Rinderpest (Cattle Plague)

Rinderpest (Cattle Plague) is an acute, highly contagious viral disease of wild and domesticated ruminants and clinically characterized by sudden onset of fever, oculo-nasal discharges, necrotic stomatitis, gastroenteritis and death.

Rinderpest or cattle plague is primarily disease of cattle and to a lesser degree of sheep, goats and wild ruminants.

Etiology

Rinderpest (Cattle Plague) is caused by Rinderpest virus, genus Morbillivirus belongs to family Paramyxoviridae.

• The rinderpest virus contain only one serotype with multiple strains vary with virulence, but all are immunologically identical.
• The infection with one strain protect against all other strains. 
• The virus is antigenically related to other members of morbillivirus groups includes, PPR virus in sheep and goat, canine distemper in dog, measles in human, phocine distemper in seals and equine influenza recently described in Australia.

The rinderpest virus is quite fragile in the environment and rapidly inactivated at pH less than 5.6 or greater than 9.6., solar radiation and desiccation.

Epidemiology

• Historically, Rinderpest was a most devasting disease spread from Asia to Europe, Middle East and Africa.
• Rinderpest is endemic in India and eradicated on 2006. The disease was eradicated from world and officially declared by OIE on May 2011.
• Non endemic area: Morbidity and mortality rate-100% and 90% respectively
• Endemic area – Case fatality rate – 30%

Host affected

• All ruminants and pigs are susceptible. Natural infection occurs commonly in cattle and buffalo
• Sheep and goats are generally less susceptible but may develop clinical disease
• Asiatic pigs are  highly susceptible and  European breeds are less susceptible
• Camels are apparently not infected and appear to have no role in rinderpest transmission and maintenance

Source of infection

• Rinderpest virus is found in all expired air, nasal and ocular discharges, saliva, faeces, milk, semen, vaginal discharge and urine.

Transmission

• Close contact with an infected animals
• Inhalation of  virus in aerosol
• ingestion of contaminated feed and water
• Rinderpest virus  is not transmitted by insect vectors

Immunity after natural infection or vaccination is life long.

Pathogenesis

Clinical signs

• It occur as peracute, acute or mild form
• Incubation period is 6-9 days

Peracute form

• Sudden onset of fever, inappetence, depression, congested visible mucous membranes, respiratory distress and death within two to three days, before oral erosions develops.

Acute form

It occur in three phases:

1. Prodromal phase
2. Mucosal phase
3. Convalescence phase

Prodromal phase (period of peak virus production)

• Fever (40.5-41.5^o c) for several days without mucosal lesion
• Anorexia, fall in milk yield, lacrimation, harsh staring coat

Mucosal phase

• Characterized by inflammation of buccal, nasal and conjunctival mucosa
• Hyperemia of vulva and swelling of vagina
• Lacrimation is profuse and then purulent accompanied by blepharospasm
• Clear blood stained  bubbly salivation is followed by purulent saliva and halitosis
• Discrete grayish necrotic lesions, appearing on inside of the lower lip, adjacent gum, on the cheek mucosa at the commissures and lower surface of the tongue
• Similar lesions are common on nasal, vulval and vagina mucosae
• Sloughing of necrotic  material leaving raw, red area with sharp edges as these coalesce to form shallow ulcers
• Severe diarrhoea, sometimes dysentery with tenesmus, appear as lesions develop in abomasums and intestine
• Abdominal pain
• Severe dehydration
• Moist reddened skin lesions occur on perineum, scrotum, flanks, inner aspect of thigh and neck, later it covered with scab. But this is less common

Convalescence phase

• Mucosal lesions heals rapidly
• Diarrhoea stops
• Abortion in pregnant animal

Subacute form

• It occur in enzootic area with lower morbidity and mortality
• Inflammation of catarrhal only
• No dysentery
• Skin form- pustule develop on neck, withers, inside the thigh without systemic reaction
• Lymphocytolysis, activate the latent infection of Anaplasma marginale

Necropsy finding

• Zone of haemorrhage and erythema running transversely across the mucosa of colon produce a characteristic striped appearance is called as zebra stripes
• Histopathological examination of tonsil-  intracytoplasmic and intranuclear inclusion bodies may be present

Sample collection

Buffy coat, lymph node biopsy, fresh spleen and gut lesions should be collected aseptically and send it  under refrigerated condition.

Diagnosis

• Based on clinical symptoms and lesion
• Marked leukopenia
• Isolation and identification of organism in tissue culture
• Detection of antigen by AGID
• Antibody detection by virus neutralization test, complement fixation test, counter immunoelectrophoesis and  ELISA

Differential Diagnosis

• Foot and mouth disease
• Haemorrhagic septicaemia
• Malignant catarrhal fever
• Bovine viral diarrhoea
• Infectious bovine rhinotracheitis

Treatment

• Treatment is ineffective and should not be undertaken
• Fluid therapy may be given

Prevention

1. Laprinised vaccine : Immunity last for 1-7 years
2. Goat tissue vaccine: Immunity last for 13 years or life long

• All outbreaks of rinderpest in virgin areas have been due to the importation of live infected animals.
• Prevention in such areas is therefore largely dependent upon vigilant control of the introduction of live animals from potentially infected areas.
• Contaminated areas should be physically cleaned of all animal waste and soiled bedding and treated with disinfection solutions of high (>10) or low (<3) pH containing solvents to destroy the virus envelope. Solutions of caustic soda and Lysol have the highest virucidal activity against virus contaminated with organic matter
• Attenuated tissue culture (bovine kidney cells, vero cells) Kabete “O” strain of RPV produced a totally safe and effective attenuated virus which has been the principal vaccine used to combat rinderpest throughout the world during the past 40 years. It induces a lifelong immunity, inexpensive and simple to produce and stable in freeze dried form.
• The only drawback of the vaccine is that after reconstitution in normal saline it has a working life of only a few hours in the hot climates
• Recombinant vaccines in which genes expressing RPV immunizing antigen are incorporated into more thermostable pox viruses have been developed and used for differentiating vaccinated animals with the infected animals and thus helps in eradication of disease
• In endemic areas calves at the age of 6-12 months vaccinated for RP. Annual vaccination of all cattle will produces highest levels of herd immunity.

Control

• Rigid slaughter and quarantine  measures
• Endemic area- annual vaccination of  all cattle and domestic buffaloe >1yr of age with  tissue culture rinderpest vaccine
• Ring vaccination of susceptible animal during outbreak
• Continuous monitoring and surveillance of animals against rinderpest
• Control of animal movement