The number of rabid bats in Prince George’s County, Md., which borders the D.C. metropolitan area, has spiked this year, causing county health officials to issue a warning to the public.

In August, nine bats in the county tested positive for rabies, and one person has come in contact with an infected bat.

Last year, only four rabid bats were found in the county, while 10 have already been found this year, according to the Prince George’s County Health Department. There have been a total of 19 rabid animals found in the county this year.

Prince George’s County Health Officer Dr. Donald Shell told Fox 5 News that warmer weather might be to blame.

“Potentially the mild winters allow the bats to survive – and there are more bats because of the milder winters,” he said.

The health department has asked people to take precautions to avoid contracting the disease. Public information specialists warned people to stay away from any unfamiliar animals, domestic or wild.

The health department said that residents should be especially wary of animals that seem friendly towards humans, because bats are normally unfriendly creatures. Bats that are seen during the day are most likely rabid, and people should not approach them.

“Really the warnings are for people who have bats in their homes. If you wake up and are not sure if you woke up with a bat in your home, call 311,” D.C. Department of Health spokesperson Dena Iverson said.

The Prince George’s County Health Department has advised residents to “bat-proof” their homes. Any opening larger than .25 by .5 inches into a home should be closed. Simple steps such as putting window screens in and trap guards under attic doors can be effective in keeping bats out.

Anyone in Prince George’s County who comes into contact with a dead, sick, or suspicious animal should call the Animal Management Division at (301) 780-7200 immediately.

Iverson said that people should take the same approach to dealing with rabid bats as they would for any other animal, such as raccoons.”