Empirical model for estimating dengue incidence using temperature, rainfall, and relative humidity: a 19-year retrospective analysis in East Delhi.

V G Ramachandran,Ajay Kumar Bansal,Shukla Das,Priyamvada Roy,Narendra Singh Mogha

doi:10.4178/epih.e2016052

V G Ramachandran, Ajay Kumar Bansal + Show 3 more

Open Access

https://doi.org/10.4178/epih.e2016052

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Abstract

OBJECTIVESAedes mosquitoes are responsible for transmitting the dengue virus. The mosquito lifecycle is known to be influenced by temperature, rainfall, and relative humidity. This retrospective study was planned to investigate whether climatic factors could be used to predict the occurrence of dengue in East Delhi.METHODSThe number of monthly dengue cases reported over 19 years was obtained from the laboratory records of our institution. Monthly data of rainfall, temperature, and humidity collected from a local weather station were correlated with the number of monthly reported dengue cases. One-way analysis of variance was used to analyse whether the climatic parameters differed significantly among seasons. Four models were developed using negative binomial generalized linear model analysis. Monthly rainfall, temperature, humidity, were used as independent variables, and the number of dengue cases reported monthly was used as the dependent variable. The first model considered data from the same month, while the other three models involved incorporating data with a lag phase of 1, 2, and 3 months, respectively.RESULTSThe greatest number of cases was reported during the post-monsoon period each year. Temperature, rainfall, and humidity varied significantly across the pre-monsoon, monsoon, and post-monsoon periods. The best correlation between these three climatic factors and dengue occurrence was at a time lag of 2 months.CONCLUSIONSThis study found that temperature, rainfall, and relative humidity significantly affected dengue occurrence in East Delhi. This weather-based dengue empirical model can forecast potential outbreaks 2-month in advance, providing an early warning system for intensifying dengue control measures.

Highlights

The dengue virus (DENV) is an arbovirus belonging to the Flaviviridae family, and is a cause of classical dengue fever (DF), dengue haemorrhagic fever (DHF), and dengue shock syndrome
The clinical criteria for DF, DHF, and DSS given in the guidelines are as follows: Clinical features of dengue fever An acute febrile illness of two to seven days’ duration with two or more of the following manifestations: headache, retroorbital pain, myalgia, arthralgia, rash, and haemorrhagic manifestations
Most of the cases were reported during the post-monsoon period each year, except in 2010, when the highest number of cases was reported during the monsoon.The average number of dengue cases per month (January to December) over the 19-year period (1997 to 2015) was plotted against the climatic factors to assess their influence on the occurrence of DF (Figures 1 and 2)

Summary

Introduction

(DSS), which are major public health problems in Delhi, India [1,2,3]. These clinical entities are caused by four DENV serotypes (DENV-1, DENV-2, DENV-3, and DENV-4), transmitted to humans by female Aedes mosquitoes (Aedes aegypti and Aedes albopictus) [3,4]. According to the 2014 to 2015 report of the National Vector Borne Disease Control Programme, dengue is endemic in 35 states and Union territories, including Delhi [5].

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