Analysis of the source of a cholera outbreak caused by O139 Vibrio cholera

Objective The study was conducted to trace the source of cholera infection by analyzing the molecular characteristics of the Vibrio cholera O139 isolates obtained from patients and snapping turtles involved in a cholera outbreak.Methods Three strains of Vibrio isolated from patients and three from snapping turtles on aquatic products markets associated with the epidemic were analyzed for the virulence-related genes(ctxAB,toxR,zot) using PCR and subtyped using PFGE.Cluster analysis was conducted using Bio-Numeric V 4.0.Results All six V.cholera strains were positive for the virulence-related genes,which indicated that they were all toxigenic.Clustering into two PFGE subtypes,these strains contained one subtype that was identically found in two isolates from snapping turtles and other three from patients,and another from turtles that formed a separate subtype.Both subtypes of the six isolates were different from those of the V.cholera O139 detected in a food-borne outbreak in other province of China,according to the information from the Pules Net China database.Conclusion The snapping turtle was a potential source of the cholera outbreak,Turtles from markets might have been contaminated with V.cholera O139 that carried virulence genes.Therefore,such aquatic products as especially snapping turtles should be focally inspected so as to better control and prevent cholera in this area.