Cattle Plague.

Rinderpest is an acute, highly contagious, viral disease of cattle, domesticated buffalo and some species of wildlife.

Etiology

Rinderpest results from infection by rinderpest virus, a member of the genus Morbillivirus of the family Paramyxoviridae. There is just one serotype of this virus, but three genetically distinct lineages –lineage 1, lineage 2, and lineage 3 - have been identified.

Transmission

Transmission of rinderpest virus usually occurs through direct or close indirect contact with infected animals. Small amounts of virus can be found in nasal and ocular secretions, saliva, milk, urine and feces beginning 1 to 2 days before the onset of fever. Blood and all tissues are also infectious before the clinical signs appear. Large amounts of rinderpest virus can be found in the animal’s secretions and excretions (including nasal and ocular discharges, saliva, feces, milk, semen, vaginal discharges and urine), as well as expired air, during the first week of clinical signs, but virus shedding decreases as specific antibodies develop and the animal recovers. Aerosol transmission is insignificant in the epidemiology of the disease, and is typically only seen over short distances in confined spaces. Vertical transmission does not occur.

Clinical Signs

Rinderpest infections can vary in severity depending on the virulence of the strain and resistance of the infected animal. A peracute form, characterized primarily by high fever and sudden death, is mainly seen in young and newborn animals. In the acute (classical) form in cattle, a prodromal period of fever, depression, decreased appetite, decreased milk yield, congestion of mucous membranes, and serous ocular and nasal discharges is followed in approximately 2 to 5 days by the development of necrotic oral lesions. Necrotic epithelium can be found on the lips, tongue, gums, buccal mucosa, soft and hard palates. These lesions begin as pinpoints but enlarge rapidly to form gray plaques or a thick, yellow pseudomembrane. They slough to form shallow, nonhemorrhagic erosions. The muzzle eventually dries and develops cracks, and the animal becomes anorexic and develops mucopurulent ocular and nasal discharges. The breath is fetid. Necrotic lesions may also be found on the nares, vulva, vagina and preputial sheath. Diarrhea usually starts a few days after the onset of oral necrosis; it is typically profuse and watery at the onset, but may contain mucus, blood and shreds of epithelium in the later stages.

Control

Rinderpest was controlled in the past by annual vaccination of all cattle and domesticated buffalo more than a year of age. Maternal antibodies to rinderpest can persist for 6 to 11 months. The Global Rinderpest Eradication Programme is believed to have eradicated or nearly eradicated this disease. As a result, vaccination has generally ended and been replaced by active and passive surveillance in domesticated animals and wildlife. Unvaccinated animals can serve as sentinels if outbreaks occur. Rinderpest is usually introduced into an area by infected animals. Outbreaks can be controlled with quarantines and movement controls, euthanasia of infected and exposed animals, decontamination of infected premises, and intensive focal vaccination.