Leptospirosis widespread, say researchers

DYNAMIC DISEASE: Senior researcher Julie Collins-Emerson says they are seeing some strains of leptospirosis more often now.
DYNAMIC DISEASE: Senior researcher Julie Collins-Emerson says they are seeing some strains of leptospirosis more often now.

Doctors can be slow to recognise the disease leptospirosis, especially those in cities, although doctors working near meat plants have more awareness, say Massey University researchers.

But infection was widespread, particularly from farm animals, and catching the disease early lessened its long-term impact, they said.

The internationally recognised team of four, made up of doctors Julie Collins-Emerson and Jackie Benschop, and professors Cord Heuer and Peter Wilson, at Massey University's Institute of Veterinary, Animal and Biomedical Sciences are world research leaders in leptospirosis disease and diagnosis in both animals and humans.

They all had specialty areas, which made them a strong group, said Benschop, a Massey University senior lecturer in veterinary public health.

Leptospirosis had been known to infect dairy cows, and while most herds were vaccinated against the disease, they could still have it and be shedding the organism, the team found.

This was a result of the way the vaccine was being used, not the effectiveness of the vaccine, which was very good, the team said.

And it was more common in sheep flocks and beef and deer herds than people thought, and even some farm dogs had the disease, they found.

It was more prevalent in New Zealand animals and people than in many European countries, and it needed to be dealt with, Benschop said.

Senior research officer Collins-Emerson said leptospirosis was thought of as a dairy farmer disease in the 1970s.

"I know dairy farmers are dealing with cows twice a day, and sheep farmers [have contact with sheep] far less often. However, leptospirosis is common in other species like deer and therefore these also pose a risk.

"In addition, leptospirosis is a dynamic disease and we are seeing some strains of the disease more often now."

Benschop said the disease caused severe "flu-like" symptoms in people and was often under-diagnosed.

They have trialled the use of a new diagnostic tool, and while more expensive, it can be used earlier than the current two-test regime.

ACC will pay if it comes back as a positive. She said it could be difficult to provide proof for ACC to accept a claim for the disease.

"Five years ago, we saw about half and half farmers and meatworkers with the disease. Now we're seeing a higher proportion of farmers with it," Benschop said.

The team said people could catch the disease through urine getting into cuts or through mucus membranes such as eyes, nose and mouth.

"It is easy to have a drink from a mug in the cowshed, and you might have a cold-sore that can let the infection into the system."

Heuer said if leptospirosis wasn't diagnosed, the bugs could stay in the body for an extended period and the disease could flare up again.

He said only some people got ill, others (about 80 per cent) had antibodies to the disease but had no symptoms.

Heuer said those notified with the disease "were only the tip of the iceberg. The average for people who have symptoms is four days off work and so for some it is much longer".

He said a pilot study had shown one-third of dairy herds which had received long-term vaccinations against leptospirosis had the disease and of those, 13 per cent of cows were shedding leptospirosis organisms in their urine. This was a result of sub-optimum vaccination procedures, not the vaccines, which were effective if used properly.

"It means people who think they are safe, are not. It is extremely alarming when workers think the herd has been vaccinated and is free of the disease. That may not be the case."

About 90 per cent of dairy herds are vaccinated.

Collins-Emerson said farmers were becoming more aware of the disease, but only 1 per cent of sheep flocks and 10 per cent of beef and deer herds were vaccinated.

Research had highlighted the prevalence of the disease and Heuer said almost every second ewe and beef cow or deer showed evidence of a prior infection and one in four were shedding the organism.

Collins-Emerson said while dry stock were handled less than dairy cows, truck drivers and meat workers should be aware of the disease in sheep.

Wilson said that in deer, the disease had been shown to significantly reduce growth rates and weaning rates. That could also be the case in sheep as well as dairy and beef cattle.

He said while awareness had been improving, action was slower, with too few farmers not reaping the rewards from vaccination.

Wilson said two-thirds of farmers would get an economic response, from vaccinations. (Vaccinations would cost less than the financial gains made from weight gain and higher weaning percentages from animals.)

Dealing with the disease and its impact on people and stock was a wake-up call for the farming industry, they said.

The Marlborough Express