A160 - CONTAGIOUS BOVINE PLEUROPNEUMONIA

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A160 - CONTAGIOUS BOVINE PLEUROPNEUMONIA

Nature of the disease
Contagious bovine pleuropneumonia (CBPP) is an acute, subacute or chronic respiratory disease of cattle caused by a Mycoplasma called Mycoplasma mycoides mycoides SC (small colony).
Classification
OIE List A disease
Susceptible species
Cattle (Bos taurus) of all ages may be affected. Cases can also occur in water buffaloes (Bubalus bubalis) and zebu (Bos indicus).
Distribution
CBPP occurs in most parts of Africa (except southern Africa). It also occurs in the Middle East and in Asia, including Thailand, Vietnam, Mongolia, Tibet, Bangladesh, Sichuan, Bhutan, Myanamar, Burma, Cambodia and Assam; CBPP is suspected in Pakistan and Nepal. The disease is present in South Europe (Spain, Portugal, Italia and
Clinical signs
CBPP has a relatively long incubation period (3-6 weeks, but may be as long as 4 months):

Acute cases, during an outbreak they seem to occur in 33% of the cases.

  • Fever (41.5°C)
  • Loss of appetite, and depression
  • Rapid abdominal respiration, grunt at expiration
  • Epistaxis, purulent or mucoid nasal discharges progressing to coughing and chest pain,
  • Sometimes abortions and stilbirths
  • Mortality of about 50% usually within 3 weeks
  • Recovered animals are weak and emaciated

In calves up to 6 months CBPP may only show as an arthritis with swelling of affected joints.

Subacute and chronic cases are common (about 44%). Clinical signs are milder:

  • Rise in temperature
  • Loss of condition
  • Respiratory problems ( may only be apparent after exercise)
Post-mortem findings
In acute cases, there is severe pneumonia with copious (up to 30L) yellow exudates. One or both lungs may be completely consolidated with a characteristic ‘marbled’ appearance. Affected areas are pink to dark red, swollen with a firm consistency. Most of the time lesions are unilateral.

In chronic cases, necrotic lung tissue becomes encapsulated. Pleural adhesions are common.

Differential diagnosis
In the acute form
  • Pleuropneumonia and bronchopneumonia from mixed infections
  • East Coast Fever
  • Traumatic pericarditis

In the chronic form

  • Hydatid cyst,
  • Actinobacillosis and tuberculosis, bovine farcy
Specimens required for diagnosis
The OIE advices to use serological tests on acute and convalescent sera. The reference test is the Complement Fixation test which is not very sensitive and therefore should be used more at a herd level rather than an individual diagnostic.ELISA (b and c), Latex Agglutination and Immunoblotting tests are also available and present both good specificity and sensibility.

Also Mycolplaspma mycoides mycoides can be detected in nasal swabs and secretions, tracheal and broncho-alveolar washes and pleural fluid,

pleural fluid, portions of affected lungs and lung sequestra (scrapings from inside the capsule) and lung-associated lymph nodes, and kidneys.

Those sample should be frozen and can be submitted for PCR, immunohistochemistry and immunobidding. Culture of Mycoplasma mycoides mycoides is possible but very difficult and is not commonly undertaken.

Transmission
The infection is transmitted by the respiratory route and the disease is spread by close contact between animals (droplets emitted by coughing animals, saliva and urine). Transplacental infection can also occur.

As the agent is not very resistant in the environment, indirect transmission is not frequent.

Chronic cases with encapsulated lesions can break down, particularly if stressed and then act as a source of infection for susceptible in-contact animals and unapparent carriers are a major source of infection.

Risk of introduction
CBPP requires close contact with infected animals to spread, so is most likely to be introduced by the importation of an infected animal or embryo.

Risk analysis followed by quarantine should always be conducted prior to introduction of live animals.

Control / vaccines
Vaccination is commonly used in countries where the disease is endemic, thermo-resistant vaccines have been developed.

If CBPP appears in a previously free country, the preferred approach should be to contain it from spreading by restricting livestock movements and to eradicate it by slaughtering all infected and in-contact herds. Effectiveness of the program can be monitored through serological sampling, and meat inspection.

References
  • Contagious Bovine Pleuropneumonia in Cattle, In Merck Veterinary Manual, National Publishing Inc. Eight ed, 1998, Philadelphia, p 1078-107
  • GEERING WA, FORMAN AJ, NUNN MJ, Exotic Diseases of Animals, Aust Gov Publishing Service, Canberra, 1995, p337-342
  • Office International des Epizooties, 2002
  • Report of the Scientific committee on animal health and animal welfare(2001), Diagnostic test for Contagious Bovine Pleuropneumonia, European Commission, SANCO/AH/R25/2001.