Malignant catarrhal fever

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Malignant catarrhal fever on the muzzle of a cow

Malignant catarrhal fever (MCF) is an infectious viral disease of cattle in New Zealand, the USA and Europe and is caused by a gammaherpesviruses (Rhadinoviridae)[1].

Two strains of MCF virus have been recognised, Ovine herpesvirus 2 (OvHV-2) and Alcelaphine herpesvirus 1 (AlHV-1), which are endemic in sheep and goats and is transmitted from healthy carriers to cattle, presumably by oral transmission of virus[2].

The virus is transmitted by nasal secretions and results in lifelong infections and death in cattle[3]. The prevalence of infection in cattle seems not to be influenced either by their age or the degree of contact with the sheep and goats.

Clinical signs

Generalised vasculitis is the cause of most systemic symptoms[4][5].

In some subclinical cases, the only signs observed are chronic alopecia and weight loss.

During outbreaks, affected cattle present with anorexia, signs of depression, diarrhea, fever and respiratory distress ultimately leading to death[6]. Catarrhal inflammation of mucous membranes is pathognomonic. Lymphadenopathy and neurological signs are also observed in severe cases.

Diagnosis

Diagnosis is based on presenting clinical signs, postmortem findings on cattle which have died, supported by laboratory examination of diseased tissue.

Definitive diagnosis requires ELISA[7], immunoflourescence and PCR assay[8] confirmation of the MCF virus.

A differential diagnosis would include bovine viral diarrhoea, rinderpest, infectious bovine rhinotracheitis and East Coast fever.

Treatment

Although many cattle do not succumb to the viral infection, recovery is slow and invariably most cases are fatal.

A vaccine is currently available which shows promise at minimising outbreak[9].

Current control measures for MCF rely on minimizing contact between carrier animals and susceptible livestock[10].

References

  1. Russell GC et al (2009) Malignant catarrhal fever: a review. Vet J 179:324–335
  2. Benetka V et al (2009) Investigation of the role of Austrian ruminant wildlife in the epidemiology of malignant catarrhal fever viruses. J Wildl Dis 45(2):508-511
  3. Davison A et al (2009) The order Herpesvirales. Arch Virol 154:171–177
  4. Simon S et al (2003) The vascular lesions of a cow and bison with sheep-associated malignant catarrhal fever contain ovine herpesvirus 2-infected CD8(+) T lymphocytes. J Gen Virol 84:2009–2013
  5. Dewals B et al (2011) Ex vivo bioluminescence detection of alcelaphine herpesvirus 1 infection during malignant catarrhal fever.. J Virol 85(14):6941-6954
  6. Moore DA et al (2010) Outbreak of malignant catarrhal fever among cattle associated with a state livestock exhibition. J Am Vet Med Assoc 237(1):87-92
  7. Burrells C & Reid HW (1991) Phenotypic analysis of lymphoblastoid cell-lines derived from cattle and deer affected with sheep-associated malignant catarrhal fever. Vet Immunol Immunopathol 29:151–161
  8. Løken T et al (2009) Infection with Ovine herpesvirus 2 in Norwegian herds with a history of previous outbreaks of malignant catarrhal fever. J Vet Diagn Invest 21(2):257-261
  9. Russell GC et al (2012) Duration of protective immunity and antibody responses in cattle immunised against alcelaphine herpesvirus-1-induced malignant catarrhal fever. Vet Res 43(1):51
  10. Bedelian C et al (2007) Maasai perception of the impact and incidence of malignant catarrhal fever (MCF) in southern Kenya. Prev Vet Med 78:296–316