Scientists from Colorado State University have found the genetic material of the Zika virus in free-ranging African bats. This discovery is the first reported detection of RNA from this virus in bats outside of controlled experiments. As reported in Scientific Reports, the animals seem to be infected naturally, or via the bite of infected mosquitos.
The Zika virus is part of the Flaviviridae family, which also includes the West Nile and dengue viruses, which are all mosquito-borne diseases in humans so it is crucial to understand how they might spread in animals too.
The team analyzed 198 samples from bats gathered in the Zika Forest and surrounding areas in Uganda. Four bats, from three different species, had the Zika virus RNA. Most of the samples predate the major Zika outbreaks, which started in Micronesia and French Polynesia before moving to the Americas.
"Our positive samples, which are most closely related to the Asian lineage Zika virus, came from bats sampled from 2009 to 2013," lead author Dr Anna Fagre said in a statement. "This could mean that the Asian lineage strain of the virus has been present on the African continent longer than we originally thought, or it could mean that there was a fair amount of viral evolution and genomic changes that occurred in African lineage Zika virus that we were not previously aware of."
Four bats out of 198 is quite a low prevalence, suggesting that bats are only accidental hosts. So they might not help to spread the virus and they might not create a reservoir for it. But more research is needed to confirm if this is indeed the case.
"Given that these results are from a single cross-sectional study, it would be risky and premature to draw any conclusions about the ecology and epidemiology of this pathogen, based on our study," Fagre added. "Studies like this only tell one part of the story."
The team also wants to understand how long the fragments of RNA persist in tissues so that they can assess when the bats were actually infected.
"There is always a concern about zoonotic viruses," senior author Assistant Professor Rebekah Kading explained. "The potential for another outbreak is there and it could go quiet for a while. We know that in the Zika forest, where the virus was first found, the virus is in non-human primates. There are still some questions with that as well. I don't think Zika virus has gone away forever."