As the spread of the Zika virus is now being considered a “public health emergency of international concern” by the World Health Organisation, the question for Hongkongers is whether or not the city has what it takes to fend off a looming health crisis. The lessons from the Sars virus outbreak in 2003 mean there is much expertise available in the city, from the vigilance of health authorities in blocking and containing previous epidemics, to the higher awareness among Hongkongers on infectious diseases. But there are a few factors not in Hong Kong’s favour when it comes to containing a possible outbreak of the virus, which has been linked to birth defects in babies. Click the above image to view in full size For one, the city is experiencing wetter, hotter, and longer summers, making it more hospitable to the mosquitoes that carry the disease. The majority of people who catch Zika show no symptoms, limiting the ability of border checks and virus surveillance and making early detection and quarantine measures almost impossible. A further concern is that the city’s public health care sector is already severely understaffed and overburdened as it reaches the winter flu peak. It is questionable whether the system is capable of handling another outbreak. To address the challenges, health minister Dr Ko Wing-man chaired an interdepartmental meeting on Monday to assess the risk of an outbreak and laid down prevention and control measures against Zika infection. A series of precautionary measures have been announced by the Centre for Health Protection (CHP) as a result. Anyone who has visited areas with active Zika transmissions cannot donate blood for 28 days, and they are advised to use condoms for sexual intercourse during this period. Those who have travelled to affected areas, including male travellers, should also continue to use mosquito repellent for 14 days after arrival back in Hong Kong to prevent them from being bitten and the virus being spread by the insects. By Friday, the virus was also to be made a statutory notifiable disease – meaning all cases must be reported by law to the Department of Health. READ MORE: World Health Organization declares Zika a global emergency University of Hong Kong microbiologist Yuen Kwok-yung has praised the CHP for responding appropriately and says all the advice should be followed. Last year was the hottest year in Hong Kong on record and last month was the wettest January since records began in 1884, with 233.8mm of rainfall – 50 per cent more than average. Warmer year-round weather and more extreme rainfall patterns will make the city even more favourable for mosquitoes, including those from the Aedes genus, says Professor Amos Tai Pui-kuen of Chinese University’s school of earth sciences. Once there is an infected patient in the city, the virus will spread through mosquito bites. READ MORE: Hong Kong’s health authority braces for arrival of Zika virus; warn of mosquitoes spreading the disease Tai says it would not be surprising if more local cases of mosquito-borne viral infections such as dengue fever are reported in future. Currently, most are imported. “The biggest concern is not average rainfall but the frequency of extreme rainfall in warmer weather,” Tai says. “Heavy rainstorms quickly create large stagnant puddles that provide them with fertile breeding spots.” Yuen says the government should enhance hygiene at mosquito black spots, such as construction sites, poorly managed recycling sites, scrap yards, construction sites, and cargo terminals. While acknowledging the need to tighten mosquito control, CHP’s controller Dr Leung Ting-hung also emphasises the importance of enhancing surveillance of this mosquito-borne disease. Hong Kong adopted an early detection approach against epidemics imported from other places in the wake of the Sars pandemic by implementing border health controls to detect suspected cases as early as possible, quarantining those infected and tracing their close contacts. READ MORE: Women warned over Zika outbreak The strategy has proven to be successful in containing early outbreaks of swine flu and Middle East respiratory syndrome, but there are aspects of the Zika virus that might make it more difficult to monitor and control. University of Hong Kong microbiologist Ho Pak-leung says the Zika virus causes no more than a mild illness in most of those infected – 75 per cent display no symptoms at all, while 25 per cent may suffer mild fever and rashes. So even when the Zika infection is made a notifiable disease from Friday, it will be difficult for health officials to obtain real figures on infection levels. Leung admits the nature of this “silent infection” will hinder screening efforts. “The virus may only present in the blood of those who are infected for a short period of time,” he says. “This is why we advised all people who had travel history to take the precautionary measures – to protect those around them.” The consequence is profound and the medical system would bear a heavy cost Dr Leung Ting-hung Leung stresses the city’s laboratory is able to conduct quick blood tests on suspected cases, with results expected the same day. Public hospitals will help pregnant women who have visited Zika-hit areas to undergo the necessary maternal check-ups and, if needed, abortion will be discussed as an option. Health officials remain concerned about new pressure on the understaffed public health care system, which is currently dealing with increased demand from the surge in seasonal flu cases. The inpatient bed occupancy rate this week has exceeded 100 per cent at all hospitals, and over 120 per cent in Caritas Medical Centre in Sham Shui Po, Yan Chai Hospital in Tsuen Wan, Princess Margaret Hospital in Kwai Chung and Tuen Mun Hospital. More than 6,000 people a day are visiting accident and emergency units, up from the average 5,000 in non-peak season. Dr Liu Shao-haei, the Hospital Authority’s chief manager of infection, emergency and contingency, says it is fortunate that most Zika cases will not require treatment. In case of an outbreak, he expects only a very small proportion of patients will develop complications that require hospitalisation. Leung agrees but say it is vital to remind the public of the importance of the precautionary measures since infections in pregnant women are linked to abnormally small heads in their babies, a brain-damaging birth defect called microcephaly. “The consequence is profound and the medical system would bear a heavy cost,” he warns. The health minister will hold another interdepartmental meeting to update and review measures against Zika on Friday. Watch: WHO warns Africa, Asia vulnerable for Zika virus