RESUMO
To eliminate transmission of Onchocerca volvulus, semiannual mass treatment with ivermectin (Mectizan; donated by Merck & Co) has been underway in Guatemala since 2000. We applied the 2001 World Health Organization (WHO) elimination criteria in the Santa Rosa focus of onchocerciasis transmission in Guatemala (10,923 persons at risk). No evidence of parasite DNA was found in 2,221 Simulium ochraceum vectors (one-sided 95% confidence interval [CI], 0-0.086%), and no IgG4 antibody positives to recombinant antigen OV16 were found in a sample of 3,232 school children (95% CI, 0-0.009%). We also found no evidence of microfilariae in the anterior segment of the eye in 363 area residents (95% CI, 0-0.08%). Our interpretation of these data, together with historical information, suggest that transmission of O. volvulus is permanently interrupted in Santa Rosa and that ivermectin treatments there can be halted.
Assuntos
Insetos Vetores/parasitologia , Onchocerca volvulus/isolamento & purificação , Oncocercose/transmissão , Simuliidae/parasitologia , Animais , Criança , Doenças Endêmicas , Ensaio de Imunoadsorção Enzimática , Feminino , Guatemala/epidemiologia , Humanos , Imunoglobulina G/sangue , Masculino , Oncocercose/epidemiologia , Oncocercose/parasitologia , Oncocercose/prevenção & controle , Estudos SoroepidemiológicosRESUMO
Onchocerciasis (river blindness), which is close to being eliminated from Guatemala through semiannual administration of ivermectin, is still transmitted in one area of the country that coincidentally receives an annual influx of migrant workers to harvest coffee. Migrant workers generally are not included in semiannual ivermectin treatments, but if infected could serve as a reservoir. We report on two studies undertaken to measure the exposure to onchocerciasis (presence of IgG4 antibodies to a recombinant Onchocerca volvulus antigen, OV-16) among migrant workers. During two coffee harvest seasons, 170 migrant workers with a history of working in the disease-endemic area were tested and 1 (0.6%, 95% confidence interval = 0-3.2%) was seropositive. This low rate of exposure in migrant workers indicates that they are unlikely to play a significant role in transmission of onchocerciasis and may indicate that transmission in the last remaining disease-endemic area of Guatemala is decreasing significantly.