Onchocerciasis in Ecuador: Prevalence of Infection on the Ecuador-Colombia Border in the Province of Esmeraldas

The prevalence of onchocerciasis infection was determined in communities on 7 rivers located in the northern area of the canton San Lorenzo province of Esmeraldas. Diagnosis of the infection was obtained by skin biopsies and recombinant antigen-based serology. No evidence of infection was detected in 9 communities studied along the Rio Mataje which forms the frontier between Ecuador and Colombia nor in 10 adjacent communities located on 5 interior rivers. Evidence for Onchocerca volvulus infection was found in 4 communities on the Rio Tululvi with the following prevalence: La Boca (3.5% by biopsy and 3.9% by serology) Guayabal (9.1% by both biopsy and serology) La Ceiva (51.5% by biopsy and 53% by serology) and Salidero (4% by biopsy and 7.7% by serology). A few individuals in these communities were seropositive for O. volvulus in the absence of detectable dermal microfilariae: these might harbor very light or prepatent infections. No clinical disease attributable to onchocerciasis was found. The infected communities will be included in the ivermectin-based National Control Program for the disease with no evidence of the infection having extended north of the Ecuadorian/Colombian border. (authors)