Wednesday 24 October 2007

Falmouth and Truro Port Health Authority

Responsible for monitoring and classification of live bivalve mollusc harvesting areas. In regards to human health.

Viral infections and shellfish
Estuaries used for sewage disposal and oysters and mussels are filter feeders (oysters filter 10-24 litres of water per hour) and can concentrate pathogens. Shellfish are usually eaten raw or lightly cooked. Main pathogens are norovirus, causing gastroenteritis and hepatitis B, and E. coli which causes food poisoning.

DSP - Diuretic shellfish poisoning
PSP - Paralytic shellfish poisoning
ASP- Amnesiac shellfish poisoning

Outbreaks caused by shellfish
Scandinavia - 1997
China - 1998
Spain - 1999
France and Italy - 2002

E. coli is present in human and animal faeces and is used as an indicator when testing but its absence does not guarantee other viruses are not present. CEFAS manages monitoring on behalf of the Food Standards Agency, which dictates policy to local enforcement agencies.

50 local enforcement agencies
16 testing laboratories
75 production areas (371 rope, trestle and natural beds)

Classification
A - less than 230 organisms per 100g - direct human consumption
B - less than 4600 per 100g - purified by depuration before consumption
C - less than 46000 per 100g - relayed for at least 2 months before reclassification as B
D - more than 46000 per 100g - not for human consumption, prohibited

Figures for England in 2007
A - 2.6%
B - 88.4%
C - 7.1%
D - 1.9%

Classification based on trends not individual results, data sets based on 10 monthly examinations with randomised timings to accommadate environmental variables such as tide, winds, rainfall runoff, sewage discharge times and seasons.

Depuration
Purification in tanks with circulated, purified seawater and UV lights for 42 hours which reduces E. coli to less than 230 per 100g (class A). Water temperature and salinity can be set for different species to induce filter feeding.

http://www.falandtruropha.co.uk/

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