BackgroundSeveral species of protozoa cause acute or chronic gastroenteritis in humans, worldwide. The burden of disease is particularly high among children living in developing areas of the world, where transmission is favored by lower hygienic standards and scarce availability of safe water. However, asymptomatic infection and polyparasitism are also commonly observed in poor settings. Here, we investigated the prevalence of intestinal protozoa in two small fishing villages, Porto Said (PS) and Santa Maria da Serra (SM), situated along the river Tietê in the State of São Paolo, Brazil. The villages lack basic public infrastructure and services, such as roads, public water supply, electricity and public health services.MethodsMultiple fecal samples were collected from 88 individuals in PS and from 38 individuals in SM, who were asymptomatic at the time of sampling and had no recent history of diarrheal disease. To gain insights into potential transmission routes, 49 dog fecal samples (38 from PS and 11 from SM) and 28 river water samples were also collected. All samples were tested by microscopy and PCR was used to genotype Giardia duodenalis, Blastocystis sp., Dientamoeba fragilis and Cryptosporidium spp.ResultsBy molecular methods, the most common human parasite was Blastocystis sp. (prevalence, 45% in PS and 71% in SM), followed by D. fragilis (13.6% in PS, and 18.4% in SM) and G. duodenalis (18.2% in PS and 7.9% in SM); Cryptosporidium spp. were not detected. Sequence analysis revealed large genetic variation among Blastocystis samples, with subtypes (STs) 1 and 3 being predominant, and with the notable absence of ST4. Among G. duodenalis samples, assemblages A and B were detected in humans, whereas assemblages A, C and D were found in dogs. Finally, all D. fragilis samples from humans were genotype 1. A single dog was found infected with Cryptosporidium canis. River water samples were negative for the investigated parasites.ConclusionsThis study showed a high carriage of intestinal parasites in asymptomatic individuals from two poor Brazilian villages, and highlighted a large genetic variability of Blastocystis spp. and G. duodenalis.

A transmissão de protozoários patogênicos pela água é um dos mais relevantes problemas de saúde pública na atualidade. Numerosos surtos epidêmicos causados pelos protozoários Giardia e Cryptosporidium ocorreram ao redor do mundo em passado recente. Entretanto, os métodos utilizados para a detecção de cistos e oocistos em amostras de água são influenciados por características físico-químicas da matriz de água, como a turbidez. Esta revisão apresenta uma análise crítica das diferentes metodologias de concentração de cistos de Giardia e de oocistos de Cryptosporidium em amostras de águas destinadas ao consumo humano. A implantação do monitoramento desses protozoários é uma necessidade no Brasil dada a recente revisão da Portaria nº 518 do Ministério da Saúde.

The goals of this study were to investigate the occurrence of Cryptosporidium oocysts and Giardia cysts in main springs of Campos do Jordão, an important tourist city, in Brazil and to gather the largest amount of parasitological data from autochthonous population that live in rural areas of this city. The membrane filtration technique followed by direct immunofluorescence assay was employed for concentration and visualization of waterborne protozoa. In the period between June 2003 and May 2004, the presence of at least one pathogenic protozoa was detected in 25.0% (3/12) of the springs studied, with mean concentrations ranging from 0.2 to 0.3 Cryptosporidium sp. oocysts and 0.07 to 0.1 Giardia sp. cysts/L. The coproparasitological investigation conducted in dwellers from two rural communities from this city revealed that 49.2% (91/185) of people had intestinal parasites. Among pathogenic protozoa, Cryptosporidium was the most prevalent species (8.1%) followed by Giardia duodenalis (5.9%), Entamoeba histolytica/Entamoeba dispar (2.7%), and Blastocystis hominis (2.2%). The most prevalent geohelminths were Ascaris lumbricoides (14.9%) and Trichuris trichiura (9.7%). This study demonstrated the contamination and the distribution of intestinal parasites, especially Cryptosporidium and Giardia species, in different springs of an important tourist city in Brazil, highlighting the need of monitoring natural water sources. The high prevalence of intestinal parasitosis detected in some specific populations of this city may function as a link of transmission of different intestinal parasitosis due to soil and water contamination, contributing to the maintenance of parasite life cycles. Therefore, the inclusion of consistent public health interventions with measures that include the protection of springs, the installation of minimum health infrastructure, and primary education of the population are widely necessary, aiming the control and prevention of parasite infections.

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