How to avoid humid, hot dengue fever in summer: Shots

Latin America has already had a record-breaking year for dengue infections, with around 10 million cases diagnosed so far.

Now, the Centers for Disease Control and Prevention is warning that the risk of mosquito-borne viruses is increasing in the United States as summer weather and holiday travel heats up.

This week, the CDC Said Healthcare workers are urging people to be vigilant and test for possible cases, especially among people with fever who have recently returned from areas experiencing a dengue outbreak.

“There is currently no evidence of widespread transmission on U.S. soil.” Gabriela Paz-Bailey“But dengue cases are increasing at an alarming rate around the world, especially in the United States,” said the head of the CDC's dengue division, who is based in San Juan, Puerto Rico. Increased travel to dengue-endemic areas is expected during the summer months, which could lead to further community transmission in the United States.”

The United States Approximately 2,200 cases So far this year, about 1,500 cases have occurred locally, most of them in Puerto Rico, where the dengue virus is considered endemic, meaning it circulates continuously.

Puerto Rico declared Public health emergency An unseasonably early surge in dengue cases in March led to a dengue outbreak that ended in March, and locally transmitted cases have also been reported in the U.S. Virgin Islands and Florida this year, according to Paz Bailey.

To be clear, the CDC isn't expecting a major nationwide surge this summer. Instead, Paz Bailey says they expect an increase in travel-related cases and associated smaller chains of community transmission, which could occur in any state where the population is already stable. Aedes aegyptiIt is the species most associated with transmission in the Americas.

in recent yearsLocalized cases of dengue have been confirmed in Arizona, California and Texas. “As temperatures rise, we need to continue to prepare and strengthen our surveillance systems to monitor new areas for dengue outbreaks,” Paz Bailey said.

Why is there a sudden increase in dengue virus infections now?

Dr. Albert Co, a Yale University public health professor who has treated dengue patients in Brazil for 30 years, said a confluence of factors related to weather, weakened immune systems and human behavior contributed to “the explosive outbreak that occurred last year.”

First, South America is warm and rainy, providing ideal conditions for mosquito breeding. Populations of potential dengue vectors are thriving. This year, mosquitoes have brought dengue fever to parts of southern Brazil and Argentina where dengue had never been found before. That's a “testament to climate change” and that mosquitoes' ranges are expanding, Ko said.

Second, dengue epidemics tend to be cyclical, with large outbreaks occurring every few years, with the most recent outbreaks occurring in 2019The cyclical pattern of dengue outbreaks is linked to the ebb and flow of population-level immunity, Koh said.

There are four different strains of dengue, and a person who recovers from one strain is protected against all strains for two years. But that immunity weakens over time, “and then… Vulnerable to the other three“Dengue has epidemic peaks,” Koh said. At the population level, immunity rises after a major outbreak, but then fades in the years that follow, causing new waves of dengue infections.

And third, the dengue virus is spreading among human travelers seeking to see family, friends and places they missed when travel came to a halt during the COVID-19 pandemic.

“Human movement plays a major role in the movement of viruses, whether short or long distances,” he said. Gonzalo Vázquez-Prokopec“Humans are vectors, they carry the virus over even longer distances than mosquitoes,” says Jonathan Myers, an environmental scientist and global health researcher at Emory University. Humans are bitten by dengue-infected mosquitoes and, often unknowingly, carry the virus wherever they go next.

About 75% of people who contract dengue have mild or no symptoms, “which means you could travel to an area with active dengue transmission, catch dengue, and then go home and transmit dengue to a mosquito,” Paz Bailey says. Those mosquitoes could then bite other people, setting off a chain of community transmission.

How bad is dengue if most people have no symptoms?

A quarter of people who contract dengue become seriously ill. “The virus spreads through the body three to four days after the bite and causes a systemic illness,” said Ko, who has treated thousands of dengue patients. “The symptoms are: [include] Fever, very bad body aches, joint pains and a very bad headache.”

Some patients may develop severe dengue fever and may experience symptoms such as: Capillary leak syndrome“The blood vessels become leaky, and the patient goes into dehydration and shock, requiring emergency medical intervention, including IV resuscitation, to save their life,” says Yale's Ko. People with fever and headaches from dengue should self-treat with Tylenol or acetaminophen and avoid aspirin, Ko says, because aspirin thins the blood and can worsen the bleeding symptoms of dengue.

Dengue fever can be severe and fatal whether you get it the first, second, third, or fourth time, but you're at higher risk for severe illness if you get it a second time, says the CDC's Paz Bailey, because of a phenomenon known as dengue fever-related illness. Antibody-dependent enhancementA first dengue infection activates a person's immune system, making it easier for the virus to infect cells the second time around.

Groups at highest risk of severe illness include infants, pregnant women and the elderly.

What precautions should I take?

Individuals must wear long sleeve shirts and pants, EPA registered insect repellentsaid Paz Bailey of the CDC.

“You can also reduce the buzzing of mosquitoes in and around your home by discarding standing water, putting screens on windows and using air conditioning where possible, which will help keep mosquitoes away,” she says.

people Fever, severe headache, and other symptoms People with dengue fever should seek medical attention, and medical personnel will assess their symptoms and travel history and, if necessary, Have a blood test.

Dengue is a nationally notifiable disease, so any cases detected need to be reported to local health authorities, which can help track where the virus is spreading and boost local education and mosquito control efforts, Ko said.

Dengue vaccine discontinued

The dengue vaccine, Dengvaxia, has been approved for use in the United States, where the dengue virus is endemic, including Puerto Rico and the U.S. Virgin Islands. But the vaccine, which requires three doses and requires multiple blood tests and repeated doctor's appointments, is difficult to administer and has been slow to gain traction. Sanofi Pasteur Production discontinued Paz Bailey said production has been halted due to lack of demand, with the remaining vaccines having an expiry date of 2026.

Yale's Koh says there are two hopes for the future: better mosquito-control measures to reduce dengue transmission and better vaccines to protect people who aren't infected.

“The bad thing about reducing infections is that people become more susceptible to infection because they're not infected,” he said. “But with the vaccine and [better] Vector control methods reduce that risk.”

Ko sees progress being made on both fronts. Potentially Interfering Bacteria Mosquito breeding and Another dengue vaccine Not approved in the U.S., but approved in some countries

Ko said better interventions that tackle mosquito-borne diseases from multiple angles could make the country's response to diseases such as dengue “considerably more effective” and save more lives.