Updated at 6.34pm: Health authorities are concerned about public health hazards after an elderly woman died on Sunday ? just days after being infested by flesh-eating flies. The Department of Health on Wednesday said the 79-year-old had lived in Tuen Mun. She became seriously ill last Thursday after coming into contact with screw-worm fly (Chrysomya bezziana) larvae. A Centre for Health Protection (CHP) spokesman said the woman had developed chills and was bleeding from a cavity in her mouth. Maggots were subsequently found in the cavity, the spokesman explained. The woman was admitted to Tuen Mun Hospital on Thursday but died three days later. This was the third case this year of a Hong Kong person being infected with screw-worm fly larvae. All the victims are believed to have contracted the disease locally. Chrysomya bezziana is a parasite. Its larvae often infest wounds and body openings in people who are already sick or weak. Health experts said the larvae ? which feed on the host?s dead or living tissue ? could cause serious tissue damage. This may ultimately kill the host. The spokesman urged people ? especially staff in homes for the elderly ? to be wary of the disease. Health workers were advised to: Treat all wounds immediately. Fluid and blood are known to attract Chrysomya bezziana. To avoid infestation, wounds should be cleaned and dressed properly; To prevent the disease spreading, fly-screening materials should be set up; Wounds should be cleaned and dressed regularly and good hygiene must be maintained.