A 17-year-old boy has become the second person to be struck down by cholera this year. Health inspectors are trying to trace the source of the infection, taking food and water samples from the youth's home in Greenwood Terrace, Chai Wan. The teenager, described as being in a satisfactory condition at Princess Margaret Hospital last night, first became ill on May 4. The case comes just three days after an 81-year-old woman from Sek Lei Pui Estate, Kwai Chung, was struck down with the disease. She was also admitted to Princess Margaret Hospital and is in a stable condition. Both are understood to have contracted the bacteria in Hong Kong. The Department of Health said yesterday no link had been made between the two cases. Health officials urged the public to be extra vigilant with personal hygiene, particularly when cooking and handling food. Inspectors were sent to the teenage victim's home and samples of food and water were taken along with environmental swabs. His parents and brother do not appear to have any symptoms of cholera. 'He had eaten a lot of food outside. It's difficult to trace what he had eaten,' a health department spokesman said. 'We have to find out where these two patients have eaten,' said associate professor of microbiology at Chinese University, Dr Julia Ling Mei-lun. 'A few years ago there was an outbreak. All the patients had eaten at seafood restaurants,' she said. In 1994, 56 people were struck down with the disease. Last year the figure was four.