OMAHA, Neb. -- A nationwide shortage of rabies vaccines has health officials cautioning people about bats.

Nebraska Public Health veterinarian Dr. Annette Bredthuaer said this is the time of year when more people come into contact with bats.

Young bats born during summer become disoriented and enter buildings. Other bats are searching for hibernation spots.

Cases of human rabies are rare in the U.S. Bredthuaer said. But bat bites are superficial and can easily be overlooked. People can be bitten in their sleep, she said.

Nine infected bats have been found this year, according to the Nebraska Department of Health and Human Services. Last year, 14 infected bats were found in the state.