Should we really be scared of bats?

22nd January 2014
By Kate Baker and Alison Peel

When you think of bats, do they conjure up images of Halloween and Dracula movies, with flocks of mammals flying into people’s faces? Or maybe you know that bats can harbour some pretty nasty viruses (for example rabies) that can infect humans? Either way, you might be a little bit scared of them.

However, did you know that there are over 1,200 species of bats and that they are present on every continent except Antarctica? Did you know that bats have pivotal roles in our planet’s ecosystem, controlling insect populations, pollinating plants and dispersing plant seeds?

Given how much we depend on our flying, furry friends and given that some of them live in close proximity with human populations, it is well worth our understanding them and the risks they do and do not pose.

We have been studying the African straw-coloured fruit bat (Eidolon helvum) that is found all throughout sub-Saharan Africa in order to understand its population structure across the continent and whether it might pose a risk to people.

Eidolon helvum often lives in big populations (up to millions of bats!) in big cities, but it carries out large-scale migrations, often disappearing for six months of the year. Very little is known about where they go, or how the bat populations in different places are connected, although people have tracked the movement of an individual bat over 2,500km!

To determine the connectivity, we performed a genetic study of bats from 12 different African countries and found that the entire continental population is panmictic (Reference 1, Peel et al, 2013). A panmictic population is one that is freely mixing with no genetic separation of the animals on the basis of geography.

So, once we knew the bats were connected across the continent, we wanted to know if they posed a risk to any people because some bat species carry zoonotic viruses (ones that can transmit from animals to humans). To do this, we looked in E. helvum for viruses using a variety of techniques including metagenomics (Reference 2, Baker et al, 2013), where we sequence everything in a sample from the bat, looking specifically for sequences of paramyxoviruses, which are viruses like mumps and measles. (Reference 3, Baker et al, 2013).

We found a lot of viruses and antibodies, which show past infection, in the bats, including some that were related to zoonoses. Amazingly, viruses that were found in the bats in Ghana were very closely related to viruses in Ugandan bats, showing that the panmictic population structure of the bats allows for the free sharing of viruses among them.

Although we’re still trying to find out for sure if these viruses are able to infect people, we now know a lot more about one of our flying, furry friends and we know that what we see happening with the viruses of this bat species in one part of the continent is likely applicable to the rest of the Africa.

Kate Baker and Alison Peel were completing their PhDs in the Department of Veterinary Medicine at the University of Cambridge and Institute of Zoology during these studies.

Kate is now a Postdoctoral Development Fellow in the Pathogen Genomics group at the Wellcome Trust Sanger Institute, working on the molecular epidemiology of enteric pathogens.

Alison is now a Postdoctoral Research Fellow at the Environmental Futures Research Institute and the School of Environment at Griffith University, Australia, where she is working with Prof Hamish McCallum on Hendra virus disease dynamics in fruit bats.

References

• 1. Peel, A et al(2013). Continent-wide panmixia of an African fruit bat facilitates transmission of potentially zoonotic viruses. Nature communications .
  doi:10.1038/ncomms3770
• 2. Baker, K et al (2013). Metagenomic study of the viruses of African straw-coloured fruit bats: Detection of a chiropteran poxvirus and isolation of a novel adenovirus. Virology. doi: 10.1016/j.virol.2013.03.014
• 3. Baker, K et al (2013). Novel, Potentially Zoonotic Paramyxoviruses from the African Straw-Colored Fruit Bat Eidolon helvum. Journal of Virology. doi: 10.1128/JVI.01202-12

Related Links:

• Department of Veterinary Medicine at the University of Cambridge
• Institute of Zoology
• Pathogen Genomics group at the Wellcome Trust Sanger Institute
• Environmental Futures Research Institute and the School of Environment at Griffith University