The Centre for Health Protection has confirmed a Chrysomya bezziana infestation case involving a 78-year-old woman living in a Sha Tin extended care hospital.

The patient developed symptoms like the swelling and bleeding of the oral cavity early this month. She has been treated by a dental surgeon and is now in stable condition. She has no recent travel history and no other patients have lesion of myiasis.

Chrysomya bezziana is an obligate parasite of mammals. The site of infestation with the larvae is usually at superficial wounds and body orifices of debilitated persons.

The larvae feed on the host's dead or 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 public, especially elderly home staff, are advised to note that:

* all wounds should be treated immediately. Wound fluids and blood are known to be attractive to Chrysomya bezziana. To avoid myiasis infections, wounds should be cleaned and dressed properly;

* fly infestation can be avoided by proofing measures, including installation of fly screening materials to human dwelling places, dressing of wounds and maintaining good ventilation;

* observe good personal and environmental hygiene; and,

* elderly home staff should ensure good environmental hygiene, be alert to inmates developing symptoms of the disease and arrange for those feeling unwell to seek prompt medical help.

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