24 Sep 2022

Why NZ remains a campylobacter capital

1:31 pm on 24 September 2022
Animation of cooked chicken

Photo: RNZ / Luke McPake

The gut infection campylobacteriosis can kill - so why is Aotearoa New Zealand still a campylobacter capital after decades spent trying to reduce rates? Is it time to take control away from the Ministry for Primary Industries and give it to public health?

In the space of three weeks Melanie Ruawai's weight plummeted by 10kg. She was suffering bouts of uncontrollable diarrhoea, along with nausea and stomach pains.

At first she told herself it was just a stomach bug she needed to ride out. For a week she survived on water and Powerade, but every time she drank, her stomach ached.

"I wasn't eating anything because I knew there was something wrong," she says.

Ruawai uses a wheelchair and to help manage her symptoms she took medication to reduce the diarrhoea. But she still wasn't getting any better.

After eight days of suffering, a doctor's visit revealed the problem: campylobacteriosis, a gut infection caused by bacteria from the genus Campylobacter, transmitted to humans from animals or animal products.

By then, Ruawai was exhausted. "They did actually want to send me to the hospital at one stage," she says.

She takes blood thinner for a heart condition, which made her case even more dangerous. "The doctor said to me, 'You realise that if you damage your bowel because you're having this problem, you could bleed to death'."

After a course of antibiotics Ruawai's health improved and slowly she began to eat again.

She's one of more than 2500 people who have been diagnosed with campylobacteriosis this year - and she's one of the lucky ones. She avoided hospital, and hasn't experienced secondary issues.

Campylobacter is the most commonly reported cause of foodborne illness in New Zealand, and it can kill. The bacteria hitches a ride into your system via water, food, drink, animals or other people. Bore water contaminated with sheep faeces caused New Zealand's most notorious outbreak in Havelock North in 2016. That crisis infected 8320 people, hospitalised 58 ,and contributed to four deaths.

Others were left permanently disabled; if you survive the infection, you can be left with paralysis and secondary conditions. Former Green Party co-leader Rod Donald died of a heart condition at the age of 49, brought on by a campylobacter infection from a "probably unknowable source", according to the coroner.

Ruawai suspects the source of her infection was chicken. "Only a very, very tiny bit, but obviously, it was enough to make me ill."

Chances are, she's right. The 'whodunnit' for an estimated 84 percent of New Zealand's campylobacteriosis cases is poultry. Despite chicken being a staple in many countries' cuisines, our campylobacteriosis rate is one of the highest in the developed world. If you exclude Covid-19 and sexually transmitted diseases, campylobacter is our biggest notifiable disease, accounting for 47 percent of reported disease.

"At one stage, New Zealand was known as the Campylobacter Capital of the World," says University of Otago epidemiologist professor Michael Baker.

Officially, 5000 to 7000 cases are reported every year, but Baker says that is likely to be only the tip of the iceberg. Only a minority of affected people will visit a doctor and provide a stool sample for testing. Using results from research conducted in the United Kingdom which looked at how often people with campylobacter go to a doctor, he's estimated chicken causes closer to 54,000 cases a year in New Zealand.

"It's the most dangerous food we're regularly taking into our homes," says Baker.

But our laws seem lax in the face of these overwhelming figures. There's no requirement to pre-test flocks before slaughter. There's no law to stop supermarkets selling infected meat to consumers, as it's intended to be cooked before being consumed. Of the 120 million chickens processed every year only a few thousand are tested at the processing stage; every week, our 15 processors test only 15 carcasses each.

Those test results take days to come back; and when the bacteria limits are breached, it's too late to halt the production line and recall chicken processed during that time period. That means chicken meat riddled with campylobacter regularly makes it into our shops and kitchens.

And it will be happening far more often than we might think. Consumer magazine's 2016 survey of 40 chickens purchased from retail outlets found 65 percent tested positive for campylobacter.

Once in your kitchen the bacteria from infected chicken can transfer onto your hands, chopping board, utensils, bench, dish cloths, and kitchen taps and potentially end up ingested. If you don't cook the chicken thoroughly, the bacteria has an expressway into your digestive system, where if it survives your stomach juices it can move to your small intestine and wreak havoc. Telltale symptoms can include nausea, fever, and diarrhoea, which is sometimes bloody.

