Neglected tropical diseases

Brazil and Venezuela sign agreement to accelerate cross-border health interventions and interrupt transmission of onchocerciasis

20 May 2014 | Geneva

Ministers of Health from Brazil and Venezuela today signed a new bilateral agreement aimed at enhancing coordinated cross-border health interventions required to interrupt transmission of onchocerciasis in the cross-border Yanomami area between the two countries.

This agreement allows both countries to extend WHO’s strategy and treat every eligible individual at risk of the infection. It also provides for additional technical and administrative personnel, improved surveillance and a joint multidisciplinary technical team to engage the Yanomami people in the decision-making process.

The most important feature of the agreement is an understanding between the two countries to conduct cross-border interventions, provide treatments and to detect any undiscovered infected communities along the border.

In the Region of the Americas, WHO and PAHO in collaboration with the Onchocerciasis Elimination Program for the Americas (OEPA) are supporting Ministries of Health to interrupt transmission.

In 2013, Colombia became the first country in the world to be verified as having eliminated the disease.

The five remaining countries in the Americas where transmission was historically documented are the Bolivarian Republic of Venezuela, Brazil, Ecuador, Guatemala and Mexico.

An international team has started the process of verification in Ecuador. Guatemala and Mexico are compiling their national dossier ahead of a similar exercise to be conducted in the future.

It is expected that the agreement will facilitate – by reaching the elimination goal in the Yanomami area – the achievement of the regional goal of elimination of onchocerciasis from the Americas.


The Onchocerciasis Elimination Program for the Americas (OEPA) began in 1992 with the objective of eliminating ocular morbidity and transmission throughout the Americas by 2012 through biannual large-scale treatment with ivermectin.

All 13 foci in this region achieved coverage of more than 85% in 2006, and transmission was interrupted in 10 out of 13 by the end of 2011.

Following successful large-scale treatment of populations in affected areas with support from The Carter Center, Colombia and Ecuador interrupted transmission of the disease in 2007 and 2009 respectively.

Guatemala and Mexico interrupted transmission in 2011. Elimination efforts are now focused on the Yanomami people living in Brazil and Venezuela.

The disease

Onchocerciasis is a parasitic disease caused by the filarial worm Onchocerca volvulus transmitted by the repeated bites of infected blackflies (Simulium spp.)

These blackflies breed in fast-flowing rivers and streams, mostly in remote villages located near fertile land where people rely on agriculture.

In the human body, the adult worms produce embryonic larvae (microfilariae) that migrate to the skin, eyes and other organs.

When a female blackfly bites an infected person during a blood meal, it also ingests microfilariae which develop further in the blackfly and are then transmitted to the next human host during subsequent bites.

Related links