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Case of flesh-eating fly triggers warning to public on hygiene

Martin Wong

Wounds and orifices of elderly or ill prone to infestation by larvae

The public were urged to guard against flesh-eating flies last night after confirmation of an attack on a 78-year-old woman living in a home for the elderly in Sha Tin.

The woman is now in a stable condition, according to the Centre for Health Protection of the Department of Health.

The centre said she became infested with the larvae of Chrysomya bezziana, also known as the screw-worm fly, inside the home in early January. Her symptoms included painful swelling and bleeding in the mouth. She was treated by a dental surgeon at the home.

The centre believed it was a local case because the woman had not travelled anywhere recently.

All patients in the extended care home had been screened for the larvae, the centre said, and all had been cleared.

Confirmation of the new case came a day after the centre reported an earlier case in its publication Communicable Diseases Watch.

The centre said that case of human Chrysomya bezziana infestation involved a 49-year-old woman who had breast cancer.

'She noticed a bloody discharge from the tumour in late October and was admitted to a hospital,' the article says. 'After admission, worms were noted over the ulcer.

'Numerous larvae were found over the ulcer base and inside ... during operative removal of the breast.'

The case was also classified as local because the woman had not travelled recently. But flies trapped in the area were not Chrysomya bezziana. And stray dogs caught in the vicinity by the Agriculture, Fisheries and Conservation Department did not carry infestations either.

The centre said the first such case was recorded in October 2002, with sporadic infestations since then. Nine cases were reported in 2003 and eight last year.

The larvae of the screw-worm fly are parasites that burrow into the flesh of mammals, the centre said. The site of infestation is usually a superficial wound or body orifice of physically debilitated people. 'The larvae feed on the host's dead and living tissue. Feeding activity of the larvae may cause serious tissue damage, resulting in loss of condition, injury to the skin, secondary invasion and death,' the centre said.

The centre warned the public, especially staff at homes for the elderly, that they should treat all wounds immediately.

'Wound fluids and blood are known to attract Chrysomya bezziana,' the centre said. Staff at homes for the elderly should ensure good environmental hygiene, be alert to inmates developing symptoms of the complaint and arrange for any inmates feeling unwell to seek medical advice promptly, the centre said.

To avoid infestations, wounds should be cleaned and dressed properly. The risk of fly infestations could be reduced by the installation of fly screens on windows and doors, immediate dressing of wounds and maintenance of good ventilation and personal and environmental hygiene, according to the centre.

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