Risk assessment of vibrio parahaemolyticus in white shrimp (Litopenaeus vannamei) from retail market

Abstract

Vibrio parahaemolyticus is the leading cause of seafood borne gastroenteritis in many countries including Thailand. It is a gram-negative, halophilic bacterium which was normally found in estuarine environment and seafood. The infection usually occurred from consuming raw, inadequate cooked, or cross-contaminated seafood. Risk assessment is a scientific tool to evaluate health hazard from V. parahaemolyticus infection. In this study, a risk of V. parahaemolyticus infection from raw shrimp consumption (Litopenaeus vannamei) was conducted. This study estimated the prevalence and level of V. parahaemolyticus in 2 retail types across 6 provinces nationwide by 3-tubes MPN. Risk assessment from raw shrimp consumption was estimated from prevalence and level of pathogenic V. parahaemolyticus carrying tdh and trh genes by multiplex PCR. The prevalence of total and pathogenic V. parahaemolyticus was 66% and 1.4%, respectively. Pathogenic V. parahaemolyticus carrying tdh and trh genes were 0.93% and 0.46%, respectively. V. parahaemolyticus isolates carrying both tdh and trh genes was not detected by multiplex PCR. Estimated daily risk for raw shrimp consumption was predicted at 1.02×10-4 equivalent to incidence rates per 100,000 people at 3,711 cases per year. Sensitivity analysis from simulation showed that risk estimates was highly correlated with probability of illness (correlation coefficient or r = 0.94), followed by time between retail to consumption (r = 0.22), concentration at consumption (r = 0.16), and dose (r = 0.15). Moreover, the study has found the proper cooking of shrimp such as 60°C for 2 minutes can reduce risk from V. parahaemolyticus to safe negligible level.