Animals farmed for meat are the main source of Campylobacter infections
Campylobacter jejuni is a bacterium commonly found in the guts of birds and mammals. In humans, it is responsible for causing more gastro-enteritis than any other identified bacterial species. Humans may contract campylobacter infections from a variety of sources. Eating raw or undercooked meat or poultry, and poor food hygiene that leads to cross-contamination of uncooked food, can cause human disease. However, humans may be exposed to the faeces of infected wild animals, and Campylobacter can survive in water. Contamination of drinking water can lead to outbreaks, and previous genetic studies have suggested that livestock are not the principal source of human infection.
A new study found that 97% of campylobacteriosis cases sampled in Lancashire were caused by bacteria typically found in chicken and livestock. The work is based on DNA-sequence comparison of thousands of bacteria collected from human patients and animal carriers. Campylobacter jejuni causes more cases of gastroenteritis in the developed world than any other bacterial pathogen, including E. coli, Salmonella, Clostridium and Listeria combined. Wild and domestic animals act as natural reservoirs for the disease, which can also survive in water and soil. However, the relative importance of these sources is unclear, and recent work has suggested that livestock are not the main reservoir for human disease. Researchers sequenced the DNA of bacteria collected from 1,231 patients and compared it to C. jejuni DNA sequences collected from wild and domestic animals, and the environment. They used evolutionary modeling to trace the ancestry of human C. jejuni back to one of seven source populations. In 57% of cases, the bacteria could be traced to chicken, and in 35 percent to cattle. Wild animal and environmental sources were accountable for just 3% of disease. These results imply that the primary transmission route is the food chain and also add new impetus to measures that reduce infection in livestock and prevent food-borne transmission.
Tracing the Source of Campylobacteriosis. 2008 PLoS Genet 4(9): e1000203
Campylobacter jejuni is the leading cause of bacterial gastro-enteritis in the developed world. It is thought to infect 2–3 million people a year in the US alone, at a cost to the economy in excess of US$4 billion. C. jejuni is a widespread zoonotic pathogen that is carried by animals farmed for meat and poultry. A connection with contaminated food is recognized, but C. jejuni is also commonly found in wild animals and water sources. Phylogenetic studies have suggested that genotypes pathogenic to humans bear greatest resemblance to non-livestock isolates. Moreover, seasonal variation in campylobacteriosis bears the hallmarks of water-borne disease, and certain outbreaks have been attributed to contamination of drinking water. As a result, the relative importance of these reservoirs to human disease is controversial. We use multilocus sequence typing to genotype 1,231 cases of C. jejuni isolated from patients in Lancashire, England. By modeling the DNA sequence evolution and zoonotic transmission of C. jejuni between host species and the environment, we assign human cases probabilistically to source populations. Our novel population genetics approach reveals that the vast majority (97%) of sporadic disease can be attributed to animals farmed for meat and poultry. Chicken and cattle are the principal sources of C. jejuni pathogenic to humans, whereas wild animal and environmental sources are responsible for just 3% of disease. Our results imply that the primary transmission route is through the food chain, and suggest that incidence could be dramatically reduced by enhanced on-farm biosecurity or preventing food-borne transmission.
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Tags: Agriculture, Bacteria, Biology, Environment, Food, Genetics, Health, Medicine, Microbiology, Science
i am interested in your report on campylobacter in wild animals.
i am a hedgehog carer and am seeing deaths that might be related to this, i’m not the only one.
is there any evidence of it in hedgehogs, any advice or help would be greatly appreciated.