What are reasons for degree of immunogenecity of Eimeria and Giardia?

Role of Cryptosporidium parvum, Giardia duodenalis and Eimeria spp. in neonatal diarrhoea complex in dairy calves in Flanders, Belgium.

Cryptosporidium parvum is one of the most common enteropathogens causing neonatal diarrhoea, in addition to Escherichia coli K99, Salmonella, rotavirus and coronavirus. Recent studies have shown that Giardia duodenalis is also a common enteric parasite in cattle. High levels of Giardia infection in young calves are considered to be clinically significant. In addition, Cryptosporidium and Giardia have zoonotic potential. Some genotypes of C. parvum and G. duodenalis can infect both cattle and humans. Coccidiosis, caused by Eimeria bovis and E. zuernii (and to a lesser extent E. Alabamensis) is another important cause of diarrhoea in cattle. Coccidiosis due to Eimeria is well known in calves 1 or 2 months to 1 year of age, but it is unclear whether E. bovis and E. zuernii contribute to the neonatal diarrhoea complex.

High prevalences of these parasites in neonates and young calves have been reported world wide, but prevalence rates differed significantly between countries. The differences in prevalence can be attributed partly to sampling design, the size of the population and diagnostic methods employed. A correlation between infection with C. parvum and G. duodenalis and diarrhoea could not always be established. However, in most studies other intestinal pathogens were not identified and the genotype of C. parvum and G. duodenalis was not determined. Since other enteropathogens, such as Eimeria spp. may enhance the pathogenic effects of C. parvum and/or G. duodenalis and since there are differences in pathogenicity between different genotypes of C. parvum and G. duodenalis, this may explain the conflicting results.

In this project the prevalence of C. parvum, G. duodenalis, E. bovis and E. zuernii in young dairy and beef calves in East-Flanders will be determined. The genotype of C. parvum and G. duodenalis isolates will be determined to estimate the risk to human health associated with C. parvum and G. duodenalis oocyst excretion. In addition, the prevalence of the different Eimeria species and the intensity of Eimeria oocyst excretion will be determined. A correlation between infection with C. parvum,G. duodenalis, E. bovis and E. zuernii and diarrhoea will be analysed. Risk factors that are associated with the presence of C. parvum, G. duodenalis, E. bovis and E. zuernii will be analysed based on a questionnaire that will be filled in on each participating farm.

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