Detection of Vibrio cholerae in environmental waters including drinking water reservoirs of Azerbaijan Ahmadov Rashid, 1 Bradd J. Haley, 2 Mukhtar Rajabov, 1† Sevinj Ahmadova, 1† Shair Gurbanov, 1 Rita R. Colwell 2,3,4,5 and Anwar Huq 2,6 * 1 Republican Anti Plague Station, Ministry of Health, Baku, Azerbaijan. 2 Maryland Pathogen Research Institute, University of Maryland, College Park, MD, USA. 3 Center of Bioinformatics and Computational Biology, University of Maryland Institute of Advanced Computer Studies, University of Maryland, College Park, MD, USA. 4 Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA. 5 CosmosID, 387 Technology Dr, College Park, MD, USA. 6 Maryland Institute for Applied Environmental Health, School of Public Health, University of Maryland, College Park, MD, USA. Summary Cholera, a globally prevalent gastrointestinal dis- ease, remains a persistent problem in many countries including the former Soviet republics of the Caucasus region where sporadic outbreaks occurred recently. Historically, this region has experienced cholera during every pandemic since 1816; however, no known comprehensive evaluation of the presence of Vibrio cholerae in surface waters using molecular methods has been done. Here we present the first report of the presence of V. cholerae in surface waters of Azerbaijan and its seasonality, using a combination of bacteriological and molecular methods. Findings from the present study indicate a peak in the presence of V. cholerae in warmer summer months relative to colder winter months. In the Caspian Sea, water tem- perature when optimal for growth of V. cholerae was significantly associated with detection of V. cholerae. Vibrio cholerae was simultaneously detected at freshwater sites including two water reservoirs. Most importantly, detection of V. cholerae in these water reservoirs, the source of municipal drinking water, poses a potential health risk to the population due to the limited and insufficient treatment of water in Azerbaijan. Routine monitoring of environmental waters used for recreational purposes, and especially drinking water reservoirs, is highly recommended as a measure for public health safety. Introduction Vibrio cholerae, the causative agent of cholera, has been isolated from marine, estuarine and fresh surface waters throughout the world. Historically, epidemic cholera was caused only by toxigenic strains of the O1 serogroup. In 1992, a new serogroup, O139, emerged and caused more than 10 000 deaths in India and Bangladesh (ICDDRB, 1993; Ramamurthy et al., 1993). Vibrio cholerae non- toxigenic non-O1/non-O139 strains may also cause small outbreaks and sporadic cases of cholera, as well as extra- intestinal infections (Safrin et al., 1988; Ko et al., 1998; Lukinmaa et al., 2006; Shannon and Kimbrough, 2006; Chatterjee et al., 2009). These mild cases often go undi- agnosed. Furthermore, inadvertently missed detection due to inadequate disease reporting systems in even highly developed countries and failure of many sick indi- viduals to seek medical attention for episodes of diar- rhoea result in considerable under-reporting of intestinal infections on a global scale (Brabazon et al., 2008; Mac- Dougall et al., 2008; Vogel, 2012). Thus, it is reasonable to conclude that the global burden of illness caused by V. cholerae, along with other infectious agents, is signifi- cantly underestimated, therefore potentially more cases occur than are revealed in the reports. In Azerbaijan, a former Soviet Union (FSU) republic and currently a member of the Commonwealth of Independent States (CIS) in the Caucasus region, cholera has been reported sporadically with large outbreaks occurring at times (Gurbanov et al., 2011). This country reported the fourth most cases of cholera of all the Soviet republics during the Soviet era of the ongoing seventh cholera pandemic (1961 to 1991) (Narkevich et al., 1993). Histori- cally, cholera outbreaks in this country have been repeat- edly linked to drinking water reservoirs that serve the majority of the urban populations (1985, 1993 and 1995) (Gurbanov et al., 2011). The Caucasus region as a whole Received 1 November, 2011; revised 26 June, 2012; accepted 30 June, 2012. *For correspondence. E-mail huq@umd.edu; Tel. (+1) 301 405 7428; Fax (+1) 301 314 1248. † Contributed equally to the laboratory analyses. Environmental Microbiology Reports (2012) doi:10.1111/j.1758-2229.2012.00369.x © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd