Tuesday, December 18, 2012

Toxic kai moana. Summer warnings

In what has been termed the worst toxic shellfish poisoning in the region's history, twenty people have become ill after eating shellfish collected in New Zealand's Bay of Plenty.  Ten of these victims have been hospitalised and two are in intensive care.

The symptoms of this type of paralytic shellfish poisoning (PSP) range from numbness of the lips, through to vascular collapse and respiratory failure.  The toxins are actually a group of chemicals called saxitoxins and gonyautoxins and are produced by certain species of algae and released into the shellfish after ingestion.

Kai Moana means seafood in the Maori language and at this time of year, when families gather at beaches for barbecues and picnics, many people will collect shellfish to eat.  Unfortunately, cooking will not destroy the toxin, which is produced by dinoflagellates ingested by the shellfish.  Though it is difficult to measure precisely, it appears that mussels filter between 8 and 10 litres of water per day, so they are able to concentrate the dinoflagellates to high levels in their gills and gut.  The dinoflagellates themselves grow more rapidly in warm water containing high levels of nutrients.  They may be responsible for 'red tides'.

The only way to be safe is to heed warnings not to collect shellfish from the affected waters.  Signs are usually erected by the Ministry of Primary Industries warning of the risk and indicating the extent of affected waters.

And while you are planning your summer picnics and barbecues, think about how you will keep your family safe from other forms of food poisoning.  Make sure that meats and fish are kept cool, and handle only with washed hands.  If you are barbecuing, make sure that food is cooked thoroughly and remember to use clean plates and utensils for serving cooked food, as raw meat may contain pathogens.

Above all, have a safe and happy Christmas holiday.  Thanks for reading Safe Food in 2012.

John




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