Experts sound alarm over tick-borne infection Powassan virus
Hot spots for a rare tick-borne disease that kills up to one in 10 patients have been revealed for the first time.
A study by the Yale School of Public Health found that the Powassan virus, also referred to as “Lyme disease’s deadly cousin,” is detected in clusters in Connecticut, New York State and Maine.
The Powassan virus is rarely diagnosed — only a few dozen cases are discovered each year — because the majority of people who contract the virus are asymptomatic.
But for some, it can lead to brain swelling and even death. One in ten people who experience severe symptoms die and half are left with lifelong disabilities or brain damage.
Maps showing the distribution of the Powassan virus in Northeast America
Cases generally emerge when ticks are most active in late spring, early summer, and mid-autumn
The virus is spread by black-legged ticks found on deer. The tick is also responsible for Lyme disease in humans
The tick that is the main disperser of Powassan is Ixodes scapularis, also known as the black-legged tick or deer tick as it occurs on deer.
The squirrel tick and groundhog tick also have the ability to spread Powassan to humans, but these ticks do not usually bite humans.
The tough black-legged tick lives in the eastern and northern Midwest of the United States and southeastern Canada, and is also a carrier of Lyme disease. It is found in wooded areas.
Symptoms usually appear within one to four weeks after being bitten by an infected tick.
Signs of infection are fever, headache, vomiting and general weakness.
There are no vaccines or drugs for the disease, but treatment instead focuses on relieving symptoms, including difficulty breathing and brain swelling.
There are two types of Powassan virus: line 1 and line 2. Only line 2 is carried by the black-legged tick.
The researchers examined 279 samples of Powassan virus line 2 found in Connecticut, New York and Maine between 2008 and 2019.
Until 2006, about one case per year was reported. The number of cases is increasing, with dozens of diagnoses per year since the end of 2010
In the US, Powassan’s disease is mainly found in the northeastern states and the Great Lakes region
By interpreting and comparing the genetic codes of the virus, the researchers tracked the expansion of the virus in the region.
They found that between 1940 and 1975, a large portion of the lineage 2 virus showed up in the Northeast.
The lineage 2 branch of the virus is responsible for the majority of Powassan cases in North America.
Until 2006, about one case per year was reported. The number of cases is increasing, with dozens of diagnoses per year since the end of 2010.
The increase may be due to more people coming into contact with ticks and more doctors checking Powassan on patients.
It was initially found in southern New York State and Connecticut. After probably jumping on migratory birds or other animal hosts, it reached Maine in 1991.
The researchers added that they only sampled a few locations, so they may have missed hot spots.
Doug Brackney, a researcher in the Division of Entomology at the Connecticut Agricultural Experiment Station, and an assistant clinical professor in the Division of Epidemiology of Microbial Diseases at YSPH, said, “If it’s anything like [the related] tick-borne encephalitis virus, [previous researchers have] estimated that these foci are typically about the size of a football field.’
The research has been published in the Proceedings of the National Academy of Sciences.
Cali Neri, 2, is being treated at Boston Children’s Hospital for severe encephalitis caused by Powassan virus infection
Cali is unable to speak or move much of her body and was treated at Boston Children’s Hospital. After finally leaving the hospital in late March, she was hospitalized again on April 11
The Powassan virus got its name after it was first found in a five-year-old boy in Powassan, Ontario.
He developed severe encephalitis and died in 1958.
In the US, Powassan’s disease is mainly found in the northeastern states and the Great Lakes region.
The virus has also been reported in Canada and Russia.
Cases generally emerge when ticks are most active in late spring, early summer, and mid-autumn.
People who work or spend a lot of time outdoors are at a higher risk of infection.
While Lyme disease takes hours to pass from an infected tick to a human, Powassan can be transmitted just 15 minutes after the tick takes hold.
The condition often progresses to meningoencephalitis – inflammation of the brain and tissues.
This can lead to an altered mental state, seizures, partial paralysis and the loss of the ability to communicate.
Chantal Vogels, a research scientist in the Division of Epidemiology of Microbial Diseases at YSPH and a co-author of the study, said: ‘We usually only see the most serious cases of disease, and those are the people who end up in the hospital. .
“But it’s probably just the tip of the iceberg.”
Cali Neri, a two-year-old from the Dannemora area, was diagnosed with Powassan virus in November last year.
The child was unable to speak or move much of her body and was treated at Boston Children’s Hospital.
After finally leaving the hospital at the end of March, she was hospitalized again on April 11.