Early promise in NZ's fight against Campylobacter

New Zealand has been acknowledged for some time as having among the highest recorded cases of campylobacteriosis in the developed world. Although the reasons for the high rates are unclear, the country is implementing risk management strategies in its battle against Campylobacter - and the distressing illness, campylobacteriosis, it causes.

"New Zealand's work in the fight against Campylobacter in poultry is being watched with interest around the world, and while we certainly can't say the problem has been solved, we're pleased the way things are going," says New Zealand Food Safety Authority (NZFSA) executive director Dr Andrew McKenzie.

"There are many hypotheses and more than one may have elements of fact. It has been said that we might have a higher rate of reporting, that we have more Campylobacter in the water and soil because we're an agricultural nation, that flies here carry it, that New Zealanders are poorer at hygiene, that we have more virulent strains of Campylobacter, and so on. We're not sure if any of these is the answer. What we do know for certain is that the organism is part of the natural gut bacteria of many birds, and so poultry often carries it. The NZFSA Campylobacter risk management strategy - which we're working through in partnership with the poultry industry - is addressing this area of certainty with the goal of reducing the numbers of Campylobacter found on chicken."

An internationally recognised problem

The complex nature of the problem is internationally recognised. Late last year a Joint World Health Organization/Food and Agriculture Organization (FAO/WHO) Codex Alimentarius Commission group was set up to look into the issue. New Zealand was asked to lead, in cooperation with Sweden, the development of a new international 'Code of Hygienic Practice for Salmonella and Campylobacter in Young Chickens (Broilers) and Chicken Meat'. About 30 countries and international organisations have volunteered to be part of the working group which has just met for the first time in Uppsala, Sweden, to work out a plan of attack for development of the Code.

Reducing bacteria loads early in the food chain

Dr McKenzie says that the despite the internationally recognised complex nature of the problem, the NZFSA strategy is showing some areas of early promise, but reiterates that there is still some way to go.

"We have said all along that there is no 'silver bullet' answer and our research, as well as international experience, is bearing this out. Work is being done on possible effective interventions at all steps along the farm-to-fork food chain. NZFSA's approach is in line with that being taken internationally to address the problem of the presence of Campylobacter in poultry, as confirmed during the first meeting of the international working group. This approach aims to produce the greatest reductions in bacteria numbers as early as possible in the food chain, as well as making further reductions at as many other points along the chain as are also practical and effective".

"A data collection process for monitoring of the prevalence of Campylobacter in flocks and on carcasses is in place and is giving us a robust base to measure the effectiveness of the real-world interventions that are made. Without this, it's impossible to determine what works effectively in a commercial environment".

"Work on international industry best practice on farms and in processing is coming along well, with these practices identified and determination of their actual application and effectiveness in the New Zealand context underway. Codes of practice that describe appropriate control measures within these two parts of the food chain have been drafted and are currently being reviewed and finalised. This work has confirmed that there is no single intervention that will completely address Campylobacter and that multiple control measures need to be applied throughout the food chain to minimise the levels of this bacteria in raw poultry."

Freezing helps reduce bacteria numbers

"A study, into the effectiveness of domestic freezing of poultry has been commissioned by NZFSA and is being carried out by Environmental Science & Research (ESR)," said Dr McKenzie. "It confirms that freezing reduces the numbers of Campylobacter that survive, but does not eliminate the problem and the magnitude of this effect appears to depend on the duration of frozen storage. In addition, there appears to be a difference between the two Campylobacter strains that are being investigated. Although this experiment has not been completed, further work is planned to confirm these findings and investigate the effect on other strains."

What is the source?

"Another piece of the puzzle that's been largely speculative until now is determining the actual (rather than suspected) source of infection. NZFSA, Massey University and MidCentral Health's work in enhancing surveillance involves an intensive analysis of current cases in the Manawatu, as soon after diagnosis of illness in people as possible. This will allow determination of the precise source that is likely to have been the cause of the foodborne illness, for example, food, drinking water, animal contact and so on. In light of preliminary poultry findings, the work is being extended to confirm that these apply elsewhere in New Zealand," said Dr McKenzie.

Cross contamination from raw poultry to other foods during processing by the retail sector has also been investigated. Food safety practices are generally pretty good but some improvements could be made, especially to better separation (by physical barriers, distance, time or use of dedicated equipment) of areas used for processing of poultry and areas used for other foods. NZFSA and the Retail Meats Association are discussing the best way to get improvements in this area.

Poultry packaging is another area of interest.

"Evaluating packaging is important, and there are some questions that need to be answered that at first thought seem obvious," said Dr McKenzie. "One example is leak-proof packaging. It may prevent the spread of Campylobacter through dripping, but does it also mean you'll be taking more of the organism into your kitchen? Can decontamination of external surfaces of packages make a difference? What sort of handling requirements need to be in place during packaging and, once the product is in the kitchen, what needs to be done so that it's unwrapped without spreading the bug? What is the level and impact of cross-contamination during handling in consumer environments?"

"All these questions have been asked and studies are in place to get the answers. There's no point making changes if the change doesn't solve the problem, and we certainly won't be thanked if it doesn't work - but adds cost for the consumer".

"That's why a key part of evaluating the outcomes of all this work is determining the likely relative effect of different interventions, under a given set of conditions. We have the first version of an internationally peer-reviewed risk model that will allow us to do that".

"Because Campylobacter is a natural part of the gut bacteria of poultry, we know we won't reduce the number of bacteria on all poultry meat to zero all the time. For this reason, consumer information will always be a key element of poultry food safety, just as it is with many other foods."