June 12, 2019
2 min read

CDC: Bats are leading cause of rabies infection in US

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Emily Pieracci, DVM, MPH
Emily Pieracci

Bats are responsible for most rabies cases in the United States, accounting for roughly 70% of locally acquired infections over the past 6o years, according to a report published today in MMWR.

Researchers warned that the disease continues to pose a risk to humans in the U.S.

“Rabid bats have been reported from every state except Hawaii,” Emily Pieracci, DVM, MPH, a veterinarian in the CDC’s Rabies Branch, said during a telebriefing. “While the majority of bats in the wild do not carry rabies, you cannot tell which bats have rabies just by looking at them.”

Pieracci said many people may not know bats can spread rabies.

Photo of a bat 
Bats are the leading cause of rabies in the U.S.
Source: Shutterstock.com

“For example, we have had several large groups of people exposed to bats in university dorms, camping lodges and schools.”

According to Pieracci and colleagues, data from 1938 to 2018 show a steady decline in human rabies cases caused by dog bites, whereas bats surpassed raccoons in 2015 as the leading cause of human rabies infections in the U.S. Bats accounted for 62 (70%) of 89 human rabies cases between 1960 and 2018, according to the study.

Further, mass bat exposures also are on the rise, according to Pieracci. These are instances where 10 or more people are exposed to a potentially rabid bat. With the coming summer months, Pieracci and colleagues warned that increased time spent outdoors — in campgrounds, parks or yards — will expose large groups of people to potential interactions with bats.

“People may not realize that bats carry rabies, so they may not see their medical provider after touching or handling a bat,” CDC Principal Deputy Director Anne Schuchat, MD, said in the briefing. “Bat bites are smaller than the top of a pencil eraser, and so they can go unnoticed. This is a problem, because rabies is deadly once symptoms start. Recognizing the risk and getting treatment fast is important.”

In 2017 and 2018, an average of 55,000 Americans received post-exposure prophylaxis (PEP) for potential rabies exposure each year, according to the findings. Schuchat noted that 70% of Americans who died from rabies in the U.S. were infected by bats.

Globally, rabies causes around 59,000 deaths each year, including approximately two in the U.S., according to Pieracci and colleagues.

“The bottom line is rabies continues to be a threat in the U.S. and abroad, and people should see their health care professionals if they think they've been bitten or scratched by an animal and before symptoms occur,” Schuchat said. “An ounce of prevention can go a long way.”


Pieracci offered suggestions to health care providers for curbing the threat of rabies.

“We recommend infectious disease doctors ask their patients about recent bites or scratches, especially from wildlife,” Pieracci told Infectious Disease News. “We want them to know that state health departments are there to assist them in conducting risk assessments for patients who have potentially been exposed to rabies.”

She said PEP recommendations differ for patients who have been prevaccinated against rabies. Preimmunized patients require only two doses of vaccine, whereas unvaccinated patients will require four doses of vaccine and one dose of immune globulin after rabies exposure, she said. – by Joe Gramigna

Disclosures: Pieracci and Schuchat report no relevant financial disclosures.