Cholera is caused by-: (A) V.cholerae O1, (B) V.cholerae O1 and O139, (C) V. cholerae O139, (D) NAG vibrios
Answer is B. Vibrio cholerae is sero-grouped on the basis of 'O' antigen into several 'O' serogroups. Of these, O1 and O139 produce the cholera toxin. Hence cholera is caused by only these 2 serogroups ( as only that enteritis is called cholera which is due to cholera toxin )