Non-linear effect of temperature variation on childhood rotavirus infection: A time series study from Kathmandu, Nepal

Dinesh Bhandari; Peng Bi; Meghnath Dhimal; Jeevan Bahadur Sherchand; Scott Hanson-Easey

doi:10.1016/j.scitotenv.2020.141376

Non-linear effect of temperature variation on childhood rotavirus infection: A time series study from Kathmandu, Nepal

Sci Total Environ. 2020 Dec 15:748:141376. doi: 10.1016/j.scitotenv.2020.141376. Epub 2020 Jul 30.

Authors

Dinesh Bhandari¹, Peng Bi², Meghnath Dhimal³, Jeevan Bahadur Sherchand⁴, Scott Hanson-Easey⁵

Affiliations

¹ The University of Adelaide, School of Public Health, Adelaide, South Australia, Australia. Electronic address: dinesh.bhandari@adelaide.edu.au.
² The University of Adelaide, School of Public Health, Adelaide, South Australia, Australia. Electronic address: peng.bi@adelaide.edu.au.
³ Nepal Health Research Council, Kathmandu, Nepal.
⁴ Public Health Research Laboratory, Institute of Medicine Tribhuvan University, Kathmandu, Nepal.
⁵ The University of Adelaide, School of Public Health, Adelaide, South Australia, Australia. Electronic address: scott.hanson-easey@adelaide.edu.au.

PMID: 32798872
DOI: 10.1016/j.scitotenv.2020.141376

Abstract

Introduction: This study aimed to investigate the effects of temperature variability on rotavirus infections among children under 5 years of age in Kathmandu, Nepal. Findings may inform infection control planning, especially in relation to the role of environmental factors in the transmission of rotavirus infection.

Methods: Generalized linear Poisson regression equations with distributed lag non-linear model were fitted to estimate the effect of temperature (maximum, mean and minimum) variation on weekly counts of rotavirus infections among children under 5 years of age living in Kathmandu, Nepal, over the study period (2013 to 2016). Seasonality and long-term effects were adjusted in the model using Fourier terms up to the seventh harmonic and a time function, respectively. We further adjusted the model for the confounding effects of rainfall and relative humidity.

Results: During the study period, a total of 733 cases of rotavirus infection were recorded, with a mean of 3 cases per week. We detected an inverse non-linear association between rotavirus infection and average weekly mean temperature, with increased risk (RR: 1.52; 95% CI: 1.08-2.15) at the lower quantile (10th percentile) and decreased risk (RR: 0.64; 95% CI: 0.43-0.95) at the higher quantile (75th percentile). Similarly, we detected an increased risk [(RR: 1.93; 95% CI: 1.40-2.65) and (RR: 1.42; 95% CI: 1.04-1.95)] of rotavirus infection for both maximum and minimum temperature at their lower quantile (10th percentile). We estimated that 344 (47.01%) cases of rotavirus diarrhoea among the children under 5 years of age were attributable to minimum temperature. The significant effect of temperature on rotavirus infection was not observed beyond lag zero week.

Conclusion: An inverse non-linear association was estimated between rotavirus incidence and all three indices of temperature, indicating a higher risk of infection during the cooler times of the year, and suggesting that transmission of rotavirus in Kathmandu, Nepal may be influenced by temperature.

Keywords: Children; Environmental factors; Epidemiology; Nepal; Rotavirus.

MeSH terms

Child
Child, Preschool
Diarrhea
Humans
Infant
Nepal / epidemiology
Rotavirus Infections* / epidemiology
Rotavirus*
Temperature