AGGLUTINATING, LETHAL TOXIN AND E1 TOR HAEMOLYSIN NEUTRALIZING POTENCY OF SERA IN CHOLERA

There is a lack of agreement as to the significance of agglutination test results in cholera, and recent epidemics of "classic" Vibrio comma and El Tor infections have provided an opportunity to compare this test with two other serological procedures recently introduced in cholera work. These are determination of the circulating antitoxin expressed as the lethal toxin neutralizing power of a serum, and determination of the haemolysin neutralizing power through serial test-tube dilutions.Applying these tests to sera from cholera patients, convalescents, carriers and contacts and from immunized persons either exposed or not exposed to cholera, the authors found the agglutination test to be a less sensitive indicator of the immunological status than the other two procedures. They therefore recommend antitoxin and antihaemolysin titration for the study of cholera patients, convalescents and carriers. In the conditions of the experiments described, the results with exposed and non-exposed vaccinated individuals were less conclusive, but nevertheless suggest that antitoxin and antihaemolysin tests may be helpful in the follow-up of vaccination experiments.