You’ve heard of ticks transmitting Lyme disease, but now some of the bugs are passing on a rare virus called Powassan that is fatal in about 15% of cases.

Read more: Lyme disease — What is it and how to avoid it

15% of people who contract Powassan could die

Powassan is a rare but deadly RNA virus with links to West Nile fever. But with only 75 reported cases over the last 10 years, this is one deadly virus you’ve probably never heard about.

Powassan can cause encephalitis (inflammation of the brain) and meningitis (inflammation of the membranes that surround the brain and spinal cord) by infecting the central nervous system.

Most cases are reported in the Northeast and Great Lakes region, according to the Centers for Disease Control and Prevention (CDC).

Fever, headache, vomiting, weakness, confusion, seizures and memory loss are among the most common symptoms.

“About 15% of patients who are infected and have symptoms are not going survive,” Dr. Jennifer Lyons, chief of the Division of Neurological Infections and Inflammatory Diseases at Brigham and Women’s Hospital in Boston, tells CNN.

“Of the survivors, at least 50% will have long-term neurological damage that is not going to resolve.”

What can you do to protect yourself?

Amid reports that 2017 is going to be a banner year for tick infestation, there are ways you can protect yourself from Powassan and other tick-borne diseases.

The CDC recommends the following steps:

• Use tick repellent with 30% DEET
• Avoid wooded and bushy areas
• Wear long sleeves, pants and closed-toe shoes when you’re in the woods
• Inspect your body thoroughly for ticks after being outdoors
• Seek medical attention promptly if you think you may have Powassan

Unfortunately, there is no vaccine for Powassan. Treatment includes respiratory support, intravenous fluids and medications to reduce brain swelling.

One final note about the DEET. Women who are pregnant or breast feeding can safely use DEET, picaridin, lemon eucalyptus or IR3535, if applied properly. Be sure to reapply every eight hours. But you shouldn’t use these products on infants younger than two months.

Learn more about best practices when it comes to applying repellents.

Read more: Deadly fungus spreading in 5 states

Could this old-fashioned mower save you money?