Resumo

FERNANDEZ, Alexis; RAMIREZ-PEREZ, Jaime; SHULER, Harland  e  RODRIGUEZ, Noris. Polymerase chain reaction (PCR) for detecting infective forms of Onchocerca volvulus in Simulium metallicum s.l. (Diptera: Simuliidae) in Venezuelan endemic areas. Bol Mal Salud Amb [online]. 2008, vol.48, n.1, pp.35-43. ISSN 1690-4648.

We present the results obtained after a parasitological study carried out in three onchocerciasis endemic areas located in the North-Central and North- Oriental foci in Venezuela. During one year, adult females of Simulium spp. were captured when landing on human attractants along rivers and in the proximity of houses where onchocerciasis cases had been detected. A total of 95,251 black flies were captured, from this total, only 0.05% were identified as S. exiguum s.l. and the rest were Simulium metallicum s.l. All the specimens were submitted to mechanical disruption for head and body separation. The heads were grouped in pools of 50 for genomic DNA extraction. The DNA was used to evaluate the natural infectivity by O. volvulus using the Polymerase Chain Reaction technique with species specific oligonucleotides. The prevalence of infective flies, was calculated using the Poolscreen program; the results indicated a positivity of 9/10,000 flies for the locality of La Cuesta (North-eastern focus, Anzoátegui State), followed for Santa Rosa (North- Central focus, Carabobo State) with a prevalence of 5/10,000, and finally La Carapa (North-eastern focus, Monagas State) with the lowest index (3/10,000) of infectivity. These results are demonstrating the utility of the technique for large scale entomological studies and the specific detection of O. volvulus, infective larvae, the causal agent of human onchocerciasis.

Palavras-chave : Onchocerciasis; Simulium metallicum; Entomology; PCR; Venezuela.