Climate and Health

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Human health is intimately related to climate as put by Hippocrates (400B.C) in his advice to physicians,

“For knowing the changes of the seasons, the risings and settings of the stars, how each of them takes place, he will be able to know beforehand what sort of a year is coming. Having made these investigations, he will have full knowledge of each particular case. He must succeed in securing health, and be triumphant in the practice of his art. And if it shall be thought that these things belong rather to meteorology, it will be admitted, on second thoughts, that astronomy contributes not a little, but a very great deal, indeed, to medicine.”

We are undertaking climate impact analysis on dengue and malaria in Sri Lanka with a view to develop early warning systems.

Activity
Objectives
 Partners Status Next Steps
Malaria Early Warning Project
(Funded by NOAA/NSF/EPRI Joint Call on Climate and Health 2003-todate)
Establish relations between climate and malaria and develop malaria early warning system for the Uva Province in Sri Lanka.

International Water Management Institute (IWMI), LDEO Climate Group, Dept. of Meteorology, Anti-Malaria Campaign of Sri Lanka (AMC), SJU, NASA GMAO
Data collection substantially completed. Downscaling of work completed for main rainy seasons, physically based hydrology model implemented over project area, analysis of remote sensing work undertaken, preliminary climate-malaria linkages have been assessed.
Develop environment based malaria risk prediction methods, integrate the models into an early warning system.

     
Climate and Hydrological Impacts on Dengue Fever.
Establish relations between climate and dengue for Sri Lanka.

Marianne Hopp, University of Toronto, Aravinda de Silva, University of North Carolina
Data collection at aggregate level completed. Analysis underway. Data to be collected at various sub-national levels
Solicit a formal project on Dengue Risk.



 

Dengue

Dengue is becoming an increasingly important public health hazard in Sri Lanka. Unlike malaria, dengue is prevalent mostly in the urban areas. Unlike malaria, which has seen many epidemics over centuries, dengue's more virulent and deadly form, dengue hemorrhagic fever (DHF) has only a history of two decades. Until recently, it was confined to the Colombo metropolitan area but since has emerged in other cities and suburbs.
A study on the link between climate and dengue in Sri Lanka is being carried out in collaboration with Prof. Aravinda De Silva of the Department of Epidemiology and Public Health of the University of North Carolina and Dr Marianne Hopp. Some of the preliminary analysis shows a strong seasonality of dengue incidence with the outbreaks being more prevalent during the boreal summer. The seasonality of dengue transmission thus differs from malaria which is a spring and fall phenomenon.

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Summary: This analysis has already shown a seasonality with a summer peak, an inter-annual relationship with seasonal climate. Work is ongoing to consolidate and extend this work.

Malaria

/files/fect//moskito.pngMalaria is endemic in 101 countries and about 40% of the world’s population is at risk. In 1998, there were 273 million cases and 1.1 million deaths worldwide. In WHO's Southeast Asia region (which includes Sri Lanka), the case load was 16 million, with 73,000 deaths. Sri Lanka spends approximately 60% of its public health budget on malaria control. Malaria incidence in Sri Lanka has increased during the past 7 years. Plasmodium falciparum, which historically has been of low prevalence in Sri Lanka, has increased from 5% to about 25% of cases over the past decade and is increasingly resistant to the main anti-malarial drug, chloroquine. With an incidence rate of almost 12 per 1000 population Sri Lanka presently ranks as one of the most severely affected countries in Asia.

Sri Lanka has a history of malaria control dating to the 1920's, but was struggling until 2000 to contain the disease because of population increase, large-scale human settlement in disease-endemic areas, rapid agro-ecological change, and altered patterns of population mobility. Malaria in Sri Lanka is unstable and fluctuates in intensity both spatially and temporally. Thus resources have to be spread to cover all potential risk areas, regardless of whether an outbreak will occur or not at a given point in time. Geographic and seasonal specificity of impending malaria risk will be particularly useful in communicating with environmental managers such as irrigation engineers who can use water management techniques to reduce mosquito breeding in pools in river beds. A major constraint to a more focused approach to malaria control is the lack of a forecasting system.

While many factors play a role in the distribution of malaria and occurrence of malaria epidemics, climate is considered a major determinant. Temperature, rainfall, and humidity affect breeding and survival of vector mosquitoes and development of malaria parasites within the mosquitoes. Historically many epidemics have occurred during drought, as river margins retreat leaving numerous pools suitable for vector breeding, or in the season following a drought when rains return to normal. This post-drought epidemic often poses a major public health problem among populations whose vulnerability is heightened due to a period of poor nutrition associated with drought and lowered agricultural output. Sri Lanka has operated very effective malaria control in the past, however it has also suffered several major epidemics which have been triggered by climatic and hydrological anomalies. Recent evidence suggests that ENSO-associated climate variability influences vector borne diseases such as malaria. However, studies at finer temporal and spatial resolutions are needed to establish the mechanisms by which ENSO and other causes of climate variability may influence the transmission of malaria

Malaria Seasonality

Disease incidence often follows closely the rainfall seasonality. Peak months of incidence are May to June and November to January.

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Project Goals

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Outputs

Publications


Papers under Review

Conference Proceedings


Reports