Detection of carriers of typhoid bacilli by sewerage-tracing surveillance in Matsuyama City.

Since periodical survey of the sewage entering the sewage-farm in Matsuyama City revealed a high incidence of Salmonella typhi of different phage types, attempts were made to trace the upstream reservoir. It was found that S. typhi was drained into a particular manhole at a distance of about 5 km from the sewage-farm. Two members of two families were found to be carriers. Further investigation detected other 25 carriers. The 27 carriers were all pupils of the same primary school. Ten of them showed mild symptoms such as fever, abdominal pain and diarrhea; the remaining 17 were asymptomatic. The phage type of 24 isolates was of Vi degraded approaching phage type A [degraded Vi(A)] and that of the other three was of type 53. The results coincided with those of the isolates from sewage.