An overview of Listeria species in Nigeria

Despite the world-wide reports of outbreaks of food-borne listeriosis, the occurrence of Listeria is still not widely reported in Nigeria. This is possibly due to lack of a large cold storage food chain and the absence of a comprehensive surveillance system for food-borne pathogens. Searches carried out on major databases revealed that Listeria has been reported in humans, animals, environment and food in Nigeria. In Nigeria, the organism has been reported in pregnant women and neonates while ruminants dominate reports of occurrence in animals. In food especially fish, L. monocytogenes is reported more than any other Listeria species. The organism has been isolated from water bodies and soils from different environments in Nigeria. However, all reports on the occurrence of Listeria spp. were based on classical serotyping, biochemical tests and dark colouration of media due to hydrolysis of aesculin with no emerging pattern of infection or dominant molecular serotype. There is an opportunity to utilize the current polymerase chain reaction based molecular techniques to characterize Listeria spp. so that accurate information on existing Listeria strains and sources of infection can be established in all regions in Nigeria.