Mussels unsafe if eaten raw

Many people in New Zealand like to eat shellfish, such as mussels, raw.  The Ministry of Health and New Zealand Food Safety Authority (Te Pou Oranga Kai O Aotearoa) has warned consumers NOT to eat fresh mussels harvested commercially in Coromandel, an area of the North Island, without cooking them to at least 65C.

The culprit for the current food poisonings is probably Vibrio parahaemolyticus, a bacterium found in marine, coastal and tidal waters, and most commonly causes gastroenteritis.  It is not normally spread person to person, though poor personal hygiene, such as failure to wash hands after handling raw shellfish, could result in infections.

Symptoms usually occur within 24 hours of eating the infected food and include

• watery diarrhoea (occasionally bloody diarrhoea)
• abdominal cramps
• nausea
• vomiting
• fever
• headache.

Image from Pathogen Profile Dictionary

https://www.ppdictionary.com/bacteria/gnbac/parahemolyticus.htm

There is a feeling among some experts that Vibrio parahaemolyticus entered New Zealand in imported fish or shellfish.  Cross contamination in the markets then allowed its spread.

Raw cookie dough and Salmonella

A recent post on FaceBook caused me some concern, amusement and despair.  The argument centred on whether you can get salmonellosis from eating raw cookie dough.  Comments ranged from serious through flippant to borderline insane.

What concerned me was the level of ignorance on basic food safety and the authoritative, but incorrect, advice given.  For example, one writer said that there was no problem with cookie dough containing raw egg, because Salmonella is found only on the outside of the shell; washing the outside of the egg would remove faecal material, rendering the eggs safe.  Both of these comments are wrong.

The egg shell is not an hermetic seal; if eggs are washed and then they cool, moisture can be drawn into the egg and bacteria on the outside may also pass through.  There is a defence mechanism in the egg white.  Lysozyme is an enzyme that can attack the cell wall of Gram positive bacteria.  Unfortunately, Salmonellae are Gram negative, so may survive.  In addition, the hen may be infected with Salmonella, so the egg may be contaminated even before the shell is formed.

Laying flocks in New Zealand are unlikely to be infected with Salmonella because of the biosecurity measures employed on New Zealand poultry farms.  The situation may be different in other countries.

Commercial cookie dough may be made with pasteurised egg, in which case any Salmonellae will have been destroyed.  But unpasteurised eggs may contain Salmonella.

Statements that athletes drink raw egg drinks for breakfast and suffer no consequences are without scientific support.  Arguments that real mayonnaise is made with raw egg are also misleading, as mayonnaise also contains vinegar, which not only loosens the emulsion, but also reduces the pH.

Most of us at some time in our lives have scraped the mixing bowl with no ill effects.  The infecting dose for Salmonella varies with the strain, and we may have been exposed to only low numbers of bacteria.   However, to eat large quantities of raw cookie dough is playing Russian roulette.


My two favourite comments from the many posts:

"I know that if you put Nutella on salmon, you get Salmonella"

"I've eaten it twice, and died both times"

Eat at your own risk?

I just spent a week in Miami attending the 6th American Society for Microbiology Biofilms Conference.  Over 400 biofilm microbiologists met to discuss all aspects of biofilm research.

Of course, nobody can sit in a darkened room and listen to heavy duty research papers all day for a week, and food microbiologists always have to investigate the local food and beverage outlets!

A couple of menus caught my eye.  One was on the waterfront in Downtown, where raw food seemed to be the major offering.  Another was in one of the glorious sidewalk restaurants on Ocean Drive.  Both had almost identical wording:
"Consuming raw or undercooked hamburgers, meats, poultry, seafood, shellfish or eggs may increase your risk of foodborne illness, especially if you have certain medical conditions".

All good, and if you want to eat such delicacies, you need to be informed of the risks.  Consumption of any of these foods can potentially lead to illness.  Consumers are totally dependent on the purity of the raw materials and the water from which they are sourced, as well as the hygiene of preparation; a range of bacteria and viruses can be found in raw foods.

I wonder what Bill Marler would have to say about such a disclaimer - is the restaurant owner absolved of responsibility, assuming they take reasonable care in preparation, if a customer can show that they became ill as a result of eating the raw or rare-cooked food?