Synonyms: CBPP; Lung Plaque; Lung Sickness
It is an acute, sub-acute, clinically inapparent or chronic disease characterized by formation of massive pathological changes in the thoracic organs specially lungs and pleura. Changes are comprised of marked oedema of interlobular septum, diffused pneumonia and sero-fibrinious pleuritis.
Distribution
The disease has been recorded since 19th century in the Central Europe. It is still an enzootic disease in many large areas in Europe, Asia and Australia. The disease has been diagnosed in China, Japan and India. In India, the disease is widely prevalent in North Eastern region. The disease has been reported from India in bovine in 1990.
Aetiology
The disease is caused by Mycoplasma mycoides var. mycoides. This organism was previously denoted as Asterococcus mycoides. The organism is pleomorphic in nature and occur in rings, globules, filamentous and in bizaree form. The organism can be stained by Giemsa. The organism can be grown in media providing 10% serum protein. It can be cultured in developing chorioallantoic membrane and tissue culture. The organism is sensitive to all environmental infuences including disinfectants, heat and drying.
Susceptible Hosts
This primarily a disease of cattle although rare, natural cases have been observed in buffaloes, yalk, bison, reindeer and antelopes. The organism can be adopted in rabbit, guineapig, mice and hamster by subcutaneous injection. Mice is considered a suitable host to enable isolation of Mycoplasma from natural field cases.
Clinical Findings
Incubation period depends on the concentration of the organisms, virulence of the organisms and immunity. The incubation period may be as short as 10 days or as long as 260 days. The clinical signs are comprised of:
- High rise of temperature
- General malaise
- Extreme depression
- Drop in milk yield
- Suspended rumination
- Anorexia
- Cough following exercise
- Persistent cough in acute attack
- Reluctant to move
- Abducted elbow
- Arched back
- Extended head and neck
- Dilated nostrils
- Panting
- Expiratory grunt
- Drooling of saliva
- Nasal discharge
- Pain on percussion
- Pleuritic frictional sound on auscultation
- Oedematous swelling of throat and dewlap
- Abortion due to invasion of placenta
- Arthritis in calf
- Carrier state following recovery
Diagnosis
This is based on the following considerations
- History: Prolonged incubation period; history of contact with infected animals
- Clinical findings: Typical signs of respiratory involvement
- Culture: Culture of organisms in special media. Pleomorphic organisms are seen in culture with predominant filamentous form.
- Dark field microscopy: It helps to differentiate mycoplasma in the pleural lymph.
- Precipitation test: Agar gel double diffusion methods is a reliable test.
- Agglutination test: This test can be adopted in the field on suspected population. This test is also useful for screening out vaccinated population.
- CFT: This is a most useful test for detecting early as well as chronic carrier.
- Intradermal test: The test is done in similar line as with Tuberculosis
- FAT: This test has been used successfully for the detection of Mycoplasma antigen in culture and antibody in sera.
- Animal inoculation test: Subcutaneous inoculation of suspected material from affected cow will produce large oedematous swelling at the site.
- Radial immuno diffusion test: This test has been used for the detection of cattle exposed to both virulent and avirulent strain.
Differential Diagnosis
The disease has to be differentiated from pneumonia, pasteurellosis and parasitic pneumonia.
Treatment
The drugs like sulphadimidine and arsenicals can be used. Streptomycin, oxytetracycline, chloramphenicol have got some effect. Tylosin tartrate is also effective. Dose is 2-5 mg/kg body weight every 12 hours. Spiramycin and Lincomycin are also useful drugs against mycoplasma.
Control
- Slaughter of all affected animals and enforcement of rigid quarantine regulation are to be made.
- Slaughter may not be possible in all the countries and therefore preventive inoculation deemed advisable.
- Movement of cattle should be restricted.
- Carrier animals should be slaughtered.
Vaccines
Vaccines those have been used are:
- Pleural exudate from natural cases has been used as vaccine.
- Cultured organisms of reduced virulence.
- Avianised vaccine of low virulence.
- A broth culture vaccine from 45th passage of avianised T1 strain.
- Broth culture vaccine
Natural lymph vaccine is unsatisfactory because of the possibility of spreading the disease. Severe reactions with this type of vaccine may cause sloughing of tail and extensive cellulitis of the hind quarters. Culture vaccines produce much less reaction but duration of the immunity is shorter from 6 to 10 months and annual vaccination is necessary. The avianised vaccine produces good immunity and a minimum local reaction following subcutaneous injection. The immunity may persist 3 to 4 years. Vaccination of calves from 2 months of age is recommended.
