Neonatal calf diarrhoea with special reference to rotavirus infections : significance, epidemiology and aspects of preventionde Verdier Klingenberg, Kerstin;
This thesis deals with neonatal calf diarrhoea (NCD) in Sweden, with special reference to bovine rotavirus (BRV) infections. Clinical significance, molecular epidemiology and aspects ofprevention were investigated.
The prevalence, incidence and role of BRV were investigated in outbreaks and endemic situations, and by an experimental study in a calfmodel. Group A BRV was found to be the most commonly occurring causative agent in NCD. The clinical signs in calves were aggravated after experimentally induced dual infection ofBRV and bovine viral diarrhoea virus (BVDV). Otherwise, dual infections were rarely detected in the herds, and Escherichia coli K99+ was a rare finding, suggesting that the indications for antimicrobial drugs in NCD therapy are few. Poor growth in diarrhoeic and recovered calves was demonstrated, which implies financial loss and stresses the need for continued milk feeding to diarrhoeic calves.
A one-step on-site BRV test was developed and evaluated. When compared to the reference ELISA, the sensitivity of this test was 89% and the specificity 99%. The simplicity and rapidity ofthe test procedure make it suitable for use in practice.
Four BRV G-types (G3, G6, G8, GIO) were detected in faecal samples, ofwhich GIO and G6 were predominant (91%). GIO was the major G-type in samples from dairy calves and G6 the sole type in samples from beef suckler calves. One major G-type persisted in a herd for a period of 4 years, probably due to the stable character ofBRV and to restricted calftrading.
Aspects of prevention and control of BRV infection were investigated in a cohort study. A dramatic decline in die incidence of NCD was demonstrated after strict closure and eradication of BVDV in a herd. This was considered to be an effect of the overall reduction ofthe herd’s exposure to pathogenic agents. An association between low serum IgG and increased incidence of diarrhoea highlights the importance of colostral feeding to newborn calves.
Attention is called to the claim that control and prevention of NCD is possible without vaccination programmes and antimicrobial therapy, by reduction of the exposure of calves to pathogenic agents through control of direct contact between cattle, and by optimal colostral feeding.
neonatal calf diarrhoea; rotavirus; bovine viral diarrhoea virus; closed herd; prevention; immunoglobulin; risk factor; G-type
Published inActa Universitatis Agriculturae Sueciae. Veterinaria 1999, number: 54
Publisher: Swedish University of Agricultural Sciences
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