Onchocerciasis in Yemen: Time to take action against a neglected tropical parasitic disease

• Published in: Acta tropica Vol. 162; pp. 133 - 141
• Main Authors: Abdul-Ghani, Rashad, Mahdy, Mohammed A.K., Beier, John C.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-10-2016
• Subjects: Animals; Humans; Ivermectin - therapeutic use; Microfilariae - drug effects; Neglected Diseases - drug therapy; Neglected tropical disease; Onchocerca volvulus; Onchocerciasis - epidemiology; Onchocerciasis - prevention & control; Simuliidae - parasitology; Simulium; Sowda; Yemen; Yemen - epidemiology; Simulium; Onchocerca volvulus; Neglected tropical disease; Sowda; Yemen
• ISSN: 0001-706X; 1873-6254
• DOI: 10.1016/j.actatropica.2016.06.017

[Display omitted]
•Onchocerciasis mainly affects poor, rural communities in western Yemeni governorates.•The disease is of the localized, hyperreactive form, referred to as sowda.•Diagnosis by skin snip examination is challenging due to the low microfilarial load.•Vector situation needs evaluation because there is no vector control.•Simulium species have not been investigated in Yemen since the 1980s.
Onchocerciasis is a neglected parasitic disease affecting the poorest underserved people in Yemen. A national control programme with goals to eliminate onchocerciasis has yet to be launched due to the current upheaval and social unrest in the country. The disease, locally termed as sowda, is unique in its clinicopathologic pattern, being of the localized, non-blinding, hyperreactive onchocercal skin disease. Although early reports identified endemic foci along seasonal watercourses, there is a need to redefine its epidemiologic patterns as well as health and socioeconomic impacts. Laboratory diagnosis of sowda among Yemeni patients is difficult due to the low load of microfilariae in skin snips and the presence of asymptomatic itching-free microfilaria carriers. Adoption of ivermectin use at three-month intervals as a control strategy has not been evaluated because the drug is mostly used in clinics and distributed to only a few affected communities. This paper addresses key aspects of onchocerciasis in Yemen and highlights the need for screening at-risk populations using highly sensitive techniques and mapping the distributions of the parasite in human and vector populations of blackflies. The new research should be integrated with the launch of a national onchocerciasis control programme to achieve onchocerciasis elimination.