Three more travellers from the United States were confirmed to have swine flu yesterday, bringing the number of cases in Hong Kong to 26. They were admitted to hospital after spending more than a day in the city. One had visited Ocean Park and another had played basketball. The first case involved an eight-year-old boy from Puerto Rico. He arrived in Hong Kong via New York at 7pm on May 29 on Cathay Pacific flight 831. He travelled with his family to a relative's home in the Wah Ming Estate, Fanling. The next day, he developed a sore throat and cold. His family took him to a herbalist and his symptoms eased. On Sunday, he went to Ocean Park. He developed a fever the next day and was taken to an estate clinic and then North District Hospital. The second case was a 19-year-old man who studies in the US. He arrived in Hong Kong from San Francisco on Singapore Airlines flight 1 on May 30. He played basketball and mahjong the next day, when he suffered a headache, shortness of breath and fever. At 10am on Monday he called an ambulance and was admitted to Kwong Wah Hospital. The third case was a 20-year-old who studies in New York. He arrived on May 28 on Cathay Pacific flight 889. On Monday he started to have a fever, cough and a headache, and took a taxi from Lok Wah North Estate to United Christian Hospital at about 11pm. The Centre for Health Protection would not trace passengers on these flights as all patients developed symptoms at least 12 hours after landing, but it urged the taxi driver who took the 20-year-old and his two sisters to hospital to come forward. Health officials have repeatedly warned that the first community case could happen at any time, but all 25 cases spotted so far have been imported, mainly from the US. But Ho Pak-leung, a microbiologist at the University of Hong Kong, said mild cases of swine flu in the community would not be picked up as most flu cases were treated at outpatient clinics or by family doctors.