The Lone Star tick (Amblyomma americanum) is known to spread several infectious diseases, including the Heartland virus.

The Lone Star tick (Amblyomma americanum) is known to spread several infectious diseases, including the Heartland virus.
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A rare but sometimes fatal tickborne infection may be expanding its range in the U.S., local and federal health officials warn in a report this week. They say that a case of Heartland virus led to a man’s death in 2021. The infection is thought to have been caught in either Virginia or Maryland—a region of the country where the virus hasn’t been spotted in humans until now.

The report was published online Thursday in Emerging Infectious Diseases by officials with the Virginia Department of Health, the Centers for Disease Control and Prevention, and the National Institutes of Health, as well as doctors at the Johns Hopkins University School of Medicine.

The man was in his late 60s and visited an emergency room in November 2021 with symptoms of fever, diarrhea, aches, and general discomfort. He didn’t appear to have any tick bites, but given his symptoms and the fact that he spent time between two homes in rural Virginia and Maryland, his doctors suspected a tickborne infection and sent him home with antibiotics. Unfortunately, two days later, he returned to the ER with new symptoms, including confusion and unsteady gait, and he was then admitted to the hospital.

The man’s health continued to worsen, and he was soon sent to a specialized care center. Despite testing for various germs, doctors couldn’t find the source of his illness. He eventually developed hemophagocytic lymphohistiocytosis, a rare but life-threatening condition in which the body’s white blood cells attack the organs. His lungs and liver started to fail, and he developed cardiac arrest. He was then placed in palliative care. Thirteen days after his symptoms began, he died.

Doctors still suspected that he had contracted an infection spread by insects or ticks. Given the possibility of an ongoing threat to the public, officials with the Virginia Department of Health launched an investigation. They sent blood samples to the CDC for more extensive testing and went to the man’s homes in eastern Maryland and central Virginia the following summer to collect ticks in the area. The CDC testing finally revealed that he was infected with the Heartland virus, and a subsequent autopsy determined that he had died from complications of the infection.

Heartland virus was discovered in 2009 by doctors at the Heartland Regional Medical Center in northwestern Missouri. It’s known to be spread by the Lone Star tick (Amblyomma americanum), which is commonly found throughout the Eastern and Midwestern U.S. Many known cases of Heartland virus have led to hospitalization and death, but it’s only been sporadically documented in humans. Around 50 cases have been reported in over a dozen states to date, including Kentucky, Indiana, and as far north as New York.

Maryland and Virginia are within the tick’s expected range, but this case of Heartland appears to be the first ever traced back to either state. Because of the larger tick population found at the man’s home in Virginia, the report authors believe he caught it there. Interestingly enough, they failed to find the virus inside ticks at either location. But that doesn’t rule out its presence in these areas, they wrote, particularly because the virus seems to circulate in ticks at very low levels. They further suspect that the man caught the infection from larval ticks, since adults typically become inactive by late October (when he was likely bit). That could also explain why he didn’t notice the initial bite, given their smaller size, and why doctors failed to find any evidence by the time he felt sick roughly two weeks later, since any bite could have healed by then.

Especially compared to much more common tickborne diseases like Lyme disease, Heartland virus is a very rare danger to humans. But it is possible that we’re missing many milder cases of Heartland or that these infections are misdiagnosed as other tickborne diseases because they tend to share common symptoms, the authors say. And thanks in part to climate change, ticks generally are expanding their distribution throughout the U.S., which will make all of the many diseases they carry a bigger threat to worry about.

“Because tick ranges are increasing overall, incidence of previously regional tickborne infections, such as [Heartland virus], likely will continue to increase,” they wrote.

More: An Emerging Virus Has Now Been Spotted in Georgia’s Ticks

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