The US is at risk for dengue fever

As the weather warms, mosquitos are expanding their range. With that, mosquito-borne illnesses are also becoming more commonplace. The newest risk to the U.S. is dengue fever, the instances of which have skyrocketed in 2024. The disease has the potential to be deadly if left untreated and is likely going to become more routine as climate change worsens. 

What is dengue fever?

Dengue fever is a mosquito-borne viral illness mostly present in tropical climates. However, the U.S. has begun to see a spike in cases amid warming temperatures. According to the Centers for Disease Control and Prevention (CDC), the U.S. saw a "higher-than-expected" 2,241 new cases, including 1,498 in Puerto Rico between January 1 and July 24, 2024. The highest number of cases in the continental U.S. was seen in Florida, New York and Massachusetts. The problem is not just limited to the U.S. "As of June 24, 2024, more than 9.7 million dengue cases have been reported in the Americas, twice as many as in all of 2023," the CDC said.

Dengue fever is spread through the Aedes species of mosquito. Symptoms of the disease can "present as fever accompanied by non-specific signs and symptoms such as nausea, vomiting, rash, muscle aches, joint pain, bone pain, pain behind the eyes, headache or low white blood cell counts," said the CDC. However, approximately 5% of cases can progress to severe dengue which can cause "plasma, the protein-rich fluid component of blood, to leak out of blood vessels," said The New York Times. "Some patients may go into shock, causing organ failure." The good news is that only one in four cases of dengue fever are symptomatic at all and even severe cases have a high rate of survival, if treated. 

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Is there a cure?

There are no antiviral medications that have been approved to treat dengue fever. Instead symptoms are managed with medication like acetaminophen and patients are advised to rest, stay hydrated and closely monitor conditions. Severe cases may require hospitalization. Some antivirals are currently in clinical trials. 

Prevention is the best option. Experts recommend "staying in places with air conditioning when possible, using insect repellent and wearing long sleeves and pants to avoid mosquito bites," said NBC News. There is one approved vaccine for dengue fever, but it is only recommended for ages 6 to 16 years in locations with high transmission levels. Infants, the elderly and pregnant people are most at risk of contracting severe dengue. 

What about the future?

Climate change does not spell optimism for mosquito-borne illnesses. "Dengue cases are likely to increase as global temperatures increase," said the CDC. "Higher temperatures can expand the range of the mosquitoes that spread dengue, as well as affect other factors that facilitate virus transmission like faster viral amplification in the mosquito, increased vector survival and changes in reproduction and biting rates." As of now, most dengue cases in the U.S. are the result of travel, but local outbreaks are starting to become more customary. 

In addition, "the spread of the disease has been exacerbated by increasingly wet and warm summer months brought forward by El Niño," said Time. The U.S. is not at severe risk just yet, thanks to air conditioning and screened windows limiting exposure to mosquitos. Cases should stay low "as long as people keep living like they're living now," Thomas W. Scott, a dengue epidemiologist and professor emeritus at the University of California, Davis, said to the Times.