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Keywords:

  • lymphatic filariasis;
  • elimination;
  • mass drug administration;
  • public-private partnerships
  • filariose lymphatique;
  • élimination;
  • administration en masse de médicaments;
  • associations publiques-privées
  • filariasis linfática;
  • eliminación;
  • administración masiva de medicamentos;
  • asociaciones publicas-privadas

Summary

  1. Top of page
  2. Summary
  3. Do we know the extent of the problem?
  4. Are the recommended strategies working?
  5. Do we have the right tools measure success?
  6. To integrate or not to integrate?
  7. What has been the role of research?
  8. Where does the money come from?
  9. Conclusions
  10. References

In 1997, the World Health Assembly resolved to eliminate lymphatic filariasis as a public health problem by the year 2020. By the end of 2004, almost half of the 83 endemic countries had initiated national programmes, providing mass drug administration to an at risk population of approximately 435 million. This remarkable achievement is the result of an enormous amount of technical, financial and political support from public and private sectors at the community, national, regional and global level. As the global programme to eliminate lymphatic filariasis enters its second quarter of operations, there are substantial opportunities to be taken and critical challenges to be addressed. These are the focus of this editorial.

En 1996, l'Assemblée Mondiale de la Santé a résolu d’éliminer la filariose lymphatique comme étant un problème de santé publique d'ici l'année 2020. A la fin de 2004, presque la moitié des 84 pays endémiques avaient initié un programme national dispensant l'administration en masse de médicaments à une population à risque d'environ 435 millions de personnes. Cet accomplissement remarquable fut le résultat d'unénorme support technique, financier et politique de la part des secteurs publics et privés au niveau communautaire, national, régional et global. Alors que le Programme d'Elimination Globale de la Filariose Lymphatique entre dans le second quart de ses opérations, il y a des opportunités importantes à saisir et des défis critiques à relever. Tels sont les focalisations de cet éditorial.

En 1996, la Asamblea Mundial de Salud se propuso eliminar la filariasis linfática como un problema de salud pública antes del año 2020. A finales del 2004, casi la mitad de los 83 países endémicos habían iniciado programas nacionales, con administración masiva de medicamentos, a una población a riesgo de aproximadamente 435 millones. Este logro remarcable es el resultado de un enorme apoyo político, financiero y técnico, tanto de sectores públicos como privados, a nivel comunitario, nacional, regional y global. Ahora, que el Programa Global para Eliminar la Filariasis Linfática entra en su segunda cuarto de operaciones, hay oportunidades substanciales y retos críticos que deben ser abordados. Este es el objetivo de esta editorial.


Do we know the extent of the problem?

  1. Top of page
  2. Summary
  3. Do we know the extent of the problem?
  4. Are the recommended strategies working?
  5. Do we have the right tools measure success?
  6. To integrate or not to integrate?
  7. What has been the role of research?
  8. Where does the money come from?
  9. Conclusions
  10. References

Determining the distribution and prevalence of infection and/or disease is one of the critical first steps of any public health programme. So far, the global programme for the elimination of lymphatic filariasis (GPELF) has employed assessment of antigenaemia (of adult worm), microfilaraemia (usually night blood) and hydrocoeles in men to decide where to start mass drug administration (MDA). Rapid mapping methods have since been developed using a combination of these tools (Gyapong & Remme 2001). These tools continue to be effective at measuring existing infections in different settings. But mapping remains incomplete in some regions of the world suspected of being endemic for lymphatic filariasis (LF). This is because of a host of delays related to technical problems with the rapid assessment tool for antigenaemia, insufficient financial resources and political instability. Thus, the initial estimate of 1.2  billion people at risk of LF globally remains a gross approximation, which needs to be refined. This should be one of the primary short-term priorities of the GPELF in order to facilitate more accurate planning for adequate financial and human resources to achieve the goal of elimination.

Are the recommended strategies working?

