Researchers from the US and the UK sequenced the DNA of bacteria collected from 1,231 patients in Lancashire, England and compared it to Campylobacter jejuin DNA sequences collected from wild and domestic animals and the environment.
Camplylobacter jejuni causes more cases of gastroenteritis in the developed world than any other bacterial pathogen, including E. coli, Salmonella, Clostridium and Listeria combined, claims the study.
According to the European Food Safety Authority (EFSA), Camplylobacter is the most frequently reported animal infection transmissible to humans, with over 175,000 sufferers in the EU in 2006 (46 cases for every 100,000 people).
Wild and domestic animals act as natural reservoirs for the disease, claims the study, and it can also survive in water and soil, but the researchers said that recent studies had contradicted the idea that livestock are the main reservoir for human disease.
However, the findings of this study, published in the journal, PloS Genetics, found that in 57 per cent of the cases, the bacteria could be traced to chicken, and in 35 per cent to cattle.
The team said that wild animal and environmental sources accounted for just three per cent of the cases studied.
Their findings are similar to the conclusions of EFSA; in its December 2007 report on zoonotic diseases, the regulator said that the most common food borne route of campylobacteriosis is through poultry meat.
The UK and US researchers said that they hope the current study will add impetus to initiatives aimed at controlling food-borne pathogens:
“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.”
The study was funded by the Higher Education Funding Council of England and the UK Department for Environment, Food and Rural Affairs (DEFRA).
Farm to fork
EFSA emphasises the importance of the farm to fork approach in combating the continuing high prevalence of infectious diseases transmissible from animals to humans.
A report from the regulator’s Biohaz panel earlier this year urges food safety authorities and the food industry to look closely at the various ways in which bacteria enter the food chain and to do their utmost to control them.
Meanwhile, resistance to antibacterials in animals is rising, says EFSA, meaning that the risk of animal-based food becoming contaminated is higher. The agency said that, at the same time, antimicrobials are also becoming less effective in fighting human infections.
EFSA said that Salmonella and Campylobacter, in particular, are becoming increasingly resistant to current antibiotic treatments.
Source: PLoS Genetics 4(9): e1000203. Published online ahead of print: doi:10.1371/journal.pgen.1000203Tracing the Source of CampylobacteriosisAuthors: D.J. Wilson, E. Gabriel, A.J.H. Leatherbarrow, J. Cheesbrough, S. Gee, et al