According to the Centers for Disease Control and Prevention (CDC), their has been approximately 75 cases of Powassan virus disease reported in the United States over the past 10 years.  Most cases have occurred in the Northeast and Great Lakes region.

Black-legged tick
Ixodes scapularis, a Black-legged tick/CDC

While that seems small compared to the major tickborne disease, Lyme disease, which the CDC reports more than 30,000 cases annually in the US and estimates more than 300,000 cases per year, Professor Durland Fish of the Yale School of Public Health says Powassan has the potential to become a serious public health concern, in fact, he says because it can be a serious disease causing fatalities and there is no treatment for it, Powassan has the potential to become a greater of a public health threat than Lyme disease.

In an interview published on the Yale School of Public Health website, Professor Fish says what’s so concerning is there has been an important change in the ecology of Powassan virus in that the deer tick has recently become infected with the virus. Until a few decades ago, it was only transmitted by a tick species that does not commonly bite humans and human cases were extremely rare.

In addition, while the CDC says most cases have occurred in the Northeast and Great Lakes region, Fish says due to the expansion in the range of deer ticks, Powassan is spreading to areas where it never occurred before. As the geographic range of Lyme disease expands, so will Powassan.

LISTEN: Dr Sheila Pinette, Director of the Maine Centers for Disease Control talks Powassan virus in this 2014 interview

Signs and symptoms of Powassan infection can include fever, headache, vomiting, weakness, confusion, seizures, and memory loss. Long-term neurologic problems may occur. Long-term sequelae occurs in approximately 50% of patients. Approximately 10-15% of cases are fatal.

There is no specific treatment, but people with severe Powassan virus illnesses often need to be hospitalized to receive respiratory support, intravenous fluids, or medications to reduce swelling in the brain.