Now and again we are reminded by an occasional outbreak of one of the enteric fevers that infection-carrier control still falls short of perfection. The attainment of perfect control would ideally entail recognition of all unwitting hosts and the eradication of their unwelcome bacterial guests. To date neither of these measures has been completely successful. Excretors of Salmonella typhosa and S paratyphi may be missed if the infection which preceded the carrier state has not been correctly diagnosed. The carrier state may persist despite cholecystectomy or treatment with antibiotics. Even ampicillin, which showed promise of bacterial eradication, has not proved completely successful. Of 52 excretors of S typhi recently reported in a series by Russell,1 three have remained chronic carriers after three months of treatment with ampicillin.
Since clearance of carrier state has not yet been attained, control becomes largely a matter of supervision and detection. Detection is by