Replies to LegCo questions

LCQ20: Measures to prevent Zika Virus Infection

Following is a question by the Hon Kenneth Lau and a written reply by the Secretary for Food and Health, Dr Ko Wing-man, in the Legislative Council today (November 30):

Question:

The second ever imported case of Zika Virus Infection in Hong Kong was confirmed on the 15th of this month. The patient went back to his residence in San Tin, Yuen Long after returning to Hong Kong from overseas on the 10th of this month, and was not admitted for isolation and management until the 12th. It is learnt that the patient started to have persistent fever when he was staying overseas, but the Temperature Check Points at the airport failed to detect his abnormal body temperature when he entered Hong Kong. In addition, it has been reported that although the ovitrap indices for Aedes albopictus in various districts were not on the high side in the last winter season, serious mosquito infestation was observed in quite a number of districts (particularly in rural areas). Quite a number of residents of villages are worried that the imported Zika virus would spread in the community. In this connection, will the Government inform this Council:

(1) whether it has assessed if the aforesaid case has revealed that there are inadequacies in the temperature checks conducted by the authorities at the boundary control points; if it has assessed, of the outcome;

(2) whether territory-wide mosquito control operations are continuously carried out at present with the aim of reducing the risk of Zika virus spreading across Hong Kong;

(3) given that oviposition traps are mainly placed in urban areas or new towns at present, whether the Government has considered placing oviposition traps in rural areas; whether it will review the effectiveness of the current practice of adopting the ovitrap indices as an indicator of the seriousness of mosquito infestation; and

(4) of the details of the mosquito prevention and control strategies currently adopted for rural areas; whether the authorities will adjust such strategies in the light of the emergence of imported cases of Zika Virus Infection in Hong Kong; if they will, of the details; if not, the reasons for that?

Reply:

President,

Zika virus is transmitted to humans mainly through bite of infected Aedes mosquitoes. Though Aedes aegypti, which is considered as the most important vector for transmitting Zika virus to humans, is currently not found in Hong Kong, other Aedes mosquito species such as Aedes albopictus widely present locally are also considered as potential vectors. Moreover, transmission of Zika virus by sexual contact has been confirmed, and other modes of transmission such as blood transfusion and perinatal transmission are also possible. As long as there is extensive international travel, there always remains the risk of introducing Zika virus or Aedes aegypti into Hong Kong. Once an overseas Zika-infected person enters Hong Kong, person-to-person transmission of the virus is possible. Besides, if the infected person is subsequently bitten by an Aedes albopictus in Hong Kong, the infected Aedes albopictus may carry the virus and lead to a secondary spread in Hong Kong. It is very common that persons infected by Zika virus will not have any symptoms and there is no medication or vaccine against Zika virus at present. For newly affected areas, their population does not generally have any immunity against Zika virus. The public should therefore stay vigilant about the potential risks of mosquito-borne diseases, while the community and various Government departments should make concerted efforts and actively participate in mosquito prevention and control.

At an emergency meeting held on February 1, 2016, the World Health Organization (WHO) declared that the recent cluster of microcephaly and other neurological disorders and their possible association with Zika virus constituted a Public Health Emergency of International Concern (PHEIC). The Government published in the Gazette the Prevention and Control of Disease Ordinance (Amendment of Schedule 1) Notice 2016 on February 5, 2016 to make Zika virus infection a statutorily notifiable infectious disease under the Prevention and Control of Disease Ordinance (Cap. 599) with immediate effect on the same day. It also announced the Preparedness and Response Plan on Zika Virus Infection on March 11, 2016 and the Alert Response Level has been activated till now (Note 1). According to the WHO's latest figure, 75 countries/areas have documented mosquito-borne transmission of the virus to date since 2007 while 12 countries/areas have documented person-to-person transmission, probably by sexual contact, since 2016.

The WHO issued a statement on November 18, 2016, indicating that Zika virus and associated consequences remain a significant enduring public health challenge requiring intense action although they no longer represent a PHEIC. Nevertheless, the Government made it clear on November 19, 2016 that Zika virus remained a challenge to public health, and Hong Kong would stay vigilant by continuing the current prevention and control strategy and maintaining the Alert Response Level. The Government will maintain its close liaison with public and private hospitals, medical professions and the community. Relevant Government bureaux/departments and organisations will continue to undertake prevention and control measures in line with the preparedness plan to ensure that measures on effective disease surveillance, vector control, examination and diagnosis, emergency preparedness, health advice, public education and risk communication are in place. The enhanced efforts on mosquito control and elimination as well as publicity and community engagement activities will also be sustained.

