This article is part of the supplement: Report of a Scientific Working Group on Serious Adverse Events following Mectizan® treatment of onchocerciasis in Loa loa endemic areas .

Review

A Framework for Decision-Making for Mass Distribution of Mectizan^® in Areas Endemic for Loa loa

David G Addiss¹, Richard Rheingans², Nana AY Twum-Danso³ and Frank O Richards⁴

¹  U.S. Centers for Disease Control and Prevention, Atlanta, GA, USA

²  Rollins School of Public Health, Emory University, Atlanta, GA, USA

³  Mectizan^® Donation Program, Decatur, GA, USA

⁴  Global 2000 River Blindness Program, The Carter Center, Atlanta, GA, USA

Filaria Journal 2003, 2(Suppl 1):S9

Published:	24 October 2003

Abstract

Background

The occurrence of Loa loa encephalopathy following mass treatment of onchocerciasis with Mectizan^® has adversely affected onchocerciasis control efforts in central Africa. Persons with very high densities of L. loa microfilaremia are at increased risk of encephalopathy, but little is known about the geographic distribution of these persons within central Africa. RAPLOA, a new technique that correlates the proportion of community members reporting a history of eyeworm with the prevalence of high-intensity L. loa microfilaremia in that community, may be useful for rapid assessment of areas at potential risk of treatment-related L. loa encephalopathy. Validation of RAPLOA is ongoing. The operational and risk-reduction advantages of RAPLOA over the current technique of village-by-village rapid epidemiologic assessment for onchocerciasis (REA) are unknown.

Methods

We developed a decision model to compare four strategies for minimizing sequelae of L. loa encephalopathy following mass treatment with Mectizan^® in areas co-endemic for onchocerciasis and loiasis: REA; RAPLOA with threshold eyeworm prevalences of 40% and 20% (RAPLOA-40 and RAPLOA-20, respectively); and combined REA/RAPLOA-40.

Results

In the model, all four strategies significantly reduced risk of death and neurologic complications from L. loa encephalopathy, but RAPLOA-20 and REA resulted in half as many such cases as did RAPLOA-40 or combined REA/RAPLOA-40.

Conclusion

RAPLOA is likely to be useful programmatically in reducing risk of L. loa encephalopathy following mass treatment with Mectizan^®. It also may be cost-saving. Before full-scale implementation, additional data are needed on geographic clustering of high-density L. loa microfilaremia and on RAPLOA's reliability and cost.