The global health burden of dengue could be much higher than previously thought. In modeling work published, a team led by Simon Hay, an epidemiologist at the University of Oxford, UK, estimated that 390 million people around the world were infected with the mosquito-borne virus in 2010, a figure more than three times greater than that given by the World Health Organization.
Only around a quarter of all the dengue cases were ‘apparent’—requiring medical treatment or making people miss work or school—so the findings are unlikely to greatly affect clinical practice. However, the large number of previously unrecognized people with mild or asymptomatic infections could have an impact on future mosquito control efforts or vaccination campaigns. “The bigger the problem, the more important become any efforts to prevent it,” says Donald Shepard, a health policy researcher at Brandeis University in Waltham, Massachusetts, who studies dengue.