Four outbreaks of shigellosis recently occurred aboard a Naval vessel (1). Several shigella carriers were found who were considered to be the source of infection in the last two outbreaks. A study of these carriers (with particular reference to their therapy) was undertaken since they constituted a major problem in eradication of the disease.
It is obvious that a large number of persistent shigella carriers can be an epidemiological problem. Manson-Bahr (2) reports an individual who excreted dysentery bacilli for a period of three years. In an excellent review, Neter (3) states that carrier rate surveys have varied from 3–80 per cent and that 3 per cent of convalescent carriers excrete organisms for more than three months after the onset of the disease. Watt et al. (4) studied 57 cases of Shigella flexneri infections. Among this group 45 individuals (79 per cent) became convalescent carriers, in 38 of whom the duration of the carrier state was determined.