Invisible threats: New tick-borne dangers found on U.S. military installations

By Douglas Holl, Defense Health Agency-Public Health

While service members train for visible threats, a nearly invisible one is emerging from our own backyards. Rare but dangerous viruses carried by ticks no bigger than a sesame seed are being detected on and around U.S. military installations, and a proactive public health program is giving us the early warning we need to stay safe.

The MilTICK SURE Path program, a national surveillance effort short for Surveillance for Understudied, Rare, and Emerging Pathogens, recently identified ticks carrying Powassan virus in Connecticut, Massachusetts, and, for the first time, Maryland. The program also confirmed the first Heartland virus–positive tick at Fort Knox, Kentucky.

While human cases are rare, these viruses can cause severe illness, making early detection a critical tool for protecting the force and military families.

What are these viruses?

Powassan virus, transmitted by the same blacklegged tick that transmits Lyme disease,is a serious threat. Not every person bitten by an infected tick will get sick, but for those who do become ill, Powassan virus can cause severe neurological disease, including inflammation of the brain, known as encephalitis. Approximately one in 10 severe cases is fatal, and half of survivors may face long-term health problems. The spread of Powassan virus is influenced by changes in climate and land use, according to a 2023 review inthe academic journal Pathogens. Heartland virus, transmitted by the lone star tick, can cause serious illness requiring hospitalization. While the virus is known to exist at low levels in areas where lone star ticks are abundant, the Fort Knox finding is the first proof of its presence on the installation itself.

“This is a public health threat that local physicians may not have been aware of, and it should be on their radar,” said Robyn Nadolny, chief of the Defense Health Agency–Public Health Vector-borne Disease Branch at Aberdeen Proving Ground, Maryland. Further research suggests the invasive Asian longhorned tick may also be able to transmit the virus, potentially creating a wider risk in the future.

The solution: A ‘force multiplier’ for surveillance

The military is actively hunting for these threats through a powerful, two-part system. MilTICK is a free service for the Department of Defense community to submit ticks for testing. Its partner program, SURE Path, acts as a “force multiplier for our surveillance efforts,” said Nadolny. It retests ticks submitted to MilTICK for a suite of rare but high-impact pathogens and shares the results with public health officials.

This "passive surveillance" relies on community participation, said Nadolny. She acknowledged this means the data isn't perfect, but stressed the overall trends can still reveal valuable information about emerging threats.

“MilTICK and SURE Path allow us to track trends in where rare pathogens are emerging,” said Nadolny. “Finding Powassan virus in Maryland is a perfect example of the kind of information that is helpful to know before human cases start so that local health providers can learn what symptoms to watch for and what treatments are available.”

Nadolny also shared the example of another parasitic tick-borne disease emerging in the Mid-Atlantic region: Babesiosis, a malaria-like disease that is more commonly found in the Northeast and upper Midwest of the United States.

“Since this parasite is not treated with the same antibiotics as other tick-borne infections, and is a common co-infection with Lyme disease, it’s important to be aware of these changing risks to enhance readiness of our military and improve community health,” said Nadolny.

The bottom line: How to protect your family and your unit

This data is used to take direct action, from reinforcing prevention for ROTC cadets undergoing summer training at Fort Knox, to helping doctors understand their local"tick-scape," said Nadolny.But for every service member, leader, and family member — the most important takeaway is prevention.

Learn more and participate

By participating in the MilTICK program, DOD civilians, contractors, service members, and their families contribute to a safer, more ready force. For more information on how to submit a tick for free identification and testing, visit the official MilTICK submission page online.

As Nadolny said, the goal is simple: “Enhance readiness of our military and improve community health.” That mission starts with each of us being prepared.

Here are resources to help service members and their families:

The Defense Health Agency is a Combat Support Agency, serving as a force multiplier for the joint services by optimizing lethality through warfighter medical readiness.

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