Mosquitoes transmit dengue fever to people throughout the Americas. Historical level And travelers from the US are bringing the potentially deadly virus home with them, with an alarming rise in cases prompting US health officials to warn of the risks.
After record numbers of people fell ill with dengue fever in South America, tropical disease cases are declining during the cool winter months, but experts warn that infections will rise across Central America, Mexico and the Caribbean as summer and hurricane season arrive in the Northern Hemisphere.
While the risk of local transmission in the continental U.S. remains low, officials are concerned about how much dengue could harbor within the country in the coming years. Climate change is causing intense droughts followed by heavy rains that could sustain the pesky mosquitoes that transmit dengue. Egyptian Aedes Mosquito Mosquitoes have never been completely eradicated from the United States.
A. egypti loves to suck human blood and there is an opportunity for it to spread in populated areas, posing a risk of sustained local transmission of dengue in the country.
“The rise in cases is to be expected,” said Dr. Albert Ko, an infectious disease epidemiologist at the Yale School of Public Health who specializes in dengue. “Climate change will accelerate the spread of dengue and other viruses. I think the question is, what do we do about it?” he added.
More people contracted dengue in the United States and its territories in the first half of 2024 than in any other year in the past decade. Cases have emerged through travel, where people are bitten by the pesky Aedes aegypti mosquito overseas, and in Puerto Rico, where a surge in infections there prompted officials to declare a public health emergency in March.
In late June, the U.S. Centers for Disease Control and Prevention issued a health advisory warning about the increased risk of dengue fever in the United States.
Recent extreme weather events, such as Hurricane Beryl, pose further risks as even the smallest standing water can provide fertile ground for mosquito breeding and the spread of dengue fever.
Symptoms and causes of dengue fever
Most people with dengue fever never develop symptoms, but those who do experience symptoms such as high fever, body aches, nausea, and a rash. Most people with dengue fever recover within a few weeks. who.
Some infections can become severe, requiring hospitalization and, in rare cases, leading to death. Severe dengue fever occurs in about one in 20 infected people and symptoms include vomiting, restlessness, rapid breathing, and blood in the gums, nose, and stool. Infants, the elderly, and pregnant women are at higher risk of developing severe symptoms. CDC Said.
Repeated infections increase the chances of developing severe dengue fever.
There are four different types of dengue virus, and immunity to each lasts only a few years.
The same Egyptian mosquito species that causes dengue fever is notorious for causing historical epidemics of deadly diseases such as yellow fever and Zika.
Dengue-carrying mosquitoes can transmit the virus to humans, but infected people, including those who don’t have symptoms, can also introduce the virus into local mosquito populations, and once infected, mosquitoes can transmit the virus throughout their short lives, WHO said, helping to keep dengue spreading.
Spreads fast and far
A. egypti mosquitoes can lay their eggs in small pockets of standing water such as bottle caps, pipes, broken pots, or anywhere water can collect.
“They’re really good at being everywhere,” said Dr. Gabriela Paz Bailey, chief of the CDC’s dengue division.
After decades of failed international campaigns to eradicate dengue and Egypt fever, the global rise of dengue is clear. In 2000, there were 500,000 cases of dengue. By 2019, there were 5.2 million cases. By 2023, the number of cases will exceed 6.5 million and dengue-related deaths will reach 7,300, the highest number ever recorded.
“Dengue is increasing rapidly and is now occurring in areas where it wasn’t previously present,” said Paz Bailey, who is based in San Juan, Puerto Rico.
About 2,700 cases have been confirmed in the United States so far this year, according to CDC data, with the majority of cases occurring in Puerto Rico during what is considered the island’s dry season.
Nearly 900 Americans have contracted dengue while traveling abroad after returning to states such as Florida, Texas, Arizona and California, where the Egyptian mosquito thrives and therefore where local transmission is more likely. Cases have also been seen in northern states, with over 140 cases in New York and 35 in Illinois, both of which are not favorable for the Egyptian mosquito.
Paz Bailey said increased travel since the COVID-19 pandemic has led to an increase in infections. Puerto Rico has a high rate of dengue infections, he said, in part because of weakened immunity from the 2015-2016 Zika outbreak. He also said the type of dengue virus is changing from dengue 1 to dengue 2 to 3.
Risks looming for the US
Much of the southern United States is ideal for the Egyptian mosquito to thrive, and climate change is expanding the range of these hot, humid habitats, officials say.
“We have to recognize the unique vulnerabilities of this region,” Dr. Peter Hotez, co-director of the Center for Vaccine Development at Texas Children’s Hospital and dean of the School of Tropical Medicine at Baylor College of Medicine, told USA Today.
In addition to climate change, he points to urbanization in areas such as Houston, a sprawling metropolitan area that is the fourth-largest city in the United States, and poverty as driving dengue’s reintroduction into the United States.
Hotez said discarded tires could be the “Ritz Carlton” for the Egyptian mosquitoes that infest the region. Additionally, Texas’ international airports allow travel to and from areas with widespread local transmission.
In muggy Houston, the recent impacts of Hurricane Beryl, combined with several days of scorching heat, have created ideal conditions for the spread of dengue fever and other vector-borne diseases, state officials said. Texas has had 10 cases of dengue fever this year, according to state health officials. So far, all are believed to be travel-related and not locally acquired.
There is currently no widely available vaccine to prevent dengue in the U.S. The best way to prevent dengue is to protect yourself from mosquito bites, which can occur at any time of the day or night.
Before going for his morning walk, Hotez says he puts on sweatpants and a sweatshirt and sprays on bug repellent to protect against mosquito bites.
