World Health Day 2015

Danny Wilson
Dr Daniel Wilson

7th April is World Health Day and marks the anniversary of the founding of the World Health Organization. This year’s theme is food safety. NDM spoke to Professor Daniel Wilson, a Group Head in Experimental Medicine, about his research on tracking micro-organisms and how this can be applied to pathogens such as Campylobacter – a common cause of food poisoning.

Q: Why is campylobacteriosis infection a problem?

Daniel Wilson: The World Health Organization expects that every year 1% of the population of developed nations will suffer campylobacteriosis, a diarrhoeal disease that can lead to serious pathological conditions as a result of the infection, such as Guillain-Barré syndrome and reactive arthritis. Infection with Campylobacter is the most commonly identified cause of bacterial gastro-enteritis, ahead of Salmonella, Escherichia coli, Clostridium and Listeria combined. The cost to the world economy of Campylobacter infection is measured in billions of dollars per year.

Q: How can genetic information be used to look at bacteria transmission?

Phylogeny of campylobacter genomes. Each black dot represents a campylobacter sampled from a human.

DW: Campylobacter jejuni and Campylobacter coli are zoonotic pathogens with wide host ranges including farm animals (cattle, sheep, poultry, pigs) and wild animals (birds and mammals) and they are routinely isolated from fresh and marine water sources, and sewage. By sampling the Campylobacter infecting humans, looking at their genomes and comparing them to samples from farm animals, wild animals and water sources, we can identify the likely sources of transmission. This information can then be used to help control outbreaks.

 Q: What techniques are you using to model disease transmission?

DW: Transmission history is recorded in the genetic diversity of pathogen populations and may be unlocked through genomic analysis. By sequencing Campylobacter genomes and modelling their evolution during transmission, we can probabilistically assign human cases to source populations. Previously we have shown that 97% of cases of campylobacteriosis are attributable to meat and poultry, with chicken and cattle the principal sources; wild animal and environmental reservoirs are responsible for just 3% of human disease. Using whole genome sequencing we are improving our understanding of transmission dynamics to help target efforts aimed at preventing food-borne transmission.