Zika Virus May Increase Risk of Mental Illness even in infants without shrunken heads

A baby with a shrunken, misshapen head is surely a heartbreaking sight. But reproductive health experts are warning that microcephaly may be only the most obvious consequence of the spread of the Zika virus.

Even infants who appear normal at birth may be at higher risk for mental illnesses later in life if their mothers were infected during pregnancy, many researchers fear.

The Zika virus, they say, closely resembles some infectious agents that have been linked to the development of autism, bipolar disorder and schizophrenia.

Schizophrenia and other debilitating mental illnesses have no single cause, experts emphasized in interviews. The conditions are thought to arise from a combination of factors, including genetic predisposition and traumas later in life, such as sexual or physical abuse, abandonment or heavy drug use.

But illnesses in utero, including viral infections, are thought to be a trigger.

A viral attack early in pregnancy can kill a fetus or stunt the growing brain, producing microcephaly, they explained. An infection later in the fetus’s development, when the brain is nearly fully formed, can do damage that is less obvious but still significant.

“It is pretty scary,” said Dr. Urs Meyer, a behavioral neurobiologist at the Swiss Federal Institute of Technology in Zurich who studies the consequences of fetal infections in lab animals. “These problems are on a continuous scale, and whether you end up with autism or schizophrenia is complex — and we really can’t predict it.”

Evidence has increased for years that mental illnesses may be linked to exposure during pregnancy to viruses like rubella, herpes and influenza, and to parasites like Toxoplasma gondii.