RESUMO
The population dynamics and prevalence of Fasciola hepatica in Galba truncatula were investigated on the Teagasc hill sheep farm in Country Mayo, Ireland from August 2006 until March 2008. Galba truncatula (n=974) were collected at fortnightly intervals in 4 snail habitats on the farm, their relative density and mean monthly rainfall and temperature were recorded. Snail abundance was associated with rainfall and temperature. G. truncatula abundance was generally low during winter 2006/2007 (December 2006-February 2007), mid spring and summer 2007 (April-July) and late autumn and winter 2007/2008 (October 2007-February 2008). Overall, two peaks in G. truncatula abundance were evident during the study period, an early spring (March) and late summer/autumn (late August-October) peak. Seasonal differences were observed in the prevalence of F. hepatica in G. truncatula, the greatest prevalence was evident in 2007 during the summer (25%) and autumn (16%). Two seasonal transmission peaks, as evident by the presence of mature infections in snails, one in summer/autumn and the other in late winter/early spring. Not unsurprising, cercariae (28%) and rediae (29%) were the predominant developmental stages observed in mature and pre-adult snails respectively. Worthy of note in this study, cercariae were also evident in pre-adult snails. The present study highlights the influence of milder temperatures and wetter conditions on both snail and fluke development. If the trend in mild and wet weather conditions continues, there is the potential for an increase in the number of G. truncatula habitats and ultimately the prevalence of fasciolosis in grazing livestock in Ireland.
Assuntos
Fasciola hepatica/patogenicidade , Fasciolíase/veterinária , Doenças dos Ovinos/transmissão , Caramujos/parasitologia , Animais , Sequência de Bases , DNA/genética , DNA de Protozoário/genética , DNA Espaçador Ribossômico/genética , Fasciola hepatica/genética , Fasciola hepatica/isolamento & purificação , Fasciolíase/epidemiologia , Fasciolíase/transmissão , Genes de RNAr/genética , Irlanda/epidemiologia , Dados de Sequência Molecular , RNA Ribossômico 18S/genética , Chuva , Estações do Ano , Análise de Sequência de DNA , Ovinos , Doenças dos Ovinos/epidemiologia , Doenças dos Ovinos/parasitologia , Caramujos/classificação , Caramujos/genética , Caramujos/crescimento & desenvolvimento , TemperaturaRESUMO
Toxoplasma gondii is a serious food-borne pathogen with a worldwide distribution. In order to assess the risk of contracting toxoplasmosis from certain foods, many studies rely on the molecular detection of T. gondii DNA. However, determining the viability of parasites in positive samples is much more problematic. In this paper we describe a novel viability assay that relies on semi-quantitative comparison of the amount of parasite DNA present in samples used to infect host cell monolayers in vitro, and the amount of DNA detected in the same monolayers after 23 days incubation. Our assay is robust, easy to perform and interpret and offers a viable alternative to bioassays, for use in epidemiological studies, or the evaluation of specific food safety treatments.
Assuntos
Cistos , Reação em Cadeia da Polimerase/métodos , Toxoplasma/isolamento & purificação , Animais , Chlorocebus aethiops , Técnicas de Cultura , Sensibilidade e Especificidade , Células VeroRESUMO
Cryptosporidium is an important cause of diarrhoeal disease worldwide and, as several recent waterborne outbreaks have shown, poses a significant threat to public health in Ireland. We identified the Cryptosporidium spp. in 199 positive human stool samples by PCR-RFLP of the 18S rRNA and COWP gene loci. Subspecies were identified in 104 samples by sequence analysis of the 60 kDa glycoprotein (gp60) gene fragment. Overall C. parvum was identified in 80%, and C. hominis in 20% of cases. No other Cryptosporidium spp. were detected. C. parvum was by far the most common species in the rural, more sparsely populated west of Ireland and exhibited a pronounced spring peak coincident with a peak in the national cryptosporidiosis incidence rate. Our data indicated a trend towards higher proportions of C. hominis in older age groups. Ninety-nine per cent of all subtyped C. parvum isolates belonged to allele family IIa, of which allele IIaA18G3R1 was by far the most common (63%). According to a recent study by Thompson and colleagues [Parasitology Research (2007), 100, 619-624] this allele is also the most common in Irish cattle. Subtyping of the C. hominis isolates indicated that they belonged to a geographically widely distributed allele (IbA10G2) known to have caused several water- and foodborne outbreaks around the world. The predominance of C. parvum, its geographic and seasonal distribution and the IIaA18G3R1 subtype underlines the importance of zoonotic Cryptosporidium transmission in Ireland.
