Excise Dutch recipes for the Zeeuwse mussel

a mussel masterclass

chief

Willem van Leeuwen

“Cooking” an important step in food safety

EU guidelines: foodsafety - shellfish production management.

Obliged monitoring in NL:

Toxins (algae biotoxins):

diarrheic-, amnesic- and paralytic shellfish poisoning (DSP,

ASP,PSP)

Bacteria:

Salmonella (human pathogen)

Escherichia coli (non pathogen)

Virus:

Hepatitis A virus

Not obliged (??) Noro virus

Prevalence of shellfish foodpathogens in NL

Based on clinical prevalence studies in Dutch healthcare centers and in the

community (general practionner)

Salmonella: in 2010, 2011 and 2012 no cases related to shellfish

consumption (data RIVM: registration food infections)

Hepatitis A virus: in 2010, 2011 and 2012 no cases related to shellfish

consumption (data RIVM: registration food infections)

The prevalence of both pathogens is extremely low among shellfish

E. coli: quantitative analysis (< 230 cfu per 100 gram) indicator of fecal

contamination of human, cattle (cause: e.g. failure of waste water

purification)

Norovirus as an example

Eating shellfish may be a risk factor for Norovirus infection.

How large is the risk for NoroV contamination of the mussel? LOW

How can we lower this risk?

Epidemiological studies of Norovirus prevalence in mussel

production areas.

Frequent screening of shellfish on the presence of Norovirus by

the mussel farmer to guarantee food safety of the product.

Viruscontrol

A collaboration between:

Qualitative and quantitative screening of shellfish

E.coli

Salmonella

Norovirus

Norovirus as an example

Worldwide prevalence among human (and mammals) of all ages

50% of gastro-enteritis cases : cause Norovirus

In NL general practionner 500.000 on annual basis, of wich1000

cases of hospitallization

Symptoms: vomiting, abdominal cramps,

non-bloody diarrhea

Diagnostic symptoms resolving 2-3 days

Incubation time: 24-48 h

Risk patients (complication): <5 y, >80 y,

pregnancy, immunocompromized patientsInfo: Infectiebulletin RIVM

Transmission

Via human fecal – oral route

Via (fecal contaminated) food, water

and shellfish (pre harvest)

Via mammals (pigs, cattle) NoV GII.4

is yet unknown (Mattison 2007, Koopmans,2004)

Not healthcare-associated

Outbreak related (close communities):Low infection dose (<10 virus particals)

Prolonged duration of viral shedding (consequences are not clear)

High stability for desinfectans (e.g. chlorine)

Repeated infections throughout life (no immunisation; short-lived immunity of 6-14

wk)

Epidemiology

Human GII.4 is also isolated from pigs and cattle meat and fecal

samples (Mattison et al 2007), but transmission is not yet studied (Koopmans 2004)

Epidemiological raise after long-term rainfall (overloaded waste water

system?) (Marshall et al 2011).

and in winterperiod.

survival NoV at Twater 4C is significantly higher than at Twater 20-23C (3

months vs 3 weeks) (Koopmans 2004)

Prevention and control

Noro is not treatable (no medicin)

Self limiting: after 2-3 days recovery, but shedding NoV (44.5 days)

after infection (reservoir) (Tu ert al 2008)

Desinfection: virus is highly stable (alcohol does not help) (Koopmans 2004)

UV, ozon and (high concentration of) CHLORIDE kills NoroV. (Richards et al

2010)

Identification of transmission

Control of food (surveillance of shore lines to identify possible

sites of NoV contamination)

Maintenance of strict hygiene by food handler.

NoV diagnostics

challenges:

<20 virus particles cause GE infection – need for highly sensitive

diagnostic techniques (Lee et al 2007)

NoroV is non culturable (Allmar & Elis, 2001) and therefore…

Quantification not possible

results with 657 copies/gram is nonsense (watch the curve!)

Virusses are too small for lightmicroscopy (labeling)

E.M. virus visible, but timely, complex and not sensitive

Last decade, these issues are resolved by the use of “molecular

techniques”: PCR (analysis of DNA)

Conclusion

the Zeeuwse mussel is

deliciouslysafe

acknowlegdements