Effects of Zika infection during infancy persists in adulthood

Zika virus infection in infants can cause seizures, and long-term deficits in brain structure and behaviour that persist into adulthood, scientists say.

Zika virus is mainly transmitted by the Aedes aegypti mosquito but it can also be transmitted by sexual contact and blood transfusion.

Adult patients infected by Zika usually present only mild symptoms such as rashes, conjunctivitis, arthralgia and mild fever that last a few days.

However, the outbreak of Zika virus in Brazil in 2015 first showed the world that Zika infection can have devastating consequences for pregnant women and their foetuses.

At the time of the outbreak, the association between microcephaly and Zika infection during pregnancy was demonstrated. It was observed that even babies born with normal-sized head can later develop symptoms associated with congenital Zika virus infection.

Today, the children of the Zika virus outbreak are no older than 3 and no one can foresee the long-term consequences these children may still suffer.

Researchers from Federal University of Rio de Janeiro in Brazil investigated the short- and long-term neurological consequences of Zika infection in newborn mice.

They infected three-day-old infant mice with the virus and monitored their behavioral and neurological development until adulthood.

The researchers found that most of the infected mice developed spontaneous seizures as soon as nine days after birth, and remained more susceptible to chemically-induced seizures in adulthood compared to controls.

Furthermore, the infected mice demonstrated reduced motor function and muscle strength during behavioral tests in infancy, and displayed short-term memory impairment in adulthood.

These behavioral deficits were also accompanied by persistent viral replication and inflammation in the brain.

Finally, administering a drug that inhibits the proinflammatory molecule TNF-alpha prevented seizures in young infected mice, suggesting that targeting cerebral inflammation could ameliorate some of the long-term consequences of neonatal Zika infection.