  1. Top of page
  2. Summary
  3. Do we know the extent of the problem?
  4. Are the recommended strategies working?
  5. Do we have the right tools measure success?
  6. To integrate or not to integrate?
  7. What has been the role of research?
  8. Where does the money come from?
  9. Conclusions
  10. References

The strategies underpinning the global programme are well documented (Ottesen et al. 1997) and have recently been reviewed extensively (Gyapong et al. 2005). These recommended strategies are: (i) MDA with single-dose albendazole and ivermectin (Mectizan®) tablets in areas, where LF is co-endemic with onchocerciasis, annually for 4–6 years, (ii) single-dose albendazole and diethylcarbamazine (DEC) in areas, where onchocerciasis is not endemic, annually for 4–6 years, (iii) exclusive use of DEC-fortified tablet or cooking salt for 1–2 years in some settings, (iv) vector control measures, especially the use of insecticide-treated materials, where appropriate and cost-effective, (v) home-based self-management of lymphoedema and elephantiasis for affected individuals and (vi) improved access to surgical intervention for men with hydrocoeles.

To date, the primary focus of the GPELF has been on the chemotherapeutic interventions, giving outstanding results: relatively high MDA coverage and dramatic reduction in microfilaraemia rates during mid-term assessments (World Health Organization 2004; 2005). However, the morbidity control activities have lagged behind. Except in a few instances, where the LF elimination activities were integrated with malaria control, vector control has had limited visibility in the GPELF so far. Over the next 15 years, this gap between MDA and morbidity control is likely to widen unless specific measures are taken to ensure that all elements of the programme are given adequate technical and financial support. As the GPELF expands and seeks to build synergies with other public health programmes, greater emphasis will need to be placed on morbidity control and vector control activities as these two elements of the programme will likely extend beyond 2020, the target year for elimination of lymphatic filariasis.

Despite the many successes of the GPELF, implementation of these strategies has been fraught with diverse problems. Relatively high rates of non-compliance with MDA in some communities (e.g. urban areas, very remote areas, migrant populations, minority groups) have caused low treatment coverage, and thus necessitated prolongation of the MDA. The scaling-up of both MDA and disease management interventions has been slow in some endemic areas. This is because of infrastructural problems such as inadequate human and financial resources as well as limited capacity of overstretched public health systems to implement large-scale campaigns. This low geographic coverage will ultimately prolong the overall duration of the MDA required in a given country/sub-region. MDA cannot be implemented at all in Loa loa endemic areas of West and Central Africa, where the risk of serious neurological adverse events after treatment with ivermectin in individuals with high levels of L. loa microfilaraemia is deemed to outweigh the benefit of mass treatment for LF elimination (Malecela-Lazaro & Twum-Danso 2004). Lack of a safe mass chemotherapy strategy for these areas threatens to further delay the declaration of elimination in the African region for many years.

In light of the data generated so far, the estimated 4–6 years of MDA for interruption of transmission seem overly optimistic. The exact duration required remains unknown, but some intervention units are completing their fifth MDA to review the ‘end-game’ strategies and refine the models to better predict the duration of the intervention required to achieve elimination. This is likely to be influenced by treatment coverage and the vector-parasite combination in question in different settings.

Do we have the right tools measure success?

  1. Top of page
  2. Summary
  3. Do we know the extent of the problem?
  4. Are the recommended strategies working?
  5. Do we have the right tools measure success?
  6. To integrate or not to integrate?
  7. What has been the role of research?
  8. Where does the money come from?
  9. Conclusions
  10. References

After several years of annual MDA, it is expected that the infection rates in a population will be so low that transmission will be insignificant or interrupted (i.e. elimination) (Ottesen 2000). Thus, success is measured in terms of suppressed or eliminated infection in individuals who were previously infected, and in terms of failure to detect new infections in those not previously infected. The current recommendation of the GPELF for the ‘end-game’ is to screen the general population for microfilaraemia and children under the age of five (i.e. born after the start of the MDA) for antigenaemia. However, as infection rates approach zero, the tools we have become less sensitive. Hence, we urgently need a commercially available antibody test to detect exposure in humans. But the ultimate test of interruption of transmission rests on infectivity rates of the mosquito vectors – therefore, the availability of affordable xenodiagnostic tools becomes more important as the GPELF approaches its target.

