Onchocerciasis in Ecuador: recent observations in the province of Esmeraldas.

To evaluate the transmission of onchocerciasis that had occurred in the past 6 years in the province of Esmeraldas, in 1986 the onchocercal focus was re-examined using the same methodology as in the original survey of 1980. An increased prevalence of infection of 73.9% was noted, with an increase of 73.0% found in the principal focus, the Santiago Basin, and a 76.7% increase in the satellite foci. In the principle focus, a higher increase was noted on the Rio Santiago (88.8%) than on the Rio Cayapas (68.6%), while an increase of only 39.7% was seen on the Rio Onzoles. Geographical extension of both the onchocercal focus and its respective hyperendemic areas were found on the Rio Cayapas and Rio Santiago. A higher increased prevalence of infection was found in the children (210.0%) than in the adults (29.5%). In the satellite foci, the Rio Canande showed the higher increase of infection (146.4%), with an increase of 61.3% seen in adults and 1409.1% in children. Active transmission of the disease exists in all onchocercal foci, each with its distinct and varying intensity.