New irrigation systems in arid regions can increase malaria risk

Researchers from the University of Michigan announced findings on Monday that show new irrigation systems in arid regions can increase the risk of malaria for more than a decade.

The researchers looked at changes in the land use and malaria risk around large irrigation projects under construction in semi-arid regions of the northeast part of the Indian state of Gujarat. The malaria risk in these arid regions rises when irrigation is introduced, due in part to increased amounts of standing water where mosquitoes breed.

"In these dry, fragile ecosystems, where increase in water availability from rainfall is the limiting factor for malaria transmission, irrigation infrastructure can drastically alter mosquito population abundance to levels above the threshold needed to maintain malaria transmission," Lead study author Andres Baeza, said.

Past evidence has shown that the benefits to food production caused by irrigation are worth a temporary increase in disease. The new study, however, shows that the transition phase from high risk to low risk disease prevalence can last for more than a decade, longer than previously thought.

"By following the changes in malaria incidence, vegetation and socioeconomic data at the level of sub-districts, we identified a transition phase toward sustainable low malaria risk lasting for more than a decade and characterized by an enhanced environmental malaria risk despite intensive mosquito control efforts," Mercedes Pascual, the Rosemary Grant collegiate professor of Ecology and Evolutionary Biology at the University of Michigan, said.