1239 GMT August 19, 2019
Researchers said the virus, which has affected more than seventy Britons, enters the brain of adults and can ‘wreak havoc’, according to express.co.uk.
They have called for all adults infected with Zika to be monitored — not just pregnant women.
The mosquito-borne causes microcephaly, a serious birth defect which causes babies to be born with brain damage and small heads and possibly even joint deformities.
However the virus was thought to have a minimal effect on adults — other than pregnant women.
Most people infected with the virus don’t show any major symptoms, although some do experience flu — including headaches, fever and pain in joints. But new research shows the effect of Zika could be more dangerous.
An experiment using mice engineers to mimic the human Zika infection show that the virus attacks immature cells in the adult brain, which are vital to learning and memory.
Over time, the scientists said that the loss of these ‘progenitor’ stem cells could lead to brain shrinkage and the type of cognitive decline which is seen in people suffering with Alzheimer’s disease.
Professor Sujan Shresta, a member of the team from the La Jolla Institute of Allergy and Immunology in California, USA, said: "Zika can clearly enter the brain of adults and can wreak havoc.
“But it's a complex disease — it's catastrophic for early brain development, yet the majority of adults who are infected with Zika rarely show detectable symptoms.
"Its effect on the adult brain may be more subtle, and now we know what to look for."
The study is the first to focus on the impact of Zika infection on the adult brain.
Results show the virus targets two specific regions of the adult brain after scents used fluorescent tags to mark when the cells were invaded by the virus.
Professor Joseph Gleeson, from Rockefeller University, said: "Our results are pretty dramatic — in the parts of the brain that lit up, it was like a Christmas tree.
"It was very clear that the virus wasn't affecting the whole brain evenly, like people are seeing in the fetus. In the adult, it's only these two populations that are very specific to the stem cells that are affected by virus. These cells are special, and somehow very susceptible to the infection.
"Based on our findings, getting infected with Zika as an adult may not be as innocuous as people think."
While healthy individuals may be able to resist the virus, those with weakened immune systems could be at serious risk, said the researchers.
Gleeson added: "In more subtle cases, the virus could theoretically impact long-term memory or risk of depression, but tools do not exist to test the long-term effects of Zika on adult stem cell populations."
The scientists said that the research raises the possibility of long term mental impairment in Zika-infected adults.
"The virus seems to be traveling quite a bit as people move around the world," said Gleeson.
"Given this study, I think the public health enterprise should consider monitoring for Zika infections in all groups, not just pregnant women."
In February, the World Health Organization declared the outbreak a 'public health emergency of international concern' as evidence grew of Zika's association with birth defects.
The virus is chiefly spread by the Aedes aegypti mosquito, which is common throughout the tropical and subtropical Americas.