Baker says higher bacteria loads normally mean a higher chance of getting sick, but if you're unlucky even a single bacterium could be enough to result in days of discomfort and dashing to the toilet.

Michael Baker

Professor Michael Baker Photo: Supplied / Composite Image - Luke McPake

Baker puts the campylobacteriosis cost to the country at $56 million a year. But it's consumers, employers and government-funded health services who foot the bill, not the poultry industry.

Our campylobacteriosis rate has dropped significantly since we earned the nickname Campylobacter Capital of the World in 2006, and infection rates have been largely stagnant since then. However, Baker says increasing hospitalisation rates could indicate infection rates are actually rising.

Food safety regulation lies with New Zealand Food Safety, which is a business unit of the Ministry for Primary Industries (MPI), not a public health agency. Baker suggests it's a conflict of interest to put food safety in the lap of the body focused on the prosperity of primary industries.

"I think the sooner that regulatory function can be taken out of MPI the better."

He's keen for a public inquiry into the topic, pointing out there was a public inquiry into the campylobacter outbreak in Havelock North. "With one food source resulting in far more campylobacter cases in New Zealand, why are we not putting the same energy into looking at that?"

Efforts are being made to reduce cases. MPI wants a 20 percent reduction in foodborne cases by the end of 2024, to bring our foodborne rate down from 88 to 70 cases for every 100,000 people.

New limits for the number of chicken carcasses allowed with campylobacter were introduced in July 2021. The new rules set a limit on how many infected samples there can be in a three-week moving window during processing. Out of 45 samples, two are allowed levels above 6000 coliform forming units (cfu) and 10 above 200 cfu.

But is this just window-dressing?

"At the moment, this food is so heavily contaminated and it's so hard for consumers to actually get rid of that bacteria from the food given that it's in almost all fresh poultry meat that's sold," Baker says. "I think it'd be unlikely to actually make a huge difference by just slightly adjusting the level."

CFU levels for chicken

Photo: RNZ

So why, after more than a decade of regulation, is New Zealand still struggling to get case numbers down?

"We've thought about this quite a lot," says Massey University epidemiologist professor Nigel French. He specialises in infectious disease epidemiology and thinks our high case numbers are due to a combination of reasons.

"One of the obvious ones is that we are great consumers of fresh poultry. Our poultry consumption is really high compared to many other countries."

We're also eating most of it fresh, not frozen. Freezing the meat can kill off large numbers of campylobacter before it hits a frying pan.

French also thinks there's a chance we're assiduous reporters and are reporting cases more than people overseas do.

Our chickens aren't more germ-ridden than their international counterparts, but he does say we have some strains of campylobacter which don't tend to be found in other countries. "It may be that we also have some strains that are particularly nasty compared to other parts of the world."

Finally, he says the way we're processing our chicken could play a part in why our rates are higher than other countries. In the US, which has a case rate of 19 per 100,000 people compared to New Zealand's 100+, chicken carcasses are cooled by air after they've been eviscerated. In New Zealand they're normally cooled in water. "Sometimes the water bath can itself can act as a source of cross-contamination," says French.

Eradication - like what has nearly been achieved with cattle-infecting bacteria Mycoplasma bovis - is extremely unlikely. It's not that campylobacter bacteria are the hardy cockroaches of the bacteria world; French says it is actually quite a weak organism, easily impacted by air, temperature, or UV light. The challenge is the size, spread and invisibility of the campylobacter army. A healthy-looking chicken can carry up to 100 million campylobacter per gram of faeces.

Culling every chicken in the country and burning sheds to the ground to rebuild from scratch isn't a solution. The bacteria exists in many creatures including, pūkeko, seagulls, starlings, cattle and sheep. Even flies caught in chicken sheds have shown traces of campylobacter, French says, suggesting there's a good chance they're able to transmit it.

Institute of Environmental Science and Research (ESR) senior scientist Dr Joanne Kingsbury has looked at where the most impact can be made in the poultry chain from farm, to processor, to supermarket, to kitchen.

Its most recent work has used genome sequencing to find out how the bacteria spreads, similar to how Covid-19 clusters have been tracked to source cases.

