The influence of diurnal temperature range on the incidence of respiratory syncytial virus in Japan.

The incidence of respiratory syncytial virus (RSV) has been reported to exhibit seasonal variation. However, the impact of diurnal temperature range (DTR) on RSV has not been investigated. After acquiring data related to cases of RSV and weather parameters of DTR in Fukuoka, Japan, between 2006 and 2012, we used negative binomial generalized linear models and distributed lag nonlinear models to assess the possible relationship between DTR and RSV cases, adjusting for confounding factors. Our analysis revealed that the weekly number of RSV cases increased with a relative risk of 3·30 (95% confidence interval 1·65-6·60) for every 1°C increase in DTR. Our study provides quantitative evidence that the number of RSV cases increased significantly with increasing DTR. We suggest that preventive measures for limiting the spread of RSV should be considered during extended periods of high DTR.

Weather variability and paediatric infectious gastroenteritis.

Investigations of the relationship between weather variability and infectious gastroenteritis (IG) are becoming increasingly important in light of international interest in the potential health effects of climate change. However, few studies have examined the impact on children, despite the fact that children are considered particularly vulnerable to climate change. We acquired data about cases of IG in children aged <15 years and about weather variability in Fukuoka, Japan from 2000 to 2008 and used time-series analyses to assess how weather variability affected IG cases, adjusting for confounding factors. The temperature-IG relationship had an inverted V shape, with fewer cases at temperatures lower and higher than ~13°C. Every 1°C increase in temperature below the threshold (13°C) was associated with a 23·2% [95% confidence interval (CI) 16·6-30·2] increase, while every 1°C increase in temperature above the threshold (13°C) was associated with an 11·8% (95% CI 6·6-17·3) decrease in incidence. The increase in cases per 1% drop in relative humidity was 3·9% (95% CI 2·8-5·0). The percentage increase of IG cases was greatest in the 0-4 years age group and tended to decrease with increasing age. We found a progressive reduction in weather-related IG cases in children aged >4 years. Our results suggest that public health interventions aimed at controlling weather-related IG may be most effective when focused on young children.

Effect of weather variability on the incidence of mumps in children: a time-series analysis.

The increasing international interest in the potential health effects of climate change has emphasized the importance of investigations into the relationship between weather variability and infectious diseases. However, few studies have examined the impact of weather variability on mumps in children, despite the fact that children are considered particularly vulnerable to climate change. We acquired data about cases of mumps in children aged <15 years and weather variability in Fukuoka, Japan from 2000 to 2008, and then used time-series analyses to assess how weather variability affected mumps cases, adjusting for seasonal variations, inter-annual variations, and temporal variations of two large epidemics in 2001 and 2004-2005. The weekly number of mumps cases increased by 7·5% (95% CI 4·0-11·1) for every 1°C increase in average temperature and by 1·4% (95% CI 0·5-2·4) for every 1% increase in relative humidity. The percentage increase was greatest in the 0-4 years age group and tended to decrease with increasing age. The number of mumps cases in children increased significantly with increased average temperature and relative humidity.

Effects of weather variability on infectious gastroenteritis.

Although multiple combinations of weather variability may contribute to an increased incidence of infectious gastrointestinal disease, few studies have investigated the association between weather variability and cases of infectious gastroenteritis. We acquired data for infectious gastroenteritis cases and weather variability in Fukuoka, Japan, from 1999 to 2007 and used time-series analysis to assess the effects of weather variability on infectious gastroenteritis cases, adjusting for confounding factors. In total, 422,176 infectious gastroenteritis cases were reported during the 9-year study period. The weekly number of infectious gastroenteritis cases increased by 7.7% (95% CI 4.6-10.8) for every 1 degrees C increase in the average temperature and by 2.3% (95% CI 1.4-3.1) for every 1% decrease in relative humidity. From 1999 to 2007, infectious gastroenteritis cases increased significantly with increased average temperature and decreased relative humidity in Fukuoka, Japan.

Impact of weather factors on Mycoplasma pneumoniae pneumonia.

BACKGROUND: Although multiple combinations of weather factors may contribute to an increased incidence of Mycoplasma pneumoniae pneumonia, few studies have investigated the association between weather factors and cases of M pneumoniae pneumonia. METHODS: Data on cases of M pneumoniae pneumonia and weather factors in Fukuoka, Japan from 1999 to 2007 were obtained and time-series analysis was used to assess the effects of weather variables on M pneumoniae pneumonia cases, adjusting for confounding factors. A total of 13 056 M pneumoniae pneumonia cases were reported during the 9-year study period, of which 12 234 (93.7%) were under 15 years of age. RESULTS: The weekly number of M pneumoniae pneumonia cases increased by 16.9% (95% CI 11.3% to 22.8%) for every 1 degrees C increase in the average temperature and by 4.1% (95% CI 2.7% to 5.5%) for every 1% increase in relative humidity. CONCLUSIONS: From 1999 to 2007, cases of M pneumoniae pneumonia increased significantly with increased average temperature and relative humidity in Fukuoka, Japan.