8th August 2022 – (Hong Kong) The Government is very concerned about a number of imported malaria cases recently recorded in Hong Kong. The Secretary for Environment and Ecology, Mr Tse Chin-wan, inspected yesterday the Food and Environmental Hygiene Department (FEHD)’s anti-mosquito measures at the hillside near Princess Margaret Hospital, Kwai Chung. He appeals to members of the public to work together to carry out mosquito prevention and control measures at their homes and surroundings, thereby keeping hazards at bay.
“Anopheline mosquito transmitting Malaria is not commonly found in Hong Kong and the risk of local transmission of malaria is extremely low. Notwithstanding this, malaria is a serious infectious disease which can be fatal if it is not treated early. Therefore, the public must not allow the relatively low risk to lower our guards. The FEHD will step up anti-mosquito work, while co-operation and support from members of the public are very important. Effective mosquito control requires the concerted efforts of all parties in society and members of the public should maintain good personal hygiene and prevent mosquito breeding in their daily lives. I appeal to all sectors of the community to take anti-mosquito measures together,” Mr Tse said.
Malaria is an infectious disease transmitted by an infected female Anopheline mosquito (malaria vector). Prevention and control of malaria vector in Hong Kong has been conducted for over 60 years. All along, the FEHD has been undergoing relevant vector prevention and control work, and classifying densely-populated places as vector control area. According to the surveillance data, malaria vector is uncommon locally. However, in view of the recent imported cases from overseas, the FEHD has stepped up the vector prevention and control work in high-risk places, including conducting vector investigation, strengthening vector prevention and control work in rivers and streams in areas within a two-kilometre radius from the residence of the patients and the places they visited (e.g. airport; relevant quarantine hotels, quarantine centre, hospitals; places passed through on the way and so on), as well as applying larvicide at appropriate locations to make it not possible for Anopheline to breed and survive.
Taking into consideration the ecology and habitat of Anopheline mosquitoes (unpolluted hilly streams providing breeding environment for Anopheline mosquitoes), staff of FEHD’s District Environmental Hygiene Offices are conducting weekly inspection of about 600 rivers or streams under control at malaria vector control zone and carrying out river clearing work, including removing rocks which obstructs smooth flow, pruning overgrown branches protruding into the rivers, clearing up floating refuse, and applying larvicide such as temephos and Bacillus thuringiensis subspecies israelensis at appropriate locations. Moreover, staff of Pest Control Advisory Section of the FEHD will conduct investigation of larvae of mosquitoes in the rivers outside vector control zones and collect adult mosquitoes nearby to survey the existence of vector Anopheline mosquitoes. Except the vector Anopheline mosquitoes identified in remote areas that were sparsely populated in 2006 and 2021 (Tai Lam Chung Reservoir in 2021), the vector Anopheline mosquitoes have not been found elsewhere in Hong Kong. From 1999 till now, the Centre for Health Protection has not recorded any locally transmitted case.
Malaria is a vector-borne infectious disease transmitted by an infected female Anopheline mosquito. When the mosquito bites a malaria patient, the mosquito will become infected and may pass on the disease when it bites another person. Malaria is not directly transmitted from person to person. However, malaria can be transmitted through contaminated blood or blood product transfusion, organ transplant, or shared needles or syringes. Malaria may also be transmitted from a mother to her foetus/newborn baby before or during delivery.
In view of the ecology and habitat of the vector as well as the urbanisation of our city, the environment that allows the breeding of the local malaria vector mosquitoes has been on the decrease, and only a very small number of malaria vector mosquitoes was recorded in remote places that were sparsely populated during mosquito surveillance. The risk of local transmission of malaria is extremely low. However, the hot and rainy summers of Hong Kong are conducive to the rapid reproduction of mosquitoes. Member of the public should stay vigilant and take anti-mosquito measures expeditiously.