Dengue fever cases more common than thought

LONDON — There may be nearly four times as many people infected with the tropical disease dengue globally than was previously believed, according to a new study.

The World Health Organization has estimated there are about 50 million to 100 million cases of dengue, also known as “break-bone fever,” every year. But new research puts the number at around 390 million — though about two-thirds of those people have only mild illness and don’t need medical attention. The study was published online Sunday in the journal Nature.

The data won’t change how patients are handled but could prompt a speedier search for a vaccine for the mosquito-borne disease. The study was funded by the Wellcome Trust, the U.S. Department of Homeland Security and others.

WHO said it wasn’t surprised by the higher estimates. “We fully agree the spectrum of dengue is very wide and there was every chance we were missing cases,” said Raman Velayudhan, the agency’s global dengue co-ordinator. WHO was not involved in the new research.

“The new numbers are not out of the realm of what was expected,” said Jeremy Farrar, director of the Oxford University Clinical Research Unit in Vietnam, one of the study authors. He said the figures came from analyzing more evidence than was used in the past and included other factors that influence dengue.