Firstly there is an epidemic of campylobacter in New Zealand. The rate of infection per 100,000 people in NZ is four times that of Australia and almost 10 times that of Norway and other European countries.
Secondly, the dominant source of infection is chicken.
In 2006, when the epidemic peaked, almost 1000 Kiwis were ill enough to be admitted to hospital. While New Zealand reacted very strongly to the issue, Professor Baker asked: "What is the impact - is it enough?" and "What can be learned from it and where do we go to from here?"
Before answering these questions we got some background to the infection some aspects of which were a surprise to the audience.
As most people know, it is killed easily by cooking. At normal room temperature it does not multiply but actually gradually dies away so leaving a chicken on the kitchen bench overnight, while leaving it open to other bacteria, will not increase the amount of campylobacter present.
But, because campylobacter survives refrigeration, while not recommended because it opens the meat to other infections, keeping chicken in the fridge is more of a risk than keeping it at room temperature.
The infection causes diarrhoea, cramps and fever lasting about a week. A person in good health will usually make a full recovery but each year a few elderly or very young people become seriously ill.
In a small number of cases (about 100 people per year in New Zealand) serious complications can occur. The most serious is the Guillain- Barre Syndrome (GBS).
While the cause is unknown the underlying mechanism involves an auto-immune disorder, which attacks the peripheral nervous system. This causes pain and muscle weakness, starting in the feet and hands. This weakness can spread to the muscles of the diaphragm necessitating mechanical help with breathing.
Before effective ventilator technology, the complaint was usually fatal. In most cases now a full recovery occurs although about one third of sufferers are left with some permanent weakness.
Although serious long-term effects are rare, because it is so widespread, the dollar cost to the New Zealand economy is by far the largest of any disease.
Professor Baker then looked at the sources of infection. His figures tell us that supermarket is almost certain to be carrying campylobacter. This is because of the modern chicken meat industry is almost totally mechanised. During the processing a proportion of the chicken guts rupture, which spread infection over most of the carcasses. The carcasses are cleaned using chlorinated water but total removal of the bacteria is almost impossible.
About 10 years ago the New Zealand Food Safety Authority (NZFSA) responded to the rising tide of campylobacter infection. This revolved around checking contamination levels at each stage in the meat production process and development of mandatory maximum levels in the process. The results were encouraging. Notification and hospitalisation rates (including cases of GBS) dropped by over 50 per cent in 2008 compared to the previous five years.
Interestingly, this reduction happened before the mandatory targets were implemented.
The reduction happened at the data-gathering stage. The implication is that when the industry became aware that strict regulation was on the way, it tightened up on its own practises. The economic benefit of regulation was even more dramatic. The reduction in campylobacter saved almost $60 million per year in health costs. This gives a benefit to cost ratio of more than 25. The message here was that investment in food safety compliance at the primary industry level has great benefits for the economy.
The New Zealand rate is still one of the highest in the world, so we haven't done enough.
Part of the problem is that poultry producers are externalising the cost while internalising the profit. The health costs of the epidemic are carried by the taxpayer via the health service, while the producer simply works to maximise profit.
It has been noted that campylobacter on chicken is killed by correct cooking, so what is going on that allows the infections to happen?
A common misconception is that washing raw chicken will reduce the risk of sickness. In fact the opposite is true. Washing the chicken is likely to spread the campylobacter to your hands and also work surfaces. If salads and other uncooked foods are then prepared on these contaminated surfaces the bacteria will be transmitted. Whenever I cut up raw chicken I use a wooden chopping board which I then scrub in very hot water and dry by standing it on top of the wood burner. The edges of the board can get a bit charred but it kills the bugs.
We are shocked by cases like 5500 cases of campylobacter linked to contaminated water in Havelock North to the point where a national inquiry was launched. The 33,000 case of campylobacter linked to contaminated chicken each year go under the radar because it has become so common.
Professor Baker's conclusion after studying the matter for 20 years is that, while education of consumers is important, regulation of producers is more effective.
■Frank Gibson is a semi-retired teacher of mathematics and physics who has lived in the Whanganui region since 1989.
