Epidemiological Investigation of a Diarrhea Outbreak in the South Pacific Island Nation of Tuvalu during a Severe La Nina-Associated Drought Emergency in 2011

摘要

The association between heavy rainfall and an increased risk of diarrhea has been well established but less is known about the effect of drought on diarrhea transmission. In 2011, the Pacific island nation of Tuvalu experienced a concurrent severe La Nifia-associated drought and large diarrhea outbreak. We conducted a field investigation in Tuvalu to identify factors that contributed to epidemic transmission in the context of a drought emergency. Peak case numbers coincided with the nadir of recorded monthly rainfall, the lowest recorded since 1930. Independent factors associated with increased risk of diarrhea were households with water tank levels below 20% (odds ratio [OR] = 2.31; 95% confidence interval = 1.16-4.60) and decreased handwashing frequency (OR = 3.00 [1.48-6.08]). The resolution of the outbreak occurred after implementation of a hygiene promotion campaign, despite persistent drought and limited water access. These findings are potentially important given projections that future climate change will cause more frequent and severe droughts. The health impacts of drought are poorly understood despite droughts affecting up to 50 million persons annually. Tropical Pacific island nations are particularly susceptible to drought, in part due to the El Nino Southern Oscillation (ENSO) cycle, a natural climate event characterized by the cyclical warming (El Nino) and cooling (La Nina) of the Pacific Ocean. Such variability affects global climate patterns and often leads to climate emergencies such as floods, cyclones, and drought. Anthropogenic climate change is projected to increase the severity and volatility of ENSO events and increase the populations adversely affected by droughts.