To date, the Centre for Health Protection (CHP) recorded two imported cases of Zika Virus Infection (Note 2). Upon receiving the notification, the CHP immediately carried out epidemiological investigation and issued isolation orders to the two patients concerned. The patients were given the necessary health education information and relevant promotional leaflets before discharge. They should apply insect repellent (for at least 21 days upon arrival from the affected areas) to avoid mosquito bites and were reminded of the need to observe safe sex after discharge. The CHP held briefings on the days of receiving the notification to report the investigation and follow-up work undertaken and issued press releases. Letters were also issued to doctors and hospitals to alert them to patients with compatible symptoms and travel history. In addition, the CHP has reported the cases to the WHO, the National Health and Family Planning Commission, and Guangdong and Macao health authorities, and maintain close liaison for the latest development. Also, a new television announcement of public interest on Zika virus started to be broadcast from November 3, 2016 onwards.

The Food and Environmental Hygiene Department (FEHD), within 24 hours after receiving the notification, conducted inspections on mosquito problem and implemented mosquito prevention and control measures in the areas within a radius of 500 metres from the residences and workplaces of the two patients and the places they visited during the infectious period (including the hospitals where they received isolation treatment). The FEHD also liaised with relevant departments and organisations (including convening district task force meetings) to enhance the anti-mosquito work under their purview. Besides, the Aedes albopictus samples collected by the FEHD were tested for Zika virus under the following circumstances:

(a) All samples collected from dengue vector surveillance program at port areas and from areas with an Area Ovitrap Index reaching 10 per cent or above in the community during the surveys conducted from August to October 2016; and

(b) As a response to the two imported cases, all samples collected from the dengue vector surveillance areas that fall within a radius of 500 metres from the residences and workplaces of the two patients, and the places they visited during the infectious period (Note 3).

The testing results of 148 samples collected so far are negative.

On strengthening the anti-mosquito work in the port areas (Note 4), in September 2016, in addition to the meetings between the Food and Health Bureau and the Airport Authority, the Tourism Commission also took the lead in meeting two cruise terminal operators, the cruise industry and representatives from major tourist attractions (including the Ocean Park, Hong Kong Disneyland Resort, Noah's Ark, Ngong Ping 360 and Peak Tram), so as to strengthen the mosquito prevention and control of the facilities in these major tourist attractions and in their vicinity, and enhance publicity and education for stakeholders.

My reply to the various parts of the question is as follows:

(1) The Department of Health (DH) currently conducts routine health surveillance at all boundary control points (BCPs) by checking the body temperature of the inbound travellers. Border staff will carry out health assessments on travellers with fever and refer them to healthcare institutions for follow-up. Health promotion has also been enhanced at BCPs through pamphlet distribution and poster display to remind travellers of the preventive measures against Zika virus. As for the latest imported Zika case, the patient concerned had developed symptoms before returning to Hong Kong. As he had taken paracetamol, the symptoms were slightly relieved and there was no sign of fever during his return flight to Hong Kong and upon entering the territory. As a result, the DH had no fever record of this Zika-infected inbound traveller. Nonetheless, the patient was referred to North District Hospital at once for isolation treatment after attending Sha Tau Kok General Out-patient Clinic. Upon laboratory confirmation, the DH immediately commenced epidemiological investigations, and requested the FEHD to carry out vector investigations and mosquito control. The management of the locations concerned was also informed of the need to intensify the necessary anti-mosquito and environmental hygiene work.

(2) The Government conducts anti-mosquito work across the territory on an ongoing basis. Details are as follows:

The Anti-Mosquito Steering Committee (AMSC) (Note 5) convenes meetings before the rainy season each year to review the dengue vector surveillance and effectiveness of the anti-mosquito measures undertaken by various departments. The meetings also discuss ways to strengthen co-operation and intensify mosquito prevention efforts, such as the territory-wide intensive anti-mosquito operations jointly conducted by the FEHD and various stakeholders to kill adult mosquitoes and clear their potential breeding grounds so as to eradicate a whole generation of mosquitoes.