Chickens don't carry campylobacter in the egg, says Kingsbury; it gets introduced to them after hatching. Much like a vegetable garden, industrially-farmed chicken flocks are 'thinned' as they grow. This involves chicken catchers coming into the shed to catch a proportion of the flock, which are sent for processing. Kingsbury says ESR found campylobacter in flocks after the catchers had removed chickens, which could indicate their clothing or equipment carried the bacteria into the shed.

Once a few birds are infected, the bacteria spreads to the entire flock.

The next step in the chain is the processors. If the removal of the gut and internal organs isn't done carefully, campylobacter bacteria from the gut can hitch a ride to the flesh. Because of the huge numbers of chickens processed, a machine does the eviscerating.

ESR studied three of New Zealand's 15 processing plants,including one it had previously studied in 2013.

The work pinpointed campylobacter levels at different points of the processing chain.

"The birds were coming into primary processing with something like an average of 10 million campylobacter cells per carcass," Kingsbury says. By the end of the processing chain campylobacter levels on the birds were so low it was sometimes hard to detect. "They had less than 30 surviving cells remaining on the carcasses."

The levels of campylobacter on birds entering processing plants was the same in both the 2013 study and the 2021 study.

"But in the 2021 study, there was something like 10 to 100 times less campylobacter on the carcasses at the end of processing"

She thinks new evisceration machines and new or improved spray washers may have helped reduce campylobacter. The biggest change, though, probably comes from the spin chiller, the penultimate step in the processing chain.

"It's a chlorine water bath and the birds are in there for quite a long period of time and that's where we see the biggest drop off of campylobacter numbers."

She puts the change down to improved management of pH and chlorine levels.

New Zealand's poultry industry body is PIANZ. Its executive director, Michael Brooks, says when it comes to reducing campylobacter transmission, focusing on processing plants makes sense, with only 15 plants in the country compared to about 140 farms.

He says there is already a high degree of oversight.

"Every plant is benchmarked every month and that information is provided to every other plant. So everyone in the industry knows how everyone else is doing."

PIANZ has proposed that the work ESR has done with the three plants, pinpointing campylobacter levels at different points in poultry processing, should be applied to all plants.

That would mean creating an industry-wide quality benchmark for each step in the processing plants, so each can track and address infection rates.

Is MPI tough enough?

New Zealand Food Safety, the arm of MPI, is responsible for setting, monitoring, and enforcing our food safety rules. Deputy director general Vincent Arbuckle is quick to acknowledge there's an issue with our campylobacter rates.

"They're not where anyone would want them to be yet," he says.

But he adds that zero risk isn't feasible.

"No country in the world would even try and eliminate campylobacter in the environment."

The agency is focused on reducing human infection rates, but there's no long-term goal beyond that target to drop cases to 70 per 100,000 people by 2024. The most recent estimate from 2020 was 77 per 100,000, but this is thought to be lower than usual due to Covid-19 restrictions.

"We're stepping down stage-by-stage in the strategy, and we're seeing what's achievable," he says.

There's no doubt infected chicken meat makes its way into supermarkets, with our 15 processors testing just 225 carcasses a week between them out of more than 2 million that are likely processed every week.

The testing strategy is aimed at picking up issues in the processing chain, not testing each chicken before letting it out the factory doors - something Arbuckle says isn't practical or possible.

"There will be a level of risk in chicken that's in the market, because it's not possible to eliminate that risk totally," he says.

But is the agency tough enough when test results show there's a problem?

"I think we are, relative to the issue itself," says Arbuckle.

2021 saw a sharp upturn in non-compliant events, where samples exceeded campylobacter limits for three consecutive weeks, although it was noted stricter rules kicked in midway through the year.

MPI doesn't apply sanctions regularly, and its most extreme sanction, closing a processor down, has never happened.

Since 2010 MPI has only intervened four times when processing plants exceeded campylobacter limits. The interventions consisted of site visits and recommendations. One processing plant which breached limits eight weeks last year never received a visit, although Arbuckle says the agency was in close contact with the company.

No non-compliance visits have been conducted since 2017.

"Going in heavy-handed and shutting places down ultimately doesn't produce a better outcome and quite possibly would end up in a lack of cooperation and possibly even a lack of willingness to disclose issues," he says. Companies have cleaned up their act without the need for New Zealand Food Safety to use the enforcement powers it has, he says.

