People living in the United States have a far greater chance of being killed by a lightning strike than by the tick-borne Powassan virus. Could that change?

By Greg Barnes

The virus carried by a tiny tick that caused the death of former U.S. Sen. Kay Hagan has never been reported in North Carolina, but that doesn’t mean it won’t get here someday.

Statistics from the Centers for Disease Control and Prevention show that the number of tick-borne diseases are increasing and spreading throughout the country, including ticks carrying the Powassan virus.

Hagan, who served as a U.S. senator from North Carolina between 2009 and 2015, died at age 66 after battling serious health complications for three years. Her funeral was Sunday in Greensboro, where she lived for decades.

According to published reports, Hagan is believed to have been bitten by a tick while hiking in the Blue Ridge Mountains in Virginia during the Thanksgiving holiday in 2016.

Hagan was hospitalized in December 2016 in Washington, D.C., where doctors said she suffered from encephalitis, an inflammation of the brain caused by the virus.

Hagan never fully recovered. There is no treatment for Powassan and no vaccine to prevent infection.

According to the CDC, about one in 10 people with severe symptoms of the disease die, and half will suffer long-term health effects, including confusion, loss of coordination, difficulty speaking and seizures. For others, the disease often goes undetected.

Still rare

The Powassan virus is rare. The CDC reports that 133 people contracted the virus between 2009 and 2018. Of those, 100 were reported in only four states — Wisconsin, Minnesota, Massachusetts and New York.

The CDC reports only one case of Powassan in North Carolina, in 2016. State health officials did not say whether that person is believed to be Hagan.

Tick-borne diseases are reported to the CDC by the county and state where infected people live, not by where they may have acquired the illness, said Dr. Alexis Barbarin, the public health entomologist with the state Department of Health and Human Services’ Division of Public Health.

Like most tick-borne diseases, the rate of reported cases of Powassan is increasing. According to the CDC, only six cases were reported across the entire U.S. in 2009. In 2017, there were 33, though that number declined to 21 the following year.

“There have been no known reported cases of Powassen virus thus far in NC,” Marcia Herman-Giddens, a professor at the University of North Carolina’s Gillings School of Global Public Health, said in an email. “Virginia has had at least one so it is probably a matter of time before we have it in NC.

“It’s possible it is here now and just hasn’t been identified,” Herman-Giddens said in a later telephone interview. “It would be pretty foolish, in my opinion, to believe that they would never get here.”

While Powassan remains rare, the number of cases of other tick-borne diseases are steadily climbing, including cases of Lyme disease and Rocky Mountain spotted fever, which are fairly common in North Carolina.

On average, the state annually reports about 600 cases of spotted fever rickettsiosis, which includes Rocky Mountain spotted fever, and 83 cases of ehrlichiosis, which is spread primarily by the Lone Star tick. In addition, the state reported 276 cases of Lyme disease, on average, each year between 2013 and 2018.

All tick-borne diseases increasing

The CDC estimates that 30,000 cases of Lyme disease are reported in the United States every year, about 10 times fewer than the number of cases that the agency believes actually occur. The number of reported cases has tripled in the United States since the late 1990s.

Statistics from the CDC show that between 2016 and 2017, the reported number of Lyme and other diseases caused by ticks increased from 48,610 to 59,349 — or slightly more than 22 percent.

Michael Reiskind, an associate professor of public health entomology at N.C. State University, said he doesn’t expect to see the Powassan virus become prevalent in North Carolina. But he and Barbarin do expect to continue to see a significant rise in the number of reported cases of Lyme and other tick-borne diseases in the state.

The reasons for the increase include the geographical spread of some species of ticks, changes in land use as people move into once-forested areas, an increasing number of hosts, such as deer and rodents, changes in reporting criteria and climate change.

In North Carolina, clinicians are required to report to their local health departments all confirmed or suspected cases of the spotted fever group of rickettsiosis, ehrlichiosis, anaplasmosis and Lyme disease. Blacklegged ticks — also called deer ticks — are most often found to carry the Borrelia burgdorferi bacteria that causes Lyme disease.

A study in 2015 found a slow but steady progression of blacklegged ticks moving southward down the Appalachian mountains from Virginia.

