All case-patients reported having acute, watery diarrhea; other signs and symptoms included vomiting (81%), rice-water stool
(66%), and leg cramps (64%).
A 3-step method was used to establish the distribution of spirochetes in rice-water stool: 1) the presence of spirochetes in rice-water stool was determined by using dark-field microscopy; 2) the diversity of Brachyspira spp.
Rice-water stool samples were collected from symptomatic cholera patients ([greater than or equal to]15 years of age with no history of antimicrobial drug therapy) during the spring cholera outbreak of 2006 in Dhaka, Bangladesh, at the International Centre for Diarrheal Disease Research, Bangladesh, as part of a larger study (14).
Besides the particular circumstance that provoked the Artibonite's outbreak, other factors may have played a role in the severity of the epidemic in Haiti: the absence of immunity among the population, the higher infectivity of epidemic strains shed in human rice-water stools
than of environmental strains, and the role of hypervirulent variant strains in provoking epidemics (24,29,30).