Myiasis is the invasion of human body or organs by larvae of fly (maggot) which caused damage. Chrysomya bezziana is one of the types of flies that can cause myiasis.

Causative agent

Many types of flies can cause myiasis in animals or humans, such as Oestroidea, Calliphoridae and Sarcophagidae. Chrysomya bezziana of the Calliphoridae family is the more common species that cause human myiasis.

Development of disease

For Chrysomya bezziana, there are 4 stages of the life cycle, from egg, larva, pupa and then to adult. An adult female fly only lays eggs on live mammals. The sites of larvae infestation are usually on superficial wounds, or mucous membranes in body orifices such as the mouth, the ear and the nose of debilitated persons. 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, staff of elderly homes are advised to observe the following measures:

• Remind residents to observe good personal hygiene:-
  Bathe daily and keep skin clean and to maintain good oral hygiene.
• Proper wound management:-
  Fluid and blood from wounds will attract Chrysomya bezziana. Therefore, all wounds should be treated and dressed properly. Staff of elderly homes should observe the wounds regularly. Seek medical attention should the wound shows symptoms of infection like bleeding, putrid discharge or pus. Besides, staff should always keep wound dressings clean and dry to avoid attracting Chrysomya bezziana.
• Ensure good environmental hygiene and maintain good ventilation:-
  Store food in refrigerator or cover the food with screen. Refuse should be kept in containers with tight-fit lid and disposed of regularly. Dead bodies of animals should be disposed of properly.
• Fly proofing measures:-
  Prevent breeding of flies through installation of fly proofing measures, such as fly screening, insect electrocuting device, or fly trap.
• Keeping of pet:-
  Pets, particular dogs and cats, have to be examined by veterinary surgeon regularly. All wounds on animals should be treated immediately and properly.
• Monitor inmates for any symptoms of myiasis:-
  Seek medical consultation promptly for inmates feeling unwell.