Economic impact of onchocerciasis control through the African Programme for Onchocerciasis Control: an overview

Mapping the burden of onchocercal skin disease

Onchocerciasis is a neglected tropical disease caused by a nematode parasite, Onchocerca volvulus, and transmitted by bites of Simulium blackflies which breed near fast-flowing rivers. In humans, thousands of microfilariae (immature worms) migrate to the skin and eyes where they cause pathology. Historically, much research was devoted to the serious effect of blindness, from which the disease earns its alternative name of 'river blindness'. Mapping the burden of onchocercal skin disease (OSD) was expedited by the development of a clinical classification and grading system that facilitated comparison of data from different countries. After successful field testing in Nigeria, the classification scheme was used in a multicountry study in seven endemic sites, to estimate the true burden of OSD across Africa. High levels of OSD were found, affecting 28% of the population. A new control programme, the African Programme for Onchocerciasis Control (APOC) was launched in 20 countries using annual doses of ivermectin, donated by Merck & Co., Inc. The multicountry study also found a close correlation between the levels of itching and OSD with the level of endemicity, as determined by the prevalence of onchocercal nodules. This enabled APOC to use Rapid Epidemiological Mapping of Onchocerciasis, which entailed identifying likely vector breeding sites near rivers, then sampling 50 adult males in nearby villages to determine the prevalence of nodules and delineate which villages required treatment. Onchocerciasis is now targeted for elimination in Africa, and the challenge is to complete Onchocerciasis Elimination Mapping of hypoendemic areas using serology.

Socioeconomic impacts of elimination of onchocerciasis in Abu-Hamed focus, northern Sudan: lessons after elimination

OBJECTIVES

Onchocerciasis is one of the most devastating neglected tropical diseases and it is mostly prevalent in Africa. The disease has important heavy social and economic burdens on the infected populations including low productivity, unemployment, social isolation, and stigma. A cross-sectional study was implemented using a well-established questionnaire to investigate the socio-economic impacts of Onchocerciasis elimination in Abu-Hamed, River Nile State, Sudan in 2015; 512 participants in ten affected communities were interviewed.

RESULTS

Our findings revealed that these communities are recovering from the social and economic burden of the diseases. Ninety percent of the research participants reported general satisfaction about elimination of the disease in their community, 48.3% of them attended secondary school or university. Only 0.6% reported unemployment. Also, 25.3% and 24.7% of the participants were workers and farmers respectively. Except about the vector biting and nuisance, the majority of the respondents (90%) had no complain related to the disease after the elimination. Also, 90.5% of the participants reported either stable or increase in their work performance during the last 12 months. About 93.8% of the respondents were engaged in normal daily life activities and involved in happy events like marriage and giving birth during the last 12 months.

Analysis of severe adverse effects following community-based ivermectin treatment in the Democratic Republic of Congo

BACKGROUND

The progress of mass, community-directed, treatment with ivermectin (CDTI) for onchocerciasis control was disrupted by severe adverse effects (SAE) in the Democratic Republic of Congo (DRC). The study aimed at determining the frequency of post-CDTI SAE as well as factors associated with the occurrence of SAE.

METHODS

Our retrospective study relied on SAE collection cards, as archived by the DRC Ministry of Health, and compiled for people who benefited from ivermectin treatment then further developed SAE. The study included 945 post-CDTI SAE recorded in DRC between 2003 and 2017. These cases occurred in 15 projects out of 22 projects implemented in the country. All cards were reviewed and analysed.

RESULTS

Between the years 2003 and 2017, the total average population treated was around 15,552,588 among which 945 cases of SAE were registered in DR Congo, i.e. 6 cases of SAE for 100,000 persons treated per year. 55 deaths related to post-CDTI SAE were recorded, which represents 5.8% of all cases of SAE. Non-neurological SAE were dominated by severe headaches (74.8%), myalgia (64.0%) and arthralgia (62.7%). Neurological SAE were mainly coma (94.1%), motor deficit (75.4%) and palpebral subconjunctival haemorrhages (38.8%). Factors associated with the occurrence of SAE were: male, age over 18 years old, alcohol consumption, hemp intake and the presence of loiasis. The study also highlighted weaknesses of the National Program for Onchocerciasis Control (NPOC)  in terms of awareness campaigns among the population.

CONCLUSION

Co-endemicity of loiasis and onchocerciasis is one of the key factors responsible for the occurrence of SAE following ivermectin treatment. Mobilization of resources necessary to the appropriate management of SAE and awareness of populations are essential to achieve onchocerciasis control in DRC.

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.

Economic evaluations of onchocerciasis interventions: a systematic review and research needs

OBJECTIVE

To provide a systematic review of economic evaluations that has been conducted for onchocerciasis interventions, to summarise current key knowledge and to identify research gaps.

METHOD

A systematic review of the literature was conducted on the 8th of August 2018 using the PubMed (MEDLINE) and ISI Web of Science electronic databases. No date or language stipulations were applied to the searches.

RESULTS

We identified 14 primary studies reporting the results of economic evaluations of onchocerciasis interventions, seven of which were cost-effectiveness analyses. The studies identified used a variety of different approaches to estimate the costs of the investigated interventions/programmes. Originally, the studies only quantified the benefits associated with preventing blindness. Gradually, methods improved and also captured onchocerciasis-associated skin disease. Studies found that eliminating onchocerciasis would generate billions in economic benefits. The majority of the cost-effectiveness analyses evaluated annual mass drug administration (MDA). The estimated cost per disability-adjusted life year (DALY) averted of annual MDA varies between US$3 and US$30 (cost year variable).

CONCLUSIONS

The cost benefit and cost effectiveness of onchocerciasis interventions have consistently been found to be very favourable. This finding provides strong evidential support for the ongoing efforts to eliminate onchocerciasis from endemic areas. Although these results are very promising, there are several important research gaps that need to be addressed as we move towards the 2020 milestones and beyond.

Modelling the impact of larviciding on the population dynamics and biting rates of Simulium damnosum (s.l.): implications for vector control as a complementary strategy for onchocerciasis elimination in Africa

BACKGROUND

In 2012, the World Health Organization set goals for the elimination of onchocerciasis transmission by 2020 in selected African countries. Epidemiological data and mathematical modelling have indicated that elimination may not be achieved with annual ivermectin distribution in all endemic foci. Complementary and alternative treatment strategies (ATS), including vector control, will be necessary. Implementation of vector control will require that the ecology and population dynamics of Simulium damnosum (sensu lato) be carefully considered.

METHODS

We adapted our previous SIMuliid POPulation dynamics (SIMPOP) model to explore the impact of larvicidal insecticides on S. damnosum (s.l.) biting rates in different ecological contexts and to identify how frequently and for how long vector control should be continued to sustain substantive reductions in vector biting. SIMPOP was fitted to data from large-scale aerial larviciding trials in savannah sites (Ghana) and small-scale ground larviciding trials in forest areas (Cameroon). The model was validated against independent data from Burkina Faso/Côte d'Ivoire (savannah) and Bioko (forest). Scenario analysis explored the effects of ecological and programmatic factors such as pre-control daily biting rate (DBR) and larviciding scheme design on reductions and resurgences in biting rates.

