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.

Men of Maori or Pacific origin, and in older age groups were at higher risk of the disease.

Dr Das said further research was needed to investigate the causes of the necrotising fasciitis.

In 2002, New Zealand doctors were been told to be careful when using a common painkiller when treating children with chickenpox - because of a link to the flesh-eating disease.

The drug, sold under brand-names including Nurofen, is in a group of non-steroidal anti-inflammatories (NSAIDs)-- which includes Voltaren - all of which have been linked to the disease.

Starship children's hospital paediatrician Dr Lesley Voss urged doctors on the Ministry of Health website to be cautious when using ibuprofen in chickenpox.

About the same time, other researchers made a separate assessment of 48 patients at Middlemore Hospital in South Auckland between 1997-2002, madeup of 27 men and 21 women whose age ranged from 19 to 80 years.

Maori and Pacific Islanders accounted for 64 per cent of the patients, despite making up only 31 per cent of the hospital population.

Streptococcus pyogenes was isolated in 54 per cent of patients, and a third of the patients had multipal microbial infections.

In 62 per cent of the cases the disease hit arms or legs, and the overall mortality rate was 29 per cent.

Independently, three Middlemore Hospital doctors have published a study in the latest New Zealand Medical Journal on necrotising fasciitis.

"The mechanism by which NSAIDs increase the risk of [the disease] may be by impairment of the immune response, or by masking of the symptoms of secondary infection, leading to delayed diagnosis and treatment," said Dr Voss.

- NZPA