A fourth bat found in Alameda County this month has tested positive for rabies, county health officials said.
The bat was found in Sunol on Saturday. County health officials announced Thursday it was confirmed to have rabies.
Three bats found in the Fremont area earlier this month tested positive for rabies as well.
A dog picked one up near the playground at Niles Elementary School last Friday and another was found March 6 near the entrance to the Wally Pond Irvington Community Center at 41885 Blacow Road, according to Fremont police.
Between two and nine rabid bats have been found in the county each year since 2001.
Rabies is a potentially fatal disease that affects the brain and nervous system. It can be prevented in humans and animals by a series of rabies vaccine shots.
Infected humans develop symptoms of rabies within one to three months. Early symptoms include fever, headache, severe fatigue and irritability. Later symptoms include difficulty walking, speaking, swallowing, confusion, hallucinations, agitation and nerve pain, according to the health department.
Rabies patients typically become comatose and die within about two weeks of becoming sick.
County health officials advise anyone who finds an ill or dead bat or skunk not to touch it and instead call animal control services.
Anyone who has contact with or is bitten by a bat should call the county health department at 510-267-3250 and then seek medical attention.