Amnesic shellfish poisoning

Amnesic shellfish poisoning is an illness caused by poisoning with a particular toxin called "domoic acid".
At times, some diatoms produce domoic acid in ocean water. Shellfish accumulate this poison, and when they are eaten by people, the people get poisoned. The symptoms may be very severe: they include permanent memory loss, brain damage, and vomiting.
This disease was discovered in 1987 in eastern Canada when many people got poisoned after eating shellfish in a restaurant. Several people died of this disease then.
Birds can get this disease too when they eat poisoned shellfish. Such birds lose the coordination ability, and may crash into car and house windows.
Scientists found that the incidents of this disease occur more frequently in the recent years.
In the United States it is illegal to catch and sell shellfish without a license. Caught shellfish have to be frequently tested. When this toxin is found in the shellfish, government bans fishing and selling it in the area.
In the UK, all shellfish caught for restaurants or sale to the public are put in clean water for at least two days before being brought to market. This is the standard way to protect from poisoning.