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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)

A retrospective study was performed comparing the number of spontaneous abortions in a hyperendemic area for onchocerciasis in Ecuador before and after invermectin treatment with that of a comparable non-endemic area. The frequency of spontaneous abortions was associated with a change in the community microfilarial load, suggesting that there may be a relationship between spontaneous abortions and infection with Onchocerca volvulus. In the endemic area, a significantly greater rate of spontaneous abortions was seen in the period before ivermectin distribution compared to that after the start of ivermectin treatments every 6 months. In the non-endemic area, no change in the rate of spontaneous abortions was seen over the same time period. In addition to the well-documented improvements in skin and ocular disease, ivermectin may also improve the reproductive health of endemic populations.

Trends in prevalence rates of onchocercal ocular lesions were examined over the period 1980 to 1990 using data from two cross-sectional surveys. There was evidence for increasing prevalence of anterior chamber microfilariae, iridocyclitis, optic atrophy, and chorioretinopathy. Large increases in prevalence, in particular, were seen for posterior segment lesions: optic atrophy increased from 2.7% to 6.4% and chorioretinopathy from 8.8% to 35.6%. Greatest increases in these lesions were seen in the Chachi which was attributed to the large increases in prevalence of microfilariae in the anterior chamber particularly in those aged 30 years or greater. The study findings suggest that ocular onchocerciasis is evolving in parallel with the well documented parasitological changes.