Bovis ISSN 2398-2993

Malignant catarrhal fever virus

Synonym(s): MCF, herpes virus

Contributor(s): Veronica Fowler , Tammy Hassel

Introduction

Classification

Taxonomy

  • Malignant catarrhal fever (MCF) virus (MCFV) group contains at least 10 members.
    • Commonly MCF is caused by two viruses:
      • Alcelaphine herpevirus 1 (A1HV-1)
      • Ovine herpesvirus 2 (OvHV-2).
    • If MCF occurs due to other agents, the spectrum and severity of lesions may differ.
  • Family: herpesviridae.
  • Genus: macavirus.
  • Species: alcelaphine herpevirus 1 and ovine herpesvirus 2.

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Clinical Effects

Epidemiology

Transmission

  • Transmission of AlHV-1 is efficient and can be vertical and horizontal within wildebeests herds. All calves will become infected within the first few months and then remain as carriers.
  • Transmission of OvHV-2 is only from sheep to susceptible hosts (it is not transmitted horizontally between infected hosts).
  • A1VH-1 is transmitted in nasal and ocular secretions, mainly in the cell-free form.
  • OvHV-2 is transmitted by the respiratory route and intermittently in nasal secretions.
  • Both viruses may also be found in feces and semen.
  • Infection of cattle is believed to arise through contact with young lambs/sheep.
Whilst the disease can be fatal in cattle and deer, they appear to be 'end-hosts' which do not transmit virus.

 

Pathological effects

  • The pathological effects are poorly understood but gammaherpes viruses have a tropism for T and B lymphocytes.
  • MCF is believed to occur following virus entry into the upper respiratory tract which results in a cell mediated response (virus infected cytotoxic T lymphocytes or NK cells) which causes tissue damage.
  • MCF has a long incubation period of 3-10 weeks, but can be as long as 9 months.
  • Following this clinical signs (peracure or chronic) appear including:
    • Fever.
    • Ocular and nasal discharge (may also include conjunctivitis and encrustation of the muzzle) .
    • Enlarged lymph nodes.
    • Mucosal lesions.
    • Neurological signs (muscle tremors, incoordination, head pressing).
    • Death within 7 days (deer can die suddenly without clinical signs).

Control

Control via animal

  • Separation of cattle and deer from sheep/lambs/wildebeest.
  • Access to contaminated fomites should be avoided.
  • Culling of sheep which are identified as being infected with the virus.
  • Cattle are dead-end hosts and do not need to be culled.
  • Early weaning of sheep can result in a OvHV-1 free herd.
  • Stress reduction.

Vaccination

  • None available.

Diagnosis

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed.
  • Li H, Cunha C W, Taus N S & Knowles D P (2014) Malignant catarrhal fever: inching toward understanding. Annu Rev Anim Biosci 2, 209-33 PubMed.
  • O'Toole D & Li H (2014) The pathology of malignant catarrhal fever, with an emphasis on bovine herpesvirus 2. Vet Pathol 51 (2), 437-52 PubMed.
  • Li H, Cunha C W & Taus N S (2011) Malignant catarrhal fever: understanding molecular diagnostics in context of epidemiology. Int J Mol Sci 12 (10), 6881-93 PubMed.
  • Russell G C, Stewart J P & Haig D M (2009) Malignant catarrhal fever: a review. Vet J 179 (3), 324-35 PubMed.

Organisation(s)


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