Comparison of Ivermectin Alone With Albendazole (ALB) Plus Ivermectin (IVM) in Their Efficacy Against Onchocerciasis

Detailed Summary

Onchocerciasis is a vector-borne nematode parasitic disease that causes severe disability. Onchocerciasis affects approximately 33 million people, mostly in 30 countries in sub-Saharan Africa (with small foci in Latin America and Yemen) 1This disease causes blindness and severe skin disease and it is spread by black flies. O. volvulus adult worms live in subcutaneous nodules. O. volvulus adult worms are larger and less sensitive to available drug treatments than those of the species that cause Lymphatic Filariasis (LF). They also have a longer lifespan (approximately 14 years rather than the estimated 7 years for LF parasites). Several programs and developments have greatly improved the Onchocerciasis. situation since the 1970's when the Onchocerciasis Control Programme (OCP) in West Africa (green countries in the map) was initiated. OCP relied exclusively on vector (black fly) control in its early years. However, following the appearance of Ivermectin (Mectizan) on the scene in the late 1980's, OCP transitioned to become a drug distribution program with annual IVM MDA in 11 countries. OCP ended in 2002. This was replaced by the African Program for Onchocerciasis Control (APOC) which coordinates community directed distribution of IVM MDA in 28 African countries (including the former OCP countries). OCP and APOC have done a good job of reducing parasite infection intensities and Onchocerciasis disease rates in many endemic countries. Unfortunately, there is no real end in sight for the APOC approach (apart from a funding endpoint in 2015); while it may be possible to eliminate Onchocerciasis. In selected areas by MDA with IVM (alone, or combined with vector control), disease control programs in most African countries will require active maintenance for many years to come. While IVR has good activity against the parasite larvae that cause disease in the skin and eye (microfilariae or Mf), it does not kill O. volvulus adult worms, and they resume production of Mf that can lead to transmission of new Onchocerciasis. Cases by black flies after a few months. APOC activities are focused on areas with high infection rates (where disease risks are highest). However, extensive areas in Africa where fewer than 20% of adult men have Onchocerciasis nodules detectable by palpation are not receiving interventions for Onchocerciasis at this time. These areas are not disease free. (Onchocerciasis dermatitis can be severe in hypoendemic areas), and they also may serve as a source for reintroduction of the parasite into previously controlled areas after interventions stop.

Study Details

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Interventions