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INTRODUCTION

Cholera is an acute infection of the small intestine caused by fecal-oral transmission of the toxigenic bacterium Vibrio cholerae serogroup O1 or O139. In individual patients, cholera presents with the sudden onset of profuse watery diarrhea that can rapidly lead to dehydration and death. In epidemic form, cholera can spread rapidly through entire countries, filling hospitals, cholera treatment centers, and cemeteries. Despite our knowledge of cholera epidemiology, microbiology, and its clinical management, and our success in protecting populations in many countries from epidemic cholera, it remains a major public health concern in Africa, Asia, and the Americas, where populations with limited access to safe drinking water and sanitation continue to suffer cholera illnesses, hospitalizations, and deaths.

Today, cholera is at a crossroads. The current and seventh cholera pandemic, which began in 1961, has lasted far longer and spread further than any of its six predecessors. Climate change, population growth, and armed conflict all have the potential to increase the risk for epidemic cholera. However, recent developments in cholera vaccination, low-cost technologies for improved access to water, sanitation, and hygiene, and the growing capacity to collect, analyze, and map data, could enable us to rapidly reduce that risk. In 2018, the World Health Assembly endorsed “Ending Cholera—A Global Roadmap to 2030,” an ambitious initiative to reduce cholera deaths by 90% and to end cholera as a public health threat in 20 countries by 2030.1 If it succeeds, the end of the seventh cholera pandemic, and perhaps of cholera as a public health threat worldwide, could be within reach.

AGENT AND DIAGNOSIS

Vibrio cholerae is a curved, motile, aerobic Gram-negative bacterium classified principally by serogroup based on the somatic O antigen.2 It survives as a free-living environmental microorganism in brackish surface waters. Although over 200 serogroups exist, only toxigenic V. cholerae serogroups O1 and O139 cause widespread epidemic and pandemic disease. Strains of V. cholerae O1 and O139 that do not produce cholera toxin may be isolated from persons with sporadic cases of acute watery diarrhea, but have not caused large epidemics.2 V. cholerae serogroup O1 is classified into two biotypes—classical and El Tor; the biotypes are further classified by serotype—Inaba, Ogawa and, rarely, Hikojima.

Isolation and identification of V. cholerae serogroup O1 or O139 from stool or rectal swabs is necessary for the confirmation of cholera.3 Fecal specimens should be collected from clinically suspect patients prior to treatment with antibiotics, preferably within 4 days after the onset of illness. Specimens can be transported to a reference laboratory at ambient temperature and should be preserved in Cary-Blair transport media if they cannot be processed within 2 hours after collection.4 In field conditions, use of filter paper as a transport medium for stool specimens is an acceptable alternative to Cary-Blair and can be as effective for the recovery and diagnosis of cholera.5,6 Traditionally, culture-based ...

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