To integrate or not to integrate?

  1. Top of page
  2. Summary
  3. Do we know the extent of the problem?
  4. Are the recommended strategies working?
  5. Do we have the right tools measure success?
  6. To integrate or not to integrate?
  7. What has been the role of research?
  8. Where does the money come from?
  9. Conclusions
  10. References

Integration of public health interventions is desirable in most settings and has been encouraged in the LF community (Molyneux & Zagaria 2002), however, putting it into operation has been problematic. Often this meant putting several interventions into one vehicle even when their goals and strategies were in different directions. Clearly, implementing integrated interventions requires a more careful approach in order to harness scarce resources without jeopardizing the goals and achievements of any one programme. On the contrary, if it is feasible to implement the GPELF in a regimented way in order to achieve the elimination goal as rapidly as possible, it should not be ruled out. In the history of international public health, no elimination campaign has been fought with integration into health systems as a pivotal strategy.

What has been the role of research?

  1. Top of page
  2. Summary
  3. Do we know the extent of the problem?
  4. Are the recommended strategies working?
  5. Do we have the right tools measure success?
  6. To integrate or not to integrate?
  7. What has been the role of research?
  8. Where does the money come from?
  9. Conclusions
  10. References

Research has been key to the development, initiation and operationalization of the GPELF. It is still perceived as pivotal to moving forward. Indeed, the Technical Advisory Group of the GPELF has been working very closely with other institutions to address many operational research issues. In December 2003, a meeting was convened back-to-back with the annual meeting of the American Society of Tropical Medicine and Hygiene in Philadelphia to address the research needs of the programme (Ottesen & Weil 2004). As a follow-up, a recently convened Scientific Working Group of the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR) identified four issues to be addressed urgently: (i) fundamental ethnographic research on reasons for compliance and non-compliance, as well as studies on how to augment compliance, (ii) providing the evidence base and tools for stopping MDA for major vector/parasite complexes, (iii) improving the evidence base for implementing and scaling-up disability prevention programmes and (iv) research to improve implementation of MDA in urban settings and where opportunities exist for integration. These are obviously addressing the key challenges of the programme and finding operational answers to them will put the GPELF on a sounder technical footing.

Where does the money come from?

  1. Top of page
  2. Summary
  3. Do we know the extent of the problem?
  4. Are the recommended strategies working?
  5. Do we have the right tools measure success?
  6. To integrate or not to integrate?
  7. What has been the role of research?
  8. Where does the money come from?
  9. Conclusions
  10. References

Two of the three chemotherapeutic interventions employed by the GPELF are donated by GlaxoSmithKline, Brentford, UK (albendazole) and Merck & Co. Inc., New Jersey, USA (Mectizan), who bear the costs of manufacturing, warehousing and shipping the drugs to the endemic countries. In some endemic communities, a few individuals volunteer their time over several days or weeks to serve as community drug distributors. Everything else in GPELF has to be purchased. Where does the money come from? To date, funding for the GPELF has come from private foundations such as the Bill & Melinda Gates Foundation, corporations such as GlaxoSmithKline and Merck, bilateral and multilateral agencies, non-governmental organizations and national health budgets of endemic countries. Most of this funding has been provided in a piecemeal fashion on an ad hoc basis. The success of the GPELF to date notwithstanding, it is unlikely that this financing mechanism will be adequate for the next 15 years, as it aims to reach the entire 1.2 billion people at risk of LF in the world with MDA, and the estimated 40 million individuals with clinical LF with the disease management interventions.

