Dr Nigel French, Massey University professor of food safety and veterinary health, told delegates at the New Zealand Milk Quality conference the risks of wider disease outbreak would only grow as raw milk’s popularity grew among a largely urban consumer base.
NZ research shows 65% of dairy farming families consume raw milk, in sharp contrast to the 3% average across all of NZ. The risk of urban consumers becoming ill from diseases including campylobacter was greater due to the growing interest by that sector in consuming it, and the lower level of acquired immunity within urban populations to such diseases, he said.
“Even with the best hygiene practice it is impossible to produce raw milk free from bacterial contamination, it is an inevitable consequence of the milking process.”
This had been highlighted recently by two significant disease outbreaks in South Canterbury, traced back to raw milk consumption.
Pathogens present in the raw milk included campylobacter, salmonella, listeria and E. coli. French said given the prevalence of pathogen-positive herds it was unsurprising there were many outbreaks around the world resulting from raw milk ingestion.
Since 2006 Environmental Science Research (ESR) had recorded 21 clusters of disease outbreaks of infection where raw milk was identified as a risk factor, against none for pasteurised milk.
The most recent campylobacter incident, recorded near Timaru, resulted in some campylobacter illnesses, and had been from a raw milk vending farm.
French said bi-monthly testing for campylobacter conducted by the farm was not sensitive enough to detect and manage the risk of infection. A later infection from raw milk consumed by children on a school trip to a farm resulted in two children being hospitalised.
Despite claims raw milk could help with ailments including skin allergies and asthma, he said the evidence remained inconclusive. He cited articles from the esteemed Pediatrics journal that noted any claims about therapeutic benefits were still anecdotally rather than scientifically based.
There had been few studies on the on-going benefits of raw milk consumption into adulthood, or if consumption in adulthood led to on-going protection.
Earlier this year the South Canterbury medical officer of health, Dr Daniel Williams, said it would be only a matter of time before someone died consuming raw milk, as the popularity of its consumption rose. His region holds the unenviable record for having the country’s highest level of campylobacter infections, with ESR data indicating a campylobacter infection rate of 321 per 100,000 people.
The E coli o157:H7 strain that affected the children drinking raw milk in South Canterbury earlier this year can cause illness ranging from mild diarrhoea to a form of kidney failure that requires dialysis, and occurs in 15% of cases. In the United States the main cause of kidney failure in children is linked to E coli o157:H7 infection.
World Health Organisation data indicates a mortality rate of 3-5%.
NZ records 100-150 cases of the infection a year, typically in children under five who come into contact with farm animals. Last year was significantly up however, with 207 cases reported.
French said the real-life stories available on the web about the effect of debilitating E coli infections on children were sobering reminders about the possible consequences of raw milk consumption.
“It is essential that if this practice is allowed to continue in NZ, those choosing to drink raw milk, and those who sell or provide it to others, are fully aware of the ‘high stakes’, and information for consumers, both for and against this practice, is provided in an appropriate way.”
Submissions to the Ministry for Primary Industries on raw milk retail regulations closed on July 8.
