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Raw chicken risks

More than half the fresh chicken products we tested contained campylobacter. Is enough being done to reduce risks from the bug?

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Every summer, thousands of people are laid low by the bug. Campylobacter is the most common cause of gastro infections in New Zealand, with rates peaking as the sun comes out and the barbie season gets into full swing.

Fresh chicken remains the main villain, considered responsible for half of all cases.

Of 40 fresh chicken products we purchased from supermarkets, 65 percent tested positive for campylobacter. The bug was detected on a range of products from chicken breasts to drumsticks.

The presence of the bug doesn’t necessarily mean you’ll get sick from the chicken but it increases the chances. Campylobacter can survive if raw chicken isn’t cooked properly. The bacteria can also be spread to other foods and contaminate surfaces where food is prepared.

Infection rates

It’s no secret New Zealand’s campylobacter rates have been stubbornly high. In 2015, the official rate was 135 cases per 100,000 people, a drop from 150 the previous year. In comparison, across the Tasman latest figures put the rate at 125 per 100,000. In the EU, it’s 65.

Contact with farm animals and swimming at polluted beaches and rivers are high on the list of risk factors associated with getting the illness (see “Infection rate” graph). Drinking contaminated water also remains a major risk as this year’s campylobacter outbreak in Hawke’s Bay showed.

But Michael Baker, professor of public health at the University of Otago, says fresh chicken is implicated in at least 50 percent of cases. The number of people who succumb to the infection from contaminated chicken is the equivalent of about six Havelock North outbreaks each year, he says.

Campylobacter rates halved after contamination limits and monitoring of fresh poultry was introduced almost 10 years ago, he says. “However, this downward trend hasn’t continued and there’s been little change in campylobacter notifications and hospitalisations since 2009.”

Michael Brooks, executive director of the Poultry Industry Association, is more upbeat. He describes the drop in campylobacter rates over the past decade as “pretty extraordinary”, considering it’s happened at the same time as poultry production has increased 30 percent. But he says industry agrees the rate needs to drop further.

Tolerance levels

The Ministry for Primary Industries, responsible for food safety, has described our campylobacter rate as “unacceptably high”. Efforts to slash the rate have continued to focus largely on the killing chain. Additional measures introduced in January 2013 required poultry processors to report the number of chicken samples with bacteria above a specified detection limit.

MPI anticipated this limit would help reduce the number of campylobacter cases in the community. But numbers remained “relatively static”.

Data show some processors have also regularly exceeded the limit. Affected chicken products can be sold in retail stores before the processor takes required corrective actions.

Between January 2013 and October 2014, there were 130 occasions where processing plants exceeded either the detection limit or a separate “enumeration limit”. The latter requires processors to report instances where campylobacter counts exceed 6000 colony-forming units (a measure of the number of viable bacteria).

Last year, MPI began consulting with industry on new performance measures to reduce the rate of fresh chickens testing positive for the bug.

One option was to set tighter detection limits but that didn’t eventuate. Instead an additional performance target was introduced in April this year for processors handling more than one million birds. The target for these processors is for campylobacter to be detected in no more than 30 percent of chickens each quarter.

Three processors weren’t meeting this target last year. The names of these companies aren’t available as MPI doesn’t release the information.

Mr Brooks says the 30 percent target is a tough one but supported by the industry which wants to see poor performers improve. He says non-compliance is a short-term, seasonal issue and some plants “might struggle a bit more”.

The ministry says its aim is full compliance by 2018. Its revamped campylobacter management strategy, yet to be published, is also targeting a 10 percent reduction by 2020 in community cases of campylobacter.

Retail testing

Mr Baker believes more could be achieved if other readily available measures were used to reduce contamination. He points to the UK where the Food Standards Agency (FSA) is publishing information on campylobacter levels found on chickens at major retail stores such as Sainsbury’s and Tescos.

FSA director of policy Steve Wearne credits the move with prompting action from retailers and processors and raising consumer awareness.

