Orf is caused by orf virus (ORFV), a highly resilient Parapoxvirus of the Poxviridae family that is related to pseudocowpox and bovine papular stomatitis. The virus has been recovered from dried crusts 12 years post-infection.
The common presenting signs are ulcerative lesions at the mucocutaneous junction of lips, mouth and interdigital skin that persistent for up to a month.
Definitive diagnosis is by use of PCR assays.
The disease must be distinguished from other causes of stomatitis including bovine mucosal disease, malignant catarrhal fever, rinderpest, peste des petits ruminants, foot and mouth disease, blue tongue, epizootic haemorrhagic disease and vesicular stomatitis.
Treatment of contagious ecythyma is usually supportive, include broad-spectrum antimicrobial therapy.
Cattle are generally immune to reinfection but vaccines re available to minimise outbreaks in susceptible or naive herds.
- Friebe A et al (2011) Characterization of immunostimulatory components of orf virus (parapoxvirus ovis). J Gen Virol 92(7):1571-1584
- Abrahão JS et al (2009) Nested-multiplex PCR detection of Orthopoxvirus and Parapoxvirus directly from exanthematic clinical samples. Virol J 6:140