Elimination of Onchocerciasis in Colombia
Onchocerciasis (river blindness) is a highly debilitating, parasitic disease endemic in many African and South American regions, caused by the nematode worm Onchocerca volvulus.1 It is transmitted though the bite of small black flies, which are known to establish breeding grounds in rapidly flowing bodies of waters, like rivers or streams.2 Common symptoms of the disease are severe itching, lesions, damage to the eyes and in some cases blindness. Luckily, the drug Mectizan® (ivermectin) can help decrease these symptoms and prevent cases of blindness; however, many who suffer from onchocerciasis are unable to afford ivermectin, enabling onchocerciasis to becoming the second leading cause of blindness, worldwide.2
It was in 1965 that the first case of onchocerciasis was detected in Colombia.1 The patient was observed to have a loss of visual functioning.1 A skin biopsy confirmed that the loss of visual acuity was due to the presence of the nematode worm in the anterior chamber of the eyes.1 This case lead to the onchocerciasis eradication program in Colombia, with the focus being put in one main location, the town of Lopez located on the Pacific Coast’s Micay River.1
After this discovery, there were three key epidemiological surveys that were conducted in 1965, 1977 and 1989, to determine the onchocerciasis transmission rates.1 The discovery of these studies was that the rates of onchocerciasis in Colombia were decreasing without any interventions in place.1 During this time period, prevalence rates dropped dramatically from 15% to 4.1% nationwide, with the bulk of the diseased population located near the Micay River headwater regions.1 Further studies lead to the discovery that onchocerciasis was present along the Colombia-Ecuador border, and its spread was linked with migrant activity across the border, thought to be originating from Ecuador.1 Thus, as Figure 1 demonstrates, Colombia had two regions narrowed down...