Haematology and pathologic changes associated with Pseudomonas aeruginosa isolated from barn swallows around poultry houses in broiler chickens

The impact of vermin found in poultry houses has increased in recent times. This study evaluated the occurrence of Pseudomonas aeruginosa in free flying barn swallows found in poultry houses in Ibadan and determined its pathogenicity in broilers. Barn swallows (23) were caught using mist nets, their oral and cloacal microbial culture yielded Pseudomonas aeruginosa. One-week-old, thirty-five broilers were divided randomly into infected (n=23) and control (n=12) groups. Each bird in the infected group was inoculated with viable infective dose of 0.5 ml of 8hr broth containing (105) CFU/ml of Pseudomonas aeruginosa via oro-nasal route. The infected group showed dullness, rales and bloody diarrhoea. The pack cell volume was consistently lower in the infected group compared to the control group although not statistically significant post-infection. The platelets count was significantly (P <0.05) higher in the infected group on day 7 pi. Total white blood cell was significantly (P <0.05) higher in the infected group on day 14 pi. There was a significant (P<0.05) increase in heterophil count on days 7 and 35 pi. The mean lymphocyte value of the infected chickens was significantly (P <0.05) lower than the control group only on day 35 pi, while the monocyte count in the infected group was significantly (P<0.05) lower on day 28 pi. Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus were sensitive to gentamycin and resistant to oxytetracycline except for Pseudomonas aeruginosa. Hepatic congestion, splenomegaly and enteritis were observed in the infected chickens. Barn swallows harbour pathogenic bacteria, causing clinico-pathological changes in chickens and may be partly responsible for transmission of pathogenic bacteria within and between poultry houses due to their free-flying habit. Adequate biosecurity measures including screening nets on poultry houses are recommended to prevent access of these free flying birds into poultry pens.