Radial counter-immunoelectrophoresis for rapid sero-diagnosis of typhoid fever.

Serum samples were collected from 24 confirmed cases of typhoid fever and 23 normal healthy controls. Convalescent sera from the patients were obtained, wherever possible, one week after the first sample. In all, 13 paired sera, 11 acute phase only and 23 normal serum samples were tested for ability to elicit precipitins to Salmonella typhi by radial counter-immunoelectrophoresis using cellulose acetate membranes. In addition, conventional counter-immunoelectrophoresis (CIE) was performed using agar-gel layer for comparison. One of 24 acute phase sera gave positive results whereas all 13 convalescent sera were positive by both methods. The radial CIE test may be useful for rapid sero-diagnosis of typhoid fever as it takes only 4 min and can be used to screen large numbers of serum samples from patients suspected of typhoid fever.