The outbreak of typhoid fever in Aberdeen during 1964 (Walker, 1965) presented an opportunity to study the antibody titres of typhoid fever patients and of TAB immunized individuals to obtain further knowledge concerning the behaviour of these titres with the passage of time.
This paper gives an abbreviated version of part of a research programme which followed the Aberdeen typhoid outbreak of 1964.
The antibody titres of patients were followed up for a period of 2 years after discharge from hospital and the findings have been compared with those in TAB immunized healthy individuals. The following points emerged:
(1) The value of the Widal test as an aid to diagnosis was limited;
(2) the flagellar antibody titre in patients' sera provided a more reliable aid towards diagnosis than did the somatic antibody titre;
(3) the response of immunized and non-immunized patients to the somatic antigens was poor and often delayed well into the period following discharge from hospital;
(4) titres of 1/40 and over for Vi agglutinins were present in immunized and non-immunized patients for at least 12 months after discharge without their being S. typhi excretors;
(5) Vi agglutinin titres as high as 1/40 were present in TAB immunized healthy individuals and also in members of the general public;
(6) the presence of S. typhi septicaemia need not result in a high antibody titre; (7) patients who relapse, may do so without enhancement of previous antibody titres and may relapse even in the presence of earlier appreciable titres.