Powassan Virus Implicated in Recent NY State Death
A recent case of Powassan virus has been reported in Saratoga County and may have been the cause of the infected patient's death. It's the 24th case in New York State since 2000, and will be reported to the CDC tomorrow, the NY Department of Health told Invisiverse. The tick-borne illness has no vaccine or specific treatments and can damage the nervous system.
The patient reportedly came in contact with a tick in May 2017, likely catching the virus at that time. The DOH confirmed the presence of the virus in the patient's blood, but not definitively its role as the cause of death. "We're not the ones who determine the cause of death, that's usually the coroner or medical examiner," DOH research scientist Brian Backenson told Spectrum News. "What the official cause of death is one thing, but it's likely that Powassan helped contribute."
Powassan virus — also called POW virus — has been found in the US, Canada, and Russia; within the US it is most often found in the Great Lakes region and the Northeast US. It is an RNA virus of the Flavivirus genus and is related to West Nile, St. Louis virus, and other tick-borne encephalitis viruses. It may be increasingly frequent, though the rarity of human cases makes it hard to be sure of a trend.
According to the CDC, there have been approximately 75 reported cases of POW virus in the past ten years. According to the latest Morbidity and Mortality Weekly Report of notifiable diseases, there were 22 cases of Powassan last year (2016) and have already been five so far in 2017, as of July 14.
Experts are worried that with high tick numbers this year, case numbers of Powassan and other tickborne diseases (including lyme, anaplasmosis, and babesiosis) could skyrocket. It's worth being aware and watching out for ticks, bites, and symptoms. Though it is not a common illness, it can be extremely dangerous.
Symptoms include fever, vomiting, weakness, headache, confusion, seizures, and difficulty with coordination and speech. Permanent neurological problems — such as headaches, memory problems, and muscle wasting — occur in about half of survivors, even after the infection itself has passed.
Infection of the central nervous system can cause encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of both the brain and the spinal cord). Ten percent of POW-related encephalitis cases are fatal. The virus has an incubation period from a week to an entire month between infection and the development of symptoms.
Both kinds of Powassan virus endemic to the US, lineage 1 and lineage 2, can cause illness in humans. Three species of ticks commonly carry POW virus, but only one — ixodes scapularis — often bites people. The virus' natural cycle that maintains it is to move back and forth between ticks and rodents (such as squirrels, woodchucks, and white-footed mice).
Humans are a dead-end host: The concentration of virus in our blood when infected is not usually high enough for a tick to bite an infected human and get infected itself to complete the cycle. The virus doesn't win either if it infects us, but that's small comfort to anyone who experiences it.
To prevent tick-borne illness, people can wear tick repellent, cover bare skin, and do tick checks. If they suspect a possible case of Powassan virus, they should seek medical care immediately; severe POW virus can require hospitalization. Because there is no medicine to fight POW virus specifically, treatment is supportive. In cases severe enough to require it, that can include intravenous fluids, respiratory support, and medication that reduces swelling in the brain.