Onchocerciasis in Ecuador: infection in children in the Santiago Basin focus, province of Esmeraldas.

The prevalence of onchocerciasis infection in children aged 1-12 in the Santiago Basin focus, province of Esmeraldas, Ecuador, was determined to see if active transmission of the disease had occurred in the past 6 years. An infection rate of 45.0% was found. Compared to that found in 1980 (14.5%), the infection rate had increased by 210.1%. The increase was greater on the Rio Santiago (340.5%) than on the Rio Cayapas (195.5%). An increase of 286% was seen in the skin microfilarial density in the 1-4 year age group, with a 56.8% increase in the 5-12 year age group. The prevalence of infection in children aged 0-4 years (those born since the first enquiry in 1980) was 64.3%, with an average skin microfilarial density of 12.2 microfilariae (mf)/mg and with 20% presenting nodules, of which 92.1% occurred in the head region. Of the 34 children examined aged less than one year, 25 (73.5%) were positive for microfilariae with an average microfilarial skin density of 9.6 mf/mg. These data suggest that there is active transmission of the disease in the Santiago Basin onchocercal foci.