Carers' Corner

Myiasis

Myiasis is the invasion of living tissue or organs by larvae of fly (maggot).

Causative agent

There are many fly families which can cause myiasis in humans such as Oestroidea (botflies), Calliphoridae (blowflies) and Sarcophagidae (fleshflies).

Chrysomya bezziana of the Callipharidae family is the most common species that cause myiasis in human in Hong Kong .

Development of disease

For Chrysomya bezziana , there are four stages in the life cycle, egg, larva, pupa and adult. An adult female fly only lays eggs on live animals. The sites of infestation are usually at superficial wounds or mucous membranes in body orifices such as the mouth, the ear and the nose. The eggs hatch within 24 hours and the larvae burrow into the host's tissue and feed on the host's dead or living tissue.  

Clinical Features

Feeding activity of the larvae may cause serious tissue damage, resulting in loss of function, injury to the skin, secondary bacterial invasion and death.  

Prevention

To prevent myiasis infestation, staffs of elderly homes are advised to observe the following measures:

•  Advise inmates to observe good personal hygiene.

•  Bath daily and keep skin clean.

•  Maintain good oral hygiene.

•  Proper wound management

•  All wounds should be cleaned and properly dressed immediately.

•  Staff should inspect wounds regularly and keep them clean and dry to avoid fly infestation.

•  Immediate medical attention should be sought if any sign of inflammation is noticed in the wounds, e.g. bleeding, pus or other discharges.

•  Ensure good environmental hygiene.

•  Store food in refrigerator or cover the food with screen.

•  Collect, store and dispose refuse in containers with tight-fit lid.

•  Dispose of dead bodies of animal properly.

•  Fly proofing measures

•  Installation of fly screening.

•  Installation of insect electrocuting device.

•  Installation of sticky fly trap

•  Keeping of pet

•  All wounds on the animal should be treated immediately and properly.

•  Pets, particular dogs and cats, have to be examined by veterinary surgeon regularly.

Staff of elderly homes should be alert to inmates developing symptoms of the disease and arrange inmates feeling unwell to seek medical consultation promptly.