A pilot study on the prevalence of loiasis in Equatorial Guinea using an accurate Nested PCR

Background: In the last years loiasis has emerged as a public health problem in areas where Loa loa is co-endemic with Onchocerca volvulus, Wuchereria bancrofti and other filarial parasites. The objective of this work was to carried out a preliminary field study on the prevalence of loiasis in Equatorial Guinea. Methods: The study design was carried out in three villages situated in the continental region and the insular region from Equatorial Guinea. A total of 236 human blood samples were obtained from individuals living in the continental region (n=142) and on the island of Bioko (n=96). Blood samples were diagnosed by leucoconcentration and microscopy examination for microfilariae of L. loa and other filarial species. The molecular diagnosis was carried out by the L. loa specific nested PCR. Results: The study results shown a 22.8% of loiasis prevalence by microscopy observation, whereas the nested PCR revealed a prevalence of 76.4% in the continental region. In the 94 samples obtained from individuals from the island of Bioko, loiasis was not detected either by microscopy analysis or by nested PCR. Conclusions: The nested PCR used in this work showed itself to be an accurate technique that detects the presence of L. loa DNA and it could be a useful complementary tool in ascertaining more precise estimates of the prevalence of loiasis in Equatorial Guinea.