A new explosive outbreak of Zika virus could happen at any time as new research shows that a single mutation could trigger a major epidemic, scientists have warned.
The virus, carried by mosquitoes, currently causes only mild illness in adults. But its effect on unborn children can be devastating, causing brain damage and birth defects.
The virus, a relative of dengue fever, is particularly noted for causing microcephaly – a severely under-sized head – in newborns.
A new paper from US scientists working at the La Jolla Institute for Immunology in California says that the medical world should be on the lookout for new mutations.
In lab tests, the team passed the virus between a mouse and mosquito cells a number of times – resulting in tiny changes that could bring about the birth of a new strain.
A new strain of the virus would be able to dodge antibodies among populations where a previous wave of infection had conferred herd immunity, the scientists warn.
The researchers write: “Since the explosive spread of ZIKV [Zika virus] in the Americas in 2015–2016, one of the key challenges has been to understand the drivers of ZIKV evolution and exploit that knowledge to facilitate the prediction of future outbreaks."
Deadly disease-carrying mosquitoes could soon become UK plague, expert warns
After the 2016 outbreak, thousands of babies were born with brain damage because their mums had been bitten by Zika-carrying bugs while pregnant.
Virologists are working to develop a vaccine that protects pregnant women but as yet there is no treatment for the disease.
Lead investigator Prof Sujan Shresta said: "The Zika variant that we identified had evolved to the point where the cross-protective immunity afforded by prior dengue infection was no longer effective in mice.
"Unfortunately for us, if this variant becomes prevalent, we may have the same issues in real life."
Speaking to the BBC, Prof Jonathan Ball, an expert in viruses at the University of Nottingham, added: "We've heard so much lately about the rapid evolution and emergence of coronavirus variants, but this is a timely reminder that shapeshifting is a common feature shared by so many viruses.
"This work shows just how rapidly a single letter change in the genome sequence of a virus can arise, and the stark impact it can have on the disease capability of a virus.
"But viruses that share these changes haven't often been seen in outbreaks and, as the authors point out, these intriguing insights require more thorough investigation."
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