RESULTS

The estimated efficacy of large-scale aerial larviciding in the savannah was greater than that of ground-based larviciding in the forest. Small changes in larvicidal efficacy can have large impacts on intervention success. At 93% larvicidal efficacy (a realistic value based on field trials), 10 consecutive weekly larvicidal treatments would reduce DBRs by 96% (e.g. from 400 to 16 bites/person/day). At 70% efficacy, and for 10 weekly applications, the DBR would decrease by 67% (e.g. from 400 to 132 bites/person/day). Larviciding is more likely to succeed in areas with lower water temperatures and where blackfly species have longer gonotrophic cycles.

CONCLUSIONS

Focal vector control can reduce vector biting rates in settings where a high larvicidal efficacy can be achieved and an appropriate duration and frequency of larviciding can be ensured. Future work linking SIMPOP with onchocerciasis transmission models will permit evaluation of the impact of combined anti-vectorial and anti-parasitic interventions on accelerating elimination of the disease.

Field-Based Evidence of Single and Few Doses of Annual Ivermectin Treatment Efficacy in Eliminating Skin Microfilaria Load after a Decade of Intervention

Background

Impact assessment of community-based ivermectin treatment control of onchocerciasis is required to determine its effectiveness. This study was conducted to evaluate geographic coverage and demographic ivermectin treatment compliance.

Methods

The number of village dosage were obtained from the community based distributors. Bioclinical data of participants comprising gender, age, number of treatment received from inception and dosage were obtained. Each participant was subjected to physical examination for palpable nodule and other skin clinical signs and symptoms of onchocerciasis. Visual acuity test was done using the Snellen illiterate E-chart. Eye examination was performed using touch loop and handheld ophthalmoscope. Skin snips from both iliac crests were incubated overnight at 28–32°C and emerged micrifilaria enumerated under an inverted microscope. The changes in epidemiological indices at post-decade of mass drug administration were compared with baseline data.

Results

Village annual ivermectin treatment doses averaged 62%, ranging between 10–100%. Individual treatment compliance rate was generally low with an average of 4 treatments and a range between 0–10. Despite variations in treatment compliance, there were significant improvements in some onchocercal morbidities. These include reduced number and severity of itching, visual impairment, papular onchodermatitis, onchocercomata (palpable nodules) and leopard skin. Ivermectin treatment halted development of new blind cases, except the case of a man who had optic nerve disease and became blind 2 years after ivermectin treatment had commenced. There was a significant overall reduction in parasite burden with very low mean skin microfilaria load of 1.7mf per skin snip and 3.7% skin mf prevalence, compared to baseline data of 17.7mf and 37.9% respectively. The palpable nodule was also drastically reduced from 14.5% to 6.4%. Outcome of this study has practically demonstrated that even a single dose ivermectin treatment is capable of clearing skin mf load on a long-term basis. This assertion is exemplified by the result obtained from Bomjock village that had taken treatment only at inception, and the prevalence rate was reduced from 70% to about 9.0% at post-decade of intervention.

Conclusion

It can be inferred that high demographic coverage with annual treatment doses, it is feasible to attain a shorter time (within a decade) contrary to the anticipated longer-term projection.

Productivity Loss Related to Neglected Tropical Diseases Eligible for Preventive Chemotherapy: A Systematic Literature Review

BACKGROUND

Neglected Tropical Diseases (NTDs) not only cause health and life expectancy loss, but can also lead to economic consequences including reduced ability to work. This article describes a systematic literature review of the effect on the economic productivity of individuals affected by one of the five worldwide most prevalent NTDs: lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminths (ascariasis, trichuriasis, and hookworm infection) and trachoma. These diseases are eligible to preventive chemotherapy (PCT).

METHODOLOGY/PRINCIPAL FINDINGS

Eleven bibliographic databases were searched using different names of all NTDs and various keywords relating to productivity. Additional references were identified through reference lists from relevant papers. Of the 5316 unique publications found in the database searches, thirteen papers were identified for lymphatic filariasis, ten for onchocerciasis, eleven for schistosomiasis, six for soil-transmitted helminths and three for trachoma. Besides the scarcity in publications reporting the degree of productivity loss, this review revealed large variation in the estimated productivity loss related to these NTDs.

CONCLUSIONS

It is clear that productivity is affected by NTDs, although the actual impact depends on the type and severity of the NTD as well as on the context where the disease occurs. The largest impact on productivity loss of individuals affected by one of these diseases seems to be due to blindness from onchocerciasis and severe schistosomiasis manifestations; productivity loss due to trachoma-related blindness has never been studied directly. However, productivity loss at an individual level might differ from productivity loss at a population level because of differences in the prevalence of NTDs. Variation in estimated productivity loss between and within diseases is caused by differences in research methods and setting. Publications should provide enough information to enable readers to assess the quality and relevance of the study for their purposes.

Exploring Consumer Perceptions and Economic Burden of Onchocerciasis on Households in Enugu State, South-East Nigeria

Introduction

Onchocerciasis or river blindness constitutes a major burden to households especially in resource-poor settings, causing a significant reduction in household productivity. There has been renewed interest from policy makers to reduce the burden of Neglected Tropical Diseases (NTDs) such as onchocerciasis on individuals and households. This paper provides new information on the patient’s perceptions of onchocerciasis and its economic burden on households in South-eastern Nigeria. The information will be useful to health providers and policy makers for evidence-informed resource allocation decisions.

Methods

Information was generated from a cross-sectional household survey conducted in Achi community, Oji River Local Government Area (LGA) of Enugu State, Southeast Nigeria. A pre-tested interviewer-administered questionnaire was used to collect data. A total of 747 households were visited randomly and data were collected using pre-tested interviewer administered questionnaire from 370 respondents. The respondents’ knowledge of the cause of symptoms of the disease, costs incurred for seeking treatment and productivity losses were elicited. Data were analyzed using tabulations and inferential statistics. A socio-economic status (SES) index was used to disaggregate some key variables by SES quintiles for equity analysis.

Results

Many people had more than one type of manifestation of onchocerciasis. However, more than half of the respondents (57%) had no knowledge of the cause of their symptoms. Male respondents had significantly more knowledge of the cause of symptoms than females (P = 0.04) but knowledge did not differ across SES (P = 0.82). The average monthly treatment cost per respondent was US$ 14.0. Drug cost (US$10) made up about 72% of total treatment cost. The per capita productivity loss among patients was US$16 and it was higher in the poorest (Q1) (US$20) and the third SES quintiles (Q3) (US$21). The average monthly productivity loss among caregivers was US$3.5.

Conclusion

Onchocerciasis still constitutes considerable economic burden on patients due to the high cost of treatment and productivity loss. Prioritizing domestic resource allocation for the treatment of onchocerciasis is important for significant and sustained reduction in the burden of the disease. In addition, focused health promotion interventions such as health education campaigns should be scaled up in onchocerciasis-endemic communities.

