foodsafety mussels
TRANSCRIPT
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