Impact of rotavirus vaccine on rotavirus genotypes and caliciviruses circulating in French cattle.

Group A rotaviruses are a leading cause of neonatal calf diarrhoea worldwide and prevention of this disease includes vaccination against these viruses. In order to highlight the potential selection of rotavirus genotypes due to immune pressure driven by vaccination, the aim of this study was to compare group A rotavirus genotypes circulating in French diarrhoeic calves in rotavirus vaccinated herds (G6P[5] vaccine) with those in non-vaccinated herds during one calving season in 2010. This study showed a high prevalence of rotavirus in both groups with no significant difference between the two. No significant differences regarding G, P and G/P rotavirus genotype distribution between the two groups were observed, with G6, P[5] and G6P[5] genotypes being by far the most prevalent. Moreover, sequence analyses of the VP7 and VP4 partial coding genes of the G6P[5] strains from this study did not allow us to distinguish them according to their origin. This study also showed that other pathogens responsible for calf diarrhoea, such as genogroup III noroviruses and neboviruses, were not more frequently associated with calf diarrhoea in vaccinated herds. Altogether, these results suggest that the studied vaccine did not promote the emergence of rotavirus genotypes or variants different from those of the vaccine or other viruses responsible for calf diarrhoea, such as caliciviruses.

Absence of ivermectin resistance in a survey on dairy goat nematodes in France.

Anthelmintic resistance is very prevalent in ruminant strongyle populations, especially in goats. Several occurrences of multiple anthelminthic resistances have been reported in goat flocks throughout the world, including resistance to the most recent macrocyclic lactones. A faecal egg count reduction test was conducted to detect resistance to ivermectin in French goat flocks. Thirty goats per flock were randomly selected in 22 flocks and allocated into two groups of 15 animals: an untreated control group and an ivermectin-treated group (0.3 mg/kg BW per os). Individual faecal egg counts and pooled larval cultures were performed 16-17 days after anthelmintic treatment for control and treated groups. FECR's were calculated for treated group vs. control one and when <95/100, were considered as indicative of anthelmintic resistance. FECR results indicated the absence of ivermectin resistance in nematode populations from all the 22 goat farms. The nematode genera involved in control groups were of Teladorsagia/Trichostrongylus, Haemonchus and Oesophagostomum/Chabertia types.