Flesh-eating bug cases treble in NZ hospitals

Scars left after a flesh-eating infection. File photo / Herald on Sunday

The number of patients in New Zealand hospitals attacked by "flesh-eating" bugs has trebled since 1990.

The three-fold increase of necrotising fasciitis in New Zealand since 1990 has been revealed to scientists at the annual UK Health Protection Agency conference in Warwick, England by Dilip Das, of the Hutt Valley district health board.

Dr Das and other Wellington researchers last year published a research paper on necrotising fasciitis and cellulitis as emerging health problems in New Zealand, which was published in the International Journal of Infectious Diseases.

This week he told the British conference that the specific factors behind the rise in the number of NZ cases were not yet known, but the researchers had ruled out changes made in 2004 to the way diseases were recorded.

The rare infection occurs in the deeper layers of skin and is typically caused by many types of bacteria entering an open wound, especially after major surgery.

While commonly known as a "flesh-eating bug", the bacteria don't actually consume the tissue, but instead destroy skin and muscle by releasing toxins.

Patients usually complain of intense pain around the infection and as the disease spreads, skin will change to a violet colour before turning black when it dies.

Cutting away infected flesh and tissue is almost always necessary to stop it from spreading, and if left untreated, the mortality rate of the infection is 73 per cent.

In Britain, an inquest was this week told a Devon shop manager, Richard Johnson, 54, who was given painkillers for arthritis died within four hours of arriving at hospital with leg pains.

When it was realised that he had the infection necrotising fasciitis surgeons amputated his left leg in a bid to save him but watched in horror as black areas spread to his abdomen while they were operating, an inquest heard.

To see how disease patterns have changed in New Zealand, Dr Das' team looked at the number of patients diagnosed with necrotising fasciitis and found the average annual incidence rate of the disease increased from 0.4 (patients) per 100,000 people in 1990-1994 to 1.33 per 100,000 people in 1995-1999.

The incidence rose further still to 1.97 per 100,000 in 2000-2006.

Over the same periods, the number of people dying from the infection also rose: "The average annual mortality rate rose significantly from 0.05 (people) per 100,000 in 1990-1994 to 0.43 per 100,000 in 2000-2006," they said.