The Hong Kong Centre for Health Protection (CHP) reported a sporadic case of human myiasis caused by the Old World screwworm in a 46-year-old woman with underlying conditions.

Myiasis life cycle/CDC
Myiasis life cycle/CDC

She lived with family in a private housing estate in Tuen Mun. Since mid-October, she attended a general outpatient clinic regularly for dressing of right breast wound.

Worms were found in the wound on October 28 and she was admitted to a public hospital for further management on the same day.

The worms were later identified as Chrysomya bezziana. Her condition remained stable and she was discharged on November 3.There was no recent travel history and her home contacts remained asymptomatic. Health advice was given to the family.

According to the Centers for Disease Control and Prevention (CDC), Myiasis is infection with a fly larva, usually occurring in tropical and subtropical areas. There are several ways for flies to transmit their larvae to people.

  • Some flies attach their eggs to mosquitoes and wait for mosquitoes to bite people. Their larvae then enter these bites.
  • Other flies’ larvae burrow into skin. These fly larvae are known as screwworms. They can enter skin through people’s bare feet when they walk through soil containing fly eggs or attach themselves to people’s clothes and then burrow into their skin.
  • Some flies deposit their larvae on or near a wound or sore, depositing eggs in sloughing-off dead tissue.

LISTEN: Screwworms: An interview with UF professor, Dr. Phillip Kaufman