People have been warned not to eat fresh scallops for the time being after 17 cases of paralytic shellfish poisoning in the past three days. The Centre for Health protection said the affected people, in nine groups, comprised six men and 11 women aged 17 to 69. They fell ill between Saturday and yesterday after cooking and eating the scallops at home. A spokesman for the centre said the main symptoms included numbness to the face, tongue and throat, limb weakness, dizziness, blurred vision, abdominal pain, nausea, vomiting and diarrhoea. The symptoms would start about half an hour to three hours after eating the scallops. Of the 17, 14 fell ill yesterday. Only one was admitted to hospital and was in stable condition in Caritas Medical Centre yesterday. The rest were treated at various hospitals and sent home. The centre said the scallops were bought fresh from several markets in different districts, including Wong Tai Sin, Sham Shui Po, Kowloon City and Tuen Mun. 'They steam-cooked the scallops before eating them,' the centre's spokesman said. Officials from the Food and Environmental Hygiene Department were investigating the source of the scallops last night. Wu Kin-yip, who has run a seafood store for more than 30 years, said scallops were popular among Hongkongers. 'Prices range from HK 50 cents to HK$4 each and they taste good,' he said. 'We have seldom heard of food poisoning from scallops but there have been scattered cases over the past five years. 'People should try to buy scallops that are fresh and should avoid eating the internal organs.' The Centre for Health Protection said shellfish poisoning could be caused by a kind of toxin called phycotoxins. These toxins are produced by algae upon which the shellfish feed.