.04 L3/2000 flies (UCL = 2.26/2000). Information exchange between the two countries led to stopping MDA in a coordinated fashion in 2018, with the exception of the hotspot at Wudi Gemzu, where MDA with ivermectin was increased to every three months to hasten interruption of transmission.

Conclusion

Coordinated stop MDA decisions were made by Sudan and Ethiopia based on data satisfying the World Health Organization’s criteria for interruption of onchocerciasis transmission. Definitions of entomological ‘hotspots’ and buffer zones around the focus are proposed.

Onchocerciasis is a vector-borne tropical disease caused by the parasitc worm, Onchocerca volvulus. The vector is Simulium flies that breed in fast flowing rivers and streams. The infection can cause skin disease and loss of vision, giving risk to the common name of ‘river blindness’ for the condition. Ivermectin (Mectizan) mass drug administration (MDA) given at high coverage for many years can interrupt transmission such that MDA can eventually be stopped. The present paper provides highlights of onchocerciasis transmission interruption in the first known coordinated international cross border focus with ivermectin MDA program in Africa, where 99% of the global onchocerciasis burden exists. This focus known as Galabat-Metema is shared between Ethiopia and Sudan, both of which have established a nationwide policy for elimination of onchocerciasis. The paper provides the history of MDA in the border area and the results leading a coordinated end to MDA in the focus in 2017.

Reaching the last mile: main challenges relating to and recommendations to accelerate onchocerciasis elimination in Africa

BACKGROUND

Onchocerciasis (river blindness), caused by the filarial worm species Onchocerca volvulus, is a serious vector-borne neglected tropical disease (NTD) of public health and socioeconomic concern. It is transmitted through the bite of black flies of the genus Simulium, and manifested in dermal and ocular lesions. Ninety-nine percent of the total global risk and burden of onchocerciasis is in Africa. This scoping review examines the key challenges related to the elimination of onchocerciasis by 2020-2025 in Africa, and proposes recommendations to overcome the challenges and accelerate disease elimination. To find relevant articles published in peer-reviewed journals, a search of PubMed and Google Scholar databases was carried out.

MAIN TEXT

Rigorous regional interventions carried out to control and eliminate onchocerciasis in the past four decades in Africa have been effective in bringing the disease burden under control; it is currently not a public health problem in most endemic areas. Notably, transmission of the parasite is interrupted in some hyperendemic localities. Recently, there has been a policy shift from control to complete disease elimination by 2020 in selected countries and by 2025 in the majority of endemic African countries. The WHO has published guidelines for stopping mass drug administration (MDA) and verifying the interruption of transmission and elimination of human onchocerciasis. Therefore, countries have revised their plans, established a goal of disease elimination in line with an evidence based decision to stop MDA and verify elimination, and incorporated it into their NTDs national master plans. Nevertheless, challenges remain pertaining to the elimination of onchocerciasis in Africa. The challenge we review in this paper are: incomplete elimination mapping of all transmission zones, co-endemicity of onchocerciasis and loiasis, possible emergence of ivermectin resistance, uncoordinated cross-border elimination efforts, conflict and civil unrest, suboptimal program implementation, and technical and financial challenges. This paper also proposes recommendations to overcome the challenges and accelerate disease elimination. These are: a need for complete disease elimination mapping, a need for collaborative elimination activities between national programs, a need for a different drug distribution approach in conflict-affected areas, a need for routine monitoring and evaluation of MDA programs, a need for implementing alternative treatment strategies (ATSs) in areas with elimination anticipated beyond 2025, and a need for strong partnerships and continued funding.

CONCLUSIONS

National programs need to regularly monitor and evaluate the performance and progress of their interventions, while envisaging the complete elimination of onchocerciasis from their territory. Factors hindering the targeted goal of interruption of parasite transmission need to be identified and remedial actions should be taken. If possible and appropriate, ATSs need to be implemented to accelerate disease elimination by 2025.

