Joint bid to cut toxic-fish risk

PUBLISHED : Monday, 02 February, 2009, 12:00am
UPDATED : Monday, 02 February, 2009, 12:00am

Hong Kong scientists are part of an international team developing better tests for toxins in coral fish with the help of the Pacific island nation of Kiribati.

The City University-led research is using coral fish samples from Kiribati to develop rapid testing methods for ciguatera and paralytic shellfish poisoning toxins.

Ciguatera food poisoning is mainly associated with the consumption of big coral fish, which accumulate the toxin in their bodies through years of eating small fish that consume toxic algae in coral reef seas. It can cause gastrointestinal and neurological symptoms in people several hours after eating the fish.

Paralytic shellfish poisoning toxin is a natural toxin sometimes found in bivalve shellfish.

Kiribati fish produce the highest levels of ciguatera toxin in the Pacific region, said associate professor Michael Lam Hon-wah.

'People in Kiribati have their own method of detecting ciguatera. They cut the fish, take a slice of the liver and wipe it around their lips. If they feel numbness, the fish might be contaminated. The whole catch will be destroyed,' Dr Lam said.

Tests for shellfish poisons existed, but it was still worth developing reference standards and rapid tests for both toxins, chair professor of biology Paul Lam Kwan-sing said.

'Incidences of food poisoning have been increasing in recent years with increasing international trade in seafood,' he said.

Using a fresh approach to diagnostics, the team was able identify new proteins in contaminated fish.

'Our preliminary data showed that these proteins were only being produced by contaminated fish,' Professor Lam said.

'If we come up with monitoring kits to detect the presence of toxins in seafood, we can single out contaminated fish without destroying the whole stock or overdoing the killing.'

A total of 385 cases of ciguatoxin poisoning affecting 1,356 people and 69 cases of shellfish poisoning affecting 145 people were reported in Hong Kong from 1997 to 2006, according to the Centre for Health Protection.

The Centre for Food Safety detected shellfish toxin last September in a prepackaged scallop during routine tests. Cases of ciguatera fish poisoning were related to live coral-reef fish imported from areas such as the Spratly Islands and the South Pacific.

The HK$3.2 million project is funded by the University Grants Committee's research grants fund.