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Malignant Catarrhal Fever Diagnosed in Texas Cattle

April 23, 2008 — 

The USDA's National Veterinary Services Laboratory (NVSL) has confirmed a diagnosis of the foreign animal disease malignant catarrhal fever (MCF) in a cattle herd in Texas.

The disease is believed to have spread to the cattle through contact with captive wildebeests on the same property. MCF poses no threat to humans and cannot be transmitted between people and animals. Although largely considered a disease of ruminants, MCF has been reported in domestic swine. The virus can be transmitted to cattle and other susceptible animals by inhalation in aerosol droplets, ingestion of contaminated feed or water, or possibly mechanical transmission by arthropods. This virus is quickly inactivated by sunlight.

"A total of 134 breeding heifers from this herd were recently shipped to Illinois, Arkansas, Alabama, Georgia, Louisiana, Mississippi and Texas. Because cattle cannot transmit the disease to other cattle or livestock, the interstate movement of these animals poses no risk," according to the USDA's Animal and Plant Health Inspection Service (APHIS) officials. [Ed. Note: According to the Center for Food Security and Public Health at ISU, there are reports of cattle-to-cattle transmission although it appears rare.]

MCF is a herpes virus, and 2 strains are known to exist -- a sheep-associated strain and a wildebeest-associated strain. Cattle can contract both strains of the disease from affected sheep or wildebeests, but do not spread either strain. The sheep-associated strain of MCF is known to occur in the United States. The wildebeest-associated strain of MCF, however, is foreign to the United States. Both strains have high fatality rates in cattle.

The symptoms of typical infections include sudden death or fever with nasal and lacrimal discharges, erosions of the mucosa, and bilateral corneal opacity, but other syndromes may be seen. Post mortem lesions that support a diagnosis of malignant catarrhal fever include corneal opacity, enlarged lymph nodes, inflammation and erosions in the nasal passages, gastrointestinal mucosa, and urinary bladder, and prominent tortuous small arteries in the subcutaneous tissue, thorax, and abdomen.

Sources:
USDA News Release, April 18, 2008

The Center for Food Security and Public Health