Intrafamilial transmission of Salmonella oranienburg

BACKGROUND: There were diffuse outbreaks of Salmonella oranienburg in Japan since March 1999 which included 1505 patients. The outbreak was caused through ingestion of a dried squid snack contaminated with S. oranienburg. Such a large number of cases has not been previously recorded in Japan or other countries. METHODS: A 9-month-old boy was admitted to our hospital with enteritis and bacteremia due to S. oranienburg. His older brother had eaten the contaminated snack. We detected S. oranienburg in the stools of five out of his six family members. RESULTS: With the exception of the index case's brother, no other family members had eaten the contaminated snack. The S. oranienburg strain detected in the family was confirmed to be the same strain by pulse field gel electrophoresis. Therefore, we presumed there had been a series of household transmissions. CONCLUSION: Our observation of intrafamilial transmission suggests that S. oranienburg may be highly infectious.