Kate M. Thomas
Campylobacter and nontyphoidal Salmonella are important bacterial enteric pathogens which can be carried by apparently healthy livestock and poultry. During slaughter and butchering processes, bacterial contamination of the carcass and meat can occur meaning consumers can be unwittingly exposed to these foodborne pathogens. Infections with foodborne bacterial pathogens are disproportionately high in Africa.
To compile data from all over Africa, we undertook a systematic review and meta-analysis, searching six databases for articles on Campylobacter and Salmonella prevalence in food animals and meat in Africa. 7604 search results were whittled down to 247 relevant articles, with 28 African countries represented, and covering buffalo, camels, cattle, goat, pig, poultry, and sheep.
In this systematic review, which was conducted in the context of our project on Hazards Associated with Zoonotic enteric pathogens in Emerging Livestock meat pathways (HAZEL), we showed, among other interesting points:
- Campylobacter and Salmonella were most prevalent in poultry and pig samples
- Campylobacter jejuni was the most predominant Campylobacter species except in pigs where C. coli predominated
- S. enterica serovar Typhimurium was the most commonly identified Salmonella serovar overall, with ~300 Salmonella serovars identified across African countries
- Several studies reported isolating S. enterica serovar Typhi, suggesting contamination from human faeces.
Not all campylobacters and salmonellas are equal – at least in terms of causes of human illness. S. entericaserovar Typhi causes typhoid fever and is only known to infect people. For those studies reporting detection of S. Typhi in the meat chain, there would appear to be serious breaches in hygiene practices somewhere along the meat chain. Work to identify which Campylobacter spp. and Salmonella serovars are coming from which food animal species, and causing human illness in East Africa, is one of the aims of the HAZEL project and we hope to report on results from those studies later this year. We are also looking into antimicrobial resistance (AMR) profiles of the bacteria to contribute to a growing body of work on the relative contributions of people and different animal species to the global AMR crisis.
The systematic review itself was published in the International Journal of Food Microbiology and is available here: https://doi.org/10.1016/j.ijfoodmicro.2019.108382