Cross-border issues: an important component of onchocerciasis elimination programmes

Endemic areas that involve national or local borders present an important challenge to the success of elimination of onchocerciasis; such cross-border endemic foci require special attention to ensure that programme activities are unified. It is vital that national programmes and the committees responsible for the oversight of progress towards elimination are aware and address such issues in their current planning and programmatic activities. Although international borders that intersect endemic zones present the biggest challenge, intracountry borders (such as between administrative districts or loiasis endemic and non-loiasis areas) can also pose problems. The recent change in the onchocerciasis programme from disease control to transmission interruption, given the historical lack of treatment in hypo-endemic areas, may have increased the already relatively high number of cross-national scenarios in Africa. It is vital that all national programmes address the issue of any cross-border endemic areas as a matter of urgency and include this important issue in their elimination plans.

Transitioning from river blindness control to elimination: steps toward stopping treatment

The transition from onchocerciasis control to elimination requires country programmes to rethink their approach to a variety of activities as they move from addressing morbidity to addressing transmission of the parasite. Although the 2016 WHO guidelines provide extensive recommendations, it was beyond the scope of the document to provide guidance on all aspects of the transition. This paper will discuss some of the important issues that programmes are grappling with as they transition to elimination and provide some potential approaches that programmes can use to address them. Although there are some data to support some aspects of the suggested approaches, operational research will be needed to generate data to support these approaches further and to determine how programmes could best tailor them to their own unique epidemiological challenges. Good communication between the national programmes and the broader global programme will facilitate the clear articulation of programmatic challenges and the development of the evidence to support programme decision-making.

Sharing public health data and information across borders: lessons from Southeast Asia

Background

The importance of data and information sharing for the prevention and control of infectious diseases has long been recognised. In recent years, public health emergencies such as avian influenza, drug-resistant malaria, and Ebola have brought renewed attention to the need for effective communication channels between health authorities, particularly in regional contexts where neighbouring countries share common health threats. However, little empirical research has been conducted to date to explore the range of factors that may affect the transfer, exchange, and use of public health data and expertise across borders, especially in developing contexts.

Methods

To explore these issues, 60 interviews were conducted with domestic and international stakeholders in Cambodia and Vietnam, selected amongst those who were involved in regional public health programmes and networks. Data analysis was structured around three categories mapped across the dataset: (1) the nature of shared data and information; (2) the nature of communication channels; and (3) how information flow may be affected by the local, regional, and global system of rules and arrangements.

Results

There has been a great intensification in the circulation of data, information, and expertise across borders in Southeast Asia. However, findings from this study document ways in which the movement of data and information from production sites to other places can be challenging due to different standards and practices, language barriers, different national structures and rules that govern the circulation of health information inside and outside countries, imbalances in capacities and power, and sustainability of financing arrangements.

Conclusions

Our study highlights the complex socio-technical nature of data and information sharing, suggesting that best practices require significant involvement of an independent third-party brokering organisation or office, which can redress imbalances between country partners at different levels in the data sharing process, create meaningful communication channels and make the most of shared information and data sets.

Onchodermatitis: Where Are We Now?

Onchocerciasis causes debilitating pruritus and rashes as well as visual impairment and blindness. Prior to control measures, eye disease was particularly prominent in savanna areas of sub-Saharan Africa whilst skin disease was more common across rainforest regions of tropical Africa. Mass drug distribution with ivermectin is changing the global scene of onchocerciasis. There has been successful progressive elimination in Central and Southern American countries and the World Health Organization has set a target for elimination in Africa of 2025. This literature review was conducted to examine progress regarding onchocercal skin disease. PubMed searches were performed using keywords 'onchocerciasis', 'onchodermatitis' and 'onchocercal skin disease' over the past eight years. Articles in English, or with an English abstract, were assessed for relevance, including any pertinent references within the articles. Recent progress in awareness of, understanding and treatment of onchocercal skin disease is reviewed with particular emphasis on publications within the past five years. The global burden of onchodermatitis is progressively reducing and is no longer seen in children in many formerly endemic foci.

The role of the NGDO Coordination Group for the Elimination of Onchocerciasis

The NGDO Coordination Group for the Control of Onchocerciasis was launched in 1992, and with the paradigm shift from control of disease to elimination of onchocerciasis transmission, the Group shifted its orientation to that new paradigm in 2013. It also changed its name, replacing 'control' with 'elimination.' In doing so, the Group has repositioned itself to build on the successes of the past to finish the job it began over 25 years ago.

