Clinical and laboratory diagnosis of contagious caprine pleuropneumonia in Qassim region, Saudi Arabia: a comparative study

摘要

Diagnosis of contagious caprine pleuropneumonia (CCPP) in Saudi Arabia mainly depends on clinical signs and post-mortem findings, in addition to limited usage of latex agglutination test (LAT). In this study, a PCR method specific for detection of Mycoplasma capricolum subspecies capripneumoniae (Mccp) was used as a direct confirmatory method and to compare it with clinical signs, necropsy lesions and LAT. During the 2016-2017 year, samples of serum, pleural fluid, lung tissue and nasal swab were collected from 40 goats with clinical signs of CCPP, which were selected from goats brought to the veterinary clinic of Qassim University from 18 goat herds and nine localities. Epidemiological data revealed 34.1%, 27.8% and 81.6% morbidity, mortality and case fatality rates, respectively. At necropsy, 31 of 40 goats (77.5%) were found with lesions matching those of CCPP. Molecular findings supported the suitability and applicability of PCR as a reliable method to diagnose and confirm CCPP directly from clinical samples. The disease was confirmed by PCR in 35 goats out of 40 (87.5%), 15 herds out of 18 (83.3%) and in all localities. Sera of 32 goats (80%) were found positive by LAT. Four of the five goats and two of the three herds negative by PCR were also negative by LAT and necropsy examination. Therefore, PCR sensitivity was considered 97.2% (35/36). Compared to the claimed high specificity and sensitivity of the used PCR method, diagnosis of CCPP based on clinical signs was found less specific and necropsy examination and LAT were less sensitive. It was concluded that molecular detection of Mccp directly in clinical samples should routinely be used to confirm diagnosis of CCPP in the region of study, prevent economic impact of wrong diagnosis and to hasten control process.