Each year before the rainy season or when necessary, the district environmental hygiene offices (DEHOs) of the FEHD convenes special anti-mosquito task force meetings with relevant departments to give them professional advice on intensifying mosquito prevention and control in places under their management. The FEHD's professional staff also provide various departments, organisations and persons in charge of private places with technical support/assistance to facilitate effective implementation of anti-mosquito measures within their respective purview. The FEHD, in collaboration with the above parties, will continue to intensify the relevant anti-mosquito work and strengthen publicity and education campaigns with a view to sustaining the effectiveness.

In addition to about 700 departmental staff responsible for pest control (including mosquito control), the FEHD also engages private contractors to provide pest control services across the territory through roving teams. During the winter season from November 2016 to March 2017, the FEHD increases the number of roving teams by 56 in order to maintain the same number of teams as in summer. Together with the additional roving teams under the District-led Actions Scheme (DAS), the number of roving teams this winter will be largely maintained at about 280 (with a workforce of about 1 680) to strengthen mosquito control in the season.

The FEHD launches territory-wide anti-mosquito campaigns in collaboration with other Government departments annually to encourage community participation in anti-mosquito work. Moreover, the FEHD, immediately after each phase of the campaign, conducts thematic mosquito prevention and control special operations to keep up its anti-mosquito efforts:

(a) The Anti-mosquito Campaign 2016 is implemented in three phases. The third phase has just been carried out from August 15 to October 21, 2016, followed by the third phase of the territory-wide thematic mosquito prevention and control special operation, running from October 31 to December 30, 2016. The publicity on mosquito control in winter has commenced in November 2016 as well; and

(b) Closely following the thematic operation will be the year-end clean-up operation, which will commence on January 3, 2017, during which mosquito prevention and control work will be enhanced. The DEHOs of the FEHD will continue to target areas which have drawn particular concerns (Note 6) within their districts and intensify mosquito prevention and control at these places in winter.

District Offices and District Councils carry out regular anti-mosquito work and mosquito preventive work, grass-cutting and cleansing of hygiene blackspots. With the full implementation of DAS in 18 districts since 2016, District Offices have, based on their district circumstances, worked closely together with District Councils and relevant Government departments in launching various initiatives that improve environmental hygiene. Making use of the DAS funding provided in 2016-17, plus the administrative support given by the Home Affairs Department (HAD), District Offices will implement a total of 40 projects relating to environmental hygiene improvement and public area management, including grass-cutting and mosquito control.

As work sites (including sites for renovation and repair) are areas with a high risk of mosquito breeding, the HAD will continue the efforts in drawing the attention of owners' corporations of those housing estates/buildings that are undergoing or will shortly undergo repair/maintenance/renovation to the importance of implementing anti-mosquito measures for prevention and control purposes. In addition, the Development Bureau (DEVB) will continue to encourage, through contractors' associations, contractors of private projects to actively participate in anti-mosquito work, liaise with the FEHD to ensure effective anti-mosquito measures are undertaken by contractors of public works projects, and closely monitor the situation of the sites of such projects through the high-level Interdepartmental Working Group on Mosquito Prevention at Works Sites. The DEVB will also consider strengthening the relevant penalty level under the existing regulatory mechanism (Note 7). Besides, the FEHD was invited by the Hong Kong Construction Industry Employees General Union and the Occupational Safety and Health Council to conduct briefings on strengthening mosquito prevention and control.

In 2016 (up to November 15), the FEHD instigated 43 prosecutions against mosquito breeding on the premises concerned under the Public Health and Municipal Services Ordinance (Cap 132), among which 30 involved construction sites and 13 involved other premises.

(3) and (4) During routine anti-mosquito operation in rural areas, the FEHD staff regularly inspect potential breeding grounds in public areas. Whenever breeding of mosquitoes or potential breeding grounds are found, immediate actions will be taken to eliminate the source or larvicides will be applied to contain the problem. Fogging will also be carried out to kill the adult mosquitoes where necessary. Moreover, the FEHD will provide technical assistance to relevant departments, organisations and the persons in charge of private places to deal with mosquito problem. In response to mosquito complaints, the FEHD will conduct investigations and enhance the relevant anti-mosquito work. The FEHD stands ready, upon invitation, to brief Heung Yee Kuk on the anti-mosquito work in rural areas.

