Improvements in the diagnosis and control of diseases of small ruminants caused by mycoplasmas

摘要

Many mycoplasmas have been isolated from sheep and goats but only a small number have been linked directly to disease. The two most important are Mycoplasma agalactiae, the cause of contagious agalactia (CA), and M. capricolum subsp. capripneumoniae, the cause of contagious caprine pleuropneumonia (CCPP) which between them are responsible for significant economic losses especially in developing countries. Their prevalence is almost certainly underreported as few countries have the facilities for isolating and growing these fastidious organisms. While M. agalactiae grows relatively well in most mycoplasma media, M. capricolum subsp. capripneumoniae requires specalized media and can still take up to 2 weeks to grow. However, advances in polymerase chain reaction (PCR) technology have greatly improved the detection of both mycoplasmas. Better serological tests also enable more rapid and specific detection of antibodies to these mycoplasmas. Eradication of mycoplasmal diseases is best achieved by the slaughter of affected and contact animals but is not always practical, especially in developing countries. Although antibiotic therapy can bring about clinical improvements, it rarely eliminates the organism. The development of resistance to the traditional antibiotics such as the tetracyclines also makes this option increasingly less successful. New vaccines offer the possibility of cheaper and more effective prophylactic measures.