Campylobacteriosis cases halved following controls on chicken meat

New Zealand's success in reducing its food borne campylobacteriosis epidemic is receiving international attention. In a paper just published in the journal, Emerging Infectious Diseases, NZ scientists report how both notified and hospitalised cases of campylobacteriosis declined by more than 50% following interventions to reduce campylobacter contamination of fresh chicken meat.

“This decline in campylobacter infection is one of the largest drops in disease incidence ever recorded for a national epidemic of this type,” says Associate Professor Michael Baker from the University of Otago, Wellington.

Campylobacteriosis rates started rising in NZ in the mid 1980s and peaked in 2006 with 15,873 notified cases. This gave NZ the highest rate reported internationally for this disease at 384 cases per 100,000 population. Rates declined rapidly in 2007 after the New Zealand Food Safety Authority and the poultry industry introduced a range of regulatory and voluntary measures aimed at reducing levels of campylobacter on fresh chicken meat.

“Following the introduction of these control measures, there were 9,000 fewer reported cases in 2008 than in 2006 and 500 fewer hospitalisations. We also estimate there are now 70,000 fewer unreported cases in the community” says lead researcher, Dr Ann Sears from the University of Otago, Wellington.

Despite the success of this control programme, NZ still has amongst the highest reported rates of campylobacteriosis in the developed world at 168 cases per 100,000 population, compared with Australia at 108 per 100,000 and the USA at 13 per 100,000. Fresh chicken meat remains the dominant source of infection in NZ.

“This is by far the largest food borne epidemic in NZ's history. It was created by producing and consuming increasing amounts of contaminated chicken meat,” says Associate Professor Michael Baker.

“We need to learn from this experience. Firstly, this success shows the importance of high quality disease surveillance, effective research, and strong regulatory agencies. We need to keep strengthening these areas,” he says.

“Secondly, investing in prevention can save NZ a fortune. Controlling this epidemic costs little compared with the estimated savings of $40 million a year from reducing rates of this disease.”

“Thirdly, we can do better. NZ initially delayed tackling this epidemic for several years, despite evidence highlighting the role of fresh chicken meat. Even now, our campylobacteriosis rates are still too high, so more work is needed. As a food-producing country we must be leaders in food safety to maintain the trust of countries we export to as well as domestic consumers.”

The package of interventions that have been successfully used in NZ to reduce chicken contamination include: setting mandatory targets for producers to reduce campylobacter contamination of chicken meat, better hygiene practices during chicken processing, and changes to the chilling processes.

“Campylobacteriosis is more serious than a minor stomach upset,” says Dr Ann Sears. “That's why it's important to bring down our high disease rates.”

Symptoms of campylobacteriosis include diarrhoea, stomach cramps, tiredness, fever, nausea and vomiting which typically last about a week. Most of those affected take time off work and school. Some have severe symptoms requiring hospital treatment and develop life threatening complications.

A multidisciplinary group of scientists contributed to this research, including researchers from the University of Otago, Wellington; Massey University, Palmerston North; ESR (Environmental Science and Research Ltd); and the NZ Food Safety Authority (now part of the Ministry of Agriculture and Forestry).

For further information, contact

Associate Professor Michael Baker
Department of Public Health
University of Otago, Wellington
Tel 64 4 918 6802
Mob 021 355 056
Email michael.baker@otago.ac.nz

Additional campylobacteriosis facts:

• Campylobacteriosis is an infection of the intestine (gut) caused by bacteria of the Campylobacter genus (Campylobacter jejuni and Campylobacter coli.)
• The incubation period is about 2-5 days after swallowing food or water contaminated with these bacteria.
• Symptoms include diarrhoea, stomach cramps, tiredness, fever, nausea and/or vomiting which typically last about a week. Most of those affected need to take time off work and school.
• Some people have severe symptoms requiring hospital treatment and some develop life-threatening complications such as invasive infections and Guillain-Barre syndrome (a form of paralysis).
• A small number of people die from campylobacteriosis and its complications. A notable example was Rod Donald, co-leader of the Green Party, who died in Nov 2005 from myocarditis (inflammation of the heart muscle) secondary to campylobacter infection.
• Campylobacteriosis is mainly food borne, with chicken meat the dominant source in NZ and many other developed countries.
• Campylobacter is easily killed by thorough cooking of food. However, heavily contaminated uncooked food can easily cross-contaminate other foods and objects such as kitchen benches and hands leading to human infection.
• Frozen chicken is considered a safer product than fresh. Freezing at the time of processing greatly reduces campylobacter contamination levels on the meat compared with chicken that is sold fresh, reducing the risk of cross-contamination.
• Campylobacteriosis was made a notifiable disease in 1980. Incidence rose steadily from the mid-1980s to a peak in 2006 with 15,873 cases (384 cases per 100,000 population).
• Campylobacteriosis has long been the most commonly notified disease in NZ, accounting for more than two-thirds (68%) of all notified disease cases in 2006.
• A large national case-control study published in 1997 reported that poultry-related exposures accounted for more than 50% of cases.
• There was increasing public health advocacy in 2006 for more rigorous controls on food borne transmission from chicken.
• In late 2006, the NZ Food Safety Authority (NZFSA) released a risk management strategy for reducing the incidence of poultry-associated food borne campylobacteriosis. Key parts of this strategy were:
• From April 2007, poultry processors were required to monitor and report campylobacter prevalence in poultry flocks and contamination levels in poultry carcases at the end of primary processing (to the NZFSA)
• From April 2008, mandatory campylobacter performance targets were introduced for all poultry processors, with escalating regulatory responses if these mandatory targets were not met, but giving flexibility about how to achieve these targets
• Compared with the pre-intervention period: The 2008 annual rate for campylobacteriosis notifications was 157 per 100,000 population, representing a 54% decline compared with the average annual rate of 354 for 2002–2006. There were 9,180 fewer notified cases in 2008 than in 2006.
• The 2008 campylobacteriosis hospitalisation rate of 7.6 per 100,000 population represented a 56% decline compared with the average rate for 2002–2006 of 17.3 per 100,000 population. There were 501 fewer hospitalised cases in 2008 than in 2006.
• Source attribution techniques based on bacterial typing of Campylobacter isolates from human cases and environmental sources demonstrated a 74% reduction in the number of cases attributed to chicken.
• There were highly significant drops in campylobacteriosis notifications in all parts of NZ and for all population groups. However, the largest drops were seen in urban populations and young adults (20–39 years).
• Following this intervention the rate of campylobacteriosis has remained at about half the pre-intervention level, with 6,694 (157 per 100,000 population) in 2008, 7,177 (166.3 per 100,000 population) in 2009 and 7,346 (168.2 per 100,000 population) in 2010. It remains the most commonly notified disease in NZ (accounting for 42% of all notifications in 2010).
• These NZ rates are however, high by international standards eg
  US (2009) – 13 per 100,000 (Source: Foodnet, based on 10 US States)
  Australia (2009) – 108 per 100,000 (Source: OzFoodNet Annual Report)

A list of Otago experts available for media comment is available elsewhere on this website.