Canterbury had record number of Legionnaires cases in 2010

Friday January 14, 2011

Canterbury had a record 62 cases of Legionnaires’ disease last year, 22 of which were in December alone – the highest number ever in a month.

The spike is prompting Canterbury District Health Board to heighten warnings about the dangers associated with potting mix and compost.

Canterbury Medical Officer of Health Dr Alistair Humphrey says it is a considerable increase on previous years and two thirds of the cases in 2010 were legionella longbeachae, the type associated with potting mix and compost.

December’s figures compare to eight cases of Legionnaires’ disease in Canterbury in November 2010, of which three patients required intensive care and one died. However, the exact cause of death of that patient remains unknown as there were complicating factors, Dr Humphrey says.

“Four people died altogether in 2010 from Legionnaires and while there have been no reported deaths this year, four patients were admitted to Christchurch Hospital’s intensive care unit (ICU) in December. One is still there and still quite unwell.  A total of 20 patients with Legionnaires were admitted to ICU last year,” Dr Humphrey says.

“Most of those patients spent between seven to 10 days in ICU, at a cost of about $4000 per day – excluding medication and any other treatments they may have required.”

The increase in reported cases appears to be a result of more sensitive testing that is able to detect milder cases of Legionnaires from the many cases of community acquired pneumonia that present every year.

“While we are finding more cases, it means we are also able to treat them earlier.  In the long run this should lead to a lower mortality from this disease, but it is too early to confirm this yet,” Dr Humphrey says.

Risk factors for contracting Legionnaires’ disease include being over 50 years of age and having a long-term illness – particularly lung disease, being a smoker or having low immunity. Symptoms of the disease may include dry coughing, high fever, chills, diarrhoea, shortness of breath, chest pains, headaches, excessive sweating, nausea, vomiting and abdominal pain.

Anyone with these symptoms who has been handling potting mix or compost recently should seek prompt advice from their general practice or medical centre.

However, Dr Humphrey wants to remind the public that prevention is always better than a cure.

There are five simple steps to avoid catching Legionnaires from potting mix or compost:

  1. Open potting mix bags carefully using scissors, rather than ripping them.

  2. Wear a disposable face mask and gloves and open the bag away from your face.

  3. Do your potting in a well ventilated area outside.

  4. Dampen down the potting mix or compost with a sprinkle of water to stop the bacteria from becoming airborne.

  5. Wash your hands thoroughly after handling potting mix and doing any gardening.

More facts about the number of Legionnaires cases in 2010:

  • In 2010 two thirds of all Canterbury cases were legionella longbeachae – the type associated with potting mix.

  • The ratio of male to female in 2010 has been 1:1.

  • The age range of cases has been from 23 to 91 years, with more than 80% over 50 years of age. Most had other chronic conditions, or were smokers (both risk factors for contracting Legionnaires).

  • More than 90% of the cases were of European ethnicity.

Page last reviewed: 14 February 2014
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