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Cycle 7 (2018 Deadline)

Developing dengue risk predictions from environmental, entomological, and societal information to aid public health management in Sri Lanka

PI: Pahalagedera Hewayalage Dona Kusumawathie (, Tropical Climate Guarantee
U.S. Partner: Aravinda de Silva, University of North Carolina Chapel Hill
Dates: November 2018 - April 2022

Project Websites: htpps://

Project 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.

7-201 Balika Training7-201 Lab Test
Project team members teaching at the Muslim Balika Vidyalaya event.Dr. Kusumawathie preparing to observe mosquito eggs through the digital microscope (photos courtesy of Dr. Kusumawathie)

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.

Summary of Recent Activities:

In the second quarter of 2021, Dr. Kusumawathie and her team managed their project activities reasonably well given the limitations due to the COVID-19 pandemic and associated quarantine restrictions. It became difficult to sustain some aspects of the laboratory and analytical work while working from home. There were difficulties in transport and subsequent problems as the public transport system was limited and travel bans were imposed between the districts and the provinces. Nevertheless, they were able to undertake some of the data and literature collection and to focus on analyzing already collected data and training the staff. Three new junior staff members joined the group: Gobishankar Sathyamohan, Varunya Amamini, and Emmanuel Gautham.

During this period, the PI and her colleagues digitized and checked the quality of the previously photographed weather data (from their visits to places with paper records), undertook statistical analysis, and drafted research papers. They also conducted some work on air quality and chemical toxicity, mainly focusing on the marine ecological disaster due to the cargo ship X-Press Pearl, which sank in late May 2021 after explosions and a prolonged fire 9.5 km off the coast of Sri Lanka’s capital. The team obtained entomological and dengue case data for the year 2020 for Matale District from the Regional Director of Health Services (RDHS) Matale, Regional Malaria Office (RMO) Matale, and the office of the Provincial Director of Health Kandy. The researchers have assembled an inventory of all available weather data for the Central Province of Sri Lanka. They have set up the software platforms for data analysis and devoted painstaking efforts to assembling the climate data to go along with the entomological, epidemiological, and demographic data.

Regarding outreach, Dr. Kusumawathie and her group prepared extended abstracts for the Sri Lanka Association for the Advancement of Science sessions on the following topics:
  • Distribution of the different dengue vectors in parts of the Matale Districts in the Central Province
  • Estimation of the relative seasonal distribution of mosquitos and Dengue Cases and Entomology in Matale District of Sri Lanka
  • Assessment of air pollution impacts on Western Sri Lanka due to the X-Press Pearl Ship Disaster
Efforts during the remainder of 2021 and into 2022 will focus on development of dengue risk prediction methods and drafting of research papers. Dr. Kusumawathie also plans to submit her team’s findings to the American Geophysical Union’s Annual Sessions in New Orleans in December.

Recent Abstracts Presented

American Geophysical Union Fall Meeting 2020, San Francisco, December 1-17, 2020, attended online:
  • Nijamdeen., A., P.H.D. Kusumawathie., S. Sasna, T. Kailaivasan, M. Randiwela, R. Bandara, et al. The Impacts of Climate Variability on Seasonality, Spatial Variability and Extremes of Dengue Transmission in Sri Lanka: Relationships of El Niño, Indian Ocean Dipole and Warming and Epidemic Incidence.
  • Ellegala, P., A. Nijamdeen, T. Hadgie, C. Gunatillake, et al. Attributing Improvement of Air Quality in Colombo to COVID19 Curfews Distracts Focus on Sri Lanka’s Major Sources of Air Pollution.
  • Thunendran, P, R. Bandara, A. Nijamdeen, C. Gunatillake, et al. Characterizing Urbanization over Two Decades in the Pinga Oya River Catchment in Central Sri Lanka Using Land Surveys and Google Earth Images for Application for Dengue and Hydrological Risk Assessment.
Sri Lanka Association for the Advancement of Science, Annual Sessions 2020, December 13-17, 2020, Kelaniya, Sri Lanka, attended online:
  • Wickramasinghe, D.H.K., P. Ellegala, C. Gunathilake, et al. Did the COVID19 Curfews or Seasonal Wind Changes Drive the Drop in Fine Air-Borne Particulate Matter in Colombo after 20 March 2020? 
  • Nijamdeen, A., P.H.D. Kusumawathie, S. Sasna, T. Kailaivasan, M. Randiwela, et al. Seasonal, Spatial, and Epidemic Characteristics of Dengue Vectors in a Rapidly Urbanizing Hill Country Locale and Its Relationships with Dengue Incidence and Climate.

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