Want to know if there will be a malaria epidemic in northwest India this year? Just check the temperature of the South Atlantic Ocean. According to HHMI Investigator Mercedes Pascual, sea surface temperature in the South Atlantic is a big determinant of levels of monsoon rain in that part of India, which in turn is linked to the number of malaria cases.
Malaria outbreaks in these semideserts of India are directly related to the severity of monsoons, according to earlier work by Pascual and her team at the University of Michigan: the more rainfall, the worse that year’s outbreak. Since monsoon season ends in September and malaria season peaks in November, malaria outbreaks could be predicted one or two months in advance.
“We were interested in whether we could use other climate measures to predict monsoon patterns and develop an even earlier warning system,” says Pascual. Her team looked at global monthly ocean temperatures over a 20-year period and compared them to rainfall patterns and the size of malaria outbreaks in India each year. They saw a clear link between abnormally cold temperatures in the tropical South Atlantic in June and July and an increase in malaria in northwest India four months later. The lower ocean temperatures led to changes in the atmosphere, which over time increased rainfall, providing the perfect breeding conditions for the malaria-carrying Anopheles mosquito. The scientists published their findings May 2013 in Nature Climate Change.
This is good news for public health authorities in India. Gaining an extra month or two to predict the severity of a malaria outbreak gives them time to better prepare drug stockpiles and enhanced mosquito control interventions, and encourage prevention efforts.