Search results for "Oocysts"
showing 10 items of 10 documents
Circadian variation in shedding of the oocysts of Isospora turdi (Apicomplexa) in blackbirds (Turdus merula): an adaptative trait against desiccation…
2009
5 pages; International audience; Many parasite species spend part of their life cycle in the external environment waiting for a new host. Emergence of parasites often occurs once a day, which may help to minimise mortality in an inhospitable environment and increase transition rates. Many intestinal parasites in birds are released in faeces only in the late afternoon. However, the adaptative significance of this pattern is unclear. One hypothesis is that a particular time of emergence may prevent parasite desiccation and therefore increase the parasite's life expectancy in the external environment. We tested this hypothesis experimentally using the blackbird (Turdus merula) infected with Is…
Survey of the occurrence of Giardia duodenalis cysts and Cryptosporidium spp. oocysts in green leafy vegetables marketed in the city of Valencia (Spa…
2022
The role of vegetables usually consumed without prior culinary treatment is known to contribute to the prevalence of foodborne diseases. Cysts and oocysts can contaminate food, which can then be the source of infection in humans. The aim of the study was to assess the occurrence of Giardia duodenalis and Cryptosporidium spp. (oo) cysts in green leafy vegetables marketed in the city of Valencia (Spain) combining parasitological methods, two real-time qPCRs and light microscopy. An experimental field study was conducted on 129 vegetable samples, 64 from conventional farms and 65 from ecological (organic) farms. The samples were washed with water, and the resulting solution after removing the …
Performance of a rapid diagnostic test for the detection of Cryptosporidium spp. in African children admitted to hospital with diarrhea
2020
Background Cryptosporidium is a protozoan parasite that causes mild to severe diarrhoeal disease in humans. To date, several commercial companies have developed rapid immunoassays for the detection of Cryptosporidium infection. However, the challenge is to identify an accurate, simple and rapid diagnostic tool for the estimation of cryptosporidiosis burden. This study aims at evaluating the accuracy of CerTest Crypto, a commercialized rapid diagnostic test (RDT) for the detection of Cryptosporidium antigens in the stool of children presenting with diarrhoea. Methods A cross-sectional study was conducted in four study sites in Sub-Saharan Africa (Gabon, Ghana, Madagascar, and Tanzania), from…
Amylopectin: a major component of the residual body inCryptosporidium parvumoocysts
2004
Amylopectin is used for carbohydrate storage in different life-stages of a number of apicomplexan parasites. We have performed an ultrastructural analysis of amylopectin granules from the oocyst residual body and sporozoites ofCryptosporidium parvum. Amylopectin granules were studiedin situand after isolation from ‘French’ press disrupted parasites, by conventional transmission electron microscopy (TEM) of sectioned oocysts and various negative staining and cryoelectron microscopy techniques. Within the membrane-enclosed oocyst residuum large amylopectin granules (0·1–0·3 μm) can be found besides a characteristic large lipid body and a crystalline protein inclusion. Smaller granules were de…
Toxoplasma gondii seroprevalence varies by cat breed.
2017
Toxoplasma gondii is a widespread zoonotic parasite that is relevant for veterinary and public health. The domestic cat, the definitive host species with the largest worldwide population, has become evolutionarily and epidemiologically the most important host of T. gondii. The outcome of T. gondii infection is influenced by congenital and acquired host characteristics. We detected differences in T. gondii seroprevalence by cat breed in our previous studies. The aims of this study were to estimate T. gondii seroprevalence in selected domestic cat breeds, and to evaluate whether being of a certain breed is associated with T. gondii seropositivity, when the age and lifestyle of the cat are tak…
Spatial and temporal structure of the trematode component community inValvata macrostoma(Gastropoda, Prosobranchia)
2008
SUMMARYWe conducted the first comprehensive study on the spatiotemporal structure of trematode communities in the large-mouthed valve snail,Valvata macrostoma. A total of 1103 snails were examined monthly between May and October 2007 from Lake Konnevesi, Central Finland, from a shallow (1–2 m deep) and an offshore site (5–6 m deep), located ca. 50–70 m apart. Snails were infected by 10 trematode species. The species composition and prevalence were strikingly different between the sites with high species diversity in the shallow site (all 10 species; total prevalence of sporocysts/rediae 12·1%, metacercariae 55·4%) compared to the deeper site (3 species; prevalence 15·0% and 1·9%, respective…
Structure of the Cryptosporidium parvum microneme: a metabolically and osmotically labile apicomplexan organelle.
2003
From an EM study of thin sections, the rod-like microneme organelles within conventionally glutaraldehyde fixed Cryptosporidium parvum sporozoites have been shown to undergo a shape change to a more spherical structure when the sporozoites age in vitro for a period of approximately 12 to 24 h. This correlates with the shape change of intact sporozoites, from motile hence viable thin banana-shaped cells to swollen pear-shaped cells, shown by differential interference contrast light microscopy of unstained unfixed and glutaraldehyde-fixed samples, as well as by thin section EM of fixed sporozoites. From negatively stained EM specimens of unfixed and fixed sporozoites the cellular shape change…
Binding and activation of human and mouse complement by Cryptosporidium parvum (Apicomplexa) and susceptibility of C1q- and MBL-deficient mice to inf…
2008
Cryptosporidium parvum is a protozoan parasite (Apicomplexa) that causes gastrointestinal disease in animals and humans. Whereas immunocompetent hosts can limit the infection within 1 or 2 weeks, immunocompromised individuals develop a chronic, life-threatening disease. The importance of the adaptive cellular immune response, with CD4+ T-lymphocytes being the major players, has been clearly demonstrated. Several non-adaptive immune mechanisms have been suggested to contribute to the host defence, such as interferon-gamma (IFN-gamma) from NK cells, certain chemokines, beta-defensins and pro-inflammatory cytokines, but the influence of the complement systems has been less well studied. We ana…
Climate change effects on trematodiases, with emphasis on zoonotic fascioliasis and schistosomiasis.
2009
The capacity of climatic conditions to modulate the extent and intensity of parasitism is well known since long ago. Concerning helminths, among the numerous environmental modifications giving rise to changes in infections, climate variables appear as those showing a greater influence, so that climate change may be expected to have an important impact on the diseases they cause. However, the confirmation of the impact of climate change on helminthiases has been reached very recently. Only shortly before, helminthiases were still noted as infectious diseases scarcely affected by climate change, when compared to diseases caused by microorganisms in general (viruses, bacteriae, protozoans). Th…
Comparison of viability assays for Cryptosporidium parvum oocysts after disinfection.
2003
Abstract In order to test various viability assays for Cryptosporidium parvum oocysts were used to infect HCT-8 cells in vitro or baby mice. Infected cells were either stained with fluorescent anti- Cryptosporidium -antibody or lysed and subjected to C. parvum- specific PCR after 48 h. Titrations with infective oocysts were performed and compared to oocysts disinfected with Neopredisan © for 2 h at varying concentrations. Caecal smears and histological sections from infected animals were examined in parallel. The number of foci of parasite development in vitro after immunofluorescent staining correlated well with the infection dose. PCR was less quantifiable and the results were not always …