Reiskind believes one of the biggest factors influencing the increasing number of tick-borne diseases in North Carolina is where and how we live. Urban sprawl into once-rural areas, where there are more rodents, deer and birds, increases the likelihood that a person will come into contact with an infected tick, Reiskind said. The number of ticks in the state also appears to be increasing, he said.

Climate change as a factor?

Reiskind isn’t sold on the notion that climate change is playing a substantial role in the increasing number of tick-borne diseases, noting that most cases are reported in colder northern states. Climate change suggests that, as temperatures warm, the geographic spread would occur northward, yet the migration is coming south, he said.

Maria Diuk-Wasser, a professor at Columbia University who specializes in tick-borne diseases, also downplays the role of climate change on the increase of the diseases in the South.

“While climate change can be partly responsible for the spread north, it cannot really be attributed to the spread south, e.g. North Carolina,” Diuk-Wasser said in an email. “Understanding the southern spread is further complicated by the fact that blacklegged ticks have been present in the south of the US all along, but they display a different behavior, they tend not to bite people because they seek for hosts lower in the vegetation. They also tend to bite lizards which do not carry the Lyme pathogen. So, it is possible that the northern ‘strain’ of the tick (human biting) is spreading south and thus causing more human disease, we’re still investigating this.”

The CDC provides a cautious warning about the effects climate change could have on the increase in tick-borne diseases.

“Changing climate patterns can alter the natural environment and longstanding ecological relationships,” the agency reports. “Since vector-borne diseases have strong environmental links, we expect that changes in seasonality and location may occur. We don’t know what those changes will be, but we know that climate is only one of several very important factors that influence the distribution and occurrence of vector-borne diseases.”

Study warns of climate change

A study published in 2018 in the Canadian Journal of Infectious Diseases and Medical Microbiology, draws a more dire conclusion.

The study — “Ticking Bomb: The Impact of Climate Change on the Incidence of Lyme Disease” — examined the relationship between climate change and Lyme disease in the 15 states that contributed to more than 95 percent of reported cases.

“Complex interactions between humans and climate change are contributing to the emergence of new diseases and the spread of already known ones to regions where they were unable to exist before.” the study concludes. “Environmental factors such as temperature and humidity have been shown to influence tick abundance, availability of hosts, their survival, and disease transmission.”

The study predicts that the number of Lyme disease cases in the United States will increase by more than 20 percent in the coming decades.

NC Health News requested an interview with Dr. Lyle Petersen, the CDC’s director of the division of vector-borne diseases with the National Center for Emerging and Zoonotic Infectious Diseases. A CDC spokeswoman, Katie Fowlie, said in an email that Petersen was not available for comment, but she provided responses to some questions.

Tick-borne diseases: tips to stay safe Tic-NC and the CDC provide tips people should use to reduce their risk of contracting a tick-borne disease by preventing bites. Among the recommendations are using EPA-registered insect repellent, wearing long-sleeve shirts and long pants, treating clothing and gear with permethrin, and avoiding wooded or brushy areas with high grass and leaf litter. After being outdoors, recommendations include checking your body and clothing for ticks, showering and tumbling clothes for 10 minutes in a dryer, and removing any ticks as soon as possible.

Fowlie said one reason for the increase in tick-borne diseases is a lack of effective prevention strategies.

Barbarin, of the state Division of Public Health, said the division is collaborating with the CDC and other state health departments to conduct tick surveillance to better understand and characterize the distribution and abundance of infected tick vectors.

The state used to do more, until the legislature in 2011 reorganized what was then the state Department of Environmental Resources and abolished its Division of Environmental Health, including its public health pest management section, which did research on diseases spread by ticks and mosquitoes and helped to protect the public.

“Since then, there have been fewer employees and less funding to do an ever bigger job,” Herman-Giddens said in her email.

Advocacy groups, such as the Tick-borne Infections Council of North Carolina, also known as Tic-NC, have assumed some of those responsibilities. Herman-Giddens co-founded the organization.

Herman-Giddens says people need to exercise extreme caution in areas where ticks are prevalent. Tick-borne diseases such as Powassan can spread within 15 minutes from the time of the bite, she said. Preventive measures surely help, she said, but it’s hard to protect yourself from such a tiny insect.

Herman-Giddens said she doesn’t think some people are being overly cautious about tick-borne diseases. If anything, she said, people are not being cautious enough.

“It is a public health crisis,” she said. “It’s just tragic, the degree it’s gotten to be.”