Since data started to be published in 2014, the agency says results have shown a reduction in the number of chickens testing positive for the highest level of contamination. There’s also been a small, but statistically significant, drop in contamination on chicken packaging.

UK consumers back public reporting: 75 percent think stores should be telling customers what proportion of chickens have high levels of contamination.

Retail testing isn’t routinely carried out here. The most recent data published by MPI reports the results of testing done in 2010 and 2011. The results showed 79 percent of 574 chicken products purchased at retail tested positive for campylobacter, although concentrations of the bacteria were generally considered low.

The ministry currently has no plans to carry out further retail surveys or publish data similar to the UK. It says it considered a retail testing programme but concluded primary processing was “the best stage in the food chain to reduce the level of campylobacter on chicken meat”.

In the wake of Havelock North’s campylobacter outbreak, government agencies are also turning their attention to risks from sources other than poultry.

We say

  • If you’re buying fresh chicken to cook at home, treat all products as if they’re contaminated.
  • Regular testing of chicken sold in retail stores should be on the agenda to give consumers better information about the products they’re buying.
  • The UK experience shows making test results public can also help spur action from both manufacturers and retailers to reduce contamination levels.

Cause and effect

Campylobacter is found in the gut of chickens and other animals. Contaminated chicken products are one of the main routes for the bacteria to be transferred to humans. Adding chlorine to water used to wash and chill the birds is among the measures poultry processors use to reduce bacteria levels before chicken arrives in store.

Campylobacter can survive if raw chicken isn’t cooked properly. Symptoms of campylobacter infection develop anywhere from one to 10 days after exposure. Typical symptoms include muscle pain, headache and fever followed by diarrhoea, stomach pain and nausea.

Most people who get the bug recover within a week without needing medical treatment. But they can still spread the infection: the bacteria shed from the gut for up to several weeks afterwards.

Some people will require hospitalisation. In 2015, 564 hospital admissions were recorded. Children under five have the highest rates of illness. Infection rates are also higher in men than women.

In rare cases, the infection may cause long-term effects such as reactive arthritis or Guillain-Barré Syndrome, an auto-immune disorder that can cause muscle weakness and paralysis.

Infection rates

Campylobacteriosis – the infection caused by the campylobacter bug – continues to be the most commonly notified disease in New Zealand, comprising 44 percent of all infectious disease notifications in 2015.

Between 2006 and 2008, the number of notified cases halved after control measures were put in place in the poultry industry. Rates have been fairly steady for much of the period since then.

In 2015, 6218 cases of campylobacteriosis were notified. Actual cases are likely to be about 10 times higher as only a minority who get the bug go to the doctor. The rate of infection was 135.3 per 100,000 compared with 150.4 per 100,000 in 2014.

Data published by the Institute of Environmental Science and Research show the number of disease outbreaks linked to campylobacter has increased steadily since 2009. An outbreak describes a situation where illness is linked to a common source. In 2009, 12 outbreaks (65 cases) were recorded compared with 35 outbreaks (241 cases) in 2014.

Year[width=20%]Number of cases[width=20%]
20008418
200110,145
200212,493
200314,788
200412,215
200513,836
200615,873
200712,778
20086694
20097177
20107346
20116686
20127016
20136837
20146782
20156218

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Reducing the risk

If you’re cooking chicken at home:

  • Wash and dry your hands every time chicken is handled

  • Store it on the bottom shelf of the fridge to prevent contact with other food

  • Use a separate chopping board and utensils for cutting raw chicken

  • Cook chicken meat thoroughly and cook before barbecuing

  • Don’t wash raw chicken as this helps spread campylobacter to other items such as hands, clothes, other food and contact surfaces.

Buying frozen chicken reduces the risk of infection as freezing cuts the number of campylobacter. EU research found freezing for two to three weeks reduces risk by more than 90 percent. Buying cooked chicken is also safer as the cooking process kills the bug.