Eating shellfish contaminated by bacteria, viruses and toxic plankton most often causes symptoms similar to those of stomach flu (stomach ache, diarrhoea, nausea and vomiting), which occur shortly after ingestion, and generally for a few hours to a few days. Sometimes, the contaminated shellfish can be responsible for far more serious infectious diseases, such as hepatitis A or typhoid fever or, in the event that other forms of toxic plankton are ingested, serious neurological and respiratory disorders that can ultimately lead to death.
The likelihood of infection is proportional to the amount ingested and the seriousness of the intoxication depends a great deal on the consumer’s physiological and immune condition. For this reason, small children, the elderly, people recovering from illness and people with weak immune systems are the most vulnerable.
The effects of chemical compounds on the health system do not occur as acutely as with microbial or phytoplankton poisoning, unless they are ingested very quickly, in large quantities. They are toxic in the long term and can carry risks if contaminated and ingested on a regular basis for many years.