Onchocerciasis is a public health problem in Nigeria, especially among the poor living in endemic communities. There is a dearth of evidence on the burden of onchocerciasis and studies suggest poor knowledge of the cause of onchocerciasis. This information could facilitate evidence-informed decisions on resource allocation towards the control of this neglected tropical disease. A cross-sectional survey was used to assess the knowledge of disease causation among patients, costs incurred for seeking treatment and productivity losses. About 43% had no knowledge of what caused their symptoms. The average monthly treatment cost per respondent was US$ 14.0. Drug cost (US$10) made up 72% of total treatment cost. The per capita productivity loss among patients was $16 and it was higher among the least poor (Q1) (US$20) and the poor SES (Q3) (US$21). The average cost of lost productivity among caregivers was US $3.5. These findings suggest that onchocerciasis still constitutes considerable economic burden on patients due to the high cost of treatment and lost productivity. This survey provided a measure of patient treatment cost in a setting with paucity of information. It also shows that targeted health education campaigns remain a fundamental policy option.

The Contributions of Onchocerciasis Control and Elimination Programs toward the Achievement of the Millennium Development Goals

In 2000, 189 member states of the United Nations (UN) developed a plan for peace and development, which resulted in eight actionable goals known as the Millennium Development Goals (MDGs). Since their inception, the MDGs have been considered the international standard for measuring development progress and have provided a blueprint for global health policy and programming. However, emphasis upon the achievement of priority benchmarks around the "big three" diseases--namely HIV, tuberculosis (TB), and malaria--has influenced global health entities to disproportionately allocate resources. Meanwhile, several tropical diseases that almost exclusively impact the poorest of the poor continue to be neglected, despite the existence of cost-effective and feasible methods of control or elimination. One such Neglected Tropical Disease (NTD), onchocerciasis, more commonly known as river blindness, is a debilitating and stigmatizing disease primarily affecting individuals living in remote and impoverished areas. Onchocerciasis control is considered to be one of the most successful and cost-effective public health campaigns ever launched. In addition to improving the health and well-being of millions of individuals, these programs also lead to improvements in education, agricultural production, and economic development in affected communities. Perhaps most pertinent to the global health community, though, is the demonstrated effectiveness of facilitating community engagement by allowing communities considerable ownership with regard to drug delivery. This paper reviews the contributions that such concentrated efforts to control and eliminate onchocerciasis make to achieving select MDGs. The authors hope to draw the attention of public policymakers and global health funders to the importance of the struggle against onchocerciasis as a model for community-directed interventions to advance health and development, and to advocate for NTDs inclusion in the post 2015 agenda.

Onchocerciasis control in the Democratic Republic of Congo (DRC): challenges in a post-war environment

OBJECTIVE

To evaluate onchocerciasis control activities in the Democratic Republic of Congo (DRC) in the first 12 years of community-directed treatment with ivermectin (CDTI).

METHODS

Data from the National Programme for Onchocerciasis (NPO) provided by the National Onchocerciasis Task Force (NOTF) through the annual reports of the 21 CDTI projects for the years 2001-2012 were reviewed retrospectively. A hypothetical-inputs-process-outputs-outcomes table was constructed.

RESULTS

Community-directed treatment with ivermectin expanded from 1968 communities in 2001 to 39 100 communities by 2012 while the number of community-directed distributors (CDD) and health workers (HW) multiplied. By 2012, there were ratios of 1 CDD per 262 persons and 1 HW per 2318 persons at risk. More than 80% of the funding came from the fiduciary funds of the African Programme for Onchocerciasis Control. The cost of treatment per person treated fell from US$ 1.1 in 2001 to US$ 0.1 in 2012. The therapeutic coverage increased from 2.7% (2001) to 74.2% (2012); the geographical coverage, from 4.7% (2001) to 93.9% (2012). Geographical coverage fell in 2005 due to deaths in loiasis co-endemic areas, and the therapeutic coverage fell in 2008 due to insecurity.

CONCLUSIONS

Challenges to CDTI in DRC have been serious adverse reactions to ivermectin in loiasis co-endemic areas and political conflict. Targets for personnel or therapeutic and geographical coverages were not met. Longer term funding and renewed efforts are required to achieve control and elimination of onchocerciasis in DRC.

The geographic distribution of onchocerciasis in the 20 participating countries of the African Programme for Onchocerciasis Control: (1) priority areas for ivermectin treatment

Background

The African Programme for Onchocerciasis Control (APOC) was created to control onchocerciasis as a public health problem in 20 African countries. Its main strategy is community directed treatment with ivermectin. In order to identify all high risk areas where ivermectin treatment was needed, APOC used Rapid Epidemiological Mapping of Onchocerciasis (REMO). REMO has now been virtually completed and we report the results in two articles. The present article reports the mapping of high risk areas where onchocerciasis was a public health problem. The companion article reports the results of a geostatistical analysis of the REMO data to map endemicity levels and estimate the number infected.

Methods

REMO consists of three stages: exclusion of areas that are unsuitable for the vector, selection of sample villages to be surveyed in each river basin, and examination of 30 to 50 adults for the presence of palpable onchocercal nodules in each selected village. The survey results and other relevant information were processed in a geographical information system. A panel of experts interpreted the data taking the river-based sampling into account and delineated high risk areas where the prevalence of nodules is greater than 20%.

Results

Unsuitable areas were identified in eight countries. In the remaining areas surveys were done in a total of 14,473 sample villages in which more than half a million people were examined. High-risk areas were identified in 18 APOC countries, ranging from small isolated foci to a vast contiguous endemic area of 2 million km² running across seven countries. In five countries the high risk area covered more than 48% of the total surface area, and 31% to 48% of the population. It is estimated that 86 million people live in high risk areas in the APOC countries.

Conclusions

The REMO maps have played a significant role in onchocerciasis control in the 20 APOC countries. All high-risk areas where onchocerciasis used to be a serious public health problem have been clearly delineated. This led to the creation of community-directed treatment projects that by 2012 were providing annual ivermectin treatment to over 80 million people.

Lymphatic filariasis and onchocerciasis prevention, treatment, and control costs across diverse settings: a systematic review

The control and eventual elimination of neglected tropical disease (NTD) requires the expansion of interventions such as mass drug administration (MDA), vector control, diagnostic testing, and effective treatment. The purpose of this paper is to present the evidence base for decision-makers on the cost and cost-effectiveness of lymphatic filariasis (LF) and onchocerciasis prevention, treatment, and control. A systematic review of the published literature was conducted. All studies that contained primary or secondary data on costs or cost-effectiveness of prevention and control were considered. A total of 52 papers were included for LF and 24 papers were included for onchocerciasis. Large research gaps exist on the synergies and cost of integrating NTD prevention and control programs, as well as research on the role of health information systems, human resource systems, service delivery, and essential medicines and technology for elimination. The literature available on costs and cost-effectiveness of interventions is also generally older, extremely focal geographically and of limited usefulness for developing estimates of the global economic burden of these diseases and prioritizing among various intervention options. Up to date information on the costs and cost-effectiveness of interventions for LF and onchocerciasis prevention are needed given the vastly expanded funding base for the control and elimination of these diseases.

