Onchocerciasis in the Americas: from arrival to (near) elimination

Abstract

Onchocerciasis (river blindness) is a blinding parasitic disease that threatens the health of approximately 120 million people worldwide. While 99% of the population at-risk for infection from onchocerciasis live in Africa, some 500,000 people in the Americas are also threatened by infection. A relatively recent arrival to the western hemisphere, onchocerciasis was brought to the New World through the slave trade and spread through migration. The centuries since its arrival have seen advances in diagnosing, mapping and treating the disease. Once endemic to six countries in the Americas (Brazil, Colombia, Ecuador, Guatemala, Mexico and Venezuela), onchocerciasis is on track for interruption of transmission in the Americas by 2012, in line with Pan American Health Organization resolution CD48.R12. The success of this public health program is due to a robust public-private partnership involving national governments, local communities, donor organizations, intergovernmental bodies, academic institutions, non-profit organizations and the pharmaceutical industry. The lessons learned through the efforts in the Americas are in turn informing the program to control and eliminate onchocerciasis in Africa. However, continued support and investment are needed for program implementation and post-treatment surveillance to protect the gains to-date and ensure complete elimination is achieved and treatment can be safely stopped within all 13 regional foci.

Figure 1

Geographic distribution and transmission status of the 13 onchocerciasis foci in the Americas as of December, 2010.

Figure 2

History of MECTIZAN treatment in the Americas and projection from 2011 - 2015. In 1995 all foci initiated 2x/year treatment. The annual peak of aggregate treatments for the region was reached in 2005. If the goals of PAHO resolution CD48.R12 are achieved, 2012 will be the final year that onchocerciasis treatment will be necessary, with all countries eligible for WHO certification of elimination no later than 2016.