Saturday, May 13, 2017

About Powassan Virus

This graphic showing the number of cases from 2006-2015, is the work of the CDC It has been known since 1958.

             In 2012 I did a series on tick borne illnesses, and then later expanded the series to include insect envenomation injuries.   Of course, public health issues change and expand over time. This is one such needed update.

                  Powassan Virus is also a tick borne virus which is a flavivirus. It is therefore related to The West Nile Virus, St. Louis Encephalitis, and some other tick borne encephalitises.  Seventy five cases of it have been proven within about the last ten years and are most often seen in in either the Great Lakes Region of the United States or the Northeastern Region of the US.   A person bitten by a tick might feel alright after contracting Powassan virus, but they may also go on to experience fever, chills, vomiting, seizures, confusion, memory loss,and potentially death.   Patients for whom the disease is identified may need hospitalization for ventilatory support, drugs to prevent brain swelling and for intravenous hydration and fever control.  A small percentage of those with this illness will die. A larger percentage of those will have permanent neurologic issues secondary to the encephalitis which is possible. When encephalitis occurs, muscle wasting, memory issues and other neurologic problems may also occur.

                  Anyone who has received a tick bite and is now sick or febrile (which means has a fever) needs to seek medical care immediately. The incubation period for Powassan Virus is one week to one month long.  There is presently no preventive vaccine available.  There are two strains of this virus that have been isolated and both are pathogenic (disease causing) in human beings. This is a nationally reportable disease.

            Although Powhassan virus is relatively rare, it is increasing in incidence. It is also found in Canada, and it is named for the place in which it was first described. It has also been detected in Russia. We do not yet know which other nations also may experience this disease. (Remember that originally Lyme Disease was only thought to be a Northeastern US issue, and that is certainly not the case now.)  Powhassan virus can be transmitted in as little as 15 minutes of having a tick embedded upon you. It is not transmissible from person to person.  I will add additional information as possible.

           Please see my prior posts on strategies for avoidance of tick bites.

Prior Posts on my series on Tick Borne Illness    (2012)

And on Envenomation Injuries:

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