NEW YORK — U.S. health officials on Tuesday warned doctors to be alert for dengue cases as the tropical disease breaks international records.
The virus, which is transmitted by mosquitoes, has been on the rise around the world, helped by climate change. In just six months, the countries of the Americas have already broken calendar year records for dengue cases.
The world health organization declared an emergency in December and Puerto Rico declared a public health emergency in March.
Dengue fever remains less common in the continental United States, but in the 50 states so far this year there have been three times as many cases as in the same period last year. Most were infections contracted by travelers abroad, and officials note there is no evidence of a current outbreak. But they also warn that local mosquitoes pose a threat.
In Tuesday’s health alert, the Centers for Disease Control and Prevention advised doctors to know the symptoms, ask questions about where patients have traveled recently and consider ordering dengue testing when appropriate.
Dengue fever (pronounced DEHN’-gay) is caused by a virus transmitted by a type of warm-weather mosquito that is expanding its geographic range due to climate change, experts say.
Many infected people do not get sick, but some experience headache, fever, and flu-like symptoms. Severe cases can cause severe bleeding, shock and death.
Repeated infections can be especially dangerous.
There are four types of dengue virus, known simply as 1, 2, 3 and 4. When someone is first infected, their body produces antibodies against that type for the rest of their life. If they are infected with another type of dengue, antibodies from the first infection may not be able to neutralize the second type – and may actually help the virus to enter immune cells and replicate.
This is a concern in Puerto Rico, which over the past two decades has been widely exposed to type 1. Last month, the island recorded its first dengue death of the year.
“We are currently seeing increases in cases due to dengue 2 and dengue 3, for which the population has very little immunity,” said Dr. Gabriela Paz-Bailey, head of the dengue department at the CDC in Puerto Rico.
There is no widely available medication for treating dengue infections.
Vaccines have been complicated. US authorities in 2021 recommended a vaccine, manufactured by Sanofi Pasteur. The three-dose vaccine was developed to protect against all four types of dengue and is recommended only for children ages 9 to 16 who have laboratory evidence of a previous dengue infection and who live in an area – such as Puerto Rico – where dengue is common.
Given these restrictions and other issues, it has not been widely used. As of the end of last month, only about 140 children had been vaccinated in Puerto Rico since vaccines became available in 2022, and Sanofi Pasteur told the CDC it will stop manufacturing the vaccine.
A different vaccine made by Tokyo-based pharmaceutical company Takeda is not currently licensed in the US. Others are under development.
Worldwide, 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 were reported, according to the World Health Organization. It has been particularly intense in the Americas, including Brazil It is Peru.
In the United States, the numbers were much more modest – about 3,000 cases last year in US states and territories. But it was the worst in a decade and included more infections that occurred locally, courtesy of native mosquitoes. Most were in Puerto Rico, but about 180 were in three US states – Florida, Texas and California.
So far this year, there have been nearly 1,500 locally acquired cases in the U.S., almost all of them in Puerto Rico.
The majority of cases in the continental United States continue to be people who became infected while traveling internationally.
It’s “a traveler’s nightmare” and a growing international concern, said Dr. Lulu Bravo, who studies pediatric tropical diseases at the University of the Philippines in Manila and who worked with Takeda on its vaccine.
“When there is an outbreak in a country, tourists may not want to come,” Bravo said.
___
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group. AP is solely responsible for all content.
This story originally appeared on ABCNews.go.com read the full story
