Rabies in Bats Around the World

Did you know that the rabies causing virus found in North and South America, Lyssavirus rabies, doesn’t actually exist in bats outside of the Americas? That doesn’t mean bats in Europe, Africa, Asia, and Oceania are free from the disease rabies, however. They are absolutely capable of developing and transmitting rabies, just not from the species found in the Americas.

In the United States, the majority of human rabies cases come from bats. Globally, however, 99% of human rabies deaths are caused by domestic dogs. This is because bats outside the Americas are not very efficient at spreading rabies from their specific lyssavirus to other species.

Learn more about rabies the virus vs rabies the disease here

The Evolutionary Origins of Lyssaviruses

Lyssaviruses, the group of viruses that cause rabies, are extremely ancient and may date back to the Cretaceous period. The ancestor of modern lyssaviruses likely emerged in ancient bats in what is now Africa, back when the continents had yet to break up entirely. Some of these ancient bats are thought to have crossed into South America, bringing an ancient lyssavirus species with them.

In the New World (North and South America), that lyssavirus eventually evolved into the species we now know today as rabies lyssavirus–the species responsible for over 99% of human rabies deaths globally. Meanwhile, in the Old World (Europe, Africa, Asia, and Oceana) over 16 different lyssaviruses evolved independently. But here is the difference: these old world lyssaviruses are specialists. Unlike rabies lyssavirus, these viruses tend to circulate in only one or a few bat species in a specific region and rarely transmit the virus to other animals.

Why Do Old World Lyssaviruses Rarely Infect Humans and Animals Other Than Bats?

Outside of the Americas, lyssaviruses are typically only found in a handful of bat species that carry them, and cross-species transmission is uncommon. Lagos bat virus, for example, is found mainly in fruit bats in Nigeria. Rare lyssavirus spillovers happen, like the case where a horse in Australia died from rabies caused by Australian bat lyssavirus, but there are no documented cases of rabies outbreaks due to other lyssaviruses outside of bats, because the infected animals are poor transmitters of these viruses.

Rabies lyssavirus, however, behaves differently. It evolved to utilize a wide range of mammalian hosts, likely because it encountered numerous adaptable terrestrial animals capable of spreading it. Rabies lyssavirus is a generalist, not a specialist, which is why it is so good at spreading and frequently causes outbreaks.

How Did Rabies Lyssavirus Reach the Old World?

If rabies lyssavirus evolved in the Americas, how did it end up in Europe, Africa, and Asia, but not in their bats? The answer is a mix of natural movement and human transportation.

It is presumed that terrestrial canids that were incubating rabies (but had yet to develop it) were able to cross arctic land bridges long before modern times. Later, humans played a major role. Transocean travel resulted in the accidental transport of infected animals between the New World and the Old World. Foxes and raccoons from North America were even deliberately imported for fur farming, many ending up developing rabies and further spreading rabies lyssavirus through terrestrial populations.

Why is Rabies Lyssavirus Not Found in Bats in the Old World?

Despite all of the movement, rabies lyssavirus is not found in Old World bat populations. Terrestrial mammals don’t typically attack bats, so without exposure, the virus never established in those bat populations.

Is Rabies a Risk in Bats Everywhere?

Except in very limited island locations (such as New Zealand), bats in every country are a rabies risk–even in countries deemed “rabies free” such as Australia, the UK, and Germany. However, while the disease rabies may be the same, the virus causing the disease is not. Outside the Americas, bats host many different species of lyssaviruses that can cause rabies, though these viruses rarely spread to other species. In contrast, in the Americas, our rabies causing virus (rabies lyssavirus) is exceptionally good at jumping to new hosts.

Please keep in mind that while other lyssaviruses may rarely infect species other than bats, it does not mean it can’t happen. The rabies from these other lyssaviruses is just as dangerous as rabies from rabies lyssavirus. Please do not touch bats, even if your country claims to be “rabies free.”

Please Do Not Touch Bats

If you see a bat that needs help, call a trained professional. If you are in the United States, Animal Help Now can help you find a licensed wildlife rehabilitator. If you bit by a bat, get medical help immediately. All lyssaviruses cause the fatal disease rabies, but the majority are 100% preventable with the traditional rabies vaccine.