Breakthrough in Campylobacter Detection10 December 2012
Scientists at Environmental Science and Research have developed new technology to track the causes of Campylobacter outbreaks within hours.
The world first technology will mean that if several people get sick at the same time, ESR can tell if they have picked up the same strain of Campylobacter from a common source and raise the alarm so food safety authorities can have unsafe food taken off the menu or destroyed or put other interventions in place.
In 2006, New Zealand had the highest rate per capita of campylobacteriosis in the world. Last year, over 6,000 people contracted the illness in New Zealand, with the majority of cases being caused by people eating contaminated food.
Campylobacter is a bacterium that causes serious illness with symptoms including diarrhoea, abdominal pain, fever, headache and vomiting and is New Zealand’s most common bacterial foodborne illness.
Dr Fiona Thomson-Carter, General Manager of ESR’s Environmental Health says Campylobacter is highly seasonal with cases peaking over summer. “It’s mainly associated with cross-contamination between cooked and uncooked food as people forget to follow the cook, clean, cover, chill public health messages for safe food preparation.”
“Anybody who has been sick with Campylobacter knows that it’s a really horrible illness, often with violent diarrhoea and it can hospitalise young, previously healthy people. Even though New Zealand’s rate of Campylobacter disease has come down it’s still a serious public health issue. New Zealand has had three times the incidence of European countries, for example.”
It is estimated Campylobacter costs the country over $50 million each year in medical treatment, on-going illness and lost work days.
In the past, it would have taken up to 3-5 days to link an outbreak to its source. Now ESR can pinpoint and identify a strain within hours to give vital results to doctors, public health and food safety officials so they can act to prevent others from getting sick.
“This new technology will be critical in identifying serious public health issues. It’s the first time it’s been applied in real life,” said Dr Thomson-Carter.
The new system called M-BiT is a type of “DNA fingerprinting” allowing scientists to see each individual strain of the bacterium as a “barcode”. Similar to human fingerprints, each strain has its own unique pattern, so ESR’s scientists can quickly tell if people are being made ill by the same strain and to help track it back to a common source.
“Within hours we can let doctors, public health and food safety officials know where people are picking up the bacterium and how to stop an outbreak from spreading.”
Dr Thomson-Carter said the “DNA fingerprinting”, or genotyping, is cutting edge technology.
“It’s a new molecular method where we take DNA from bacteria, and produce a DNA “fingerprint” within hours – meaning each strain appears as an individual ‘barcode’ to help us assess if they might be linked to the same source of infection.”
ESR has developed and successfully trialed the new genotyping system, which offers the fastest response of any definitive DNA-based typing system yet known. Speed in genotyping means measures can be put in place faster to contain the cause, reducing the social and economic impacts of an outbreak.
Test results can also easily be exchanged and compared between laboratories and might even provide an insight into how much risk to human health is posed by any one strain.
As campylobacteriosis is a global health issue, several laboratories overseas have expressed an interest in using this rapid subtyping system.
ESR is now trialing the M-BiT technology on other foodborne bacteria such as E. coli O157:H7 and the assay is poised for commercial sale by an international company early next year.
The new system was trialed recently when over 100 residents in Darfield became ill. Using the innovative new typing method, DNA ‘fingerprints’ from strains of Campylobacter were obtained within just a few hours of isolating the strains. The fingerprints showed the strains were from a common source and combined with epidemiological information, confirmed the source of infection was a contaminated water supply.
About 10 percent of those who contract campylobacteriosis are hospitalised. At its most serious Campylobacter victims can develop arthritis and on rare occasions people can develop Guillain-Barre syndrome, a disease that involves the immune system attacking the body's nerves, resulting in paralysis that can last several weeks.
Campylobacter means "twisted bacteria". There are over 20 species of Campylobacter, and C. jejuni and C. coli are the most frequently implicated in human disease.