Reaching the london declaration on neglected tropical diseases goals for onchocerciasis: an economic evaluation of increasing the frequency of ivermectin treatment in Africa

Although switching from annual to biannual ivermectin treatment yields small additional health benefits, in the context of elimination goals its benefit is pronounced, increasing the feasibility of and shortening the time frames for reaching proposed operational thresholds for stopping treatment.

Background. Recently, there has been a shift in onchocerciasis control policy, changing from prevention of morbidity toward elimination of infection. Switching from annual to biannual ivermectin distribution may accelerate progress toward the elimination goals. However, the settings where this strategy would be cost effective in Africa have not been described.

Methods. An onchocerciasis transmission framework (EpiOncho) was coupled to a disease model in order to explore the impact on disability-adjusted life years averted, program cost, and program duration of biannual ivermectin treatment in different epidemiological and programmatic scenarios in African savannah.

Results. While biannual treatment yields only small additional health gains, its benefit is pronounced in the context of the elimination goals, shortening the time frames for and increasing the feasibility of reaching the proposed operational thresholds for stopping treatment. In settings with high precontrol endemicity (and/or poor coverage and compliance), it may not be possible to reach such thresholds even within 50 years of annual ivermectin, requiring adoption of biannual treatment. Our projections highlight the crucial role played by coverage and compliance in achieving the elimination goals.

Conclusions. Biannual ivermectin treatment improves the chances of reaching the 2020/2025 elimination goals, potentially generating programmatic cost savings in settings with high precontrol endemicity. However, its benefit and cost are highly sensitive to levels of systematic noncompliance and, in many settings, it will lead to an increase in costs. Furthermore, it may not always be feasible to implement biannual treatment, particularly in hard-to-reach populations. This highlights the continued need for a macrofilaricide.

Knowledge and beliefs about onchocerciasis among rural inhabitants in an endemic area of Ethiopia

A cross-sectional study was conducted to assess the knowledge and beliefs about causes, transmission, prevention and control of onchocerciasis among rural inhabitants in an endemic area of Ethiopia. Descriptive and quantitative information was collected using focus group discussions and a pretested structured questionnaire. Onchocerciasis affected and unaffected respondents' knowledge and beliefs regarding onchocerciasis were compared. Overall, 75.9% (192/253) of study subjects were aware about onchocerciasis. During the survey, 66.9% of affected, and 45.5% of unaffected respondents knew that onchocerciasis was transmitted through blackfly bites. About 53% of unaffected and 60% of affected respondents thought that onchocerciasis was preventable and the majority of the affected respondents felt that it was curable. Chi-square statistical analysis found a significant association between affected and unaffected individual's knowledge and beliefs about causes, transmission, prevention and control of onchocerciasis. Although the majority of respondents had ample awareness, a sizable proportion still had misconceptions and misunderstandings about causes, transmission, prevention and control of onchocerciasis. Therefore, appropriate communication strategies should be developed to create the awareness regarding the role of blackflies in onchocerciasis transmission, the importance of proper prevention techniques, early diagnosis and treatment to bring a constructive outcome in the near future.

Incrimination ofSimulium thyolense(Diptera: Simuliidae) as the anthropophilic blackfly in the Thyolo focus of human onchocerciasis in Malawi

The sibling species of the Simulium damnosum complex that are potential vectors in the foci of human onchocerciasis found in southern Malawi (the southern-most foci in Africa) were identified, using a combination of cytotaxonomic and molecular techniques. Simulium thyolense was found to be the most abundant species within the foci (representing 91% of the larvae collected), whilst S. kilibanum and cytoforms of the 'Ketaketa' subcomplex were the dominant members of the complex found outside of the foci. As all 188 biting female flies collected from the Thyolo, Mwanza and Mulanje foci were identified as S. thyolense, this species is probably the only significant vector of Onchocerca volvulus in the area, and the other Simulium species collected are assumed to be zoophilic. The results confirm the diagnostic value of the size of the amplicon(s) produced in PCR based on the sequences coding for the internal-transcribed-spacer region of the nuclear ribosomal DNA (ITS-1 rDNA), with a characteristic 340bp amplicon for S. thyolense. Chromosomal polymorphisms within S. thyolense indicate some degree of geographical isolation of the 'Thyolo-Mulanje' focus from the Mwanza focus.

Disease control priorities for neglected tropical diseases: lessons from priority ranking based on the quality of evidence, cost effectiveness, severity of disease, catastrophic health expenditures, and loss of productivity

BACKGROUND

In the context of limited health care budgets in countries where Neglected Tropical Diseases (NTDs) are endemic, scaling up disease control interventions entails the setting of priorities. However, solutions based solely on cost-effectiveness analyses may lead to biased and insufficiently justified priorities.

OBJECTIVES

The objectives of this paper are to 1) demonstrate how a range of equity concerns can be used to identify feasible priority setting criteria, 2) show how these criteria can be fed into a multi-criteria decision-making matrix, and 3) discuss the conditions under which this decision-making procedure should be carried out in a real-world decision-making context.

METHODS

This paper draws on elements from theories of decision analysis and ethical theories of fair resource allocation. We explore six typical NTD interventions by employing a modified multi-criteria decision analysis model with predefined criteria, drawn from a priority setting guide under development by the WHO. To identify relevant evidence for the six chosen interventions, we searched the PubMed and Cochrane databases.

DISCUSSION

Our in vitro multi-criteria decision analysis suggested that case management for visceral leishmaniasis should be given a higher priority than mass campaigns to prevent soil-transmitted helminthic infections. This seems to contradict current health care priorities and recommendations in the literature. We also consider procedural conditions that should be met in a contextualised decision-making process and we stress the limitations of this study exercise.

CONCLUSION

By exploring how several criteria relevant to the multi-facetted characteristics of NTDs can be taken into account simultaneously, we are able to suggest how improved priority settings among NTDs can be realised.

African Programme For Onchocerciasis Control 1995-2015: model-estimated health impact and cost

BACKGROUND

Onchocerciasis causes a considerable disease burden in Africa, mainly through skin and eye disease. Since 1995, the African Programme for Onchocerciasis Control (APOC) has coordinated annual mass treatment with ivermectin in 16 countries. In this study, we estimate the health impact of APOC and the associated costs from a program perspective up to 2010 and provide expected trends up to 2015.

METHODS AND FINDINGS

With data on pre-control prevalence of infection and population coverage of mass treatment, we simulated trends in infection, blindness, visual impairment, and severe itch using the micro-simulation model ONCHOSIM, and estimated disability-adjusted life years (DALYs) lost due to onchocerciasis. We assessed financial costs for APOC, beneficiary governments, and non-governmental development organizations, excluding cost of donated drugs. We estimated that between 1995 and 2010, mass treatment with ivermectin averted 8.2 million DALYs due to onchocerciasis in APOC areas, at a nominal cost of about US$257 million. We expect that APOC will avert another 9.2 million DALYs between 2011 and 2015, at a nominal cost of US$221 million.

