We defined a case as acute, watery diarrhea in a person >5 years of age admitted to the Haitian Group for the Study of Kaposi’s Sarcoma and Opportunistic Infections (GHESKIO) cholera treatment center (CTC) in Cité de Dieu slum after November 1, 2010. Enumerators administered a standard questionnaire in Haitian Creole to CTC patients or their caregivers to gather demographic, clinical, and treatment information; food and beverage exposures in the 3 days before illness onset; and water, sanitation, and hygiene practices. Enumerators visited each case-patient’s household to observe living conditions; water storage and treatment practices; and handwashing technique, which included an assessment of soap use, lathering, and drying procedure. Enumerators enrolled 2 sex-, age group– (5–15 years, 16–30 years, 31–45 years, and >45 years), and neighborhood-matched controls per case-patient by skipping the immediate neighbor and going house to house until 2 controls were identified. An identical questionnaire that included household observations was administered to controls.
We used exact conditional logistic regression to compute matched odds ratios (mORs) with 95% confidence intervals (CIs). For protective food exposures, we calculated a food diversity score for each participant based on the total number of distinct food items consumed in the 3 days before illness onset. We created a 2-level categorical diversity score variable based on the median score. The study protocol was approved by the Haitian Ministry of Public Health and Prevention and the GHESKIO institutional review board.
We enrolled 53 case-patients and 106 controls. The median ages of case-patients and controls were 29 (range 6–80) and 30 (range 6–85) years, respectively; 45% of case-patients and controls were female. Of participants >15 years of age, 84% self-reported as literate; 37% of case-patients and 57% of controls spoke French (mOR 0.3, 95% CI 0.1–0.8). Participant households were located in the greater Port-au-Prince area ().
Figure Locations of the Haitian Group for the Study of Kaposi’s Sarcoma and Opportunistic Infections Cholera Treatment Center and case-patient households in Port-au-Prince, Haiti, 2010. Cross indicates cholera treatment center location; circles indicate (more ...)
All case-patients reported having acute, watery diarrhea; other signs and symptoms included vomiting (81%), rice-water stool (66%), and leg cramps (64%). Reported illness onset dates ranged from December 10 through 19. Of 53 case-patients, 20 (38%) were treated with oral rehydration solution at home prior to admission, and 39 (74%) sought care at a GHESKIO CTC on the first day of symptom onset. CTC treatment included ORS (85%), intravenous fluids (55%), and antimicrobial drugs (9%).
Water sources, which included purchased bags, purchased bottled or filtered water, piped water, and water collected from a tanker, did not differ between case-patients and controls (). Bladder water (chlorinated water stored in flexible plastic tanks in internally displaced person camps) seemed protective (mOR indeterminate, 95% CI 0–0.9), although exposure frequency was limited and a point estimate could not be calculated. Controls were more likely than case-patients to have treated their drinking water by boiling or chlorinating before the outbreak began in Port-au-Prince (mOR 0.3, 95% CI 0.1–0.9) and to have used proper handwashing technique (mOR 0.2, 95% CI 0.03–0.7).
Characteristics of cholera case-patients and controls, Port-au-Prince, Haiti, December 2010*
Food exposures implicated as risk factors for transmission in previous cholera outbreaks in the Americas were not associated with illness, including food or drink purchased from a street vendor, cold leftover food, cold rice, raw food, and seafood (). Of 60 food exposures included in the questionnaire for the 3 days before illness onset, 29 (48%) were protective against cholera; CIs did not overlap. The median food diversity score for case-patients and controls in the 3 days before illness was 23 (range 4–50). A higher percentage of controls (56%) than case-patients (28%) consumed more than the median number of 23 items in the 3 days before illness (mOR 0.3, 95% CI 0.1–0.6).
Food diversity score, proper handwashing, and treating drinking water were included in a multivariate model (). All 3 remained protective against illness, although treating drinking water did not reach statistical significance (mOR 0.4, 95% CI 0.1–1.1). All socioeconomic status variables were considered for model inclusion, but none affected the direction or effect size of predictor variables for cholera.
Practices independently associated with cholera prevention in a multivariate model case–control study, Port-au-Prince, Haiti, December 2010*