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From VOA Learning English, this is the Agriculture Report.
Irrigation systems can make a big difference in agricultural production. Irrigation can also improve the lives of farm families. However, a new study says bringing water to dry areas can also spread malaria.
The study describes how irrigation water can lead to an increase in malaria cases — an increase that can last for years. Malaria is spread by mosquitoes. The insects reproduce in standing water. So when a dry area is irrigated, the disease can appear and spread. Mercedes Pascual is a scientist at the University of Michigan. She and her team studied areas in northern India where irrigation systems were built over a number of years. They compared how malaria progressed with the spread of irrigation. She and the other scientists found that after farmers began irrigating their crops, the risk of malaria rose sharply. At first, the team thought the number of cases rose because there was little effort to control mosquitoes. But, the study found that was not the case. The researchers found that high rates of malaria continued for 10 years or longer even after mosquito control efforts were in place.
Mercedes Pascual suggests that irrigation projects need to limit places where mosquitoes might reproduce. She also says health officials may need to try other methods of malaria prevention that would work for long periods of time. The researchers agree that irrigation helps farming in areas with low rainfall. But, Mercedes Pascual and her team discovered that irrigation also can bring years of high rates of malaria. The only way to avoid the problem is through better planning and control measures.