C.D.C. Warns Doctors About Dengue as Virus Spreads to New Regions

Federal health officials warned that the risk of contracting dengue in the United States has increased this year, a worrying sign as global cases of the mosquito-borne disease hit record numbers.

In the first half of this year, countries in the Americas reported twice as many cases as were reported in all of 2023, the Centers for Disease Control and Prevention reported Thursday in an alert to health care providers.

The region has seen nearly 10 million cases of the virus so far in 2024, most of which originated in outbreaks in South American countries like Brazil and Argentina.

While the local transmission of the virus in the mainland United States has been limited, Puerto Rico, which is classified as having “frequent or continuous” dengue risk, declared a public health emergency in March and has reported nearly 1,500 cases.

Cases of dengue fever, a mosquito-borne viral illness that can be fatal, are surging around the world. The increase is occurring both in places that have long struggled with the disease and in areas where its spread was unheard-of until the last year or two, including France, Italy and Chad, in Central Africa.

There have even been a few hundred cases of local transmission in the United States. Florida health officials urged the public to take precautions — like wearing bug spray and dumping out standing water — after reporting a locally acquired case of dengue this month.