Intestinal parasite infections in a rural community of Rio de Janeiro (Brazil): Prevalence and genetic diversity of Blastocystis subtypes.

BACKGROUND: Intestinal parasitic infections are considered a serious public health problem and widely distributed worldwide, mainly in urban and rural environments of tropical and subtropical countries. Globally, soil-transmitted helminths and protozoa are the most common intestinal parasites. Blastocystis sp. is a highly prevalent suspected pathogenic protozoan, and considered an unusual protist due to its significant genetic diversity and host plasticity. METHODOLOGY/MAIN FINDINGS: A total of 294 stool samples were collected from inhabitants of three rural valleys in Rio de Janeiro, Brazil. The stool samples were evaluated by parasitological methods, fecal culture, nested PCR and PCR/Sequencing. Overall prevalence by parasitological analyses was 64.3% (189 out of 294 cases). Blastocystis sp. (55.8%) was the most prevalent, followed by Endolimax nana (18.7%), Entamoeba histolytica complex (7.1%), hookworm infection (7.1%), Entomoeba coli (5.8%), Giardia intestinalis (4.1%), Iodamoeba butchilii (1.0%), Trichuris trichiura (1.0%), Pentatrichomonas hominis (0.7%), Enterobius vermicularis (0.7%), Ascaris lumbricoides (0.7%) and Strongyloides stercoralis (0.7%). Prevalence of IPIs was significantly different by gender. Phylogenetic analysis of Blastocystis sp. and BLAST search revealed five different subtypes: ST3 (34.0%), ST1 (27.0%), ST2 (27.0%), ST4 (3.5%), ST8 (7.0%) and a non-identified subtype. CONCLUSIONS/SIGNIFICANCE: Our findings demonstrate that intestinal parasite infection rates in rural areas of the Sumidouro municipality of Rio de Janeiro, Brazil are still high and remain a challenge to public health. Moreover, our data reveals significant genetic heterogeneity of Blastocystis sp. subtypes and a possible novel subtype, whose confirmation will require additional data. Our study contributes to the understanding of potential routes of transmission, epidemiology, and genetic diversity of Blastocystis sp. in rural areas both at a regional and global scale.

[Socio-cultural and ethical factors involved in the diagnosis of schistosomiasis mansoni in an area of low endemicity]. / Fatores sócio-culturais e éticos relacionados com os processos de diagnóstico da esquistossomíase mansônica em área de baixa endemicidade.

Five annual parasitological surveys and one serological survey, respectively based on the Kato-Katz and free sedimentation methods and the Western blot technique, were conducted in Sumidouro, Rio de Janeiro, Brazil, an endemic county for schistosomiasis. Possible influences of the use of these methodologies on social, cultural, and ethical aspects of the study population were also evaluated. Having the opportunity to choose the different techniques was a conclusive issue influencing participation by the population. Prevalence rates of positive results for stool tests were: 11.6% (1995); 8.8% (1996); 12.2% (1998); 5.9% (1999); and 3.2% (2000). In the period during which the serological survey was performed, the use of laboratory testing in association with analysis of clinical data and available data on transmission and treatment generated a diagnostic procedure termed "coproseroepidemiology". This methodology contributed to significant improvements in the accuracy of measurement of local schistosomiasis prevalence, indicating that epidemiological surveillance could help prevent the recurrence of high prevalence rates. The fact that Biomphalaria glabrata was replaced by Melanoides tuberculata in the main transmission focus contributed to a significant decrease in infection rates.

Fatores sócio-culturais e éticos relacionados com os processos de diagnóstico da esquistossomíase mansônica em área de baixa endemicidade / Socio-cultural and ethical factors involved in the diagnosis of schistosomiasis mansoni in an area of low endemicity

Foram realizados em Sumidouro, Rio de Janeiro, Brasil, município endêmico para a esquistossomíase, cinco inquéritos parasitológicos anuais e um sorológico, baseados nas técnicas de Kato-Katz, sedimentação espontânea e western blot. Avaliou-se ainda a interveniência de fatores sociais, culturais e éticos na aplicação de tais métodos junto à comunidade. A possibilidade de opção foi decisiva para a participação das pessoas. As prevalências pela coproscopia foram: 11,6 por cento (1995); 8,8 por cento (1996); 12,2 por cento (1998); 5,9 por cento (1999); 3,2 por cento (2000). No ano de realização da sorologia, os resultados dos exames laboratoriais associados às informações sobre a transmissão, o acompanhamento clínico dos infectados e seus históricos de tratamento, geraram um procedimento diagnóstico nomeado coprosoroepidemiologia que refletiu mais precisamente a prevalência local. Confirmou-se que a vigilância epidemiológica evitaria o recrudescimento da prevalência. A substituição de Biomphalaria glabrata por Melanoides tuberculata no principal foco de transmissão, contribuiu para a queda acentuada dos índices de infecção.