In recent years, resources for LF elimination in the international arena have dwindled, due in part to a shift in the priorities of major international donors, and to the apparent increase in the proportion of international donor funds available in their local offices in poor countries compared with their headquarters in western countries (Molyneux & Zagaria 2002). These factors, coupled with the possibility of accessing external debt relief funds for public health programmes in low-income countries meeting the criteria for designation as a Highly Indebted Poor Country by the World Bank and the International Monetary Fund, LF national programmes have been encouraged to mobilize resources locally/nationally to implement their programmes with varying degrees of success. In as much as this should be encouraged, it should be a supplement to centrally mobilized resources at the global level rather than a replacement for the latter, otherwise most endemic countries (especially the low-income countries in Africa) will not be able to achieve elimination. Indeed, many countries in Africa are currently unable to initiate MDA after completing mapping, primarily because there are no resources available. Throughout history, no global elimination or eradication programme has depended solely on the ability of endemic countries to mobilize all the required funding. The LF programme is unlikely to be the first. And even if it were, economic disparities across international borders and regions will ensure that elimination at the global level will not be declared for decades to come. Thus, fund raising at both the global and regional level must be intensified if the gains of the last 5 years are to be maintained, and if global elimination is to be achieved by 2020.

Conclusions

  1. Top of page
  2. Summary
  3. Do we know the extent of the problem?
  4. Are the recommended strategies working?
  5. Do we have the right tools measure success?
  6. To integrate or not to integrate?
  7. What has been the role of research?
  8. Where does the money come from?
  9. Conclusions
  10. References

The GPELF provides a wonderful opportunity to rid the world of a major public health menace. The technical delivery of the programme has so far been excellent but could be refined with more research. Enthusiasm from endemic countries has also been great. However, demand for technical and financial assistance from the endemic countries far outweighs the available means at the global/regional level. This has resulted in a prolonged period of disease mapping, delay in initiating MDA, slow scaling-up of national programmes to cover all populations at risk, and in stagnation of the number of active programmes.

An urgent financial plan to mobilize resources at the regional/global level is required to sustain the gains of this elimination programme and to maintain momentum for the future. In our view, this is paramount to the success of the programme. Asking individual countries to do it on their own will only achieve some degree of success that may at best be described as control not elimination.

References

  1. Top of page
  2. Summary
  3. Do we know the extent of the problem?
  4. Are the recommended strategies working?
  5. Do we have the right tools measure success?
  6. To integrate or not to integrate?
  7. What has been the role of research?
  8. Where does the money come from?
  9. Conclusions
  10. References
  • Gyapong JO & Remme JHF (2001) Validation of a rapid assessment method for the distribution of bancroftian filariasis. Transactions of the Royal Society of Tropical Medicine and Hygiene 95, 681686.
  • Gyapong JO, Kumaraswami V, Biswas G & Ottesen EA (2005) Treatment strategies underpinning the global programme to eliminate lymphatic filariasis. Expert Opinion in Pharmacotherapy 6, 179200.
  • Malecela-Lazaro M & Twum-Danso N (2004) The lymphatic filariasis (LF) research forum: towards developing a strategic plan for research to support the global program to eliminate LF (GPELF): program implementation. American Journal of Tropical Medicine and Hygiene 71, 1619.
  • Molyneux DH & Zagaria N (2002) Lymphatic filariasis elimination progress in global programme development. Annals of Tropical Medicine & Parasitology 96 (Suppl. 2), 515540.
  • Ottesen EA (2000) The global programme to eliminate lymphatic filariasis. Tropical Medicine and International Health 5, 591594.
  • Ottesen EA & Weil GJ (2004) The lymphatic filariasis (LF) research forum: towards developing a strategic plan for research to support the global program to eliminate LF (GPELF): introduction. American Journal of Tropical Medicine and Hygiene 71, 12.
  • Ottesen EA, Duke BOL, Karam M et al. (1997) Strategies and tools for the control/elimination of lymphatic Filariasis. Bulletin of the World Health Organization 75, 491503.
  • World Health Organization (2004) Report on the mid-term assessment of microfilaraemia reduction in sentinel sites of 13 countries of the global programme to eliminate lymphatic filariasis. Weekly Epidemiological Record 79, 358365.
  • World Health Organization (2005) Global programme to eliminate lymphatic filariasis. Weekly Epidemiological Record 80, 202212.