Fourth teenager from Sheung Shui college tests positive for enterovirus 71 A fourth teenager at a Sheung Shui secondary school was confirmed yesterday to be suffering from hand, foot and mouth disease. The 15-year-old boy first developed symptoms on May 18, including blisters on his hands and feet and lesions in his mouth. He did not need to be admitted to hospital. The disease is caused by enterovirus 71 (EV71) A spokesman for the Centre for Health Protection said the boy was studying in the same school, TWGHs Kap Yan Directors' College in Choi Yuen Estate, where a 15-year-old girl was confirmed to have the virus on May 26. The girl's symptoms began on May 21. Two boys, both 15, were confirmed to have the same disease on Tuesday. The students were not classmates, the centre said. Health advice has been offered to the school, which is now under medical surveillance. So far this year, there have been five local cases of EV71. The fifth case involved a 16-year-old boy from a different school. Two siblings, a 10-year-old girl and her seven-year-old brother, who were confirmed to have the virus in April, are believed to have caught it on the mainland. A centre spokesman said EV71, which usually infects young children, can also infect teenagers because of close contact in schools and playgrounds. EV71 causes hand, foot and mouth disease and, rarely, encephalitis. Hong Kong has been hit with sporadic outbreaks in recent years, with the most recent large outbreak involving 60 people in 1998. There were eight cases last year and 35 in 2004. Meanwhile, a 36-year-old Malaysian tourist was yesterday confirmed to have dengue fever. The man arrived in Hong Kong last Saturday and went to the accident and emergency department of Queen Elizabeth Hospital with symptoms including fever, headache, cough and rash. He did not need to be admitted and left for Malaysia on Tuesday. His case brings to 12 the number of dengue fever cases in the city this year, all imported. Five cases were imported from Indonesia and five came from Thailand. One case visited the mainland and Indonesia and another came from Sri Lanka. The centre said: 'It is essential that people stay alert to the threat of dengue fever and help in the reduction of mosquito breeding.' Travellers are advised to wear long-sleeved tops and trousers and use insect repellant and mosquito nets. Anyone feeling unwell after their trip should consult a doctor as soon as possible. Meanwhile, the condition of a 49-year-old Yuen Long housewife with suspected Japanese encephalitis has improved from critical to serious, the centre said last night. The woman, who has not travelled outside Hong Kong recently, was admitted to Tuen Mun Hospital on May 25.