A Community-Based Trial of Ivermectin for Onchocerciasis Control in the Forest of Southwestern Cameroon: Clinical and Parasitologic Findings after Three Treatments

Somo, R. Moyou; Ngosso, A.; Dinga, J. S.; Enyong, Peter; Fobi, Grace

doi:10.4269/ajtmh.1993.48.9

Cited by 20 publications

(8 citation statements)

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“…Other authors have assumed that four rounds of ivermectin treatment would reduce the prevalence of troublesome itching by 85% [71], but this optimistic expectation is not supported by the results of [72] or our modelling outputs. With the exception of two studies by Whitworth et al [73,74], which concluded that ivermectin had no effect on skin disease, our projected reductions are in broad agreement with the literature [53,72,75-77]. Subsequent studies by Whitworth et al using a longer time period and an improved study design, reported a reduction in troublesome itch of 30% after six years of annual ivermectin treatment [76].…”

Section: Discussionsupporting

confidence: 87%

Modelling the impact of ivermectin on River Blindness and its burden of morbidity and mortality in African Savannah: EpiOncho projections

et al. 2014

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BackgroundThe African Programme for Onchocerciasis Control (APOC) has refocused its goals on the elimination of infection where possible, seemingly achievable by 15–17 years of annual mass distribution of ivermectin in some African foci. Previously, APOC had focused on the elimination of onchocerciasis as a public health problem. Timeframes have been set by the World Health Organization, the London Declaration on Neglected Tropical Diseases and the World Bank to achieve these goals by 2020–2025.MethodsA novel mathematical model of the dynamics of onchocercal disease is presented which links documented associations between Onchocerca volvulus infection and the prevalence and incidence of morbidity and mortality to model outputs from our host age- and sex-structured onchocerciasis transmission framework (EpiOncho). The model is calibrated for African savannah settings, and used to assess the impact of long-term annual mass administration of ivermectin on infection and ocular and skin disease and to explore how this depends on epidemiological and programmatic variables.ResultsCurrent onchocerciasis disease projections, which do not account for excess mortality of sighted individuals with heavy microfilarial loads, underestimate disease burden. Long-term annual ivermectin treatment is highly effective at reducing both the morbidity and mortality associated with onchocerciasis, and this result is not greatly influenced by treatment coverage and compliance. By contrast, impact on microfilarial prevalence and intensity is highly dependent on baseline endemicity, treatment coverage and systematic non-compliance.ConclusionsThe goals of eliminating morbidity and infection with ivermectin alone are distinctly influenced by epidemiological and programmatic factors. Whilst the former goal is most certainly achievable, reaching the latter will strongly depend on initial endemicity (the higher the endemicity, the greater the magnitude of inter-treatment transmission), advising caution when generalising the applicability of successful elimination outcomes to other areas. The proportion of systematic non-compliers will become far more influential in terms of overall success in achieving elimination goals.

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Section: Discussionsupporting

confidence: 87%

Modelling the impact of ivermectin on River Blindness and its burden of morbidity and mortality in African Savannah: EpiOncho projections

et al. 2014

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“…During the period when vector control was the only strategy for control of onchocerciasis, persons already afflicted with onchocercal skin manifestations did not benefit directly from the intervention. Early studies suggested that ivermectin was associated with improvement in severe itching and a decrease in the prevalence and severity of skin lesions (Somo et al. 1993; Whitworth et al.…”

Section: Onchocercal Skin Diseasementioning

confidence: 99%

Impact of ivermectin on illness and disability associated with onchocerciasis

Tielsch

Beeche

2004

Tropical Med Int Health

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SummaryThe Onchocerciasis Control Program (OCP), one of the most successful vertical disease control programs in the history of public health, came to an end in 2003 with devolvement of responsibilities for control program activities passed to the countries affected. Fortunately, 15 years ago the Mectizan Ò Distribution Program (MDP) was founded to provide a complementary approach to controlling the disabling consequences of this parasitic infection. With over 250 million doses of ivermectin distributed over the past 15 years, the MDP is well on its way to both solidifying the progress made by the OCP and extending program reach well beyond the boundaries of the OCP. Through the extensive clinical testing protocols implemented in a variety of countries in Aftica, ivermectin has been proven to be a safe and highly effective treatment for onchocerciasis. Regular distribution to populations living in endemic areas has demonstrated significant reductions in blinding ocular complications, transmission, and disability caused by onchocercal skin disease. As yet undocumented, are the likely significant impact regular population dosing with ivermectin has on intestinal helminth infections, lymphatic filariasis, and human scabies infection. While there are significant barriers to continued program success, focussed attention on expanding and improving community-directed ivermectin distribution is likely to lead to further progress against this resilient infection.

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“…10,11 Except for pruritus and serious hyperkeratosis, onchocercal skin lesions were not significantly modified by ivermectin treatment in these studies. In Burundi, the diminution of both itching and scratch marks was very pronounced, even more so in the group with biannual treatments.…”

Section: Resultsmentioning

confidence: 69%

“…DISCUSSION There have not been many community trials conducted that compared the efficacy of ivermectin on the parasitologic changes and/or the adverse reactions after annual or biannual treatments. [10][11][12] These studies reported that a six-month therapy regimen had a slight advantage in terms of an antiparasitic effect compared with an annual treatment. Adverse reactions were milder after second or third treatments, whether these were given annually or biannually.…”

Section: Resultsmentioning

confidence: 99%

Treatment of onchocerciasis with ivermectin (Province of Bururi, Burundi): parasitologic and clinical evaluation of different periodicities of treatment.

Vyungimana¹,

E²

1998

The American Journal of Tropical Medicine and Hygiene

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Abstract. To find out whether biannual treatments of onchocerciasis with ivermectin were necessary or whether annual treatments could suffice, parasitologic and clinical results in Burundi were compared at 12 months after a single treatment and after two treatments with an interval of six months. Adverse reactions were also compared at 12 months, after a second or third treatment, respectively. The biannual treatment resulted in a greater reduction of parasitologic parameters, had a longer-lasting effect on itching, and produced less side effects (especially itching, rash, and swellings) at 12 months than an annual treatment. Skin lesions were not significantly modified by any of the treatment schemes at 12 months. Notwithstanding this slight advantage of biannual treatment, operational constraints forced us to choose an annual distribution of ivermectin. With minimal resources, a distribution scheme was organized that was adapted to the different levels of endemicity of onchocerciasis. The results of this study may be of interest to policy makers and public health officials in areas where logistical and resource issues severely restrict the scope of treatment programs. In view of the planned activities of the African Programme of Onchocerciasis Control, the achievements in Burundi indicate that even with limited resources, an appropriate annual distribution scheme can give meaningful results. In spite of the persistence of skin lesions, their severity decreased and most patients considered that their condition had improved even after just one year.

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A Community-Based Trial of Ivermectin for Onchocerciasis Control in the Forest of Southwestern Cameroon: Clinical and Parasitologic Findings after Three Treatments

Cited by 20 publications

References 0 publications

Modelling the impact of ivermectin on River Blindness and its burden of morbidity and mortality in African Savannah: EpiOncho projections

Modelling the impact of ivermectin on River Blindness and its burden of morbidity and mortality in African Savannah: EpiOncho projections

Impact of ivermectin on illness and disability associated with onchocerciasis

Treatment of onchocerciasis with ivermectin (Province of Bururi, Burundi): parasitologic and clinical evaluation of different periodicities of treatment.

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