U.S. rabies cases rose 17 percent just this summer, according to a new federal advisory.

The surge was tied to multiple high-profile outbreaks and mass exposure events, the Centers for Disease Control and Prevention said Thursday.

Maryland health officials warned residents in August of a beaver attack on a 10-year-old girl, and previous reports detailed similar attacks on teenagers.

National Park Service officials said rabid bats were swooping parkgoers at Olympic National Park in August and a dead bat tested positive for rabies in Yosemite National Park earlier this month.

Reports of rabid raccoons have ballooned in New York this summer and New York City data shows close to 20 cases across the boroughs since June.

That forced officials to deploy fish-scented bait packets in parks and wooded areas, according to The New York Times.

The CDC did not offer an explanation for the increase, but there have been more encounters with wildlife due to urban expansion, drought and growing animal populations.

People contract rabies after they are bitten or scratched by an infected animal, which is most commonly a bat, fox, skunk or raccoon.

More than four million Americans report being bitten by animals each year and nearly 3 out of 4 Americans live in a community where animals carry rabies.

Federal data shows there are typically around 4,000 cases of the virus each year, with fewer than 10 deaths.

The disease infects the central nervous system, leading to flu-like illness, confusion, agitation, aggressive behavior, anxiety and hallucinations.

Infections are fatal if people don’t receive medical care before these symptoms start, which can occur after weeks or even months following a bite or scratch, the CDC says.

Access to rabies treatment is why there are so few deaths, and 100,000 Americans are vaccinated against rabies following a potential rabies exposure every year.

Medical care after a rabies exposure includes wound care, a medication that provides protective immune antibodies and a series of four or five vaccines.

But there are also increased reports of treatment administration errors, the CDC said.

Vaccinations can also be complex and expensive, costing thousands of dollars for people without health insurance.

That’s why knowing when people need the shots is crucial.

“Proper administration of rabies vaccine and human rabies immune globulin is critical to ensuring patients receive effective protection while avoiding unnecessary treatment, costs and strain on supplies,” the agency wrote in a statement.