A Tasman District Council environmental scientist who contracted leptospirosis says it was a "freak" event.

Trevor James believes he picked up the disease after getting a blob of mud in his mouth while installing sediment plates in the Waimea Estuary near Nelson.

Leptospirosis is caused by bacteria that can attack organs, causing liver or kidney damage. The disease has to be notified to Public Health.

The Ministry of Health says sources of infection can include contact with animals or with soil and water contaminated by animals. Most cases in New Zealand have been associated with meat processing or farms.

James was on the first day of a two-week holiday with his family in Australia when he got a fever and thought it was flu.

"I had a bit of a remission but then on the fifth day, whammo - I had a temperature, fever, and a massive headache."

He was admitted to hospital, where doctors thought he might have a recurrence of malaria, but tests came back negative.

James was given morphine for the extremely painful headache, and antibiotics to counter what the doctors thought might be typhus or leptospirosis.

James spent six days in hospital, an experience he described as intense and surreal, and was discharged two days before the end of his holiday.

Back at the council, he worked half-days for the first week, but is now working fulltime again.

About 20 per cent of James' job involves working in waterways. He said that he was unconcerned about doing so.

James emailed colleagues around the country who work in coastal environments, as well as freshwater scientists, and found that only one had contracted leptospirosis - a compliance officer who inspected dairy cows in the Bay of Plenty five years ago.

"There have been some other cases of other illnesses, but even those are few and far between. In Manawatu, the risk would be higher, but I still think our region is low-risk."

James, who has fully recovered, was to have another blood test today. From that, doctors were likely to be able to identify which animal the disease came from.

"If it's pigs or dairy, we will try to go up the catchment and look at what's there. I suspect it might be difficult," he said.

If it was from rats or mice, there was not much that could be done, he said.

Nelson Medical Officer of Health Dr Jill Sherwood said it was one of two leptospirosis cases being investigated.

There had been two other confirmed cases this year - one in a shepherd and the other in a sheep, cattle and deer farmer, both in Tasman district.

She said a person had to be exposed to animal urine to become infected, usually through the nose, mouth or open cuts.

The disease was not passed from person to person, and in James' case there was no risk to the public, she said.

- © Fairfax NZ News