A cross sectional study on Salmonella in apparently healthy sheep and goats slaughtered at Elfora and Luna export abattoirs, Ethiopia

A cross-sectional study was conducted between November 2015 and March 2016 on apparently healthy slaughtered sheep and goats, and clean knife at Luna and Elfora export abattoirs located at Modjo and Bishoftu towns to estimate the prevalence of Salmonella in sheep and goats, to assess the hygienic condition of flaying knife, and to isolate and identify the prevalent Salmonella sub-species. A total of 525 samples consisting of cecum (n=122), liver (n=122), mesenteric lymph nodes (n=122), abdominal muscle (n=122) from 44 sheep and 78 goats and 37 pooled knife samples were collected. The samples were examined for the presence of Salmonella following the conventional techniques of ISO standard and using OMNILOG bacterial identification system, GEN III microplate for confirmation and sub species identification. From the total of 122 animals examined, 21 (17.21%) were positive of which 12 (9.83%) were sheep and 9 (7.38%) were goats, and none of the samples from pooled knife swabs were positive for Salmonella. Statistically significant difference (P=0.04) in the prevalence of Salmonella was observed between the two species. The frequency of isolation was 10 (3.89%) and 11 (4.10%) from Luna and Elfora abattoirs, respectively. As a result, there was no significant difference (P =0.884) in the prevalence of Salmonella isolation between the two abattoirs. Of the total 488 tissue samples examined from apparently healthy slaughtered sheep and goat, 21 (4.3%) samples were Salmonella positive. Salmonella was isolated from 6.56% mesenteric lymph nodes, 5.73% cecum, 4.09% liver and 0.82% abdominal muscle samples. However, there was no significant difference between tissues (P=0.13). From the 21 isolated Salmonella species, 20 of them were confirmed to be the pathogenic Salmonella enterica subspp. enterica and 1 isolate was the non-pathogenic Salmonella enterica subspp. salamae. The results of this study showed the potential risk of sheep and goats as sources of pathogen for humans in the study area. These findings stressed the need for implementation of preventing close contact of offal and carcass during evisceration.