Heavy Rainfall Events and Diarrhea Incidence: The Role of Social and Environmental Factors

• Published in: American journal of epidemiology Vol. 179; no. 3; pp. 344 - 352
• Main Authors: CARLTON, Elizabeth J, EISENBERG, Joseph N. S, GOLDSTICK, Jason, CEVALLOS, William, TROSTLE, James, LEVY, Karen
• Format: Journal Article
• Language: English
• Published: Cary, NC Oxford University Press 01.02.2014; Oxford Publishing Limited (England)
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Biological and medical sciences; Child; Child, Preschool; Diarrhea; Diarrhea - epidemiology; Diarrhea - etiology; Diarrhea - prevention & control; Drinking water; Drinking Water - adverse effects; Ecuador - epidemiology; Environment. Living conditions; Epidemiology; Gastroenterology. Liver. Pancreas. Abdomen; General aspects; Humans; Incidence; Infant; Infant, Newborn; Intervention; Longitudinal Studies; Medical sciences; Middle Aged; Miscellaneous; Original Contributions; Other diseases. Semiology; Poisson Distribution; Population Surveillance; Public health. Hygiene; Public health. Hygiene-occupational medicine; Rain; Regression Analysis; Risk Factors; Sanitation; Seasons; Social Environment; Stomach. Duodenum. Small intestine. Colon. Rectum. Anus; Water Purification; Water Quality; Water treatment; Young Adult; South America; Ecuador; America; ISE, Ecuador; Water treatment; Ecuador; Climate; Diarrhea; Environmental factor; Vulnerability; Epidemiology; Incidence; heavy rainfall events; Rain; Health and environment; Digestive diseases; Intestinal disease; Environment; social vulnerability; Social aspect; Public health; rain; water treatment; climate; diarrhea
• ISSN: 0002-9262; 1476-6256
• DOI: 10.1093/aje/kwt279

The impact of heavy rainfall events on waterborne diarrheal diseases is uncertain. We conducted weekly, active surveillance for diarrhea in 19 villages in Ecuador from February 2004 to April 2007 in order to evaluate whether biophysical and social factors modify vulnerability to heavy rainfall events. A heavy rainfall event was defined as 24-hour rainfall exceeding the 90th percentile value (56 mm) in a given 7-day period within the study period. Mixed-effects Poisson regression was used to test the hypothesis that rainfall in the prior 8 weeks, water and sanitation conditions, and social cohesion modified the relationship between heavy rainfall events and diarrhea incidence. Heavy rainfall events were associated with increased diarrhea incidence following dry periods (incidence rate ratio = 1.39, 95% confidence interval: 1.03, 1.87) and decreased diarrhea incidence following wet periods (incidence rate ratio = 0.74, 95% confidence interval: 0.59, 0.92). Drinking water treatment reduced the deleterious impacts of heavy rainfall events following dry periods. Sanitation, hygiene, and social cohesion did not modify the relationship between heavy rainfall events and diarrhea. Heavy rainfall events appear to affect diarrhea incidence through contamination of drinking water, and they present the greatest health risks following periods of low rainfall. Interventions designed to increase drinking water treatment may reduce climate vulnerability.