The recipient of an MD from New York Medical College, Dr. Stephen J. Marks is a vascular neurologist at Neurology Associates of Westchester. Dr. Stephen J. Marks is currently investigating powassan virus infections.

A rare disease, powassan virus is spread to humans by a bite from an infected tick. Three main types of ticks that can cause the infection include the groundhog tick, squirrel tick, and deer tick. Two of the arachnids, the groundhog tick and the squirrel tick, bite people less often and rarely spread the infection. The deer tick often bites people, although its main hosts are white-footed mice and deer. The virus is not carried by every tick, and not everyone bitten by a tick carrying the virus becomes infected. The disease cannot be transferred from person to person, and an infected person cannot transfer the disease to another tick when bitten, because the virus only occurs in extremely small quantities in the blood of infected humans.

In humans, powassan virus often causes no symptoms. However, in cases with symptoms, these can begin anytime ranging from one week to months after the bite, and can initially include headache, fever, vomiting, and weakness. In severe cases, powassan virus can cause serious brain or spinal cord diseases, such as encephalitis and meningitis. Complications of these severe conditions include seizures, loss of coordination, confusion, and sometimes death. Currently, there is no vaccine or treatment for powassan virus. Contracting the virus can be prevented by avoiding ticks.