Seasonal Climatological Suitability for Malaria Transmission

Where malaria is not adequately controlled, the seasonality of climate greatly influences the seasonality of malaria transmission. Specifically, rainfall plays an important role in the distribution and maintenance of breeding sites for the mosquito vector (Anopheline species). Temperature regulates the development rate of both the mosquito larvae and the malaria parasite (Plasmodium species) within the mosquito host. Relative humidity and temperature play an important role in the survival and longevity of the mosquito vector.

Here we present a clickable map interface that describes where, when and for how long the combination of climatic conditions may be suitable for malaria transmission in the Africa continent.

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Map Description
Please note that the above map is based on a theoretical model of climate data and is not based on actual malaria data. Therefore, it may not accurately resemble actual malaria transmission status on a local scale.

The map displays the number of months during the year that are suitable for malaria transmission, based on monthly climatological averages*. Suitability is defined as the coincidence of precipitation accumulation greater than 80 mm, mean temperature between 18°C and 32°C, and relative humidity greater than 60 percent. These are rough thresholds that are intended to describe conditions that are suitable for both the development of the falciparum parasite and the life cycle of the mosquito vector.

*Additional analyses that display how often these conditions have actually occurred in the historical record may be accessed by clicking on the map at the location of interest.

Dataset Documentation
Precipitation Climatology
Data: Monthly precipitation over land areas on a 0.5° x 0.5° lat/lon grid
Base Period for Climatology: 1951-2000
Data Source: University of East Anglia (UEA CRU TS 2.0)

Temperature Climatology
Data: Monthly temperature over land areas on a 0.5° x 0.5° lat/lon grid
Base Period for Climatology: 1951-2000
Data Source: University of East Anglia (UEA CRU TS 2.0)

Relative Humidity Climatology
Data: Monthly specific humidity data (converted to rh) on a 2.5° x 2.5° lat/lon grid
Base Period for Climatology: 1951-2000
Data Source: National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR CDAS/Reanalysis)

Epidemiological Mask
Data:  Mask illustrating areas where malaria is considered to be epidemic. Areas where malaria transmission is considered absent or endemic are therefore excluded. This mask is based purely on climatic constraints to malaria transmission, and does not yet account for areas in the northern and southern margins of the continent where control has eliminated malaria risk.
Reference:  WHO: Final report on the 3rd meeting of the RBM Technical Resource Network on Epidemic Prevention and Control. Geneva: World Health Organization; 2002.

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