Seasonality of influenza and its association with meteorological parameters in two cities of Pakistan: A time series analysis.

Nadia Nisar,Chinmay Laxmeshwar,Uzma Bashir Aamir,Fariha Munir,Jaya Prasad Tripathy,Nazish Badar,Syed Sohail Zahoor Zaidi,Aashifa Yaqoob

doi:10.1371/journal.pone.0219376

Abstract

BackgroundInfluenza is known to have a specific pattern of seasonality the reasons for which are yet to be fully ascertained. Temperate zones show influenza epidemic during the winter months. The tropical and subtropical regions show more diverse influenza outbreak patterns. This study explores the seasonality of influenza activity and predicts influenza peak based on historical surveillance time series data in Islamabad and Multan, Pakistan.MethodsThis is a descriptive study of routinely collected monthly influenza sentinel surveillance data and meteorological data from 2012–16 in two sentinel sites of Pakistan: Islamabad (North) and Multan (Central).ResultsMean number of cases of influenza and levels of precipitation were higher in Islamabad compared to Multan. Mean temperature and humidity levels were similar in both the cities. The number of influenza cases rose with decrease in precipitation and temperature in Islamabad during 2012–16, although the same cannot be said about humidity. The relationship between meteorological parameters and influenza incidence was not pronounced in case of Multan. The forecasted values in both the cities showed a significant peak during the month of January.ConclusionThe influenza surveillance system gave a better understanding of the disease trend and could accurately forecast influenza activity in Pakistan.

Highlights

Influenza is a communicable respiratory disease caused by the influenza virus
This study explores the seasonality of influenza activity and predicts influenza peak based on historical surveillance time series data in Islamabad and Multan, Pakistan
The influenza surveillance system gave a better understanding of the disease trend and could accurately forecast influenza activity in Pakistan

Summary

Introduction

Influenza is a communicable respiratory disease caused by the influenza virus. The disease severity may range from mild to severe, sometimes leading to fatality, especially among infants, elderly, immune-compromised persons and various other high risk groups.The World Health Organization (WHO) has reported 3–5 million cases of severe illness and 290,000–650,000 deaths worldwide in 2017 due to seasonal influenza epidemics [1].Influenza is known to have a specific pattern of seasonality the reasons for which are yet to be fully ascertained [2]. Studies report that temperate zones show influenza epidemic during the winter months of November-March in northern hemisphere and May-September in southern hemisphere [3,4]. Annual epidemics occur in the tropical locations that usually coincide with the rainy season, while biannual incidence is the norm in some regions, and influenza activity occurs throughout the year in other countries [3]. There is limited understanding about the epidemiology of influenza and the characteristics of seasonal influenza in the tropical region where there is influenza activity all throughout the year.[5,6]. Temperate zones show influenza epidemic during the winter months. The tropical and subtropical regions show more diverse influenza outbreak patterns. This study explores the seasonality of influenza activity and predicts influenza peak based on historical surveillance time series data in Islamabad and Multan, Pakistan

Methods

Results

Conclusion