Ruth Semira Rodríguez Alarcón

Elevada porcentagem de blastocistose em escolares de São Paulo, SP

As a part of medical assistance activities, parasitological examination of fecal samples from 227 school children from a public institution of São Paulo (SP) revealed a rather high proportion of results positive for Blastocystis hominis. Other protozoan and worm species were markedly scarcer, a peculiar situation according to our judgement. It is acknowledged that blastocystosis is still largely an indefinite and controversial subject, which deserves adequate analysis to avoid drawbacks in the sphere of action of public health and general medical assistance.

Microwave treatment of human milk to prevent transmission of Chagas disease

It is recognized that breast feeding is an alternative means of transmission of Chagas disease. However, thermal treatment of milk can prevent this occurrence. As domestic microwave ovens are becoming commonplace, the efficacy of microwave thermal treatment in inactivating Trypanosoma cruzi trypomastigotes in human milk was tested. Human milk samples infected with T. cruzi trypomastigotes (Y strain) from laboratory-infected mice, were heated to 63 degrees C in a domestic microwave oven (2,450 MHz, 700 W). Microscopical and serological examinations demonstrated that none of the animals inoculated orally or intraperitoneally with infected milk which had been treated, got the infection, while those inoculated with untreated, infected milk, became infected. It was concluded that the simple treatment prescribed, which can easily be done at home, was effective in inactivating T. cruzi trypomastigotes contained in human milk.

Parasitoses intestinais de indígenas da comunidade Mapuera (Oriximiná, Estado do Pará, Brasil): elevada prevalência de Blastocystis hominis e encontro de Cryptosporidium sp e Cyclospora cayetanensis

Occurrences of intestinal parasitosis in Indians of the Mapuera community (Oriximina, State of Para, Brazil) were evaluated. Within the context of group assessment, this study makes a contribution towards adequate knowledge of this subject, which is significant from a medical-sanitary point of view. Parasitological examination of feces from 83 individuals, performed using four different methods, could be considered to have reasonable amplitude for establishing diagnoses. Protozoan cysts and helminth eggs of many types were found, even with significant percentages. The frequent presence of Blastocystis hominis (57.8%), along with findings of Cryptosporidium sp (3.6%) and Cyclospora cayetanensis (10.8%), deserved highlighting with specific comments. The findings show that these Indians live in an environment in which poor hygiene conditions prevail. In particular, these facilitate the dissemination of protozoa and helminths through contact with the soil or through intake of contaminated water and food.

Observações sobre Blastocystis hominis e Cyclospora cayetanensis em exames parasitológicos efetuados rotineiramente

We report some observations made from routine parasitological examinations on feces. The methods of Faust et al. and of spontaneous sedimentation in water are not enough to identify Blastocystis hominis. Significant percentage presence of this protozoan was found, especially when staining with iron hematoxylin was performed. Cyclospora cayetanensis was found in 0.7% of the cases, which suggests that this parasite should also routinely be investigated by appropriate techniques.

The detection of Trypanosoma cruzi in Triatoma infestans: comparison of a PCR-based assay with microscopical examination.

The laboratory diagnosis of human American trypanosomiasis (Chagas disease) is currently usually based on serology or the detection of a Trypanosoma cruzi parasitaemia (Maldonado et al., 2004). Unfortunately, most of the serological methods perform poorly when used to detect the re-activation of infections, and are therefore not recommended for determining post-treatment cure (PortelaLindoso and Shikanai-Yasuda, 2003). Parasitaemia can be detected by the direct microscopical examination of samples of blood or buffy coats, haemoculture or xenodiagnosis. Although xenodiagnosis remains the ‘gold standard’, this technique requires expertise and is both cumbersome and time-consuming, often requiring 30–60 days to yield a final result. Despite these drawbacks, xenodiagnosis is indicated in the acute phase of disease or during possible reactivation, whenever the other techniques give negative results (Luquetti and Rassi, 2000). Romaña and Briones (1954) found that infections could sometimes be detected in triatomine bugs fed on acute cases of Chagas disease as early as 6 days post-feed. In the last decade, the use of PCR to detect the DNA of Try. cruzi in faecal samples collected from bugs used in xenodiagnosis has not only increased the sensitivity of the diagnosis but also shortened the time needed to obtain a useful result (Russomando et al., 1996; ShikanaiYasuda et al., 1996). The aim of the present study was to explore and compare the potential usefulness of PCR and direct microscopical examination for detecting Try. cruzi infection in bugs used for xenodiagnosis. Most (220) of the 275 bugs used — thirdand fourth-instar, laboratoryreared Triatoma infestans — were fed on BALB/c mice that had been experimentally infected with the Y strain of Try. cruzi, while the mice were in the acute phase of disease and had low parasitaemias (of approximately 10 parasites/ml blood). The aim of using mammalian hosts with low parasitaemias was to mimic the situation found, during re-activation of Chagas disease, in immunosuppressed heart-transplant patients. The other 55 bugs were fed on uninfected mice, as negative controls. Digestive-tract samples (faeces or abdominal contents) were collected from 25 bugs (20 that had fed on infected mice and five of the negative controls) 1, 2, 3, 4, 5, 10, 15, 20, 25, 30 and 60 days post-feed, with different bugs being used at each timepoint. Each sample was split into two aliquots. A subsample (2–10 ml) of one aliquot was mixed with one to five volumes of 0.9% NaCl solution and then checked by microscopy (at 6400, as a wet smear), while the same volume of the other aliquot was checked by PCR (see below). The primers used in the PCR — F2 (59TGC ACT CGG CTG ATC GTT TTC GAG-39) and B3 (59-AGG GTT GTT TGG TGT CCA GTG TGTG-39), both produced by Integrated DNA Technologies (Belo Horizonte, Brazil) — were designed to produce a 144-bp amplicon from the TCZ repetitive sequence of Try. cruzi (Moser et al., 1989). Genomic DNA was extracted, from a mixture of a digestive-tract aliquot Annals of Tropical Medicine & Parasitology, Vol. 101, No. 5, 461–465 (2007)

Identification of Cryptosporidium spp. oocysts in fecal smears stained with Heidenhain's iron hematoxylin

There is no paucity of methods for diagnosing Cryptosporidium spp. infection. The merits of immunoassays notwithstanding, microscopic identification of Cryptosporidium spp. oocysts in fecal samples remains an important diagnostic procedure. It owes the persistence of its use to such characteristics as dispensing with expensive equipment and kits, requiring only basic laboratory facilities, and having a low probability of false positive results when permanent slides are prepared, which can be re-examined in case of doubt. Cryptosporidium spp. oocysts can be readily identified in fecal smears prepared according to a regressive iron hematoxylin staining technique. The number of steps and their duration, as well as costs, were reduced to a minimum without loss of image quality and permanence of the preparations.

Uma avaliação sobre a eficácia do método CSF no diagnóstico de helmintíases intestinais

The recently proposed CSF method for diagnosing intestinal helminthiases was compared with the other methods (direct; Faust et al.; spontaneous sedimentation in water; and Kato-Katz) that are routinely for this purpose. The CSF method performed satisfactorily, thus showing that this technique can be adopted for use in diagnoses or epidemiological analyses.

Conservação de oocistos de Cryptosporidium em fezes para exame parasitológico

By using a simple and easily available device which contains a 10% buffered formaldehyde solution, fecal samples are rendered odorless and can be stored at room temperature with no biosafety hazards. Cryptosporidium oocysts contained in such fecal samples can be identified without difficulty by using the Kinyoun method. This system permits an adequate preservation of the material, which facilitates the execution of tasks related to assistance and epidemiology.