Fifty-seven new O serogroups have been added to the existing serotypin
g scheme of Vibrio cholerae to extend the scheme from O84 to O140. Pro
minent new additions were serogroups O139 and O140. The reference stra
in of O139 was isolated from a patient from an epidemic of cholera-lik
e diarrhea in Madras, Southern India. Serogroup O140 was assigned to a
group of V; cholerae strains which were tentatively named as the ''Ha
kata'' serogroup and which possessed the C (Inaba) factor but not the
B (Ogawa) nor the A (major specific antigen of O1 serogroup of V. chol
erae). As all antisera against reference strains of V; cholerae contai
ned some amount of antibody to the rough (R) antigen, all diagnostic O
antisera must be absorbed with the reference rough strain, CA385.