New Zealand is officially in the grip of a salmonella epidemic, with a record number of cases being reported.
Greg Simmons from Auckland District Health Board says the salmonella epidemic is due to a new strain, STM 160, which killed large numbers of sparrows last winter.
Doctor Simmons says research on 117 cases could not identify any especially risky foods, and it appears the bacteria are spreading from infected people, untreated drinking water and wild birds.
He says the epidemic is likely to last two to three years.
The Ministry of Health says the figures seem to reflect a genuine rise in the number of people getting sick - not just the number of general practitioners telling the authorities about it.
Health authorities are repeating warnings to beware of wild birds in the wake of the record high levels of salmonella.
Common symptoms of salmonella include vomiting and diarrhoea, which strike within hours of infection.
Campylobacter is similar, although the symptoms take two to five days to emerge.
The Australia New Zealand Food Authority says food poisoning is notoriously under-reported, with estimates of the real number as high as one in five people infected each year.