Dengue And Climate

in Sri Lanka

Project Details

Summary of Progress – Year 1:


By the end of year 1 (in October 2019), we had collected most of the required and available data on dengue cases, as well as entomological, demographic, and meteorological data for Sri Lanka with higher resolution data for its Central Province, particularly for the Kandy District. Although we have digitized, cleaned up, and mapped some of the data and undertaken some analysis, some gaps and shortcomings remain to be addressed in the second year.


We have now digitized monthly dengue case data nationally for the 25 districts and are refining this data temporally. In addition, we are building the weather history to go with this data.


We have mapped sub-district level demographic, entomological, and dengue case analysis for the Central Province which comprises the Kandy, Matale and Nuwara Eliya districts. These data were mapped as a time-series for 2 decades. Weather and Entomological data for these provinces are largely compiled and the work of building sub-district variables is going on. We have launched an analysis of climate histories during dengue epidemics in the Kandy District.


We have undertaken detailed demographic, entomological, and dengue case analysis at the village level in one sub-district that has been a dengue hotspot in the past. In addition, we have mapped dengue cases in all sub-districts to begin their comparison of climate and dengue at a fine-scale. 


We have also progressed in setting up the weather and environmental monitoring for a locality in one sub-district and for key location in various districts, including eight automatic weather stations in the Central Province plus instrumentation to monitor water and air quality in several other key locations.

The aim is to conduct village-level analysis in one sub-district (Akurana) to go along with sub-district-level analysis for the whole province.


We have also obtained a basic set of laboratory instruments to assess larval abundance, temperature, humidity, and air, and water quality, as all of these factors affect the vector cycle.


Engagement of government stakeholders is a crucial part of this project, and the outreach efforts of the PI and her team have built strong linkages with Central Province health staff. Entomological officers from the health service have agreed and been trained on performing some of the laboratory work for the project. Our staff participated in the Central Province Health Conference.

We also were provided permission to extend the duration of our data collection by the new Provincial Director of Health for the Central Province.

We also met with the Provincial Director of Health in the neighboring North-Western Province during this period. We have prepared the paper work


We have contributed to the Central Province Health conferences, to three meetings organized at village level by the local government officials in relation to dengue, solid waste management and air quality – all with implications for dengue. We also participated in programs in schools.


As the project moves into its second year in late 2019, we will continue pursuing their work plan, including laboratory analysis of entomological, water, and air samples and assimilation of data from their weather stations and other instruments. In particular, they will be looking at the impacts of the built environment, urbanization, and associated demographic changes on the incidence of dengue. The researchers will remain in close collaboration with the Sri Lankan public health sector and do further outreach with schools and other community groups. Technical reports and research articles will be produced as the analysis move forward.

Proposal Overview:


Dengue is a major vector-borne viral disease that has become a serious public health problem in Sri Lanka and elsewhere, but the lack of a vaccine against it means that control programs rely on management of environmental and human factors. Dengue is highly intermittent, has some seasonality, and is showing an exponential rise in the last few decades (Hopp & Foley, 2003). Dengue outbreaks are primarily associated with climatic variables such as rainfall, temperature, and relative humidity. Usually peak transmission occurs after the rains in the areas where the mosquito population is high and temperature and humidity levels are optimal. Nevertheless, there can be situations where transmission is enhanced during droughts, as water storage becomes more important. Though the risk of epidemics is contingent on a complex set of social, environmental, climatic, and epidemiological factors and their prediction is fraught with uncertainty, climate is a critical factor. As there is a 1-2 month lag between heavy rains and dengue transmission, targeted weather monitoring can give advance warning of dengue risks and trigger alerts to the authorities to launch cleanup programs of potential breeding sites.

To address the problem of dengue in Sri Lanka, this project involves entomological surveillance, weather and climate impact analysis, vulnerability analysis, and the development of monitoring systems for mosquito abundance and vulnerability. The scientific objectives are to (1) identify relationships between prevalence and transmissivity of the dengue vectors and weather using routinely collected data; (2) identify relationships between abundance of vectors, incidence of dengue, and weather in the country’s Central Region; and (3) develop dengue risk prediction methodology based on weather for high-risk centers. Through these efforts the PI and her team will develop an early warning system for dengue risk using weather, climate, entomological and epidemiological information for Sri Lanka, working in close collaboration with the Central Province Health Department and National Dengue Control officials. These government officials will be engaged in helping to develop the risk prediction methodology and formats for dissemination. The PI and her team will share their results and recommendations with public health officers and other interested stakeholders via the Internet and in-person workshops.

Project Duration: November 2018 – October 2020


  • Principal Investigator: Dr. Kusumawathie Pahalagedera (TCG)
  • Co-Principal Investigators: Dr. Ranmalee Bandara (TCG)


  • Aravinda de Silva, University of North Carolina Chapel Hill
  • Sewwandhi Chandrasekera
  • Madhura Weerasekera
  • H.M. Faizal, Regional Malaria Officer, Central Province Directorate of Health


  • National Academy of Sciences
  • PEER site – Link


  1. Consult stakeholders and assess needs   
  • Develop an information management system 
  • The sensitivity of Dengue cases to key elements        
  • Develop dengue risk prediction with/without data on key elements         
  • Implement Dengue Risk Predictions monthly      
  • Scientific and Sectorial communications               
  • Capacity Building

What has been done?

Data Collection

  • Most of the required and available data on dengue cases, as well as entomological, demographic, and meteorological data, have been collected.

Dengue Analysis in one locality

  • The researchers have undertaken detailed demographic, entomological, and dengue case analysis at the village level in one sub-district (Akurana) that has been a dengue hotspot in the past.

Dissemination and Training

  • Training of junior scientists
  • Awareness program for community groups and school students

Weather and Environmental Monitoring

  1. Automatic weather stations setup
  2. Water and air quality monitoring instruments setup


1st and 2nd Quarterly Report:  October 2018 – March 2019 3rd Quarterly Report:  April 2019 – June 2019

Quarterly Summary Report


4th Quarter

Annual Summary Report: 2018 – 2019


5th Quarter

Summary Report