The FEHD has put in place an enhanced dengue vector surveillance programme for monitoring the distribution of Aedes albopictus in selected areas and for evaluating the effectiveness of mosquito prevention and control work carried out by various parties. The data collected also provide an informed basis for timely adjustment to mosquito control strategies and measures. Following the WHO's recommendations, the FEHD's dengue vector surveillance programme closely monitors places with higher risk of spreading dengue fever. Places where local dengue fever cases occurred and densely populated areas, such as housing estates, schools and hospitals, will be targeted to ensure effective monitoring and control of vector mosquitoes in these areas. In other words, the setting of ovitraps for Aedes albopictus is determined by factors such as population density and the risk of spreading dengue fever and related diseases, but not on the basis of delineation of urban areas/new towns or rural areas.

The FEHD carries out its daily anti-mosquito work with reference to the results of dengue vector surveillance, and takes targeted action in the light of each district's circumstances. To tackle the mosquito problems in rural areas, the FEHD has sustained its efforts in paying special attention to mosquito control in village houses. Moreover, the FEHD has been installing mosquito screens at the vent pipes of septic tanks of private village houses since March 2016 as a proactive measure to prevent mosquito breeding in septic tanks. It plans to assess the situation before the rainy season in 2017 for any further actions. The FEHD will also stay alert of those areas which are prone to mosquito breeding, such as land filling sites in rural areas, and carry out inspections and take appropriate measures to prevent mosquito breeding.

The Drainage Services Department (DSD) regularly inspects river channels and drainage facilities under its management in rural areas to examine the need for any necessary anti-mosquito measures and the effectiveness of those implemented. If any hygiene problems (e.g. the presence of stagnant water) are spotted, the contractor concerned will be asked to take immediate action by applying appropriate larvicides. In response to the most recent Zika virus case, the DSD has increased the frequency of inspecting the polder area and the inlets and outlets of river channels in San Tin to once a week, and arrange to clear litter and apply appropriate larvicides in these areas on a weekly basis. Moreover, the number of larvivorous fishes reared in the polder area in San Tin will be increased to further contain the problem.

Members of the public living in rural areas may install mosquito screens on windows and doors if necessary. Those staying in the natural environment should take appropriate personal protective measures against mosquitoes, such as avoiding staying in the vicinity of shrubby areas for a long time, wearing light-coloured long-sleeved clothes and long trousers and applying insect repellent containing N, N-diethylmetatoluamide (DEET). Members of the public may report any mosquito problems found to the Government by calling 1823.

Note 1: In response to the activation of the Alert Response Level under the Preparedness and Response Plan on Zika Virus Infection, the departments concerned have stepped up the cleansing work and mosquito prevention and control measures. The following are some examples:

(a) The DEHOs of the FEHD convene monthly anti-mosquito task force meetings with relevant departments to review the mosquito prevention and control work;

(b) The Lands Department adopts and maintains the reinforced mosquito prevention and control measures as planned. These measures include enhancing the inspection frequency (at least once a week) of government land sites under their control, promptly conducting necessary cleaning and grass cutting work on government land sites and enhancing supervision of their site contractors to step up frequency (at least once a week) and intensity of anti-mosquito work; and

(c) The Leisure and Cultural Services Department conducts daily cleaning and inspection at all its venues to reinforce the efforts in clearing stagnant water and debris and ensure that all water containers are covered tightly; conducts weekly specific mosquito control and cleaning operations at the venues; and promotes the message of mosquito prevention and control by displaying posters and banners at its venues, conducting roving exhibitions, broadcasting announcements in the public interest and distributing leaflets.

Note 2: The two cases were reported on August 25 and November 15, 2016 respectively.

Note 3: The surveillance area with ovitraps for Aedes albopictus involved in the second confirmed case is Sheung Shui. As the index of that location for November was zero, no sample was available for testing.

Note 4: The FEHD will continue to work closely with the Airport Authority, the MTR Corporation and freight forwarding companies etc. with a view to strengthening the anti-mosquito work in the port areas.

Note 5: The AMSC is chaired by the Permanent Secretary for Food and Health (Food) and comprises senior officers from various government bureaux and departments.

Note 6: Examples include areas concerned with previously reported local dengue fever cases, single-block buildings, rural village houses, areas in close proximity to residential buildings, typhoon shelters, schools, construction sites, illegal cultivation sites, hospitals, container terminals and cargo working areas in port areas, cross-boundary check points and cross-boundary ferry terminals.

Note 7: According to the existing regulatory mechanism, the qualification of the contractors on the List of Approved Contractors for Public Works to bid public works will be affected if they repeatedly breach legislation related to mosquito control.

Ends/Wednesday, November 30, 2016
Issued at HKT 20:02
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