Powassan virus is a disease found in North American and Russia. The first case of Powassan virus was discovered in a young boy in 1958 in the Canadian town of Powassan, Ontario. Although cases of this disease are rare, they’ve been increasing in recent years, particularly in the Northeast and Great Lakes region of the United States. 

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Signs and Symptoms 

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 Often, those infected by Powassan virus don’t exhibit symptoms. For those that do, they’re usually fever, vomiting, headache, and fatigue. Acute symptoms can develop between 1 day and 1 month after being bitten by a tick. 

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Powassan virus can also lead to encephalitis or meningitis. Cases that develop into these infections are considered severe. Symptoms associated with severe Powassan virus are seizures, aphasia, cranial nerve palsies, and mental confusion. Additionally, about 10% of those who contract the severe disease die from it. Those who survive often have chronic problems like recurring headaches, loss of muscle strength, and memory problems. 

 

Unlike Lyme disease, a rash at the site of the tick bite is not a symptom of Powassan disease. Therefore, doctors will test a patient for Powassan disease based on other acute symptoms, their history of exposure to tick habitats, or blood sampling. Not many laboratories offer the proper tests, however, so diagnosis can be difficult. 

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 What is the Bacterium that Causes Powassan Virus?  

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Powassan virus is not caused by a bacterium but by a flavivirus. Flavivirus is a genus of viruses which are typically carried and transmitted by ticks and mosquitoes. Other common flaviviruses are Yellow Fever, Dengue Fever, and Zika virus caused by mosquitoes; common ones associated with ticks are Tick-Borne Encephalitis, Kyansanur Forest Disease, Alkhuma Disease. 

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Like with all tick-borne diseases, Powassan virus is spread when a tick bites and feeds on a mammal infected with the virus. The tick then passes the virus onto its next host when it feeds again, possibly to a human host. The most common mammals with this virus that ticks feed on are rodents. Additionally, Powassan virus is the only known tick-borne flavivirus in North American that can infect humans. 

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Which Type of Tick Carries Powassan Virus? 

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Powassan virus is transmitted by 6 known tick species, the 4 most common being the black-legged tick, the groundhog tick, the American dog tick, and the squirrel tick. All 4 of these species are present in Connecticut. The groundhog tick and squirrel tick are unlikely to bite humans, but the black-legged tick bites humans frequently. 

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 The black-legged tick frequently feeds on white-tail deer in addition to humans. Groundhog ticks and squirrel ticks prefer to feed on smaller mammals like groundhogs, mice, squirrels, weasels, and skunks. The Groundhog tick prefer warm climates and shaded, sandy areas. They can also be found inside houses, in cracks and crevices and along kennel ceilings. 

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The black-legged tick and groundhog tick resemble each other in appearance, but only the black-legged tick is a known vector for Lyme disease. 

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Cures and Treatments 

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Currently, there is no known cure for Powassan virus and it cannot be treated with antibiotics like Lyme disease. Those who contract the virus are usually treated for brain swelling since the virus can cause encephalitis. Patients are also usually given medicines for respiratory support, as well as intravenous fluids. 

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How long does Powassan virus last? Those with acute symptoms may experience relief after receiving treatment. However, those who have more severe symptoms usually spend the rest of their lives with neurological problems – recurring headaches, loss of muscle mass, and memory loss. 

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Areas in Danger of Being Bitten 

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The most reported cases of tick-borne Powassan virus are in Minnesota, Wisconsin, Pennsylvania, Massachusetts, New York, and Maine. On a map of Powassan virus incidence, you’ll see the most cases reported in Minnesota and Wisconsin. In Connecticut, there were 4 confirmed cases of Powassan virus in 2019.  https://portal.ct.gov/DPH/Epidemiology-and-Emerging-Infections/Powassan-virus-disease 

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There were few cases of the disease when it was first discovered, on average 1 per year in the United States. The incidence of Powassan virus has increased, though, to almost 10 cases per year. In 2019, an 80-year-old man from New Jersey was the first person to be diagnosed and to die from Powassan virus disease. It was concluded that he was bitten by an infected tick while in his yard, outside his home. Health professionals are concerned that there’s a spike in the spread of Powassan virus, predicting more cases will be reported in 2020.  https://www.healio.com/infectious-disease/emerging-diseases/news/print/infectious-disease-news/%7Bd5fb59d5-d4d8-419f-8203-4091fa5768d7%7D/tick-borne-powassan-virus-spreads-in-us 

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Final Thoughts 

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Although Powassan virus is a rare disease, it is a dangerous one. It can be fatal, and there’s no sure way to treat it like with other tick-borne diseases. Consequently, prevention is essential to ward off Powassan virus. Avoid tick habitats when possible and if you do venture outdoors, treat your clothes with permethrin beforehand. In addition, always check yourself for ticks before coming back indoors. Check out the CDC’s guide on tick bite prevention for more info. https://www.cdc.gov/ticks/avoid/on_people.html 

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