Dengue fever, West Nile virus and malaria cases are cropping up in the U.S. Do I need to worry?

Cases of dengue fever, West Nile virus and malaria, which spread by infected mosquitos, have recently been making headlines in the U.S. (Illustration by Kyle McCauley; Photo: Getty Images)

Mosquito-borne illnesses get attention every summer, but this year feels a little different. West Nile virus, malaria and dengue fever have garnered media attention, making many people wonder just how concerned they should be about both illnesses.

It’s important to note that you can’t get these illnesses without being bitten by an infected mosquito, but mosquito bites are also incredibly common in the warmer months. So, how concerned should you be about West Nile virus, malaria and dengue fever in the U.S.? Infectious disease experts break it down.

What's happening?

West Nile virus and malaria have gotten a lot of attention over the last few weeks, and with good reason. So far in 2023, there have been 69 cases of West Nile virus detected in the U.S. over 16 states, according to data from the Centers for Disease Control and Prevention (CDC). Of those, 55 have caused neuroinvasive disease, which means it can cause brain and spinal cord infections such as meningitis, encephalitis or acute flaccid paralysis, per the CDC. However, that data is a little complicated (more on that in a moment).

But dengue fever is suddenly making headlines after health officials in Florida said in a surveillance report that the state has seen 10 locally-acquired cases of the virus this year, meaning people were infected in the U.S. from mosquitoes here. Two have been in Broward County, while eight have been in Miami-Dade County.

There are typically around 2,000 cases of malaria diagnosed in the U.S. each year, per the CDC, but the disease is usually detected in people who travel to the states from areas outside the country where malaria is common. However, the latest cases have been locally acquired. Locally acquired cases have been detected in both Florida and Texas.

“It’s summertime and mosquito populations are up there,” Dr. William Schaffner, an infectious disease specialist and professor at the Vanderbilt University School of Medicine, tells Yahoo Life. “In recent decades, there as been a slight increase in West Nile infections during this point in time, but the locally acquired malaria is something new.”

Do I need to worry?

Doctors say it depends. “We’ve been hearing a lot about malaria because it’s fairly exotic,” Dr. Thomas Russo, a professor and chief of infectious diseases at the University at Buffalo in New York, tells Yahoo Life. “Locally acquired transmission has occurred eight times. It’s unusual, but not unprecedented — but it’s very uncommon and treatable."

Malaria can cause symptoms such as fever and flu-like illness, along with anemia and jaundice, per the CDC.

Worth noting: Russo says that locally acquired cases of malaria “will likely burn out at some point,” given that the mosquitoes that can carry it only live for eight or so days.

With dengue fever, Russo says that "the level of concern should be low, but not zero." Dengue fever can cause high fever, headache, body aches, nausea and rash, per the World Health Organization (WHO). In severe cases, it can be fatal.

"There have been cases over the past few years of dengue in Florida and Texas that appear to be locally acquired in the state," Russo says. "We have the vector in this country and that mosquito is fairly widespread."

But West Nile is a different concern. “West Nile is a completely different beast,” Russo says. While many people can get the disease and have no symptoms, he points out that others can develop flu-like illness and even serious brain infections. “A big concern with West Nile is that a minority of individuals could develop neurological complications,” Russo says.

He stresses that, while the latest data looks like the majority of people in the U.S. with West Nile virus have neurological conditions, the “vast majority of cases of West Nile virus go undetected.” Doctors often only think to test for West Nile virus when someone develops serious neurological complications, he says. That means there are a lot of people who get West Nile virus who don’t even know they have it.

If so, what should I be worried about? And what can I do about it?

Doctors say that the average person should not worry about the risk of contracting malaria, dengue fever or West Nile virus. “The concern should not be anything to panic about,” Schaffner says. “But there are things you can do to reduce your risk.”

The most important thing you can do is to wear insect repellent if you’re going outdoors in areas where mosquitoes are prevalent, “particularly if you’re living in areas where these cases have occurred,” Schaffner says.

The CDC recommends picking an insect repellent that’s registered with the Environmental Protection Agency and contains one of the following ingredients:

  • DEET

  • Picaridin

  • IR3535

  • Oil of lemon eucalyptus (OLE)

  • Para-menthane-diol (PMD)

  • 2-Undecanone

It’s also a good idea to wear loose-fitting, long-sleeved shirts and long pants to protect yourself, use screens on windows and doors to keep out mosquitos, and run your air conditioner if you own one, the CDC says.

“Additionally, people need to minimize standing water, which mosquitoes use to lay eggs, by cleaning up trash and other receptacles in their yard,” infectious disease expert Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security, tells Yahoo Life.

The main takeaway

Experts say that you shouldn’t be overly alarmed about the risk of malaria, dengue fever and West Nile virus in the U.S. — but that it’s important to know that the diseases are in the country.

West Nile cases in particular may also become more common with time. “There is an increasing concern of more of these infections happening as the country gets warmer,” Russo says. “The secret is mosquito control and to not get bitten by mosquitoes, if you can help it.”