Background
Microsporidia are obligate intracellular parasites that infect a broad range of vertebrates and invertebrates. They have been increasingly recognized as human pathogens in AIDS patients, mainly associated with a life-threatening chronic diarrhea and systemic disease. However, to date the global epidemiology of human microsporidiosis is poorly understood, and recent data suggest that the incidence of these pathogens is much higher than previously reported and may represent a neglected etiological agent of more common diseases indeed in immunocompetent individuals. To contribute to the knowledge of microsporidia molecular epidemiology in HIV-positive patients in Nigeria, the authors tested stool samples proceeding from patients with and without diarrhea.
Methodology/Principal Findings
Stool samples from 193 HIV-positive patients with and without diarrhea (67 and 126 respectively) from Lagos (Nigeria) were investigated for the presence of microsporidia and
Cryptosporidium
using Weber’s Chromotrope-based stain, Kinyoun stain, IFAT and PCR. The Weber stain showed 45 fecal samples (23.3%) with characteristic microsporidia spores, and a significant association of microsporidia with diarrhea was observed (O.R. = 18.2; CI: 95%). A similar result was obtained using Kinyoun stain, showing 44 (31,8%) positive samples with structures morphologically compatible with
Cryptosporidium
sp, 14 (31.8%) of them with infection mixed with microsporidia. The characterization of microsporidia species by IFAT and PCR allowed identification of
Enterocytozoon bieneusi
,
Encephalitozoon intestinalis
and
E. cuniculi
in 5, 2 and 1 samples respectively. The partial sequencing of the ITS region of the rRNA genes showed that the three isolates of
E.bieneusi
studied are included in Group I, one of which bears the genotype B.
Conclusions/Significance
To our knowledge, this is the first report of microsporidia characterization in fecal samples from HIV-positive patients from Lagos, Nigeria. These results focus attention on the need to include microsporidial diagnosis in the management of HIV/AIDS infection in Nigeria, at the very least when other more common pathogens have not been detected.
A study was conducted to detect and identify enteric microsporidian species in 43 children from Oyo state, Nigeria. Using nested polymerase chain reaction, 9.3% of the children were identified as positive for Enterocytozoon bieneusi. DNA sequencing of the PCR products showed the presence of three known genotypes (two isolates of genotype D and one of genotype K) and one new genotype. This study suggests that either human or animal (or both) could be the infection source for the children, since identified genotypes D and K have been previously detected in both immunocompromised and immunocompetent patients and domestic animals. The identification of high diversity also suggests intensive transmission of microsporidiosis in the studied area.
Molecular characterization of Cryptosporidium spp. and Enterocytozoon bieneusi has improved our understanding of the transmission of both organisms in humans. In this study, to infer possible infection sources, Cryptosporidium spp. and E. bieneusi in fecal specimens from 90 HIV-infected patients attending antiretroviral clinics in Lagos, Nigeria were detected and genotyped by PCR and DNA sequencing. Cryptosporidium spp. and E. bieneusi were identified in four and five patients, respectively, including the occurrence of subtype IeA11T3G3 of Cryptosporidium hominis in two patients, subtype IIcA5G3k of Cryptosporidium parvum in one patient, and Type IV of E. bieneusi in four patients. Among the remaining positive patients, one had mixed infection of Cryptosporidium meleagridis and C. hominis and one had mixed E. bieneusi genotypes. These data highlight a possible difference in major transmission routes (anthroponotic vs. zoonotic) between Cryptosporidium spp. and E. bieneusi in HIV+ patients in the study area.
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