Powassan virus, for example, causes swelling in the brain that can lead to permanent neurological damage. It's fatal in about 10 percent of cases.
Some ticks even carry another disease that can give you a meat allergy. Researchers warn it's getting more common, but they're still learning about how and why the disease spreads. The Centers for Disease Control and Prevention isn't tracking it closely yet.
Luckily, those diseases are still relatively rare, especially compared with Lyme. For example, in the decade since 2006, the CDC recorded fewer than seven cases of Powassan virus on average every year.
The CDC recommends people avoid tick-borne diseases by using insect repellent, staying out of brush and tall grass, and taking showers after visits to tick country. If you're bitten, tell your doctor about any fever or rash.