Mycoplasma ovipneumoniae identified as the main aetiological agent of respiratory disease in goats from a case-control study in Savannakhet province of Lao PDR

Abstract

Clinical signs of respiratory disease are common in Lao goats. To identify the causative agents involved in this clinical syndrome, a matched case-control study was conducted across 70 smallholder goat holdings in Savannakhet province. Fifty paired nasal swab samples were collected from goats with respiratory signs (cases) and unaffected (control) goats from 27 goat holdings. The majority of cases (84 %) were from goats < 12 months of age. Samples were tested using quantitative PCR assays targeting possible pathogens causing respiratory disease. Mycoplasma ovipneumoniae, the cause of atypical pneumonia, was prevalent in both case (94 %) and control (76 %) groups and was identified as the principal causative agent based on odds ratio of presence (4.9) and a significantly higher pathogen load in case goats. Prolonged close contact between goats during confinement in often poorly constructed goat houses, likely facilitates transmission and progression from carrier to clinical status under the Lao goat production system. Mannheimia haemolytica was detected in 60 % of case and 52 % of control samples with no significant difference in pathogen load, while Pasteurella multocida was detected in only 2 % of control samples indicating no major role in causation for these pathogens. Mycoplasma capricolum subsp. capripneumoniae, respiratory syncytial virus and bovine parainfluenza 3 virus were not detected in any samples. Phylogenetic analysis showed no genetic variation of M. ovipneumoniae in the study samples and close similarity to recent isolates from China, US and Turkey. Improved housing conditions may be helpful in controlling atypical pneumonia in Lao goats and antibiotic treatment of goats with severe signs of respiratory disease was found to be effective.