What does Ukraine have to do with America's vanishing bats? Scientists explain
Bats are dying en masse in the US due to a virus brought from caves in Ukraine (photo: Stephen Alvarez/National Geographic)
Research shows that the deadly white-nose syndrome, which is devastating bat populations in the US, has an unexpected origin. The source of this dangerous fungus is caves in the Podillia region of Ukraine, from where it likely spread via speleologists. Nature reports on how Ukrainian caves became the cause of a deadly disease affecting bats in the US.
It turns out that the cause of the deadly disease affecting bats in the United States of America, known as white-nose syndrome, is... the caves of Podillia in Ukraine.
According to scientists, during the 1990s and 2000s, speleologists introduced fungus spores into caves in the US, where it began to infect local bat populations on a massive scale.
This disease has already led to a catastrophic 90% decline in the population of some bat species, which in turn has caused a significant increase in the number of harmful insects that these animals once successfully controlled.
Where did the deadly threat come from?
Scientists have long suspected that the fungus "Pseudogymnoascus destructans," the causative agent of white-nose syndrome, arrived in North America from Europe. Researchers collected nearly 5,500 fungus samples from caves in 27 European countries to pinpoint their origin. By comparing the genomes of these samples with the genome of the fungus affecting American bats, they found that there are two variants of the fungus circulating in Europe — Pd-1 and Pd-2.
The Pd-1 variant caused bat deaths in the US. Its genome was found to be nearly identical to fungi discovered in caves in the Ternopil region, specifically in the world's longest gypsum cave—Optimistic Cave—and the nearby Ozerna Cave.
Since both of these caves were popular tourist destinations in the 1990s and 2000s, scientists believe that tourist speleologists inadvertently transferred the fungal spores between continents.
Spread of the white-nose syndrome pathogen in Europe. The two yellow dots in Ukraine mark the caves where the same strain that causes the disease in American bats was found (photo: Fischer et al/Nature, 2025)
Why were American bats affected more severely?
So far, only the Pd-1 variant has been found in the US. This strain is less dangerous for European bats, as they have developed a certain level of immunity. However, due to the lack of such immunity in American bats, this variant caused significantly higher mortality among them.
Scientists especially emphasize the importance of thoroughly disinfecting gear after visiting caves, as the European Pd-2 variant is far more deadly. Its introduction to the US would be catastrophic.
In addition to white-nose syndrome, bats face other challenges:
- Increased child mortality in the US has already been linked to bat deaths, as farmers are forced to use more harmful insecticides to combat insects that were previously kept in check by bats.
- The Russian war in Ukraine has also caused bat deaths, trapping them in destroyed buildings in Kharkiv and leaving them without shelter.
- While seemingly positive, the shift toward pesticide-free farming has reduced insect diversity in gardens, leading to fewer bat visits and a loss of their food source.
