Elimination of onchocerciasis from Colombia: first proof of concept of river blindness elimination in the world

Abstract

BackgroundOnchocerciasis is a chronic parasitic infection originally endemic in 13 discrete regional foci distributed among six countries of Latin America (Brazil, Colombia, Ecuador, Guatemala, Mexico and Venezuela). In Colombia, this disease was discovered in 1965 in the Pacific Coast of the country. The National Onchocerciasis Elimination Program was established in 1993 with the aim of eliminating disease morbidity and infection transmission. In 2013, the World Health Organization (WHO) verified Colombia as free of onchocerciasis, becoming the first country in the world to reach such a goal. This report provides the empirical evidence of the elimination of Onchocerca volvulus transmission by Simulium exiguum (s.l.) after 12 years of 6-monthly mass drug administration of Mectizan® (ivermectin) to all the eligible residents living in this endemic area.MethodsFrom 1996 onwards, a biannual community-based mass ivermectin administration programme was implemented, complemented by health education and community participation. In-depth parasitological, serological and entomological surveys were conducted periodically between 1998 and 2007 to evaluate the impact of ivermectin treatment according to the 2001 WHO guidelines. When the interruption of parasite transmission was demonstrated, the drug distribution ceased and a three-year post-treatment surveillance (PTS) period (2008–2010) was initiated.ResultsAfter 23 rounds of treatment, parasitological and ophthalmological assessments showed absence of microfilariae in skin and anterior chamber of the eyes. Serological tests proved lack of antibodies against O. volvulus in children under 10 years-old. A total of 10,500 S. exiguum flies tested by PCR had no L3 infection (infectivity rate = 0.0095%; 95% CI: 0.0029–0.049) during 2004, indicating interruption of parasite transmission. However, biannual ivermectin treatments continued until 2007 followed by a 3-year PTS period at the end of which 13,481 flies were analyzed and no infective flies were found (infectivity rate = 0%; 95% CI: 0.0–0.014).ConclusionsThese results fulfilled the WHO criteria for onchocerciasis elimination. Consequently, in 2013 Colombia was verified as free of onchocerciasis, demonstrating that elimination of this neglected tropical disease is an achievable goal and paving the way for an elimination agenda to be followed by other endemic countries in Latin America and Africa.

The Galabat-Metema cross-border onchocerciasis focus: The first coordinated interruption of onchocerciasis transmission in Africa

“…Aside from pool size, techniques were the generally performed under the same protocol in the two laboratories. The pools analyzed contained only heads that had been separated from the bodies as previously described [24]. The heads were then analyzed using the standard O-150 PCR assay [25].…”

Onchodermatitis: Where Are We Now?

“…By the end of 2012, transmission had been eliminated in 11 of the 13 foci in the Americas [ 6 ]. Elimination was first demonstrated by Colombia in 2103 [ 76 ], followed by Ecuador in 2014, Mexico in 2015 and Guatemala in 2016 [ 77 ]. Elimination of transmission in Ecuador was particularly gratifying as the main vector here, Simulium exiguum , was a very effective transmitter of infection and the skin and eye disease in this focus was probably the most severe in the Americas [ 78 ].…”

Anthelmintic drug discovery: target identification, screening methods and the role of open science

“…Ivermectin must therefore be administered annually or twice-annually for many years to eliminate the parasite in the population. Progress has been impressive: onchocerciasis has been largely controlled as a public health problem in most of Africa [56], and four countries in the Americas -Columbia, Ecuador, Guatemala and Mexico -have achieved elimination of the parasite [57,58].…”