A Time-Series Analysis of Rainfall and Respiratory Syncytial Virus Cases in Children Under Five Years Old in Pathumthani, Thailand

ารวิเคราะห์ความสัมพันธ์เชิงอนุกรมเวลาระหว่างปริมาณฝนกับจำนวนผู้ป่วยโรคติดเชื้อไวรัสอาร์เอสวีในเด็กอายุต่ำกว่า 5 ปี จังหวัดปทุมธานี ประเทศไทย

Abstract

Respiratory Syncytial Virus (RSV) infection is a major respiratory disease in children under five years of age, as it can lead to severe illness, exhibits seasonal outbreaks during the rainy season, and represents a significant public health concern as well as an economic burden for affected families.

Objective: To examine the time-series relationship between daily rainfall and the number of respiratory syncytial virus (RSV) cases among children under five years of age, and to assess the lagged effects of daily rainfall on RSV incidence in Pathum Thani Province, Thailand.

Methods: A retrospective observational time-series study was conducted using secondary daily RSV cases records between June 30and September 30, 2025 (a total of 93 days). Daily rainfall data were obtained from NASA climate and meteorological databases. Descriptive statistics were used to summarize the data, and negative binomial regression models were applied to analyze the association between rainfall and RSV cases. Lag effects of rainfall were evaluated to capture delayed impacts on RSV incidence.

Results: During the 93-day study period, the mean number of RSV cases was 2.13 cases per day. Daily rainfall on the same day (lag 0) and three days after rainfall (lag 3) showed significant positive associations with the number of RSV cases (p < 0.05). The fitted models demonstrated good overall fit (p < 0.05). Each 1-mm increase in daily rainfall was associated with an approximately 4% increase in the expected number of RSV cases on the day of rainfall (IRR = 1.040, 95% CI: 1.02–1.08) and an approximately 5% increase three days after rainfall (IRR = 1.050, 95% CI: 1.02–1.08).

Conclusions: The findings indicate that rainfall is an important environmental predictor of RSV incidence among children under five years of age. Incorporating rainfall information into surveillance systems may support early warning, preparedness, and the timely implementation of public health measures to control RSV transmission in local settings.