CONCLUSIONS

Our simulations suggest that APOC has had a remarkable impact on population health in Africa between 1995 and 2010. This health impact is predicted to double during the subsequent five years of the program, through to 2015. APOC is a highly cost-effective public health program. Given the anticipated elimination of onchocerciasis from some APOC areas, we expect even more health gains and a more favorable cost-effectiveness of mass treatment with ivermectin in the near future.

Neglected tropical diseases and the millennium development goals: why the "other diseases" matter: reality versus rhetoric

Since 2004 there has been an increased recognition of the importance of Neglected Tropical Diseases (NTDs) as impediments to development. These diseases are caused by a variety of infectious agents - viruses, bacteria and parasites - which cause a diversity of clinical conditions throughout the tropics. The World Health Organisation (WHO) has defined seventeen of these conditions as core NTDs. The objectives for the control, elimination or eradication of these conditions have been defined in World Health Assembly resolutions whilst the strategies for the control or elimination of individual diseases have been defined in various WHO documents. Since 2005 there has been a drive for the expanded control of these diseases through an integrated approach of mass drug administration referred to as Preventive Chemotherapy via community-based distribution systems and through schools. This has been made possible by donations from major pharmaceutical companies of quality and efficacious drugs which have a proven track record of safety. As a result of the increased commitment of endemic countries, bilateral donors and non-governmental development organisations, there has been a considerable expansion of mass drug administration. In particular, programmes targeting lymphatic filariasis, onchocerciasis, schistosomiasis, trachoma and soil transmitted helminth infections have expanded to treat 887. 8 million people in 2009. There has been significant progress towards guinea worm eradication, and the control of leprosy and human African trypanosomiasis. This paper responds to what the authors believe are inappropriate criticisms of these programmes and counters accusations of the motives of partners made in recently published papers. We provide a detailed response and update the information on the numbers of global treatments undertaken for NTDs and list the success stories to date.The paper acknowledges that in undertaking any health programme in environments such as post-conflict countries, there are always challenges. It is also recognised that NTD control must always be undertaken within the health system context. However, it is important to emphasise that the availability of donated drugs, the multiple impact of those drugs, the willingness of countries to undertake their distribution, thereby committing their own resources to the programmes, and the proven beneficial results outweigh the problems which are faced in environments where communities are often beyond the reach of health services. Given the availability of these interventions, their cost effectiveness and the broader development impact we believe it would be unethical not to continue programmes of such long term benefit to the "bottom billion".

The African Programme for Onchocerciasis Control: impact on onchocercal skin disease

OBJECTIVES

To assess the long-term impact of the African Programme for Onchocerciasis Control on itching and onchocercal skin disease (OSD).

METHODS

Seven study sites in Cameroon, Sudan, Nigeria and Uganda participated. Two cross-sectional surveys were conducted of communities meso- and hyper-endemic for onchocerciasis before and after 5 or 6 years of community-directed treatment with ivermectin (CDTI). Individuals were asked about any general health symptoms including itching and underwent full cutaneous examinations. Onchocercal skin lesions were documented according to a standard classification.

RESULTS

Five thousand one hundred and ninety three people were examined in phase I and 5,180 people in phase II. The presence of onchocercal nodules was a strongly significant (P < 0·001) risk factor for all forms of onchocercal skin disease: APOD (OR 1·66); CPOD (OR 2·84); LOD (OR 2·68); reactive skin lesions (OR 2·38) and depigmentation (OR 3·36). The effect of community-directed treatment with ivermectin was profound. At phase II, there were significant (P < 0·001) reductions in the odds of itching (OR 0·32), APOD (OR 0·28); CPOD (OR 0·34); reactive skin lesions (OR 0·33); depigmentation (OR 0·31) and nodules (OR 0·37). Reduction in the odds of LOD was also significant (OR 0.54, P < 0.03).

CONCLUSIONS

This first multi-country report of the long-term impact of CDTI reveals a substantial reduction in itching and OSD. APOC operations are having a major effect in improving skin health in poor rural populations in Africa.

The economic benefits resulting from the first 8 years of the Global Programme to Eliminate Lymphatic Filariasis (2000-2007)

BACKGROUND

Between 2000-2007, the Global Programme to Eliminate Lymphatic Filariasis (GPELF) delivered more than 1.9 billion treatments to nearly 600 million individuals via annual mass drug administration (MDA) of anti-filarial drugs (albendazole, ivermectin, diethylcarbamazine) to all at-risk for 4-6 years. Quantifying the resulting economic benefits of this significant achievement is important not only to justify the resources invested in the GPELF but also to more fully understand the Programme's overall impact on some of the poorest endemic populations.

METHODOLOGY

To calculate the economic benefits, the number of clinical manifestations averted was first quantified and the savings associated with this disease prevention then analyzed in the context of direct treatment costs, indirect costs of lost-labor, and costs to the health system to care for affected individuals. Multiple data sources were reviewed, including published literature and databases from the World Health Organization, International Monetary Fund, and International Labour Organization

PRINCIPAL FINDINGS

An estimated US$21.8 billion of direct economic benefits will be gained over the lifetime of 31.4 million individuals treated during the first 8 years of the GPELF. Of this total, over US$2.3 billion is realized by the protection of nearly 3 million newborns and other individuals from acquiring lymphatic filariasis as a result of their being born into areas freed of LF transmission. Similarly, more than 28 million individuals already infected with LF benefit from GPELF's halting the progression of their disease, which results in an associated lifetime economic benefit of approximately US$19.5 billion. In addition to these economic benefits to at-risk individuals, decreased patient services associated with reduced LF morbidity saves the health systems of endemic countries approximately US$2.2 billion.

CONCLUSIONS/SIGNIFICANCE

MDA for LF offers significant economic benefits. Moreover, with favorable program implementation costs (largely a result of the sustained commitments of donated drugs from the pharmaceutical industry) it is clear that the economic rate of return of the GPELF is extremely high and that this Programme continues to prove itself an excellent investment in global health.

Programmes, partnerships, and governance for elimination and control of neglected tropical diseases

Neglected tropical diseases represent one of the most serious burdens to public health. Many can be treated cost-effectively, yet they have been largely ignored on the global health policy agenda until recently. In this first paper in the Series we review the fragmented structure of elimination and control programmes for these diseases, starting with the ambiguous definition of a neglected tropical disease. We describe selected international control initiatives and present their effect, governance arrangements, and financing mechanisms, including substantial drug-donation programmes. We also discuss efforts to exploit shared features of these diseases by integration of selected control activities within countries, thus creating economies of scope. Finally we address the challenges, resulting from the diversity of disease control approaches and governance structures-both nationally and internationally-and provide some suggestions for the way forward.

