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Contagious Caprine Pleuropneumonia (view source)
Revision as of 13:05, 6 April 2011
, 13:05, 6 April 2011no edit summary
== Clinical Signs ==
== Clinical Signs ==
The animal may appear generally depressed, dull, weak and lethargic. They will often be pyrexic and have signs of weight loss of reduced weight gain. If the animal is in milk then milk yield will be severely reduced. Sometimes the disease may manifest as sudden death only.
The animal may appear generally depressed, dull, weak and lethargic. The animal will be pyrexic and have signs of weight loss of reduced weight gain. If the animal is in milk then milk yield will be severely reduced. Sometimes the disease may manifest as sudden death only.
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Respiratory signs include bilateral nasal discharge, dyspnoea, tachypnoea and coughing. Some goats may appeaer to be in severe respiraotry distress.
Respiratory signs include bilateral nasal discharge, dyspnoea, tachypnoea and coughing. Some goats may appeaer to be in severe respiraotry distress.
== Diagnosis ==
== Diagnosis ==
In the field, diagnosis of mycoplasma pneumonia cannot be established on clinical signs or on postmortem examinations alone. In outbreaks of classical acute CCPP, the high mortality and typical early thoracic lesions in goats are highly indicative of M. capricolum subsp. capripneumoniae infection, but all cases of caprine mycoplasmosis need additional laboratory tests to establish a presumptive diagnosis.
In the field, diagnosis of mycoplasma pneumonia cannot be established on clinical signs or on postmortem examinations alone. In outbreaks of classical acute CCPP, the high mortality and typical early thoracic lesions in goats are highly indicative of M. capricolum subsp. capripneumoniae infection, but all cases of caprine mycoplasmosis need additional laboratory tests to establish a presumptive diagnosis.
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An 'in the field' diagnostic procedure is the latex agglutination test (LAT) (Rurangirwa et al 1987b). This test is based on a polysaccharide isolated from Mccp (Rurangirwa et al 1987a) which is used to sensitise latex beads. The sensitised latex beads are then used to detect serum antibodies from goats infected with CCPP (Rurangirwa et al 1987b). The specificity of LAT was assessed using WM25 monoclonal antibody which is specific for Mccp (Rurangirwa et al 1987c; Belton et al 1994) and reacts with the polysaccharide (Rurangirwa et al 1992). The specificity of LAT was further confirmed by evaluating specific growth inhibiting rabbit antisera to various mycoplasma isolates (Rurangirwa et al 1987c). The sensitised latex beads are stable at 4°C, room temperature and 37°C for over one year. Thus the long shelf-life of the beads at different temperatures makes it possible to prepare large amounts which can be stored until used. The latex agglutination test is an excellent procedure for the diagnosis of CCPP and can be run in two minutes on samples of whole blood or serum, requires no sophisticated equipment or storage facilities and is adaptable to any laboratory or field conditions - an example of a pen-side diagnostic test. The test is carried out by mixing a drop of the sensitised beads with a drop of blood or serum from the suspected animal on a glass slide for one minute and the results read visually and recorded as positive or negative. LAT combined with presenting clinical signs and necropsy indicating fibrinous pleuropneumonia is confirmatory of Mccp associated CCPP.
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Definite diagnosis is made by the isolation of M. capricolum subsp. capripneumoniae from clinical samples, usually lung tissue and may be a long and difficult process. The success of isolation depends primarily on the attention that is given to sample collection.
Definite diagnosis is made by the isolation of M. capricolum subsp. capripneumoniae from clinical samples, usually lung tissue and may be a long and difficult process. The success of isolation depends primarily on the attention that is given to sample collection.
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Until recently, isolation was the only way to confirm the presence of CCPP. Diagnostic systems based on PCR have been developed for the rapid detection, identification and differentiation of members of the M. mycoides cluster and the specific identification of M. capricolum subsp. capripneumoniae (Bashiruddin et al., 1994; Hotzel et al., 1996).
Until recently, isolation was the only way to confirm the presence of CCPP. Diagnostic systems based on PCR have been developed for the rapid detection, identification and differentiation of members of the M. mycoides cluster and the specific identification of M. capricolum subsp. capripneumoniae (Bashiruddin et al., 1994; Hotzel et al., 1996).
The diagnosis of outbreaks of CCPP is complicated by other infectious agents causing similar syndromes. Pleuropneumonic disease resembling Mccp-associated CCPP can also be produced by Mycoplasma mycoides subsp. capri (Mmc) and caprine variants of M. mycoides subsp. mycoides (Mmm). Mmc was originally considered to be the cause of CCPP, but its full importance as a pathogen of goats has now become doubtful, both because of the discovery of the Mccp and because many isolates previously classified as Mmc have subsequently been found to be caprine variants of Mmm. Mmc has been isolated from several countries in Africa and Asia, and from Australia. The disease reproduced experimentally with Mmc is largely restricted to the thoracic cavity, with or without a septicaemic phase and death. In contrast, caprine variants of Mmm generally causes a syndrome which may include not only pleuropneumonia but also mastitis, polyarthritis, keratoconjunctivitis, acute septicaemic death, sometimes with symptoms of the central nervous system, and abortion. Mmm is a major cause of disease in goats in USA, France, Israel and India. Experimentally, the disease caused by Mccp differs from that produced by Mmc and Mmm in: being readily contagious and fatal to susceptible goats; not affecting sheep or cattle; not producing local oedematous reactions when injected subcutaneously; and being characterised histo-pathologically by an interstitial, intralobular oedema of the lung, compared with the thickening of the interlobular septa which is seen with Mmc and Mmm (Kaliner and MacOwan 1976). Pasteurella haemolytica (both biotypes A and T) and P. multocida have also been associated with pleuropneumonia in goats, although experimental evidence of their pathogenicity in this host is meagre.
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