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Resurgence of cholera linked to iced tea, unboiled water consumption
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The chances of infection from cholera were heightened for people in Ben Tre, southern Vietnam, when they drank iced tea or did not always boil their drinking water according to a study published in PLOS Neglected Tropical Diseases.
Two of 25 river water samples and one of six wastewater samples from the area tested by researchers were contaminated with Vibro cholerae O1 Ogawa carrying cxtA.
“Prior to implementation of control measures, Vietnam suffered a disproportionate burden of cholera,” Thuong V. Nguyen, MD, PhD, DTM&H, senior medical epidemiologist at the Pasteur Institute in Ho Chi Minh City, Vietnam, and colleagues wrote. “[A vaccination program], in conjunction with improved personal hygiene and access to potable drinking water associated with both health promotion programs and economic growth, led to a substantial drop in the number of notified cholera cases. However, these gains have not been sustained.”
To examine whether cholera is transmitted in the midst of an outbreak, a matched case-control study was conducted in Ben Tre. The potential risk factors associated with cholera infection were also analyzed.
Between May 9 and August 3, 2010, 60 patients with diarrhea with confirmed cholera infection were included in this study as case-patients, who were then matched one to four- to controls based on commune, sex, and 5-year age groups. They then assessed risk factors and took environmental samples from the case-patients’ villages for the purpose of recognizing sources of contamination.
When compared with just 3% of controls, 22% of case-patients drank iced tea within 1 week before onset. An increased number of case-patients also drank water with ice (81% vs. 68%), unboiled water (65% vs. 43%) and sedimented river water (12% vs. 5%). Case-patients also were more likely to use river water for bathing (52%), brushing teeth and gargling (33%) and cooking (42%), results that are nearly two times higher than seen in controls.
Factors that protect against cholera infection in controls included using stored rain water for drinking (89%) and cooking (41%), eating cooked seafood (81%), steamed vegetables (31%) and raw vegetables (32%). Living situations also contributed to protection from infection, with 2% of controls living with people who had acute diarrhea compared with 15% of case-patients.
The researchers call for future microbiological and epidemiological investigation on cholera in commercial ice in Vietnam.
“Locally, iced tea is made by adding cooled boiled tea to a glass or bottle of ice. Ice is typically bought from street vendors rather than prepared at home in rural or semi-rural areas of Vietnam because less than one-eighth of rural households own a refrigerator,” Nguyen and colleagues wrote. “In Vietnam where untreated wells and surface water — such as river water — have been commonly used for making commercial ice, it is possible for V. cholerae to be introduced into commercial ice, and such contamination could have triggered this resurgence of cholera in Ben Tre province.” — by Katherine Bortz
Disclosure: The researchers report no relevant financial disclosures.
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