Performance of predictors: evaluating sustainability in community-directed treatment projects of the African programme for onchocerciasis control

The predictors of sustainability of community-directed treatment with ivermectin (CDTI) at four implementation levels were evaluated in 41 African Programme for Onchocerciasis Control (APOC) projects, encompassing 492 communities in 10 countries. A model protocol provided information on indicators corresponding to nine aspects of a project that is likely to be sustainable at community level after the cessation of external support. Six of the nine aspects had components of community ownership as predictors of project sustainability. Quantitative and qualitative assessments were used to obtain individual community scores and an overall sustainability score for each project graded on a scale of 0-4. Of the 41 projects evaluated, 70% scored "satisfactorily" to "highly sustainable" at the community level. We found variations among countries and that health system weaknesses could hamper community efforts in sustaining a project, such as when ivermectin was delivered late. Community ownership was of primary importance to the community score, and the community-level scores correlated with overall project sustainability. The therapeutic coverage achieved in each project correlated with the ratio of volunteer ivermectin distributors per population served. Surprisingly, the performance of these distributors was not affected by the direct incentives offered, and coverage appeared to be highest when cash or in-kind compensation was not given at all. Although further research is required, anecdotal evidence pointed to diverse indirect benefits for distributors-political goodwill, personal satisfaction and altruistic fulfillment. The results demonstrate that community ownership is among the important determining factors of sustainability of community-based programmes.

River blindness: a success story under threat?

The success of the Onchocerciasis Control Programme is undeniable and exemplary, say the authors, but it is too early to claim victory against river blindness.

The antipoverty vaccines

The neglected tropical diseases represent a group of parasitic and bacterial diseases, occurring primarily in rural areas or impoverished urban areas of developing countries. Because of their chronic and stigmatizing character and their impact on child development, pregnancy outcomes, and worker productivity, the neglected tropical diseases are considered poverty-promoting conditions. Through the activities of public-private partnerships, first or second-generation recombinant vaccines for three of these conditions--hookworm, leishmaniasis, and schistosomiasis, have undergone early development and clinical testing. However, through the acquisition of extensive bioinformatics information or animal model testing for several other neglected tropical diseases pathogens, it is possible to consider new generation vaccines as well for amebiasis, Buruli ulcer, Chagas disease, Chlamydia infections (including trachoma), leprosy, leptospirosis, and the treponematoses. Early development of such antipoverty vaccines will require the establishment of product development public-private partnerships and partnerships with innovative developing countries where these diseases are endemic.

Transmission of Onchocerca volvulus and prospects for the elimination of its vector, the blackfly Simulium neavei in the Mpamba-Nkusi focus in Western Uganda

The transmission of Onchocerca volvulus Leuckart (Spirudida: Onchocercidae) and the prospects of Simulium neavei Roubaud (Diptera: Simuliidae) vector elimination through ground larviciding were investigated in the Mpamba-Nkusi focus, western Uganda. Transmission levels and the initiated vector elimination activities were assessed to supplement the ongoing ivermectin mass distribution programme. Searches for breeding sites, adult fly catches, dissection of flies, river treatment with temephos (Abate) and a review of annual ivermectin treatment data were conducted. High levels of crab infestation with S. neavei sensu stricto immature stages were recorded; 57.9% and 100% for the Mpamba and Nyabugando river systems, respectively. The mean numbers of larvae/pupae per crab were 3.6 +/- 0.5 in the Mpamba and 20.6 +/- 1.8 in the Nyabugando systems. Pre-intervention mean biting densities were 39 and 32 flies/(man day) in 2001 and 2002, respectively, and an annual biting rate in 2001 of > 14 000. The bimodal biting pattern of S. neavei s.s. consisted of two peaks; one in the morning (09.00-10.00 hours) and one in the afternoon (14.00-15.00 hours) with a mid-day lull in biting. The infection/infective rates were 13.3%/2.8% and 16.6%/2.9% in the dissected parous flies from the Mpamba and Nyabugando river systems, respectively. Out of approximately 1000 parous flies, 129 and 109 were found to be harbouring infective larvae of Onchocerca volvulus in their heads from the Mpamba and Nyabugando river systems, respectively. In spite of the > 10 years of ivermectin treatment, at a mean coverage of 71.3%, infection remained relatively high. Ground larviciding with temephos (Abate) initiated in June and October 2002 had a significant impact. In the Mpamba river system there was a significant (P < 0.001) reduction in positive crabs from 57.9% in 2001 to 0.06% in 2003 and a decrease in the mean number of larvae/pupae per crab from 3.6 +/- 0.5 in 2001 to 0.0007 +/- 0.0001 (P < 0.002) in 2003. Similarly, in the Nyabugando river system, a significant (P < 0.001) reduction in crab infestation from 100% in 2001 to 0.06% in 2003 and a decrease in the mean number of larvae/pupae per crab from 20.6 +/- 1.8 in 2001 to 0.06 +/- 0.03 in 2003. Drastic reductions were observed in the mean number of biting flies from 3 flies/h in 2001 to 0 flies/h in 2003 and the annual biting rates fell from 14,235 flies/year in 2001 to only 730 flies/year in 2003. These data suggest that substantial progress towards the goal of S. neavei s.s. vector elimination has been made and this will enhance the ongoing ivermectin treatment in this isolated focus.

Guide to blackflies of the Simulium damnosum complex in eastern and southern Africa

At least 26 members of the Simulium damnosum Theobald complex (Diptera: Simuliidae) are known from eastern Africa, most of which are assumed to be non-anthropophilic and some are restricted to small areas of endemicity. Their discovery was based on polytene chromosome inversion polymorphisms and since then they have been cited as cytological entities, but, in many cases, with inadequate descriptions (e.g. without illustrations of the chromosomes). The present distribution, taxonomy and vector identity have been re-evaluated during the last decade in conjunction with ongoing onchocerciasis control programmes. Here, a summary of the relevant data is presented, integrating results of cytotaxonomic, morphotaxonomic and molecular investigations into a guide that provides a comprehensive system of identification for the cytoforms 'Kagera', 'Kasyabone', 'Kibwezi', 'Kisiwani', 'Kisiwani E', 'Kulfo', 'Linthipe', 'Mombo', 'Mutonga', 'Njombe', 'Nkusi', 'Nkusi SA', 'Nkusi SW', 'Nyika', 'Pienaars', 'Sanje', 'Sebwe', 'Turiani', Simulium damnosum sensu stricto, Simulium kaffaense Hadis et al., Simulium kilibanum Gouteux, Simulium kipengere Krueger, Simulium latipollex (Enderlein), Simulium pandanophilum Krüger, Nurmi & Garms, Simulium plumbeum Krueger, Simulium thyolense Vajime et al. and for five newly recognized molecular forms of 'Nkusi' and S. kilibanum. All taxa except S. pandanophilum are assigned to one of five subcomplexes (damnosum, Ketaketa, Kibwezi, Sanje, squamosum) within the S. damnosum complex. The guide encompasses anthropophilic and non-anthropophilic segregates for the whole of eastern and southern Africa, and is not restricted to larval chromosome criteria; in many cases it also allows the typing of adult flies.

Control of Onchocerciasis

Onchocerciasis is a filarial infection which causes blindness and debilitating skin lesions. The disease occurs in 37 countries, of which 30 are found in Africa (the most affected in terms of the distribution and the severity of the clinical manifestations of the disease), six in the Americas and one in the Arabian Peninsula. The latest WHO Expert Committee on Onchocerciasis estimated that in 1995 around 17.7 million persons were infected, about 270,000 of whom were blind and another 500,000 severely visually impaired. The disease is responsible for 1 million DALYs. Eye disease from onchocerciasis accounts for 40% of DALYs annually although severe skin disease is also recognized as of public health significance. Great progress has been made in the last thirty years in the control of onchocerciasis, both in Africa and the Americas, and this progress has been due largely to international public-private partnerships, sustained funding regional programmes, and new tools and technology. Landmarks in the global control of river blindness include the significant success of the Onchocerciasis Control Programme of West Africa (1975-2002), and the donation of ivermectin (Mectizan) by Merck & Co. Inc., in 1988, a medicine that is distributed to millions free of charge each year. Future major technical challenges of onchocerciasis control include ivermectin mass administration in areas co-endemic for the parasite Loa loa in the light of possible severe adverse reactions, ivermectin treatment in hypoendemic areas hitherto excluded from African control programmes, sustainability of ivermectin distribution, post-control surveillance for recrudescence detection, surveillance for emergence of resistance, and decisions of when to stop mass ivermectin treatments. There is the need to develop the appropriate information systems and diagnostic tools to help in accomplishing many of these tasks. A search for a second-line treatment or as an additional drug to ivermectin as well as a search for a macrofilaricide are issues that need to be addressed in the future.

Research for control: the onchocerciasis experience

Onchocerciasis control has been very successful in Africa and research has played a critical role. An overview of the main epidemiological and implementation research activities undertaken over the last 20 years in collaboration with the African onchocerciasis control programmes and of the impact this research had on control is given. The research included the development of epidemiological modelling and its application in programme evaluation and operational planning, research on disease patterns and disease burden in different bioclimatic zones to justify and guide control operations, community trials of ivermectin to determine its safety for large-scale use and its impact on transmission, rapid assessment methods to identify target communities for treatment and community-directed treatment for sustained drug delivery. Lessons learned during this unique collaboration between research and control are discussed.

An investigation of persistent microfilaridermias despite multiple treatments with ivermectin, in two onchocerciasis-endemic foci in Ghana

If ivermectin-based programmes for the control of human onchocerciasis are to be successful, the drug must remain effective for as long as necessary. In an open, case-control study, an attempt was made to determine if the persistent, significant, Onchocerca volvulus microfilaridermias seen in some individuals who had received at least nine treatments with ivermectin were the result of the development of drug resistance in the parasite. Twenty-one of these 'sub-optimal' responders (cases) were matched, by age, weight, number of treatments, locality and skin microfilarial counts, with seven amicrofilaridermic responders and 14 ivermectin-naive subjects. The number of treatments taken, any potential drug interactions and significant underlying disease were determined from detailed clinical and laboratory studies. Each subject was treated with ivermectin during the study, so that plasma concentrations of the drug could be determined for 72 h from the time of dosage. The microfilarial and adult-worm responses to this treatment were assessed from skin microfilarial counts (obtained before the treatment and at days 8, 90 and 365 post-treatment), day-90 embryogrammes, and the results of fly-feeding experiments. Parasite-sensitivity criteria for various time-points were derived from earlier data on skin microfilaridermias and the effects of ivermectin on the adult worms. The results indicate that the significant microfilaridermias that persist despite multiple treatments with ivermectin are mainly attributable to the non-response of the adult female worms and not to inadequate drug exposure or other factors. The possibility that some adult female worms have developed resistance to ivermectin cannot be excluded. These results justify the routine monitoring of treatment efficacy in any ivermectin-based programme of disease control.

Economic evaluation of Mectizan distribution

The distribution of ivermectin has dramatically altered the nature of onchocerciasis control. Existing economic analyses of ivermectin distribution programmes show that these programmes have a highly beneficial impact. Most analyses have estimated the economic benefits in terms of increased labour productivity as a result of reductions in blindness, and in terms of additional land-availability because of a reduced transmission of the parasite. Economic evaluations of the Onchocerciasis Control Program (OPC) in West Africa have calculated a net present value - equivalent discounted benefits minus discounted costs - of $485 million for the programme over a 39-year period, using a conservative 10% rate to discount future health and productivity gains. The net present value for the African Program for Onchocerciasis Control (APOC) is calculated at 88 million US dollars over a 21-year time period, also using a 10% discount rate. Cost-effectiveness analyses of ivermectin distribution have found a cost of 14-30 US dollars per disability-adjusted life-year prevented - estimates comparable with other priority disease control programmes. However, the economic success of ivermectin distribution is sensitive to the fact that the drug itself has been donated free of charge. The market value of Merck's donations to the APOC for just 1 year considerably outweighs the benefits calculated for both the OPC and the APOC over the life of these projects. Pending the development of an effective macrofilaricide, the distribution of ivermectin will remain a public health priority into the foreseeable future.

Mectizan Donation Program: evaluation of a public-private partnership

The Mectizan Donation Program (MDP) has been perceived as a highly effective public health programme, and as a possible model for addressing future problems in international health. This evaluation examines how the MDP partnership has been functioning from the perspectives of partner organizations. The results of a survey of 25 partners show that the perceived benefits far outweigh the problems, and that the direct costs to the organizations have been minimal. The partnership is rated highly on many aspects of governance and management, with relatively few problems identified. A factor analysis demonstrated that a wide range of factors have influenced the partners' perceptions. The benefits with the largest weights appear to be those related to external perceptions of the organization, and those indicating that the organization feels that its opinions will matter and lead to action in the partnership. The biggest factors influencing the positive perceptions on the governance and management of the MDP partnership appear to be the involvement of senior leaders from different organizations, and being able to agree on priorities. The MDP has been able to involve a large and heterogeneous number of partner organizations through relatively informal mechanisms that rely on goodwill and reciprocity. The survey results show how there was a strong alignment of the MDP with the interests of the various partners, and that a manageable number of problems were addressed and services provided. While having long-term goals, the MDP and the onchocerciasis control programmes have been effective at demonstrating the effectiveness of the approach through regular, professional, and outcome-oriented evaluations. Although the MDP is considered to be central to concerns of national officials, this feature is not rated as high as public perceptions, the internal characteristics of the partnership, or its accomplishments. Similarly, the need to secure resources is not viewed as a major determinant of the partnership's success, perhaps because resources were readily available through Merck and the partner organizations and programmes. These findings, along with the strategic and operational success of the MDP confirm the view that this type of public-private partnership should be pursued vigorously in other areas of public health. Other potential partnerships would do well to examine the characteristics of the MDP partnership, with careful attention to the features of its governance and the management, including a strong alignment of interests with partners, balancing a long-term vision with clarity of roles and intensive management of coordination, and professional and results-oriented accountability.

Eliminating onchocerciasis as a public health problem: the beginning of the end

Onchocerciasis is one of the diseases targeted by Vision 2020. It is the world's second leading infectious cause of blindness, responsible for at least one million blind or severely visually disabled people. The Onchocerciasis Control Programme (OCP) in sub-Saharan Africa will be closed down in 2002, after 27 years of operation. This is the clearest indication that the prospects of eliminating onchocerciasis as a public health problem may be achieved by the end of this decade. The programme's potential now is to serve as a model of global and multiple partnership, to address other poverty related, serious and intractable problems such as needless blindness in the world.