The names of the processing plants which breach the limits aren't made public. RNZ's Official Information Act request for the information was denied on the grounds it would "unreasonably prejudice the commercial position" of the companies.

In the United Kingdom, it's a different story. Naming and shaming is part of the strategy to reduce rates.

There, testing is done at a retailer level and retailers have to publish results. Shoppers can see whether chicken sold at Tesco, Aldi, Sainsbury's or one of the six other major chains is meeting targets set by the UK Food Standards Authority in its attempt to tackle campylobacter.

Arbuckle says New Zealand Food Safety has previously surveyed contamination levels at supermarkets but decided retail outlets aren't the best place to control campylobacter. Tests during processing provide information which can be acted on to reduce levels.

Adding another layer of costly testing at supermarkets could hit shoppers in the pocket, he says.

So for New Zealand consumers, it's a case of buyer beware and handle with care. The percentage of positive results from chickens tested during processing has reduced since the days when we were nicknamed the Campylobacter Capital of the World. But they're not at zero. The last link in the chain from infected chicken to illness is often the measures taken in kitchens.

"Consumers are part of the control system for campylobacter because it's not feasible to guarantee to consumers, and no producer does, that there is a zero risk with poultry," says Arbuckle.

PIANZ's Michael Brooks has a simple message for people at home. "If I had one phrase to say, I would say wash your hands, not your chickens. We are surprised by the number of people who wash chicken and that's just the wrong thing to do," says Brooks.

Both Arbuckle and Brooks mention consumer education so would either be in favour of health warnings on the packaging, like what's on cigarette or alcohol products?

"I would certainly be in favour of saying things like 'Do not wash your chicken'," says Brooks.

Arbuckle isn't opposed to labels. "If it really did make a big difference or we could prove through some sort of research that it would, we'd be open to it."

Labelling is something Professor Michael Baker has researched. Shoppers outside supermarkets were quizzed about chicken-handling rules, almost half didn't know washing chicken could splash bacteria around the kitchen. They were also asked how important safety labelling is, with more than half saying a large, brightly coloured warning label was 'very necessary' or 'essential'.

Baker shared the results with MPI.

"Absolutely nothing happened," he says.

"I found that was very disappointing. I think that's just another reason why we need to shift regulation of food safety in New Zealand, take it out of the food producers' hands and put it into an agency that's concerned with public health. I think the regulators have sat on their hands for decades over this."

But Arbuckle says there's a benefit in foodborne illnesses having their own watchdog like New Zealand Food Safety, as it means one agency has a "laser focus" on the issue.

"The risk of transferring responsibility to the Ministry of Health is that they are also grappling with a large number of other public health issues, still coming out of Covid-19," he says. "I guess the risk might be that it has to be prioritised against a range of other public health issues."

He says a public inquiry into our campylobacter rates wouldn't uncover much which isn't already known. "It's very transparent. The problem has been well known, there's been a very public strategy, information is publicly available.

"We have the best of minds on it, and will continue to. So I think that's the best form of public inquiry you can get."

PIANZ's Michael Brooks doesn't have an opinion on whether regulation should be shifted to a public health body, saying it's not a question for the industry. He says the industry already funds "hundreds of thousands'' of dollars of scientific research in an effort to reduce campylobacter rates.

Professor Nigel French gives another view, noting the fractured nature of regulation. "We have a situation where if it's food, it's MPI's domain and where it's water, for example, it's an issue of health domain." He believes better collaboration between agencies is needed.

A Ministry of Health spokesperson says the Ministry already works closely with New Zealand Food Safety and shifting responsibility isn't included in the current health reforms. A decision to shift it in the future would fall to government ministers.

Food Safety Minister Meka Whaitiri says more work needs to be done to reduce campylobacter rates, but thinks a public inquiry wouldn't provide any useful information.

She's happy with the responsibility for food safety falling under MPI, saying New Zealand Food Safety "sits at the intersection of food production throughout the supply chain which enables it to best identify and manage potential food safety issues".

"I consider New Zealand Food Safety to be the best-placed agency to manage food safety."

In July 2022, the latest figures available, 357 people were infected with campylobacteriosis compared with 340 in July 2021.