Onchocerciasis (river blindness) – more than a century of research and control

Abstract

This historical review on River Blindness, onchocerciasis, is written in honour of (i) the 120-year anniversary of the Bernhard Nocht Institute for Tropical Medicine (BNITM), founded in 1900 in Hamburg in the sequel of a tremendous cholera outbreak that hit Hamburg in 1892, (ii) the 75-year anniversaries of Acta Tropica and (iii) the Swiss Tropical and Public Health Institute (Swiss TPH), both founded in 1944 in Basel by the renowned scientist of tropical medicine Rudolf Geigy . Geigy was the first director of the former Swiss Tropical Institute (STI) and simultaneously the first editor of Acta Tropica.River Blindness caused by the tissue filaria Onchocerca volvulus was one focus of research in the BNITM over almost 60 years documented in about 300 publications. Consequently, in this historical review article we have cited major articles based on research conducted at the BNITM.In addition to this historical review article on onchocerciasis two historical articles on 75 year of both, Acta Tropica and Swiss TPH, are jointly published in in one issue of Acta Tropica.

An Overview of the Management of Mansonellosis

“…9,10,27 These past successes support the hypothesis that the elimination of these diseases can be achieved with iMDA and only a limited amount of alternative interventions and thus that filarial disease management resources should be focused on attaining these goals using existing tools rather than developing potential alternatives. 9,10,24,64 And although it is widely accepted that additional tools will be needed to complement iMDA for the WHO to achieve its ambitious filarial disease elimination targets, insect vector targeting tools (such as insecticideimpregnated bed nets for lymphatic filariasis control and organophosphate ground larviciding [treating of specific rivers with temephos] for the control of onchocerciasis) are likely to be more often deployed as complementary interventions owing to their proven utility in filarial disease control. 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.…”

“…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. 9,10,13,23 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.…”

“…9,10,24 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.…”