zoonoses and communicable diseases common to ... - PAHO/WHO

FOOD POISONING CAUSED BY VIBRIO PARAHAEMOLYTICUS 141with a darker green center. As a pre-enrichment medium, water with 1% peptone and3% salt can be used. Wagatsuma medium is used to determine whether the cultureis Kanagawa-positive or negative.Prevention: The main recommendation is to cook shellfish, crustaceans, and fishat a sufficiently high temperature (15 minutes at 70°C) to destroy V. parahaemolyticus,with particular attention to the volume of the seafood in order toachieve the appropriate temperature.However, the well-established custom in some countries of eating raw seafoodmakes it very difficult to enforce the recommendation to inactivate V. parahaemolyticusin fish, crustaceans, and mollusks by sufficiently cooking these foods.An experiment conducted to study the increase of hemolysin in comparison with thebacterial count reached the conclusion that the toxin appears when V. parahaemolyticusreaches the level of 10 6 per gram and continues to increase with multiplication ofthe microbe. At 35°C it reached 32 units of hemolysin per gram after 24 hours; at 25°Cit reached this level after 48 hours. Once formed, hemolysin is quite stable. Hemolysinshowed its maximum heat resistance at a pH of between 5.5 and 6.5. The Kanagawahemolysin in shrimp homogenate proved to be stable for 17 days when kept at 4°C; attemperatures between 115°C and 180°C, it took between 48.1 and 10.4 minutes forthermal inactivation as demonstrated in rats (Bradshaw et al., 1984).The results of this and other experiments indicate that from the outset it is necessaryto prevent the load of V. parahaemolyticus in seafood as much as possible. Acontra-indicated practice is washing fish or other seafood in contaminated estuarinewater. Cold storage is recommended as soon as possible after cooking. Table surfaceswhere these products are processed should be waterproof and must be completelycleaned with fresh water (without salt) as there may be cross contamination,particularly from salted foods.BibliographyBenenson, A.S., ed. Control of Communicable Diseases in Man. 15th ed. An official reportof the American Public Health Association. Washington, D.C.: American Public HealthAssociation; 1990.Bradshaw, J.G., D.B. Shah, A.J. Wehby, et al. Thermal inactivation of the Kanagawahemolysin of Vibrio parahaemolyticus in buffer and shrimp. J Food Sci 49:183–187, 1984.Chakrabarti, M.K., A.K. Sinha, T. Biswas. Adherence of Vibrio parahaemolyticus to rabbitintestinal epithelial cells in vitro. FEMS Microbiol Lett 68:113–117, 1991.Doyle, M.P. Pathogenic Escherichia coli, Yersinia enterocolitica, and Vibrio parahaemolyticus.Lancet 336(8723):1111–1115, 1990.Kelly, M.T., E.M. Stroh. Urease-positive, Kanagawa-negative Vibrio parahaemolyticusfrom patients and the environment in the Pacific Northwest. J Clin Microbiol 27:2820–2822, 1989.Klontz, K.C. Fatalities associated with Vibrio parahaemolyticus and Vibrio cholerae non-O1 infections in Florida (1981 to 1988). South Med J 83:500–502, 1990.Magalhães, V., R.A. Lima, S. Tateno, M. Malgahães. Gastroenterites humanas associadas aVibrio parahaemolyticus no Recife, Brasil. Rev Inst Med Trop Sao Paulo 33:64–68, 1991a.Magalhães, M., V. Malgahães, M.G. Antas, S. Tateno. Isolation of urease-positive Vibrioparahaemolyticus from diarrheal patients in northeast Brasil. Rev Inst Med Trop Sao Paulo33:263–265, 1991b.