The death of a Miami woman in her 30s from locally acquired dengue fever highlights the need for awareness of a potentially fatal mosquito-borne virus that’s now found in the United States.
Once only seen in hot and steamy tropical or subtropical locales, dengue has been on the rise in parts of the southern United States due to global warming, travel and other factors. While most Americans still contract the disease while traveling to parts of the world where dengue is endemic, there have also been cases of locally acquired dengue in the United States, including a 2019 outbreak in Miami.
This can occur when a local mosquito feeds on a person who is infected with dengue and then pass the disease on to others.
Spread by a bite from an infected Aedes mosquito, dengue can cause a high fever, rash and muscle or joint pain. In severe cases, dengue can cause potentially fatal bleeding and shock. Each year, up to 400 million people will become infected with dengue and about 22,000 will die from this disease, according to the U.S. Centers for Disease Control and Prevention.
In 2019, Florida saw 413 folks diagnosed with dengue, most of whom had recently traveled to Cuba. This outbreak sired 18 locally acquired cases, including one that resulted in the young Miami woman’s death. To determine the source of the infection, doctors reviewed the woman’s travel history and performed genetic sequencing of the virus, which confirmed that it was locally acquired.
Her story is the basis of a letter in the June 10 issue of the New England Journal of Medicine. It should serve as a cautionary tale, said co-author Dr. Stephen Morris, an infectious disease specialist at Jackson Memorial Hospital in Miami.
“Florida is a sort of a quasi-endemic area for dengue now,” he said. “We should expect this as a risk moving forward, and doctors in the southern U.S. should know that dengue is on the table as a possible diagnosis.”
There is no widely available vaccine to prevent dengue, Morris said. To stave off infection, “use a good bug spray, cover your skin and avoid areas with a lot of standing water,” he said. Mosquitoes like to lay eggs near standing water in buckets, bowls, flower pots and vases.
Screens on doors and windows can also keep mosquitoes out, Morris said.
There is no rapid test for dengue either so it can take several days to make a diagnosis, explained study co-author Tyler Sharp, an epidemiologist at the CDC’s dengue branch in San Juan, Puerto Rico.
A delay in diagnosis played a role in the Miami woman’s death. “If you think it could be dengue, treat it as if they have it, and if it’s negative, there is no downside,” Sharp said.
Treatment involves hydration and close monitoring of vital signs. “Tell your doctor if you have been to an area where dengue is endemic or if someone you know has recently been diagnosed with dengue as it may not be front of mind to many doctors,” he said.
Controlling mosquitoes at the community level has been more challenging, said Sharp.
“We need to raise awareness and develop, evaluate and ultimately implement tools to fight dengue in South Florida and elsewhere,” he said.
There are ways of reducing the mosquito population that are currently being explored. For example, as part of a controversial study, Florida released genetically modified male mosquitoes that pass on a gene that kills female offspring before they mature. Only female Aedes aegypti mosquitoes can bite and spread dengue.
Unless and until the mosquito population is reduced, “it is very important to be aware of dengue in Florida, Texas and Hawaii as we know that mosquito vector is there,” said Yesim Tozan, an assistant professor of global health at the NYU School of Global Public Health in New York City.
Fortunately, most local outbreaks in the United States have been limited as mosquitoes can’t fly too far, she said.
“We need to be vigilant about fever and illness particularly when we know mosquitoes are active,” Tozan said. Mosquito season spans from spring to fall.
“Climate change is making us see severe weather like unexpected rain and fluctuating temperatures and mosquitoes are very sensitive to this, so all of a sudden we have breeding activity when we normally would not,” explained Tozan, who was not involved in the new report.
“Be an educated traveler,” she said. “If you are coming back from areas where dengue and other mosquito-borne diseases are prevalent, share your travel history with your doctor.”
The U.S. Centers for Disease Control and Prevention offers more on dengue prevention.
SOURCES: Stephen Morris, MD, infectious disease specialist, Jackson Memorial Hospital, Miami; Tyler Sharp, PhD, epidemiologist, CDC Dengue Branch, San Juan, Puerto Rico; Yesim Tozan, PhD, assistant professor, global health, NYU School of Global Public, New York City; New England Journal of Medicine, June 10, 2021