As of 2010[update], dengue fever is believed to infect 50 to 100 million people worldwide a year with 1/2 million life-threatening infections.[1] It dramatically increased in frequency between 1960 and 2010, by 30 fold.[2] This increase is believed to be due to a combination of urbanization, population growth, increased international travel, and global warming.[1] The geographical distribution is around the equator with 70% of the total 2.5 billion people living in endemic areas from Asia and the Pacific.[2] Many of the infected people during outbreaks are not virally tested, therefore their infections may also be due to chikungunya, a coinfection of both, or even other similar viruses.