17 May 2010
The Centre for Health Protection (CHP) of the Department of Health today (May 17) urged members of the public to avoid eating fresh scallops in the meantime to prevent paralytic shellfish poisoning.
A spokesman for CHP said that as at noon today, the Centre had received reports of 17 people falling sick after consuming fresh scallops and suspected of having paralytic shellfish poisoning since May 15. The majority of reports (14 persons) was received today.
The 17 affected patients, who came from nine clusters, comprised six men and 11 women aged between 17 and 69. Their main symptoms included facial, oral, tongue and throat numbness, limb weakness, dizziness, blurred vision, abdominal pain, nausea, vomiting and diarrhea about half an hour to three hours after consuming scallops at home on May 14 and 16.
Among them, 16 people attended Accident and Emergency Departments of Queen Elizabeth Hospital, Tuen Mun Hospital and Caritas Medical Centre. One was admitted to Caritas Medical Centre. All of them are in stable condition.
According to preliminary histories, the fresh scallops were bought from several markets from different districts comprising Wong Tai Sin, Sham Shui Po, Kowloon City and Tuen Mun.
The cases have been referred to the Food and Environmental Hygiene Department for follow up action.
Members of the public should seek medical advice immediately if they develop shellfish poisoning symptoms and save any leftovers for investigation and laboratory testing.
CHP's investigation continues.
Shellfish poisoning can result from ingestion of shellfish contaminated with a kind of toxin called phycotoxins. These toxins are produced by free-living micro-algae, upon which the shellfish feed.
"Bivalve shellfish such as scallops, clams, mussels, oysters, fan shells, which are filter-feeders and naturally ingest the toxic algae in water, are common vehicles responsible for shellfish poisoning.
"When the algae are toxin-producing, the toxins will be concentrated in the shellfish tissue, particularly in the inside organs. The amount of toxin in the shellfish depends on the number of toxic algae ingested," the spokesman said.
Depending on the type of toxins, the clinical symptoms of shellfish poisoning include tingling, numbness, burning of perioral region, diarrhoea, abdominal pain, nausea and vomiting. Severe cases may have difficulty in speaking or breathing. Symptoms usually occur a few minutes to a few hours after consumption of the contaminated shellfish.