Onchocerca volvulus infection and serological prevalence, ocular onchocerciasis and parasite transmission in northern and central Togo after decades of Simulium damnosum s.l. vector control and mass drug administration of ivermectin

Background

Mass drug administration (MDA) of ivermectin has become the main intervention to control onchocerciasis or “river blindness”. In Togo, after many years of MDA, Onchocerca volvulus infection has declined dramatically, and elimination appears achievable, but in certain river basins the current situation remains unknown. We have conducted parasitological, serological, ophthalmological, and entomological assessments in northern and central Togo within the river basins of Ôti, Kéran and Mô.

Methodology/Principal findings

Examinations were completed in 1,455 participants from 11 onchocerciasis sentinel villages, and O. volvulus transmission by Simulium damnosum sensu lato (s.l.) was evaluated. In children (aged 1–10 years), the prevalence of microfilariae (Mf) was 2.3% and in adults it ranged from 5.1 to 13.3%. Positive IgG4 responses to O. volvulus adult (crude) worm antigen (OvAg) and the recombinant Ov16 antigen were in all-ages 48.7% and 34.4%, and 29.1% and 14.9% in children, respectively. In the river basin villages of Kéran, Mô and Ôti, the IgG4 seroprevalences to OvAg in children were 51.7%, 23.5% and 12.7%, respectively, and to the Ov16 antigen 33.3% (Kéran) and 5.2% (Ôti). Onchocerciasis ocular lesions (punctate keratitis, evolving iridocyclitis and chorioretinitis) were observed in children and young adults. O. volvulus-specific DNA (Ov150) was detected by poolscreen in vector samples collected from Tchitchira/Kéran(22.8%), Bouzalo/Mô(11.3%), Baghan/Mô(2.9%) and Pancerys/Ôti(4.9%); prevalences of O. volvulus infection in S. damnosum s.l. were, respectively, 1%, 0.5%, 0.1% and 0.2%.

Conclusions/Significance

In the northern and central river basins in Togo, interruption of O. volvulus transmission has not yet been attained. Patent O. volvulus infections, positive antibody responses, progressive ocular onchocerciasis were diagnosed, and parasite transmission by S. damnosum s.l. occurred close to the survey locations. Future interventions may require approaches selectively targeted to non-complying endemic populations, to the seasonality of parasite transmission and national onchocerciasis control programs should harmonize cross-border MDA as a coordinated intervention.

Mass drug administration (MDA) with ivermectin has become the main tool in the efforts to control and eliminate onchocerciasis (“river blindness”). In some areas, and after many years of MDA, levels of Onchocerca volvulus infection (the causative parasite) have declined greatly, and elimination appears achievable. In certain river basins of northern and central Togo, the present epidemiological situation remains unknown. The guidelines of the World Health Organization recommend that before ivermectin MDA can be stopped, interruption of O. volvulus transmission must be demonstrated. To this end, parasitological, serological, ophthalmological, and entomological assessments were conducted in the Ôti, Kéran and Mô river basins. O. volvulus infections and positive antibody responses were found in children aged ≤10 years and adults. Progressive ocular onchocerciasis was diagnosed, and parasite transmission by Simulium damnosum s.l. (the disease vector) occurred close to the survey locations. Thus, O. volvulus transmission continues in northern and central Togo, and future interventions may require approaches selectively adapted to seasonal migration of non-complying endemic populations in and out of the river basins, as well as seasonal transmission by the vectors. National control programmes should harmonize cross-border MDA as a coordinated intervention.

