¿Oncocercosis en Colombia? Una revaluación del foco de López de Micay

Abstract

Human onchocerciasis was first described as existing in Colombia in 1965 in a small focus in Lopez de Micay on the Pacific Coast. Subsequent follow-up of the focus 12 years later showed that infection-prevalence had fallen from 15 to 7.5%. Since no patients were reported thereafter, the focus was considered to have been extinguished until 1989, when a child with occular keratitis was referred to the University Hospital in Cali. Onchocerciasis was confirmed by skin,snip examination. In July 1989 a multidisciplinaty team conducted a new survey in the area. Skin biopsies were obtained from 170 individuals. Infection-prevalence detected by skin-snip examination was 4.1% (71170). Ten percent of the surveyed males and 0.9% of the females had detectable microfilariae (mf) in skin. Microfilariae density in skin varied between 0.5 mf per milligram of skin to 47 mflmg and was directly related to the patients' age. Neither palpable subcutaneous nodules nor dermal alterations attributable to the parasite were detected in any of the patients. Occular pathology was found in two patients, consisting of bilateral keratitis and retinal degeneration, respectively. Simuliid activity at the time of the survey was very low and collection was not attempted. We hypothesise that active transmission may be taking place further upstream, where vector activity is greater. An increase in non-immune human settlement in the area is expected, due to the future construction of hydroelectrical plants and related connecting highways. Questions are therefore raised concerning the impact of immigration of naive population to this hypoendemic focus.