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Even Bats Need Vaccines


René F. Najera, DrPH

May 26, 2019

Bats are amazing creatures, when you think about it. They're mammals, like you (if you're a human reading this), and they can fly, like birds. They work as pollinators going from tree to tree, spreading pollen that fertilizes tree fruits. They also work as pest controllers by eating small rodents and insects. Recently, in North America, a fungal disease called "" has been spreading from one bat colony to another, decimating colonies and placing several species of bats on the endangered species list (if they weren't there already). According to the National Park Service:
"Researchers call the disease “white-nose syndrome” (WNS) because of the visible white fungal growth on infected bats’ muzzles and wings. This cold-loving fungus infects bats during hibernation, when the bats reduce their metabolic rate and lower their body temperature to save energy over winter. Hibernating bats affected by WNS , which results in using up fat reserves and then starvation before spring arrives. The visible signs of WNS show the disease is in a later stage. These bats are already dealing with , such as acidification and dehydration. Even before the infected bats start to wake more often, infection with the fungus causes bats to use energy twice as fast as healthy bats, according to ."
Well, now there is hope that this infection can be brought under control. Researchers have adapted a racoon poxvirus with DNA from the fungus that causes white-nose syndrome in order for the virus to express fungal proteins on its surface. When given to the bats, the bats' immune system reacts to the fungal proteins, triggering an immune response to the fungus without giving the bats a disease. From the :
"Wild little brown bats (Myotis lucifugus) were vaccinated before being exposed to the fungus. Of 10 bats given a combination of both vaccines, only one developed lesions within the experiment’s 100-day hibernation period. Because little brown bats don’t do well in captivity, the team struggled with dwindling sample sizes, so it was hard to compare these numbers to other individual treatments. But 14 of the other 23 bats, or 61 percent, that didn’t get this vaccine combo developed lesions. In a second trial aimed at confirming the results, researchers vaccinated bats both orally and by injection. After 126 days, about 88 percent of bats that received oral versions of both vaccines survived the effects of the fungus, compared with 30 percent of unvaccinated bats (and 80 percent of bats vaccinated by injection). Bats that survived the experiments lost an average of about 34 percent of their body weight, while bats that died had lost about 55 percent. Researchers suspect that slowing the fungus growth or reducing the intensity of infections may have helped vaccinated bats sleep more peacefully and maintain more of their weight and energy."
Other ways to deliver the vaccine are being researched, along with different formulations of the vaccine. Scientists hope to bring this disease under control soon, hopefully saving bat populations and keeping the delicate balance of their habitats as intact as possible. Featured image of two bats in Brazil via ().


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