Rinderpest

RINDERPEST

Synonym : Cattle plaque

Definition

  • Acute, highly contagious viral disease of cattle characterized by high fever, necrotic stomatitis, gastroenteritis, diarrhoea and high mortality caused by morbillivirus

Etiology

  • Morbillivirus
  • The virus is antigenically closely related to the viruses of canine distemper, PPR of sheep and goats and measles of humans.

Incidence

  • The disease has been the foremost cause of death in cattle in most African and Asian countries including India
  • Rinderpest has not been reported since June 1995 in Indian suncontinent
  • The seriousness of disease madeto start first Veterinary College in 1762 at Lyons, France.

Susceptibility

  • Mainly cattle and buffaloes, but also reported in sheep,goat and pigs
  • Reported in deer, antelope, wild buffaloes, wild boars, bushbuck, warthogs and giraffe
  • Mortality is 100 % in exotic breeds and 20-50 % mortality in indigenous breeds

Transmission

  • Incubation period is 2 to 3 days in experimental inoculation and in contact infection is 6 to 9 days
  • Virus excreted in body secretions
  • Ingestion of contaminated feed and water
  • Inhalation (or) mechanical transmission

Pathogenesis

  • The virus is inhaled in infected droplets
  • It penetrates through the epithelium of upper respiratory tract and multiplies in the tonsils and regional lymph nodes
  • From here it enters the blood in mononuclear cells which disseminate to other lymphoid organs, lungs and epithelial cells of mucous membranes
  • Rinderpest virus has a high degree affinity for lymphoid tissue and mucous membrane of alimentary tract
  • Pronounced destruction of lymphocytes in tissues and it is responsible for marked leucopoenia
  • Focal necrotic stomatitis and enteritis are the direct result of viral infection and replication in the epithelial cells in the alimentary tract.
  • Death is usually from severe dehydration but in less acute cases, death may be from activated latent parasitic or bacterial infections
  • These infections aggravate because the animal is immunosuppressed as a result of destruction of lymphoid organs by the virus

Clinical Signs

  • Fever (104-105 0F), restlessness, dryness of the muzzle and constipation
  • Other signs include photophobia, excessive thirst, starry coat, retarded rumination, anorexia and excessive salivation
  • Rashes may develop in those parts of the body where the hair is fine in nature
  • Mucous membrane of lips, gums and tongue revealed small vesicles resembling bran like deposits
  • 'Shooting diarrhoea' with foetid odour
  • Dehydration
  • Marked leucopoenia with drop in lymphocyte count

Gross lesions

Virus produce lesions in the oral mucosa after settling in the cells following a viremic state

  • Fore stomach are free
  • Abomasum reveals necrotic foci and haemorrhagic streaks more seen at the pyloric region.
  • Folds of abomasum are thick and oedematous
  • If the disease progress, abomasal mucosa shows irregular ulcers of different size.
  • The virus has got affinity for lymphoid tissue and in the intestine, peyer's patches are swollen and ulcerated
  • Duodenum and ileum revealed streaks of haemorrhages and erosions
  • In the large intestine, ileo caecal valve may be markedly swollen
  • Linear haemorrhages on the folds of mucosa of rectum appear like 'Zebra marking' which is pathognomonic in Rinder pest
  • Lesions are more severe in large intestine with ulceration and diphtheitic patches
  • Liver: Chronic passive congestion resulting from cardiac and pulmonary complications
  • Petechiae and erosions in the larynx
  • Tracheal haemorrhages
  • Alveolar and interstitial emphysema
  • Subepithelial and subendocardial haemorrhages
  • Petechiae and erosions may be seen in the bladder and vagina
  • Purulent conjunctivitis and ulceration of cornea may be noticed
  • In sheep and goat, mouth lesions are usually not seen

Microscopic lesions

  • Epithelial surface reveals ulcers, haemorrhages, oedema, necrosis and leucocytic infiltration along with multinucleated cells
  • Eosinophilic cytoplasmic inclusion bodies form in the mucosal epithelial cells and giant cells. Intranuclear inclusion bodies are rare.

Diagnosis

  • Symptoms and lesions
  • Complement fixation test (CFT)
  • Agar Gel Precipitation Test (AGPT)
  • Virus isolation and diagnosis on tissue cultures
  • Using specific cDNA probes, isolates of rinderpest and PPR viruses can be differentiated presently
  • Polymerase chain Reaction (PCR)
Last modified: Saturday, 17 December 2011, 9:55 AM