LONDON — There may be nearly four times as many people infected with the tropical disease dengue globally than was previously believed.

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 in the journal Nature.

The data could lead to a speedier search for a vaccine for the mosquito-borne disease, which causes symptoms including fever and severe joint pains. The disease mostly affects people in Asia, Africa and Latin America.