Swarms of bats have taken up unwelcome residence at Zachary High, the University of Louisiana at Monroe and Vermilion Parish’s Gueydan High in recent weeks.

The animals are currently migrating north from Mexico to reach their breeding grounds by spring, said Kevin Koski, owner of United Bat Control.

State public health veterinarian Gary Balsamo said Louisiana doesn’t have a lot of caves, so bats that don’t like trees take up in large buildings with high ceilings – a school gym or cafeteria, an apartment complex, a church or even a hospital.

Bat infestations are “a very common problem,” he said.

Koski said school infestations tend to grab the most attention because of disruptions to classes, concerns from parents and worries that a youth could be injured.

Louisiana Department of Wildlife and Fisheries biologist Keri Lejeune said the state doesn’t have enough staff to respond to infestations so contracts the work out to private companies like United Bat Control.

To catch the creatures, wildlife removal specialists close all the doors and windows where a colony is hiding. Then the dusk-time stakeout begins, Balsamo said.

Crews wait for the bats to wake up for their nocturnal foraging and look to see where the small mammals may have found a hole or fissure to wriggle in and out of the building. While the bats are out, the team tries to seal all those entryways so they can’t get back in, the veterinarian said.

Then health officials help make sure a building is safe. Bats themselves can transmit rabies, and their guano contains a fungus that can lead to a respiratory infection known as histoplasmosis, Balsamo said. The fungus occurs naturally in some soil and animal droppings, but large quantities of guano could give a person a cough and fever,. In rare cases, he said, it can be fatal for patients with weakened immune system.

UL-Monroe Public Relations Director Hope Young said the school is still cleaning the ventilation systems in Sugar Hall a week after the arrival of the bats.

Classes in parts of the science building have been moved temporarily. No one was hurt during the event, and the campus is taking it in stride. There’s even been a tongue-in-cheek push to change the mascot from the Warhawk to the Warbat, Young said.

The university played host to an indeterminate number of Brazilian free-tailed bats, also known as Mexican free-tailed bats. It’s the usual suspect when Koski’s company gets called in to clear an infestation.

Though his business didn’t respond to any of the most recent incidents, Mexican free-tailed bats tend to travel in colonies ranging from a couple hundred to a couple thousand, Koski said.

Vermilion Parish school officials told KATC-TV they estimated they had about 600 bats and shared photos of dozens of the animals huddling in tight masses in corners of the ceilings at Gueydan High. The school closed for two days while the bats were ushered out.

Zachary school officials did not respond to requests for comment but posted on social media in late January that they were able to keep holding classes in some areas while others were closed for cleaning because they had separate HVAC systems.

Professionals must remove or chemically treat air ducts so the fungus from the guano doesn’t spread, Balsamo said. Companies use various sterilizers and deodorizers, Koski added.

A typical school treatment might cost $10,000 to $25,000, depending on multiple factors, Koski said.

He heard of an unusual Utah case where a school system paid about $350,000, though they had been plagued by problems, including recent infestations of 1,000, and 5,000 bats at a pair of high schools, according to the Deseret News.

Follow Steve Hardy on Twitter, @SteveRHardy.