Dengue Fever Threatens the U.S.

The specific breed of mosquitoes that carry the four different viruses that spread dengue fever are now regularly found in the southern parts of the United States, but recently the insects have been located in the Bay Area in California and Washington, D.C., NBC reports.

Climate change is expanding the footprint of Aedes aegypti mosquitoes, which carry dengue viruses, past the tropics and into territories further north such as the U.S. Mosquitos can spread parasites such as malaria and viruses like dengue, West Nile, and Zika.

A 2019 study said dengue causes the greatest human disease burden of any arbovirus, with an estimated 10,000 deaths per year in more than 125 countries. Dengue symptoms are usually fever, headache, fatigue, nausea, vomiting, rash, and body aches. Dengue becomes deadlier the more times a human is infected.

While about half the global population currently lives in areas that are environmentally suitable for dengue transmission, by 2080, the study predicts an additional 2 billion people will be threatened by dengue fever.

This year, Latin American is enduring its worst dengue fever outbreak on record, and the virus has infected approximately 2 million people in the region. The recorded cases so far this year are almost three times greater than last year with also experienced historic numbers. In 2023, the Pan American Health Organization reported a record 4.1 million cases, more than 400% greater than the five-year average.

While Aedes aegypti mosquitoes are found in the U.S., it doesn’t necessarily mean the pests are carrying the dengue viruses. Locally infected people remain rare in the continental U.S. Last year, California health officials reported the state’s first case of dengue. Locally transmitted dengue fever infections also have been reported in Arizona, Florida, and along the coast of Texas.

The U.S. Centers for Disease Control and Prevention does not anticipate outbreaks of dengue fever in the continental U.S., but travelers to infected regions with outbreaks could bring the virus back to the U.S. Humans also act as reservoirs for dengue, and the more people infected allows for greater probably of the mosquitos spreading the viruses. For example, Florida has reported only seven cases of locally transmitted dengue so far this year, but 176 dengue cases in total from residents who were infected in other countries. In 2023, the Florida Health Department reported 173 locally transmitted cases.

While a vaccine exists for dengue in the U.S., currently only children ages 9 to 16, who have previously had a dengue infection qualify and live in places were dengue is endemic qualify. Endemic locations include American Samoa, U.S. Virgin Islands, and Puerto Rico, which is currently experiencing an outbreak and has exceeded historical numbers already this year.

As CMM previously reported, the World Health Organization recently reported that insufficient data is available on the actual and potential impacts of climate change on malaria and neglected tropical diseases, such as dengue.