The geographical distribution of Salmonella typhi and Salmonella paratyphi A and B phage types during the period 1 January 1970 to 31 December 1973. A report of the International Federation for Enteric Phage-Typing (IFEPT).

The frequency distribution is presented of the Vi-phage types of Salmonella typhi and of the phage types of S. paratyphi A and S. paratyphi B, examined by the National Centres represented in the IFEPT from 1970 to 1974. The most common types encountered in this international study were A and E1 (= E 1 a), as has been previously observed. There was, however, a wide range of types, many of which are characteristic of particular geographical zones. The occurrence of such types out of their habitual context indicates their ''exotic'' origin, providing a useful clue to their probable source. Plasmid-mediated chloramphenicol resistance appeared in epidemic typhoid fever for the first time during this period. It occurred in Mexico, India, Vietnam and Thailand, and has assumed important proportions. All the plasmids concerned belonged to compatibility group H 1. The study of this phenomenon continues, and the findings will appear in future reports.