CDC: 14 cases of dengue fever reported in Colorado

(NEXSTAR) – Federal health officials warned doctors around the U.S. this week to look out for signs patients may have dengue fever, a virus spread by mosquitoes that's surging worldwide . Cases in the U.S. are three times higher than this time last year.

Most of the cases in the U.S. are in people who recently traveled abroad to regions where dengue is spreading quickly. Only one state so far, Florida, has evidence of local transmission, the Centers for Disease Control and Prevention said. U.S. territories Puerto Rico and the Virgin Islands are also seeing local spread of the disease.

Cases associated with travel are more common. Thirty-eight states plus D.C. have reported at least one case of dengue fever this year.

According to the CDC, there have been 14 reported cases of dengue fever in Colorado so far this year. Last year, there were 20 total.

A spokesperson for the Colorado Department of Public Health and Environment told FOX31 that Coloradans are typically infected when traveling.

"All reported cases of dengue fever in Coloradans both this year and in 2023 are related to travel to areas where dengue fever is endemic," the CDPHE spokesperson said.

One of those places is Puerto Rico, a territory that declared a public health emergency because of the amount of dengue fever cases.

Of the 2,241 cases reported nationwide, more than half were reported in Puerto Rico with 1,498 cases so far this year, and 745 cases have been deemed to be travel-related, according to the CDC.

Dengue fever cases rising nationwide

The map below shows which states have and have not reported confirmed cases of dengue to the CDC: gray indicates zero known cases, pale green indicates one to four confirmed cases, teal represents five to 49, and blue is for states with 49 to 250 cases of dengue fever.

Florida has 191 confirmed cases, New York has 134 and Massachusetts has 50, according to CDC tracking.

For an interactive version of the map above, check the CDC's website here .

In a health alert Tuesday, the CDC advised doctors to know the symptoms, ask questions about where patients recently traveled and consider ordering dengue tests when appropriate.

The virus is spreading fastest in tropical, warm countries, where warm-weather mosquitoes that carry the disease thrive. These mosquitoes are expanding their geographic range because of climate change, experts say.

Across the world, more than 6.6 million infections were reported by about 80 countries last year. In the first four months of this year, 7.9 million cases and 4,000 deaths have been reported, according to the World Health Organization. It's been particularly intense in the Americas, including in Brazil and Peru .

About 1 in 4 dengue fevers are symptomatic, the CDC says. Symptoms, if they do occur, show up typically five to seven days after infection. People often feel fever and other flu-like symptoms such as nausea, vomiting, aches, rashes, joint and bone pain and headaches.

Severe cases can cause serious bleeding, shock and death. There is no widely available medicine for treating dengue infections.