CDC Issues Warning of Increased Dengue Virus Risk Across US

The CDC says that dengue fever cases have hit record highs in Latin America.

A brigade fumigates to combat dengue amid a surge in cases nationwide in Buenos Aires, Argentina, Tuesday, March 26, 2024. AP Photo/Natacha Pisarenko

The U.S. Centers for Disease Control and Prevention (CDC) sent a health alert on Tuesday that warned doctors to be on alert for dengue fever cases as the mosquito-borne disease continues to spread worldwide.

The virus has been on the rise worldwide and in the Americas in recent months, officials said. Some countries have broken calendar-year records for dengue cases, while the U.N. World Health Organization declared an emergency over dengue in December.

In its bulletin on Tuesday, the CDC told doctors to be aware of the symptoms of the viral infection and to ask patients questions about where they recently traveled. Doctors are also advised to order tests for dengue if need be.

Some 2,241 cases have been reported in 2024 across 50 states and another 1,498 cases in Puerto Rico, a U.S. territory. The territory declared an emergency for dengue in March amid a rise in cases.

There were 3,036 dengue cases reported in the United States, Puerto Rico, and other territories last year, according to the CDC. In Latin America, nearly 10 million cases of the virus have been reported, or about twice as many as all the cases reported in 2023, the CDC advisory said.

A separate CDC page shows that most South American and Central American countries, including Mexico and Brazil, have reported higher-than-normal numbers of dengue. It noted that the virus can be considered a year-round risk, and in some areas, there are outbreaks every two to five years.

There is no widely available medicine for treating dengue infections. Vaccines have been problematic because there are four types of dengue that can infect people.

U.S. officials in 2021 recommended one vaccine made by Sanofi Pasteur. The three-dose vaccine is built to protect against all four dengue types and is recommended only for children ages 9 to 16 who have laboratory evidence of earlier dengue infection and who live in an area where dengue is common, such as Puerto Rico.

In the advisory, the CDC said that doctors should “recognize the critical phase of dengue” when the fever begins to decline and lasts between 24 and 48 hours. “During this phase, some patients require close monitoring and may deteriorate within hours without appropriate intravenous (IV) fluid management,” it added.

For the public, the agency suggested using mosquito repellents during travel to areas with frequent dengue outbreaks, wearing loose-fitting and long-sleeved shirts and pants, using air conditioning and window screens, and dumping or draining out containers that contain standing water, which is where mosquitos breed.

Individuals who are planning international travel to an area with frequent outbreaks or continuous transmission of the virus should protect themselves “from mosquito bites during and after your trip,” the CDC said.

The federal health agency said it will also use other measures, including expanding laboratory testing to diagnose suspected dengue cases and providing more information to the public about the virus.

Symptoms and Signs

Dengue, which is sometimes referred to as “breakbone fever,” is caused by a virus transmitted by a type of infected Aedes species mosquito’s bite.

Health officials say that some people can experience no signs or symptoms of a dengue infection. But when symptoms do occur, they can be mistaken for another illness such as influenza.

Symptoms usually start between four and 10 days after being bitten by a dengue-infected mosquito, according to the Mayo Clinic. It generally causes a high fever of 104 degrees Fahrenheit and can include several other symptoms.

That includes muscle, bone, or joint pain; vomiting, nausea, pain behind the eyes; swollen glands, and a rash. In some cases, the symptoms can become life-threatening in what is known as “severe dengue,” dengue hemorrhagic fever, or dengue shock syndrome, says the clinic on its website.

The severe symptoms often can occur after the fever goes away and can include persistent vomiting, abdominal pain, fatigue, rapid breathing, bleeding gums or nose, blood in stool or vomit, restlessness, thirst, pale and cold skin, and weakness.

Complications from severe forms of the disease can lead to organ damage, severe bleeding, and breathing problems, says John Hopkins Medical School.

Since there is no specific treatment for dengue, the main focus involves dealing with pain symptoms. Acetaminophen is generally used to deal with the pain, but drugs such as aspirin, ibuprofen, and other non-steroidal anti-inflammatory drugs are generally avoided because they increase the risk of bleeding, according to WHO.

According to a paper published in the National Library of Medicine, the most popular traditional herbs used for dengue are Carica papaya, or just papaya, and Euphorbia hirta, known as the Asthma-plant. Another research paper has noted that Cissampelos pareira, or velvetleaf, is sometimes used.