The Centre for Health Protection (CHP) on Thursday said it's investigating a cluster of imported malaria cases from Africa.
The CHP said 30 people arriving in Hong Kong from July 1 to August 1 were found to have the mosquito-borne infectious disease, with 21 of them flying in from Guinea.
All 30 patients were male.
The CHP said one of them, 52, died during hotel quarantine. Post-mortem results revealed that he carried the malaria parasite.
The other patients were sent to public hospitals for treatment. Four of them were in intensive care, 15 in stable condition and 10 discharged.
The companions of these patients have been put under medical surveillance, the CHP said, adding that those with symptoms would be sent to hospitals for tests.
The CHP said malaria is a serious and sometimes fatal disease caused by a group of malaria parasites commonly found in many parts of tropical and sub-tropical areas such as Africa, Southeast Asia and South America.
It's transmitted by an infected female Anopheline mosquito.
Infectious disease specialist Wilson Lam described the cluster as unusual.
"To the best of my knowledge, this cluster of cases are actually workers from Africa who worked around the same time and the same location, so probably they acquired malaria from the same source and they developed symptoms and signs of malaria at the same time more or less," he told RTHK.
The CHP said the Anopheline mosquito has not been found in urban areas in Hong Kong in recent years, so the risk of local transmission of malaria is extremely low.
It noted that the last local malaria infection was recorded in 1998, while there were seven imported cases in 2020 and four in 2021.
Lam too doesn't see a high risk of local infections in Hong Kong, but said authorities should monitor if imported cases would keep rising.
"These cases were transported from the airport to the quarantine hotels point to point and then from the hotels to the hospitals point to point without too much exposure to outside or outdoors," he said.
"The second reason is that we don't really have a lot of the mosquitoes which are responsible for the transmission of malaria."
Symptoms of malaria include fever, vomiting, diarrhoea and abdominal pain, while complications include anaemia, organ failure, coma and death if the disease is not treated promptly.
The CHP urged the public to maintain strict environmental hygiene, mosquito control and personal protective measures both locally and during travel.
The Hospital Authority said it had held an urgent meeting with infectious disease experts on the cluster of imported malaria cases. It said it had put in place contingency measures including the allocation of isolation beds and treatment plans, adding that it would closely monitor the situation.
Last updated: 2022-08-04 HKT 22:34