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To expand the representation for phylogenetic analysis, ten additional complete Entamoeba small-subunit rRNA gene sequences were obtained from humans, non-human primates, cattle and a tortoise. For some novel sequences no corresponding morphological data were available, and we suggest that these organisms should be referred to as ribosomal lineages (RL) rather than being assigned species names at present. To investigate genetic diversity and host specificity of selected Entamoeba species, a total of 91 new partial small subunit rRNA gene sequences were obtained, including 49 from Entamoeba coli, 18 from Entamoeba polecki, and 17 from Entamoeba hartmanni. We propose a new nomenclature for significant variants within established Entamoeba species. Based on current data we propose that the uninucleated-cyst-producing Entamoeba infecting humans is called Entamoeba polecki and divided into four subtypes (ST1-ST4) and that Entamoeba coli is divided into two subtypes (ST1-ST2). New hosts for several species were detected and, while host specificity and genetic diversity of several species remain to be clarified, it is clear that previous reliance on cultivated material has given us a misleading and incomplete picture of variation within the genus Entamoeba. [Copyright &y& Elsevier]

Detection of intestinal parasitic protists, commonly referred to as ‘intestinal protozoa,’ by PCR is increasingly used not only for identification or confirmation but also as a first-line diagnostic tool. Apart from the ability to sample correctly and extract parasite DNA directly from faeces, primer and probe specificity and sensitivity affect predictive values and hence the utility of diagnostic assays. Molecular characterization of intestinal protists is necessary to design primers and probes because this is the basic material for current and future improved diagnostic PCRs for either detecting all genetic variants or specifically differentiating among such variants. As an example, this paper highlights the existence of interspecific and intraspecific genetic diversity among intestinal, unicellular parasites and its implications for nucleic acid-based diagnostic assays. [ABSTRACT FROM AUTHOR]

Abstract: Six ssrRNA gene sequences were obtained by PCR amplification of DNA from uninucleated Entamoeba cysts isolated from fresh faeces of sheep, cows, a roe deer and a reindeer. Phylogenetic analysis using sequences of non-, uni-, quadri- and octonucleate cyst-producing Entamoeba spp. for comparison showed that all six isolates formed a separate clade nested within the clade of quadrinucleate cyst producers. The data indicate that Entamoeba bovis can be isolated from ruminant hosts other than cattle, and we suggest that organisms clustering with the sheep and cattle isolates analysed in the present study be named E. bovis. [Copyright &y& Elsevier]

Background: Based on stool microscopy, an E. histolytica/E. dispar prevalence of 18.6% was found in León, Nicaragua about 10 years ago. Since then, new non-microscopic methods have been developed to discriminate between pathogenic E. histolytica and nonpathogenic E. dispar. The main objectives of the present study were to evaluate the true prevalence of E. histolytica among individuals with diarrhea and to assess the diagnostic procedures carried out at the health center level. Methods: A descriptive study was carried out on patients with diarrhea. Parasite detection was performed by conventional microscopy on native preparations or concentrated and stained specimens, Triage Parasite Panel and by PCR for both E. histolytica and E. dispar. Results: In 134 individuals with diarrhea, the prevalence of intestinal parasites was 69% as detected by direct stool examination. E. histolytica/E. dispar was found in eight (6%) of the samples, but the health centers reported 24%. In the Triage Parasite Panel only one case of E. histolytica/E. dispar was found. Analysis by PCR showed E. dispar in ten (7.5%) and E. histolytica in two cases (1.5%). The detection of intestinal coccidia and Dientamoeba fragilis required additional staining methods. Conclusions: PCR results showed that E. histolytica is a rare finding in patients with diarrhea. At the health centers, E. histolytica, E. histolytica/E. dispar were clearly overdiagnosed, with the consequence of overtreatment. [Copyright &y& Elsevier]

Abstract: We believe that we present the first evidence of zoonotic transmission of the bird parasite, Cryptosporidium meleagridis. Despite being the third most common cause of human cryptosporidiosis, an identified zoonotic source has not been reported to date. We found Cryptosporidium oocysts in pigs, sheep/goats, hens and broiler chickens on a farm with suspected zoonotic transmission. By DNA analysis we identified C. meleagridis in samples from one human, three chickens and one hen. Sequencing of the ssrRNA and 70kDa Heat Shock Protein (HSP) genes showed identical C. meleagridis sequences in the human and chicken samples, which is evidence of zoonotic transmission. The HSP70 sequence was unique. [Copyright &y& Elsevier]