Onchocerciasis: the clinical and epidemiological burden of skin disease in Africa

An attempt was made to assess the true public-health importance of onchocercal skin disease throughout the African region and hence provide an objective basis for the rational planning of onchocerciasis control in the area. The seven collaborative centres that participated in the study (three in Nigeria and one each in Ghana, Cameroon, Tanzania and Uganda) were all in areas of rainforest or savannah-forest mosaic where onchocercal blindness is not common. A cross-sectional dermatological survey was undertaken at each site following a standard protocol. At each site, the aim was to examine at least 750 individuals aged 5 years and living in highly endemic communities and 220-250 individuals aged 5 years and living in a hypo-endemic (control) community. Overall, there were 5459 and 1451 subjects from hyper-and hypo-endemic communities, respectively. In the highly endemic communities, the prevalence of itching increased with age until 20 years and then plateaued, affecting 42% of the population aged 20 years. There was a strong correlation between the prevalence of itching and the level of endemicity (as measured by the prevalence of nodules; r=0.75; P<0.001). The results of a multivariate logistic regression analysis showed that, at the individual level, the presence of onchocercal reactive skin lesions (acute papular onchodermatitis, chronic papular onchodermatitis and/or lichenified onchodermatitis) was the most important risk factor for pruritus, with an odds ratio (OR) of 18.3 and 95% confidence interval (CI) of 15.19-22.04, followed by the presence of palpable onchocercal nodules (OR=4.63; CI=4.05-5.29). In contrast, non-onchocercal skin disease contributed very little to pruritus in the study communities (OR=1.29; CI=1.1-1.51). Onchocercal skin lesions affected 28% of the population in the endemic villages. The commonest type was chronic papular onchodermatitis (13%), followed by depigmentation (10%) and acute papular onchodermatitis (7%). The highest correlation with endemicity was seen for the prevalence of any onchocercal skin lesion and/or pruritus combined (r=0.8; P<0.001). Cutaneous onchocerciasis was found to be a common problem in many endemic areas in Africa which do not have high levels of onchocercal blindness. These findings, together with recent observations that onchocercal skin disease can have major, adverse, psycho-social and socio-economic effects, justify the inclusion of regions with onchocercal skin disease in control programmes based on ivermectin distribution. On the basis of these findings, the World Health Organization launched a control programme for onchocerciasis, the African Programme for Onchocerciasis Control (APOC), that covers 17 endemic countries in Africa.

Rapid epidemiological mapping of onchocerciasis (REMO): its application by the African Programme for Onchocerciasis Control (APOC)

One of the fundamental challenges that the African Programme for Onchocerciasis Control (APOC) has had to face is how to identify the endemic communities where its mass ivermectin-treatment operations are to be carried out in conformity with its stated objective of targetting the most highly endemic, affected and at-risk populations. This it has done by adopting a technique, known as the rapid epidemiological mapping of onchocerciasis (REMO), that provides data on the distribution and prevalence of onchocerciasis. Integration of the REMO data into a geographical information system (GIS) enables delineation of zones of various levels of endemicity, and this is an important step in the planning process for onchocerciasis control. Zones are included in (or excluded from) the APOC-funded programme of community-directed treatment with ivermectin (CDTI), depending on whether or not their levels of onchocercal endemicity reach the threshold set by APOC. This review describes the application of the REMO/GIS technique by APOC in its operations, and identifies the remaining related challenges.

The achievements and challenges of the African Programme for Onchocerciasis Control (APOC)

The main strategy of APOC, of community-directed treatment with ivermectin (CDTI), has enabled the programme to reach, empower and bring relief to remote and under-served, onchocerciasis-endemic communities. With CDTI, geographical and therapeutic coverages have increased substantially, in most areas, to the levels required to eliminate onchocerciasis as a public-health problem. Over 20 million people received treatment in 2000. APOC has also made effective use of the combination of the rapid epidemiological mapping of onchocerciasis (REMO) and geographical information systems (GIS), to provide information on the geographical distribution and prevalence of the disease. This has led to improvements in the identification of CDTI-priority areas, and in the estimates of the numbers of people to be treated. A unique public-private-sector partnership has been at the heart of APOC's relative success. Through efficient capacity-building, the programme's operations have positively influenced and strengthened the health services of participating countries. These laudable achievements notwithstanding, APOC faces many challenges during the second phase of its operations, when the full impact of the programme is expected to be felt. Notable among these challenges are the sustainability of CDTI, the strategy's effective integration into the healthcare system, and the full exploitation of its potential as an entry point for other health programmes. The channels created for CDTI, could, for example, help efforts to eliminate lymphatic filariasis (which will feature on the agenda of many participating countries during APOC's Phase 2). However, these other programmes need to be executed without compromising the onchocerciasis-control programme itself. Success in meeting these challenges will depend on the continued, wholehearted commitment of all the partners involved, particularly that of the governments of the participating countries.

Partnership and promise: evolution of the African river-blindness campaigns

This article describes the evolution of the partnership, between various health and developmental agencies, that has sustained the campaign against river blindness in Africa. The international community was oblivious to the devastating public-health and socio-economic consequences of onchocerciasis until towards the end of the 1960s and the beginning of the 1970s. Then a 'Mission to West Africa', supported by the United Nations Development Programme, and a visit to the sub-region by the president of the World Bank culminated, in 1974, in the inauguration of the Onchocerciasis Control Programme in West Africa (OCP). OCP was a landmark event for the World Bank as it represented its first ever direct investment in a public-health initiative. The resounding success of the OCP is a testimony to the power of the partnership which, with the advent of the Mectizan Donation Programme, was emboldened to extend the scope of its activities to encompass the remaining endemic regions of Africa outside the OCP area. The progress that has been made in consolidating the partnership is discussed in this article. The prospects of adapting the various strategies of the African Programme for Onchocerciasis Control, to entrench an integrated approach that couples strong regional co-ordination with empowerment of local communities and thereby address many other health problems, are also explored.

Community financing of local ivermectin distribution in Nigeria: potential payment and cost-recovery outlook

The preferred payment mechanism in a community financing scheme for local ivermectin distribution was elicited from randomly selected household heads from three communities in Nigeria using interviewer-administered structured questionnaires. The majority of the respondents in the three communities were prepared to pay for local ivermectin distribution. Additionally, the average amounts the respondents were prepared to pay per person treated ($0.28, $0.30 and $0.38 in Nike, Achi and Toro, respectively) were all more than the $0.20 ceiling recommended by the partners of the African Programme on Onchocerciasis Control (APOC). Thus, the cost-recovery outlook is bright in these communities. However, the preferred payment modality varied. Fee-for-service was the predominant payment modality in the Achi and Nike communities, while the Toro community preferred pre-payment. This study demonstrates that many communities have different payment preferences for endemic disease control efforts. This knowledge will help in developing acceptable and sustainable schemes. The imposition of unacceptable payment mechanisms will lead to an unwillingness to pay.