Prevalence of Listeria species in dairy farms in Khartoum State (Sudan)

Abstract

This is a cross sectional study conducted at Khartoum State, Sudan with the objective of investigating the occurrence of Listeria spp. in dairy farms and associated environment. One hundred and twenty dairy farms were included in the study (720 samples of milk, teats, utensils, feed, water and air were collected). Conventional microbiological methods to isolate and identify Listeria spp. were done. The overall prevalence of Listeria spp. was 14.7%. Seven species of Listeria were isolated from milk and other sources in dairy farm environment. The identified animal pathogenic Listeria spp. include. L. monocytogenes and L. ivanovii, Other isolated Listeria spp. were L. seeligeri, L. welshimeri, L. innocua. L. grayi and L. murrayi. The presence of Listeria spp. in milk were L. monocytogenes (2.5%), while 1.7% for each of L. seeligeri, L. welshimeri and L. ivanovii were found. The most frequently isolated species was L. welshimeri (33.3%). High prevalence of Listeria spp. was observed in water (24.2%) followed by teats (20.0%), feed (16.7%) and utensils (14.2%) compared to milk (7.5%) and air (5.8%). Dairy farm hygiene and environment have the significant impact on the prevalence of Listeria spp. This study concluded that diversity of the prevalence of Listeria spp. in dairy farm environment necessitates conduction of microbial risk assessment in milk value chain.