Frempong, Kwadwo K., Walker, Martin, Cheke, Robert ORCID: 0000-0002-7437-1934, Tetevi, Edward J., Gyan, Ernest T., Owusu, Ebenezer O., Wilson, Michael D., Boakye, Daniel A., Taylor, Mark J., Biritwum, Nana-Kwadwo, Osei-Atweneboana, Mike and Basanez, Maria-Gloria (2016) Does increasing treatment frequency address sub-optimal responses to ivermectin for the control and elimination of river blindness? Clinical Infectious Diseases, 62 (11). pp. 1338-1347. ISSN 1058-4838 (Print), 1537-6591 (Online) (doi:https://doi.org/10.1093/cid/ciw144)

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Abstract

Background
Several African countries have adopted a biannual ivermectin distribution strategy in some foci to control and eliminate onchocerciasis. In 2010, the Ghana Health Service started biannual distribution to combat transmission hotspots and sub-optimal responses to treatment. We assessed the epidemiological impact of the first 3 years of this strategy and quantified responses to ivermectin over two consecutive rounds of treatment in 10 sentinel communities.

Methods
We evaluated Onchocerca volvulus microfilarial intensity and prevalence in those aged +/-20 years before the first, second and fifth (or sixth) biannual treatment rounds using skin snip data from 956 participants. We used longitudinal regression modelling to estimate rates of microfilarial repopulation of the skin in a cohort of 217 participants who were followed-up over the first two rounds of biannual treatment.

Results
Biannual treatment has had a positive impact, with substantial reductions in infection intensity after 4 or 5 rounds in most communities. We identified three communities—all having been previously recognised as responding sub-optimally to ivermectin—with statistically significantly high microfilarial repopulation rates. We did not find any clear association between microfilarial repopulation rate and the number of years of prior intervention, coverage, or the community level of infection.

Conclusions
The strategy of biannual ivermectin treatment in Ghana has reduced O. volvulus microfilarial intensity and prevalence, but sub-optimal responses to treatment remain evident in a number of previously and consistently implicated communities. Whether increasing the frequency of treatment will be sufficient to meet the World Health Organization’s 2020 elimination goals remains uncertain.

Item Type:	Article
Additional Information:	© The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. This is an Open Access article distributed under the terms of the Creative Commons Attribution License.
Uncontrolled Keywords:	Onchocerciasis, Ivermectin, Treatment, Biannual, Sub-optimal responses
Subjects:	Q Science > QH Natural history > QH301 Biology
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > Natural Resources Institute > Agriculture, Health & Environment Department
Last Modified:	12 May 2020 10:59
URI:	http://gala.gre.ac.uk/id/eprint/14820

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