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

Abstract

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

An Overview of the Management of Mansonellosis

“…Effective and co-ordinated helminth disease control programmes have been in operation for well over 70 years. 13,[23][24][25][26][27] Many of these programmes, which have in recent years focused on the use of anti-helminthic MDA and (to a lesser extent) vector control, have enjoyed substantial and sustained financing for almost a century. 9,10,13,23 Typically, these programmes are co-ordinated by regional and national governments, often with financial and expert support from the WHO, the WB and various nongovernmental organisations (NGOs), like the Bill and Melinda Gates foundation.…”

“…9,10,24 In addition to this, the fact that doxycycline regimes used for filarial disease treatment also prevent the inclusion of pregnant women and young children under 8 (who can be affected by neurological disorders) from being included in treatment programmes, means that while doxycycline does have a good safety profile, when used alone, it may not always be possible to achieve the treatment coverage levels required to break filarial parasite transmission. 9,10,24 Unfortunately, this is compounded by the fact that microfilariae persist in a doxycycline-treated individual's blood for several months after they are treated and even though experimental work suggests that Wolbachia-free microfilariae cannot develop properly in their insect vector hosts, it is unlikely that doxycycline treatment will be as effective as existing treatments at breaking filarial parasite transmission and thus that any doxycycline treatment should be complemented with traditional anti-filarial therapeutics (ivermectin for onchocerciasis, DEC or albendazole [or both] for lymphatic filariasis) wherever possible. 9,10,24 Perhaps, however, the factor most limiting a greater use of doxycycline treatment regimes in filarial disease management is that effective filarial disease treatment with doxycycline requires daily or twice daily administration of the drug for periods of between 4 to 6 weeks.…”

“…9,10,24 Unfortunately, this is compounded by the fact that microfilariae persist in a doxycycline-treated individual's blood for several months after they are treated and even though experimental work suggests that Wolbachia-free microfilariae cannot develop properly in their insect vector hosts, it is unlikely that doxycycline treatment will be as effective as existing treatments at breaking filarial parasite transmission and thus that any doxycycline treatment should be complemented with traditional anti-filarial therapeutics (ivermectin for onchocerciasis, DEC or albendazole [or both] for lymphatic filariasis) wherever possible. 9,10,24 Perhaps, however, the factor most limiting a greater use of doxycycline treatment regimes in filarial disease management is that effective filarial disease treatment with doxycycline requires daily or twice daily administration of the drug for periods of between 4 to 6 weeks. These longterm regimens make doxycycline-based MDA (dMDA) programmes much more logistically difficult and expensive to implement than iMDA programmes.…”

“…Test-and-treat strategies can reduce the expense of dMDA (by preventing public health professionals investing considerable time treating individuals that are not infected with the targeted filarial parasite), but even when such approaches are adopted dMDA is still far more expensive and complex to implement than iMDA. 9,10,24,66 And even though costeffective diagnostic tools have been developed to assist with test-and-treat dMDA approaches, existing tools are not all field-friendly and not always accessible everywhere MDA is needed. 1 Although thus iMDA strategies offer little clinical benefit to any individual accepting treatment and none to those uninfected (they offer a benefit to the whole treated community through reducing the number of new infections in any treated area), they are unlikely to be replaced by ethically more sound doxycycline-based test and treat strategies that offer a potential cure to those treated as well as, in the case of lymphatic filariasis, sometimes offering a direct clinical benefit by providing relief from the symptoms caused by their infections.…”

“… 9 , 10 , 13 , 23 To date, most of this helminth disease control financing that has been directed towards filarial disease management has been spent on the management of lymphatic filariasis and onchocerciasis. 9 , 10 , 13 , 23 , 24 Far less financing has been directed to the management of other filarial diseases, with most not directed to these two key filarial diseases being directed to dirofilarial disease control. 28 , 29 Almost no dedicated financing has been directed to the management of mansonellosis.…”