Leptospirosis: global disease, local phenomenon

Incidence of leptospirosis in meat workers has been trending downwards for the past eight years since 2004, but there is still no room for complacency.

Leptospirosis is a bacterial disease present around the world. It is spread by bacteria in the urine of infected mammals – predominantly rats overseas – and can cause fatal illness in humans, starting with flu-like symptoms that can progress to kidney and/or liver failure. However, New Zealand is unique in that it is predominantly an occupationally-acquired disease. Meat and farm workers and veterinarians, who all work closely with mammals, are particularly at risk.

Massey University researchers in the Institute of Veterinary, Animal and Biomedical Sciences (IVABS) Department recently presented results from their work in different areas of the disease in animals and humans to a meeting in Wellington. The Farmers Leptospirosis Action Group (FLAG) meeting was organised by Rural Women New Zealand, which has been actively fund-raising for research by the Massey team over the past 30 years.

PhD student Juan Sanhueza, from Chile, presented figures illustrating that meat workers and farm workers accounted for 82 percent of the 113 notified cases of leptospirosis in 2012, Of those, the majority were farm workers. The chart also showed that there had been a rapid fall in notifications among meat workers since a peak in 2004.

Research involving the meat industry had identified that the main risk areas for urine splashes were early in the slaughter chain – principally in the yards, slaughterboard and dressing areas. Addressing of effective protection methods and raising awareness of the disease with workers had all contributed to the decline in cases, he said. The industry’s new health and safety guidelines include advice on protection from leptospirosis.

However, the disease can also be carried ‘silently’ without symptoms, a study showed. Sanhueza presented a chart showing sero-prevalance, demonstrating that meat workers had been exposed to the bacteria at some point as they had antibodies in their blood. Sixty two out of 567 (10.9 percent) workers tested in eight plants around the country last year were found to be sero-positive to two of the most common varieties in New Zealand, Hardjo or Pomona. This compares to 4.7 percent of a tested group of working veterinarians and 4.1 percent of farm workers seropositive to the Harjo, Pomona or Ballum varieties.

With an estimated under-reporting rate of 43 times in the general New Zealand population, better education of workers and general practitioners is required, the researchers have concluded.

The Massey team also presented recent research showing how the disease is affecting farmers, dogs and livestock on-farm; the production effects in sheep and beef cattle; and diagnostic tests for acute animal disease.

The Meat Industry Association, meat processors, Meat Workers Union and Deer Industry New Zealand were thanked for their contributions to the research.

For more information, visit www.leptospirosis.org.nz

This article has appeared in Food NZ magazine (December/January 2013) and is reproduced here with permission.

Be the first to comment

Leave a Reply