Cases of leptospirosis among rural people are remaining steady, despite a cattle vaccination campaign against the disease.
The potentially fatal bacterial disease is passed from livestock to people through urine, and dairy workers are among those most at risk.
An article in the New Zealand Medical Journal says the number of people suffering from the disease fell from 677 in 1979 to 179 three years later, after a cattle vaccination programme was started. But the rate has remained steady since 1997, with about 100 cases a year.
Regional Medical Officer of Health Margot McLean, one of the article's authors, said there were a number of ways to bring that figure down.
"Probably in the context of dairy farms, the most important measure is the vaccination programme for all stock and, if stock are being moved around ... that the farmer is sure of what the vaccination status is of that stock," she said.
"In terms of other ways to minimise the risk, because vaccination isn't 100 percent, it's avoiding direct contact with the urine, so being really careful around cuts, scratches and breaks in the skin, because leptospirosis can get in through skin breaks as well as through the mouth, nose and eyes."
It was important to use appropriate protective gear in the milking shed, to provide hand-washing facilities and to not eat or smoke in the shed, Dr McLean said.