Powassan Virus: What You Need To Know

An alarming tick-born virus has emerged in the Northeast and poses risks to adults and children. Powassan virus is a tick-borne disease that can be transmitted to humans and has no known cure. It has long-term neurological consequences for at least half of those infected and in some cases it is fatal. The news of the virus is trending on Twitter and is one of Facebook's top stories. So what is Powassan virus and are you and your kids at risk of infection? What are the signs and symptoms of the virus? If it's not curable, can it be prevented?

Definition: According to the CDC, Powassan virus is a Flavivirus that is transmitted to humans by the black- legged deer tick (and some other tick types as well). Humans are dead end hosts, meaning humans can't transmit the disease to another host once they are infected. Powassan causes no symptoms in some, and very severe symptoms in others, including encephalitis, or swelling of the brain, which can be fatal. Half of patients who are diagnosed with Powassan go on to develop long-term sequelae including muscle wasting, memory loss, and chronic headaches. Whereas Powassan is a virus, Lyme disease is a bacterial infection; both are transmitted by deer ticks. A tick needs to feed for 24 -48 hours before it can transmit the Lyme infection to a human. In order for a tick to transmit Powassan virus, it only needs to be attached for as little as an hour or two (and studies in mice have shown 15 minutes). "It is pretty scary," said Judy Stone, MD, an infectious disease specialist and blogger for Forbes.com. "The tick doesn't have to be attached for long to transmit infection."

Statistics: There have been approximately 60 reported cases in the last ten years, mostly in the Northeast and Great Lakes areas. However, more than half of these cases were reported in the last four years and the numbers seem to be increasing as recognition of the signs and symptoms and diagnostic testing improve. Diagnosis is still in its infancy due to the rarity of the virus and not all cases are symptomatic. People have tested seropositive in our area (lower Westchester) without symptoms. Those cases would not have been reported and therefore the true prevalence is likely higher than the data suggests. Ticks in Branford and Bridgeport, Connecticut recently tested positive for being carriers of Powassan virus, so epidemiologists have warned the public that this tick-borne threat is real and prevention measures should be taken seriously. Most cases of Powassan occur in late spring, early summer, and mid fall since that is when the ticks that carry the virus are most active.

Signs and Symptoms: If symptomatic, a person may develop a fever, headache, vomiting, weakness, confusion, seizures, and memory loss. If it worsens, a person may develop encephalitis or respiratory failure. Half of symptomatic people will go on to experience chronic neurologic effects from Powassan virus.

Diagnosis/Treatment: If a person shows signs or symptoms of Powassan virus, medical attention should be sought immediately. Although it is not typically tested for, it can be detected in blood and spinal fluid. There is no treatment. Supportive care will be given including IV fluids, respiratory support, and medications to reduce swelling of the brain.

Prevention: Preventiing Powassan virus is particularly important since it is incurable and has the potential to be fatal. Avoid brushy or wooded areas and areas with overgrown grass. Long pants should be worn even if it's hot outside and pants should be tucked into socks. Long sleeves should be worn as well. Places like EMS and REI sell lightweight and breathable clothing. Do a full body check when you return home from the outdoors. Parents should be especially mindful of checking their children's hair. DEET insect repellant works to repel ticks –- use DEET with a minimum concentration of 20%. Dr. Stone recommends using DEET with a concentration of 30-50% and re-applying it to bare skin every 4-6 hours. Clothing and gear can be treated with Permethrin. Although natural repellants may claim to deter ticks, these have not been proven by the EPA to prevent ticks from attaching to clothing and skin.

For more information, see the CDC website.