The CDC says that cases of the dengue virus have increased, particularly in New York and New Jersey. Officials say 41 cases of the mosquito-borne illness have been reported in the Garden State. Pennsylvania has reported 25 cases, while Delaware has only reported four.
There are more than 2,500 infections in the U.S. so far.
Most people became sickened while traveling, according to officials. What is dengue, and where is it common? Dengue is a mosquito-borne virus that is spread mainly via the Aedes aegypti mosquito, which is also known to carry several other viruses such as yellow fever, chikungunya and Zika, according to the CDC. Dengue is endemic in more than 100 countries in tropical and subtropical climates, mostly in urban and semi-urban areas, according to WHO.
It's also endemic in the US territories of Puerto Rico, the US Virgin Islands and American Samoa. More than 34,000 locally acquired cases were reported in the US between 2010 and 2023, according to CDC data. A handful of outbreaks of locally transmitted cases have been reported in states with warmer climates, including Florida, Texas, Hawaii and Arizona.
California reported its first locally-transmitted case in Pasadena last year. But almost all US cases are reported in Puerto Rico, says Dr. Gabriela Paz-Bailey, chief of the Dengue Branch in the Division of Vector-Borne Diseases at the CDC's National Center for Emerging and Zoonotic Infectious Diseases, told CNN previously.
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