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Powassan Disease: Another Reason to Avoid Tick Bites?

Although Lyme disease is one of the most recognized tick-borne illnesses, newer and less-known tick-related diseases can cause serious and deadly symptoms. One prime example is Powassan disease, a rare disease caused by a virus that is related to the West Nile and Zika viruses.

Powassan disease is contracted by the bite of a tick. It is able to infect the nervous system, causing severe damage. Ticks that carry Powassan disease are prevalent in New England, the Great Lakes states, and additional areas along the eastern seaboard.

“Approximately 10 percent of patients suffering from the disease do not survive,” said Dr. Jennifer Lyons, Chief of the Division of Neurological Infections and Inflammatory Diseases at Brigham and Women’s Hospital. “In addition, about half of those infected with the virus are left with permanent neurologic damage. Although Powassan disease is rare, it is important to take precautions and protect yourself against tick bites.”

Powassan vs. Lyme

While the same species of ticks can transmit both diseases, there are a number of key differences between Powassan disease and Lyme disease. While Powassan disease is caused by a virus, Lyme is caused by a bacterium. Powassan disease can be transmitted less than 15 minutes after the initial tick bite, while it is generally believed it takes at least 24 hours for a tick to be attached to someone in order for that person to develop Lyme disease.

Perhaps the most significant differences lay in the symptoms. Powassan initially results in patients feeling ill with fever, followed by severe cognitive loss and inability to care for themselves days later. Seizures, as well as difficulty breathing and maintaining heart rate, are also common. In Lyme, symptoms like joint pain, high fever, Bell’s palsy (facial drooping), neuropathy (nerve symptoms), and occasionally meningitis can sometimes take weeks to develop.

Treatment also varies greatly between Powassan and Lyme. There is no known treatment for Powassan disease. Patients usually receive supportive care in a hospital intensive care unit (ICU), with a breathing tube, blood pressure support, and external nutrition supply, while the immune system fights the virus and the body recovers. Lyme disease can usually be treated outside of the hospital with antibiotics and other medications.

Increase in Tick-borne Illnesses

Tick-borne illnesses are likely on the rise for several reasons. Longer stretches of good weather provide more chances for humans to interact with ticks. It's also probable that the viruses and bacteria that cause these diseases are infecting more ticks.

“Another possibility is that we simply are recognizing tick-borne illnesses more frequently,” said Dr. Lyons. “Now that we know what Powassan disease is, we know to test for it in patients who come in with suspicious symptoms.”

Protection from Tick-borne Illnesses

To protect yourself from tick-borne illnesses, wear long, light-colored clothing treated with permethrin when you are in the woods or near tall grasses. Tuck your pants into your socks, and apply DEET to exposed skin. Make sure to check yourself carefully after you have been outside.

“If you are bit by a tick and start to develop symptoms that are worrisome, including fever, headache, confusion, or breathing difficulties, seek medical attention immediately,” said Dr. Lyons.

Learn more about Powassan disease in this video with Dr. Jennifer Lyons, Chief of the Division of Neurological Infections and Inflammatory Diseases at Brigham and Women’s Hospital.