We examined Twitter postings from the first 100 days of the Haitian cholera outbreak. Twitter is a microblogging service in which users can give information in 140 character length posts, 'Tweets'. We selected Tweets containing the word 'cholera' including those with the Twitter hashtag identifier ('#cholera'). Our search captured English, French and Spanish mentions of the word cholera. We define an outbreak as cholera incidence beyond an isolated case. Six countries in which cholera did or was suspected to have spread, and without endemic cholera, were examined: Canada, Dominican Republic, Mexico, Spain, USA and Venezuela. We first collected 'Twitter Updates' for each country, Tweets that came from users in a particular country, normalized by the number of Twitter users in the country. Second, we filtered Tweets in which the keyword cholera as well as a country's name was mentioned, 'Twitter Mentions'. Logistic models were constructed to analyze the relationship between volume of updates and mentions and the occurrence of a secondary cholera outbreak in the chosen countries. We evaluated our models through the Hosmer-Lemeshow (HL) test and also by cross-validation with data from Puerto Rico, in which there was concern of a potential outbreak.