Effects of El Niño/La Niña on the Number of Imported Shigellosis Cases in the Republic of Korea, 2004-2017.

Jong-Hun Kim,Jisun Sung,Hae-Kwan Cheong,Ho-Jang Kwon

doi:10.3390/ijerph18010211

Abstract

Shigellosis is a major diarrheal disease in low- and middle-income countries. Although the incidence of such diseases in South and Southeast Asia has been associated with climate fluctuations linked to the El Niño–Southern Oscillation (ENSO), the impact of ENSO on shigellosis infections remains unknown. Data reported to being infected with shigellosis while traveling abroad from 2004 to 2017 were obtained from the Korea Centers for Disease Control and Prevention. We investigated the relationship between the Oceanic Niño Index (ONI) and Indian Ocean Dipole Mode Index and the relative risk of shigellosis in outbound travelers using distributed lag linear and non-linear models. From 2004 to 2017, 87.1% of imported shigellosis was infected in South and Southeast Asian countries. The relative risk of imported shigellosis infection in outbound travelers increased as the ONI decreased. In the association with the five-month cumulative ONI, the relative risk of infection continuously increased as the La Niña index gained strength. Climate fluctuations associated with the La Niña phenomenon in South and Southeast Asian countries can lead to issues in sanitation and water safety. Our findings suggest that the decreasing trend in the ONI is associated with an increased incidence of shigellosis in these countries.

Highlights

Shigellosis is a clinical syndrome with symptoms such as nausea, vomiting, diarrhea, and abdominal cramps caused by the Shigella species invading intestinal epithelial cells [1,2]
We reported that the risk of infection with shigellosis in South Korean travelers returning from South and Southeast Asian countries is influenced by the Oceanic Niño Index (ONI), a large-scale oceanic index
We analyzed the relationship between the ONI and the Dipole Mode Index (DMI) and the relative risk of shigellosis for overseas travelers

Summary

Introduction

Shigellosis is a clinical syndrome with symptoms such as nausea, vomiting, diarrhea, and abdominal cramps caused by the Shigella species invading intestinal epithelial cells [1,2]. Shigella is an important etiologic agent of travelers’ diarrhea and is only carried by humans and upper primates [3] It is mainly transmitted between people through the fecal–oral route and through the intake of contaminated food or water. Diarrheal diseases, including shigellosis, are well known as climate-sensitive diseases; their incidence usually increases with the occurrence of drought or floods. This is related to poor hygiene, sanitation, and a lack of clean drinking water.

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