"Cross-border collaboration in onchocerciasis elimination in Uganda: progress, challenges and opportunities from 2008 to 2013"

Background

Until recently onchocerciasis was prevalent in 37 out of 112 districts of Uganda with at least 3.8 million people at risk of contracting the disease, but following the launching of community-directed treatment with ivermectin (CDTI) in 1996 and the adoption of an onchocerciasis elimination policy in 2007, the country has made significant progress in combating the disease. By 2015, interruption of transmission had been achieved in ten of the 17 onchocerciasis foci, but cross-border foci remained particularly problematic, and therefore within the onchocerciasis elimination framework, Uganda embarked upon addressing these issues with its neighbouring countries, namely the Democratic Republic of Congo (DRC) and South Sudan. This paper summarises the experience of Uganda in addressing cross-border issues on onchocerciasis elimination with DRC.

Main achievements and lessons learned

The key achievements comprise of the adoption of an elimination policy by the Government of Uganda, cross-border meetings, training DRC technical staff and entomological/ epidemiological surveys. The first strategy meeting was held in Kampala in 2008, but the second strategy meeting was not held in Kinshasa until 2013. The involvement of the high-level officials from the Ministry of Health of DRC was critical for the success of the second strategy meeting, and was precipitated by collaboration to control an outbreak of Ebola Virus. Both meetings demonstrated the political commitment of endemic countries and allowed the implementation of a joint action plan. Important steps in establishing a mutually respected elimination targets was agreed on during cross border meetings.

The African Programme for Onchocerciasis Control facilitated and funded these initial meetings, thus overcoming some political and financial challenges faced by both countries. This highlighted the need for multilateral organisations such as the Expanded Special Project for the Elimination of Neglected Tropical Diseases in cross-border activities for other Neglected Tropical Diseases.

The collaboration between both countries facilitated the training of technical staff from DRC in entomology which facilitated joint cross-border activities to update the epidemiological understanding of onchocerciasis in Beni and Mahagi districts in North Kivu and Ituri Provinces respectively. In Nebbi district, Uganda, 23.7% of crabs were infested by the vector Simulium neavei compared with 6.3% in Mahagi district, DRC. Rapid Epidemiological Assessment (REA) revealed nodule prevalence of 3.2% and onchodermatitis at 26.4% from five villages in DRC.

Conclusion

Political commitment of both countries and the support from APOC allowed two cross-border meetings which were critical for the implementation of initial cross border activities for onchocerciasis elimination.

The interruption of Onchocerca volvulus and Wuchereria bancrofti transmission by integrated chemotherapy in the Obongi focus, North Western Uganda

Intervention

Few studies have documented the interruption of onchocerciasis and Lymphatic Filariasis (LF) by integrated chemotherapy in Uganda. The study describes the interruption of transmission of the two diseases co-endemic in Obongi focus, north western Uganda. Base line data for Onchocerciasis and LF were collected in 1994 and 2006, respectively. Annual mass drug administration for onchocerciasis (Ivermectin) and Lymphatic Filariasis (Ivermectin + albendazole) was conducted for 20 and 6 years, respectively. Thereafter, assessments by skin snip, larval searches in rivers and human landing catches were performed. Children <10 years were screened for IgG4 antibodies using Ov16 ELISA technique in 2013. LF Pre-TAS and TAS1 were conducted in sentinel sites. ITN coverage and utilization for the implementation unit was also reported.

Intervention coverage

Onchocerciasis treatment coverage was <80% but improved with the introduction of CDTI in 1999. While for LF, effective coverage of >65% was achieved in the six treatment rounds. Household ownership of ITN’s and utilization was 96% and 72.4%., respectively.

Impact

Parasitological examinations conducted for onchocerciasis among 807 adults and children, revealed a reduction in mf prevalence from 58% in 1994 to 0% in 2012. Entomological monitoring conducted at the two sites had no single Simulium damnosum fly caught. Serological analysis using Ov16 ELISA for onchocerciasis revealed that out of the 3,308 children <10 years old screened in 2013, only 3/3308 (0.091%) positive cases were detected. All Ov16 positive children were negative when tested for patent infection by skin snip PCR. A reduction in LF microfilaria prevalence from 2.5% (n = 13/522) in 2006 to 0.0% (n = 602) in 2014 was observed. LF TAS1 conducted in 2015 among 1,532 children 6–7 years, all were negative for antigens of W. bancrofti.

Conclusion

The results concluded that interruption of onchocerciasis and LF has been achieved.