Shellstock Abstract

Development of smart TTI-labels indicating risk of Vibrio growth in fresh molluscan shellfish for human consumption.

 Peter Ronnow Ph.D., Vitsab International AB, Sweden


During the years 1989 to 2002, the U.S. FDA recorded 341 cases of Vibriosis.
The majority of these sicknesses were related to the consumption of raw oysters. More than 52% of the severely infected persons died as a cause of the Vibrio infection.
The Center for Disease Control and Prevention (CDC) started in May in 2013 to monitor the occurrence of Vibrio paraheamolyticus in costal-waters of USA in 13 states with federal and state partners.
By the end of September 104 cases of Vibriosis were reported from consuming raw or undercooked shellfish, primarily oysters.

The growth of Vibrio spp. in shellfish after harvest is a typical time-temperature relationship which can be used as a predictive model for growth of Vibrio species. With the predictive growth models of Vibrio paraheamolyticus and Vibrio vulnificus, supplied by FDA researcher John Bowers, Vitsab developed new TTI-formulations well adapted to the Vibrio species growth.



During the oyster harvest season in the summer of 2015 several new TTI-formulations were used in collaboration with Kristin Derosia-Banik, State of Connecticut, Department of Agriculture, Bureau of Aquaculture and Laboratory services.


Oysters were harvested in Long Island Sound outside the town Norwalk by a local oyster producer. At harvest the oysters close up and during storage on boat deck the temperature inside oysters quickly rise to levels where Vibrio species have high or very high growth rates and within in a number of hours, can reach several doublings constituting a significant health risk when consumed raw.


It was suggested to oyster growers by Kristin Derosia-Banik to use a cooling procedure to control oyster temperature during harvest minimizing Vibrio counts in the oysters.



In the present oyster harvest study the Shellstock TTI-labels, indicated if Vibrio spp. growth have exceeded either one or three doublings proving that these Shellstock-TTIs are a useful and powerful tool in validating improved handling and cooling procedures.


Applying the developed TTI-labels in the further transport of oyster to customers, locally as well as for longer national transports is a perfect means to validate a proper chill chain for the full length of molluscan shellfish distribution.