Contagious bovine pleuropneumonia
Aetiology Epidemiology Diagnosis Prevention and control References
AETIOLOGY
Classification of the causative agent
Mycoplasma mycoides subsp. mycoides SC (bovine biotype)
Mycoplasmas are microorganisms deprived of cell walls and are, therefore, a) pleomorphic and b) resistant to antibiotics of the beta-lactamine group, such as penicillin
Growth of the mycoplasma is relatively fastidious and requires special media rich in cholesterol (addition of serum).
There is only one antigenic type
Resistance in the environment and to chemicals
Mycoplasma mycoides subsp. mycoides (SC) is not resistant in the environment and transmission requires close contact
Temperature: In saline solution - susceptible to 45°C/120 min and/or 47°C/2 min In lymph - susceptible to 45°C/240 min and/or 60°C/2 min It is: Inactivated by acid and alkaline pH Susceptible to ether, mercuric chloride (0.01%), calcium hydroxide, phenol (1%/3 min), and formaldehyde solution (0.5%/30 seconds) Survival: Survives well in frozen tissues
EPIDEMIOLOGY
Hosts
Cattle (Bos taurus), zebu (Bos indicus) and water buffalo (Bubalus bubalis). Wild bovids and camels are resistant
Transmission
- Aerial, mostly by direct contact: droplets emitted by coughing animals, saliva, and urine. Transmission up to several kilometres has been suspected under favourable climatic conditions
- Transplacental infection can occur
- Inapparent carriers are a major source of infection
- Cattle movement is important in the spread of the disease
Virulent material
Lungs, pleuropneumonia lymph and possibly brain, liver, kidneys, lymph nodes, uterus, fetus and fetal membranes, and urine
Occurrence
CBPP is widespread in Africa and it is also present in other regions of the world, including southern Europe, the Middle East and parts of Asia. In Africa, its economic importance is particularly high in Sahelian and Sahelo-Sudanese countries
For detailed information on occurrence, see recent issues of World Animal Health and the OIE Bulletin
DIAGNOSIS
Incubation period is 1-3 months (sometimes longer)
During an outbreak of natural disease, only 33% of animals present symptoms (hyperacute or acute forms), 46% are infected but have no symptoms (subclinical forms) and 21% seem to be resistant
Clinical diagnosis
In adults
- Moderate fever with respiratory, pulmonary and pleuretic symptoms: polypnoea, characteristic attitude (elbows turned out, arched back, head extended), cough (at first dry, slight, and not fitful, becoming moist)
- When the animal gets up or after exercise, breathing becomes laboured and grunting can be heard
- At percussion, dull sounds can be noticed in the low areas of the thorax
In calves
- Pulmonary tropism is not the general rule, and infected calves present arthritis with swelling of the joints
- Co-existence of pulmonary symptoms in adults and arthritis in young animals should alert the clinician to a diagnosis of CBPP
Lesions
- Important amount of yellow or turbid exudate in the pleural cavity (up to 30 litres) that coagulates to form large fibrinous clots
- Fibrinous pleurisy: thickening and inflammation of the pleura with fibrous deposits
- Interlobular oedema, marbled appearance due to hepatisation and consolidation at different stages of evolution usually confined to one lung
- Sequestrae with fibrous capsule surrounding grey necrotic tissue in recovered animals
Differential diagnosis
Acute form
- East Coast fever
- Acute bovine pasteurellosis
- Bronchopneumonia and pleuropneumonia resulting from mixed infections
Chronic form
- Hydatid cyst
- Actinobacillosis and tuberculosis, bovine farcy
Laboratory diagnosis
Procedures
Identification of the agent
- Isolation of pathogen and identification by metabolic and growth inhibition tests
- MF-dot
- Polymerase chain reaction
Serological tests
- Complement fixation (prescribed test in the Manual). This test should be used only at herd level and never for individual diagnosis
- Competitive ELISA (under validation by International Atomic Energy Agency and several reference laboratories), and haemagglutination
- Agglutination test can be used as penside test in active outbreaks at the herd level
Samples
- Lung lesions, pleural fluids, lymph nodes, lung tissue exudate - frozen for isolation of the organism
- Acute and convalescent sera
PREVENTION AND CONTROL
No efficient treatment. Antibiotic treatment should be prohibitedSanitary prophylaxis
- In disease-free areas: quarantine, serological tests (complement fixation) and slaughtering of all animals of the herd in which positive animals have been found
- Control of cattle movements is the most efficient way of limiting the spread of CBPP
Medical prophylaxis
- In infected areas: a CBPP vaccine containing T1 strain is widely used
- A CBPP-rinderpest combined vaccine is sometimes used
Surveillance
Recommended Standards for Epidemiological Surveillance for Contagious Bovine Pleuropneumonia were drawn up by an OIE Ad hoc Group on 7-9 June 1993. After revision, these standards were approved by the International Committee during the 63rd General Session
REFERENCES AND OTHER INFORMATION
- Reference experts and laboratories
- Classified as an OIE List A disease (A060)
- Chapter 2.1.6. in the Manual of Diagnostic Tests and Vaccines for Terrestrial Animals.
- Terrestrial Animal Health Code
- Other references - see the Index
- World Animal Health .
- Current Animal Health Status (Disease Information, PPCB)
- Recommended standards for epidemiological surveillance systems for Contagious Bovine Pleuropneumonia.
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