Cholera in Yangon, Myanmar, 2012–2013

To the Editor: Vibrio cholerae O1, a causative agent of cholera, is classified into 2 biotypes, classical and El Tor.Since 1817, cholera has spread from the Indian subcontinent to other regions of the globe 7 times (1).However, little information on the occurrence of cholera and V. cholerae in Myanmar has been published.Here, we report cholera cases and characterization of 58 clinical isolates of V. cholerae O1 serotype Ogawa recovered from patients with diarrhea in Yangon, Myanmar, during February 2012-June 2013.During February and August 2012, rectal swab specimens were collected from patients suspected of having cholera in 4 hospitals in Yangon: New Yangon General Hospital, North Okkalapa General Hospital, Thingangyun Sanpya General Hospital, and Yangon Children Hospital.The specimens were cultured on thiosulfate citrate bile salts sucrose agar plates.After overnight incubation, several colonies that resembled to those of V. cholerae were confirmed as serogroup O1 by using slide agglutination tests with specific monoclonal antibodies (2).Of the tested specimens, 34 isolates carried the tcpA gene, encoding the structural subunit of toxin-coregulated pilus, and the rstR gene, the repressor gene in the cholera toxin encoding (CTX) phage (3); these results may indicate that these strains belonged to the El Tor biotype.However, identification of the sequence type of the cholera toxin B subunit gene in these isolates revealed that they were of classical type (ctxB Cla ).Thus, these isolates were classified as atypical El Tor V. cholerae O1 (4)