Powassan Virus

June 14, 2022

Recently, a woman died in United States due to infection of tick-borne Powassan virus. She was in her 90s. She is the second person to test positive for Powassan virus in 2022.

What is Powassan virus?

Powassan virus is a Flavivirus, which is transmitted by ticks. This virus is found in North America and Russian Far East. It is named after the town of Powassan, Ontario. In Powassan town, this virus was first identified in 1958, for the first time.

Where is the virus found?

Powassan virus is found in the warm climate across Eurasia. In Eurasia, it is a part of tick-borne encephalitis virus-complex. In Russian Far East, it appears to be introduced there 70 years ago.

Types of Powassan virus

Two types of Powassan virus are found in North America viz., lineage 1 and lineage 2.

Evolution of the virus

Powassan virus is an RNA virus, that split into two separate lineages namely

Lineage I– It is labelled as “prototype” lineage; and
Lineage II– It is labelled as deer tick virus (DTV) lineage.

Lineage II has the most genetic variation. It is most likely the ancestral lineage, splitting due to positive natural selection. DTV is very closely related to Powassan virus.

How does this virus spread?

It spread through the bite of a tick infected with Powassan virus.

Symptoms of virus

Many people infected with the virus have no symptoms. Some shows mild symptoms like- Fever, Headache, Weakness, Vomiting, Encephalitis, Seizures, and Meningitis. Long-term neurologic symptoms include headaches and memory problems. Death is possible but it is rare.