What Is Heartland Virus? Tickborne Disease May Be Expanding Its Reach Across the U.S.

A man in the Maryland and Virginia region died of the Heartland virus in 2021, suggesting that the tickborne disease may be expanding its reach across the United States, according to a report published by the Centers for Disease Control and Prevention.

Heartland virus (HRTV) disease is an emerging tickborne illness in the U.S., spread by lone star ticks (Amblyomma americanum). Though the virus is typically found in southern and midwestern states in the U.S., the CDC report highlighted a fatal case of HRTV in the Mid-Atlantic region, suggesting that it may be more widespread.

“We are still learning about the virus including what areas are at risk,” study co-author Susan Hills, MBBS, MTH, medical epidemiologist with the CDC Arboviral Diseases Branch, told Health in a statement. “This case was important to highlight because it occurred in an area where we had not previously seen human disease cases.”

HRTV infections are still considered rare—there have been about 60 cases reported in the U.S., as of November 2022. But researchers hypothesize that condition may be more common, since many people only receive HRTV diagnostic tests if their symptoms are severe.

Here’s what experts had to say about how dangerous HRTV could be, who’s most at risk, and how to stay safe heading into the spring and summer months.

How Do You Get Heartland Virus?

HRTV is considered an emerging tickborne illness, and was first discovered in two Missouri farmers in 2009. As a result, there are still many things that researchers are trying to discover about HRTV and the ticks that carry the infection.

HRTV is carried and spread by tick bites, similar to Lyme disease. However, while Lyme disease is a bacterial infection transmitted through the bite of blacklegged ticks, HRTV is a viral infection spread by lone star ticks.

HTRV is much less common than other tickborne illnesses like Lyme disease, but the transmission risks may be similar. The lone star tick can be found from Iowa to Texas in the west, and its range stretches through every U.S. state to the east, from Florida to Maine. Not every one of these states has reported a HRTV infection, though there are still a large number of people at risk of contracting the illness.

In particular, men over 50 with multiple underlying conditions seem to be at the greatest risk of getting severe HRTV infections.

“Men are far more likely than women, still, to put themselves in circumstances where you're exposed to the ticks,” Michael Decker, MD, MPH, adjunct professor of preventive medicine at the Vanderbilt University Medical Center, told Health. Men may be more likely to be working as farmers, foresters, or have other occupations where they may get more tick bites, he said.

But beyond gender, the fact that more older and people with underlying conditions seem to get HRTV is a bit more complicated to explain.

“Risk for arboviral infections (viruses spread by ticks and mosquitoes) generally increases with age and among people with underlying medical conditions that affect their overall health status,” Dr. Hills said.

Scientists are still working to figure out why this is the case, but the overrepresentation may be due to the fact that less severe infections—ones that don’t require hospitalization or medical assistance—are being missed in younger or healthier people.

“People with underlying diseases are more likely to get seriously ill, and then end up in a hospital where there’s a chance somebody will think to test them correctly,” Dr. Decker said.

It's possible that there are hundreds or even thousands of Americans in these regions who've had mild cases of HRTV. But researchers need to conduct large population antibody tests to see how common the illness really is.

“What’s reported is only the most severe cases," Dr. Decker said. "There’s almost certainly many more cases that aren’t reported, which are mild."

Getting Sick with Heartland Virus

After a person is bitten by a tick carrying HRTV, they may start feeling sick after a period of a few days to a few weeks.

Symptoms for HRTV can range widely, and oftentimes mimic those of other diseases. People with this infection can expect symptoms such as:

• Fever
• Fatigue
• Headache
• Decreased appetite and nausea
• Muscle or joint pain

If someone does decide to seek care after being bitten by a tick, their doctor may prescribe them antibiotics, which are usually effective against other tickborne illnesses, Dr. Hills said. If a patient doesn't respond to that treatment—and the patient lives in a region where HRTV is present—a doctor may test them, which involves a blood test that is then sent to the CDC, Dr. Decker explained.

But again, classic HRTV symptoms and the diagnosis process may be driving underreported cases. With milder illness, people may not think to seek medical treatment and will recover from the virus on their own. And if someone does go in, their doctor may not even think to test for HRTV since it is still relatively unknown, Dr. Decker said.

Despite the hurdles, many people are still diagnosed with HRTV, particularly if they have more severe cases of the infection. People with weakened immune systems and other underlying health conditions may have a harder time fighting off the virus, and cases can turn severe or even fatal in some instances.

Researchers are still trying to determine what’s going on in the body with these severe infections, though the effects can be broad.

“All we know is what we can see,” Dr. Decker said. “The virus seems to spread widely in the body. It seems to damage the organs that it spreads to. One of those, an early marker of it, appears to be the bone marrow. Because suddenly the characteristics of your blood changes.”

In these severe cases, people may lose white blood cells and platelets, which prevent infections and help with clotting, respectively. People may also have higher levels of liver enzymes in the blood, a sign that the virus is attacking the liver, Dr. Decker added. Eventually, the infection can overwhelm the body and the patient may die. In the case of the patient in the CDC report, the man died of acute respiratory failure, renal failure, and a cardiac arrest.

In these more severe instances, patients will likely need to be hospitalized so they can receive fluids, supportive care for pain, or help with related problems that come up during the course of illness. Still, there are no antiviral treatments available for HRTV.

Staying Safe

In the absence of HRTV treatment options, Drs. Hills and Decker emphasized that the best thing to do is to avoid getting infected in the first place—this means preventing tick bites whenever possible, especially if you live in the Midwest, Southern, or Eastern U.S.

A person can do this by using quality bug spray, avoiding grassy, brushy, or wooded areas where ticks live, showering after being outdoors, and checking their body and clothing for ticks after they've been outside, Dr. Hills said.

This is especially true in the spring and summer months—all reported cases of HRTV have happened between April and September, so now is the time to be on high alert for tick bites.

“Ticks can be found all over the United States, even if they don’t carry HRTV, they may carry other germs that can make people sick,” Dr. Hills said. “It’s important that people take steps to prevent tick bites no matter where they live.”

With this newly reported case in the Mid-Atlantic region, it’s possible that the virus could be present in lone star ticks in other states in the U.S. as well. These ticks have expanded their range over the last 20 to 30 years, Dr. Hills said, which could possibly be because of climate change.

But avoiding tick bites altogether isn’t a foolproof solution, Dr. Decker added. Ticks are often a part of life for people who spend time outdoors in the summer, no matter how committed someone is to preventative measures. And some ticks may be as small as the head of a pin, he said, making bites even harder to avoid.

So as researchers continue to learn more about HRTV, it’s important that everyday people and healthcare professionals alike are aware of the potential threat of this disease.

In addition to doing their best to avoid tick bites, people should seek medical assistance if they start to feel ill from a tick bite, Dr. Hills said. This may open up a clearer picture for researchers to get a better handle on the disease.

“Now that we know HRTV can be found in the Maryland and Virginia region, we can alert providers in this area to consider HRTV disease,” Dr. Hills said. “CDC can perform diagnostic testing to confirm whether a patient’s illness is caused by the virus.”