Assuntos
Giardia lamblia/classificação , Giardia lamblia/genética , Doenças dos Ovinos/parasitologia , Animais , Proteínas do Citoesqueleto/genética , DNA de Protozoário/genética , DNA de Protozoário/isolamento & purificação , Fezes/parasitologia , Técnica Direta de Fluorescência para Anticorpo , Genótipo , Giardia lamblia/isolamento & purificação , Epidemiologia Molecular , Reação em Cadeia da Polimerase , Prevalência , Proteínas de Protozoários/genética , Análise de Sequência de DNA , Doenças dos Ovinos/epidemiologia , Carneiro Doméstico , Espanha/epidemiologiaAssuntos
Portador Sadio/parasitologia , Doenças dos Bovinos/parasitologia , Criptosporidiose/veterinária , Cryptosporidium/classificação , Cryptosporidium/isolamento & purificação , Animais , Bovinos , Criptosporidiose/parasitologia , Cryptosporidium/genética , DNA de Protozoário/química , DNA de Protozoário/genética , Fezes/parasitologia , Proteínas de Choque Térmico HSP70/genética , Contagem de Ovos de Parasitas , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , EspanhaRESUMO
The efficacy of alpha-cyclodextrin against infection by Cryptosporidium parvum was evaluated using in vitro and in vivo models. Cyclodextrins are water-soluble cyclic hexamers of glucose units with hydrophobic cavities capable of solubilizing lipophiles and are widely used as drug excipients in the pharmaceutical industry. The viability of purified C. parvum oocysts, exposed for 30, 60, 90, 120 min and 24h to different concentrations of alpha-cyclodextrin (2.5, 5, 7.5, 10, 12.5 and 15%), was evaluated by inclusion or exclusion of two fluorogenic vital dyes and by an excystation technique. Preventive and curative efficacies against cryptosporidial infections, at different doses (2.5 and 5%) and regimes of administration of alpha-cyclodextrin, were determined in an experimental neonatal mice model. Results of the viability assay showed a decrease in oocyst viability that was associated with an increase in exposure time, for each of the concentrations used. Moreover, a high proportion of nonviable oocysts (81%) was observed when C. parvum oocysts were exposed to alpha-cyclodextrin (2.5%) for 24h. The intensity of infection, determined 7 days post-inoculation by examination of intestinal homogenates, was significantly lower (P<0.05) than in the control litters, for all the assays carried out with alpha-cyclodextrin. Only 38.8% of the animals became infected when the alpha-cyclodextrin solution (5%) was administered 2h before inoculated oocysts, and every 24h at 1 and 2 days post-inoculation.
Assuntos
Criptosporidiose/tratamento farmacológico , Cryptosporidium parvum/efeitos dos fármacos , Ciclodextrinas/farmacologia , Ciclodextrinas/uso terapêutico , alfa-Ciclodextrinas , Animais , Animais Recém-Nascidos , Ciclodextrinas/administração & dosagem , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Corantes Fluorescentes , Humanos , Camundongos , Organismos Livres de Patógenos EspecíficosRESUMO
An epidemiological study was carried out on farms in Galicia (NW Spain) to investigate the prevalence of and the risk factors associated with the spread of infection by Cryptosporidium parvum in calves of less than 3 weeks of age. A total of 22 cattle farms (10 beef herds and 12 dairy herds) were visited once every 21 days between January and December 2000. A faecal sample was collected directly from the rectum of each of the 844 calves born during the study period. Each sample was studied macroscopically to establish its consistency as liquid, soft or solid, and the presence of mucus or blood noted. C. parvum oocysts were identified by direct microscopic examination and the intensity of infection established semiquantitatively as slight, moderate or severe. Of the 844 calves, 404 were found to have the parasite in their faeces, i.e. the prevalence was 47.9%. Statistical analysis of the risk factors such as general characteristics of the farm and the housing conditions of the calves, revealed three variables that significantly effect the risk of cryptosporidial infection in suckling calves: the method of cleaning, the type of flooring and the frequency of cleaning.
Assuntos
Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/parasitologia , Criptosporidiose/veterinária , Cryptosporidium parvum/crescimento & desenvolvimento , Criação de Animais Domésticos , Animais , Animais Recém-Nascidos , Bovinos , Criptosporidiose/epidemiologia , Criptosporidiose/parasitologia , Fezes/parasitologia , Feminino , Modelos Logísticos , Análise Multivariada , Contagem de Ovos de Parasitas/veterinária , Prevalência , Fatores de Risco , Espanha/epidemiologiaRESUMO
During calving time on an experimental farm, 32 newborn calves were selected at random and monitored for infection with Cryptosporidium parvum for the first 30 days of their lives. The animals were fed pooled colostrum for 2-3 days after birth and housed in individual pens, which were washed daily using a pressure hose. Fecal smears were examined by microscopy after staining with carbol fuschin for visualization of oocysts. Oocyst shedding was scored semiquantitatively according to the average number of oocysts in 20 randomly selected fields at 1000x magnification. All the animals acquired the infection before 18 days of age. The period of maximum risk was between 9 and 12 days; 50% of the animals were infected by 9.4 days of age. It was found that the earlier the animals acquired the infection, the longer the patent period. Oocyst shedding, which did not always begin with the onset of diarrhea, lasted between 8 and 23 days (mean 12.4+/-3.3 days). Furthermore, fecal samples from 32 periparturient cows (within +/-7 days of giving birth) were filtered, concentrated and examined for oocysts using a fluorescent monoclonal antibody test, which revealed that six of the cows, although asymptomatic, were excreting C. parvum oocysts.
