Hong Kong authorities issued an amber travel warning alert for Singapore yesterday over the country’s Zika virus situation with the number of cases confirmed to be locally transmitted in the island nation having risen to 189. An amber travel alert in a three-tier system issued by the Security Bureau means there are signs of threat and that travellers should monitor the situation and exercise caution. The mosquito-borne virus can cause microcephaly, a serious birth defect, manifesting in an underdeveloped brain and small head. Adults infected display flu-like symptoms such as mild fever, skin rash, conjunctivitis, muscle and joint pain. A government spokesman said it was necessary to alert those travelling to Singapore given the persistent and rapid increase in the number of cases, and the close contact between the two cities. Health minister Dr Ko Wing-man said if the epidemic in Singapore is stable and under control, the government will consider removing the alert. He added whether alerts would be issued for other affected regions depended on how close their contact with Hong Kong is and the speed and pattern of outbreaks. Zika cases jump in Singapore: first pregnant woman and 21 Chinese nationals among infected The Hospital Authority also announced yesterday that it will collaborate with the Centre for Health Protection to provide serology testing for targeted pregnant women to rule out Zika infection. According to Dr Dominic Tsang Ngai-chong, chief infection control officer of the Hospital Authority, the Zika test currently used in Hong Kong can only detect the disease in patients who are infected. Those who were infected but have since recovered can only be identified using serology testing – blood tests that detect antibodies – which was previously unavailable in the city. Joseph Tung Yiu-chung, the Travel Industry Council’s executive director, said there are currently eight tour groups comprising 180 people, travelling in Singapore and Malaysia. From today to September 19, 40 groups with 750 people will visit Singapore, he added. Tung said those who would like to cancel the trip might not be able to get a full refund. But he said travel agencies had indicated they might offer full refunds for pregnant women on a case by case basis. A report published in top medical journal The Lancet said around 2.6 billion people living in parts of Asia-Pacific and Africa are at risk of Zika infection. Hurricane Hermine batters Florida and raises fear of spread of Zika virus China came in second for the number of people at risk of being infected by the virus. Seventy-two countries and territories, including Brazil and the US, have reported evidence of mosquito-borne Zika virus transmission since 2007, according to the World Health Organisation. The Food and Health Bureau advised pregnant women and women preparing for pregnancy not to travel to Singapore. The bureau also said pregnant women should attend antenatal check ups regularly and inform doctors of their recent travel history. They are also advised against sex with a partner who had travelled to affected areas, or to take precautions by using condoms. All travellers are advised to use mosquito repellents containing DEET during their stay in and after returning from Singapore for a period of at least 21 days.