Effect of El Niño Southern Oscillations on the incidence of enteric fever in Ahmedabad, India from 1985 to 2017

Veena Iyer; Susanna Cottagiri; Ayushi Sharma; Divya Nair; Dileep Mavalankar; Mehul Raval; Bhavin Solanki

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Effect of El Niño Southern Oscillations on the incidence of enteric fever in Ahmedabad, India from 1985 to 2017

Author: Veena IYER ¹ ; Susanna COTTAGIRI ¹ ; Ayushi SHARMA ¹ ; Divya NAIR ¹ ; Dileep MAVALANKAR ¹ ; Mehul RAVAL ² ; Bhavin SOLANKI ³
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1. Indian Institute of Public Health Gandhinagar, Opposite Air Force HQ, Near Lekavada Bus Stop, CRPF P.O.
2. ICT Department, School of Technology, Pandit Deendayal Petroleum University
3. Medical Officer of Health, Ahmedabad Municipal Corporation
Publication Type:Journal Article
Keywords: El Niño; El Niño Southern Oscillations; Enteric fever and climate; Indian Ocean Dipole; La Niña and Enteric fever; Salmonella and climate; Typhoid
From: Asian Pacific Journal of Tropical Medicine 2019;12(12):552-558
CountryChina
Language:Chinese
Abstract: To explore the relationship between climate variables and enteric fever in the city of Ahmedabad and report preliminary findings regarding the influence of El Niño Southern Oscillations and Indian Ocean Dipole over enteric fever incidence. Method: A total of 29 808 Widal positive enteric fever cases reported by the Ahmedabad Municipal Corporation and local climate data in 1985-2017 from Ahmedabad Meteorology Department were analysed. El Niño, La Niña, neutral and Indian Ocean Dipole years as reported by the National Oceanic and Atmospheric Administration for the same period were compared for the incidence of enteric fever. Results: Population-normalized average monthly enteric fever case rates were the highest for El Niño years (25.5), lower for La Niña years (20.5) and lowest for neutral years (17.6). A repeated measures ANOVA analysis showed no significant difference in case rates during the three yearly El Niño Southern Oscillations categories. However, visual profile plot of estimated marginal monthly means showed two distinct characteristics: an early rise and peaking of cases in the El Niño and La Niña years, and a much more restrained rise without conspicuous peaks in neutral years. Further analysis based on monthly El Niño Southern Oscillations categories was conducted to detect differences in median monthly case rates. Median case rates in strong and moderate El Niño months and strong La Niña months were significantly dissimilar from that during neutral months (P<0.001). Conclusions: El Niño Southern Oscillations events influence the incidence of enteric fever cases in Ahmedabad, and further investigation from more cities and towns is required.