Hybrid El Tor Vibrio cholerae O1, Kuwait

To the Editor: The traditional causative agent of cholera, Vibrio chol-erae O1, has 2 biotypes, classical and El Tor. The current seventh pandemic that began in 1961 and has spread to much of the world is caused by the El Tor biotype. This biotype has replaced the classical biotype responsible for the previous pandemics. The classical and El Tor biotypes are differentiated by phenotypic tests (1), and several nucleotide base differences occur at positions 115 and 203 in the ctxB gene (C in both positions in the classical and T in both positions in the El Tor biotype). These differences translate to histidine at amino acid position 39 and threonine at amino acid position 68 for the B subunit of cholera toxin (CT) in the classical biotype and ty-rosine and isoleucine, respectively, for the corresponding amino acids in the El Tor biotype (2). Recently, 3 variants of the El Tor biotype have been found. These are the Matlab variants, which could not be biotyped because they have a mixture of classical and El Tor traits (1); the Mozambique variant, which has a typical El Tor genome but a tandem repeat of the classical CTX prophage located in the small chromosome (3); and the hybrid El Tor variant, which has a typical El Tor biotype and an El Tor CTX prophage but produces CT of the classical type (4). This hybrid El Tor variant has replaced the El Tor biotype in Dhaka and other parts of Bangladesh (4) and in India (5), Japan, Hong Kong, Zambia, the People's Republic of China, Sri Lanka, and Vietnam (6). Kuwait was affected by cholera in the mid 1960s during the current seventh pandemic. Subsequently, cholera disappeared from Kuwait as living standards improved. Screening of ≈5,000 acute-phase diarrheal stool samples in the mid-1980s in a major hospital in Ku-wait did not yield V. cholerae O1 (7). The occasional cholera cases detected in Kuwait are imported, mainly from Asia through expatriate workers. Two adult men, one who had just arrived from India and one who had just arrived from the Philippines, were admitted with severe watery diarrhea, vomiting, and dehydration to the Al-Adan Hospital, Kuwait, in November and December 2008, respectively. The patient from India reported eating in restaurants, and the patient from the Philippines had consumed fi sh soup just before the journey. Both patients were initially rehydrated with intravenous fl uids. Stool cultures were …