Scientists from Columbia University and the Norwegian Institute of Public Heath have discovered that women actively infected with genital herpes during early pregnancy was twice as likely to have a child diagnosed with autism spectrum disorder (ASD) later on in life.
The study, published in mSphere -- a journal of the American Society for Microbiology, is the first the provide evidence of the associated between the anti-herpes simplex virus-2 (HSV-2) antibodies and risk for ASD in children.
"We believe the mother's immune response to HSV-2 could be disrupting fetal central nervous system development, raising risk for autism," says lead author Milada Mahic, a post-doctoral research scientist with Columbia University's Center for Infection and Immunity and the Norwegian Institute of Public Health.
Scientist do not believe that the risk is tied to direct infection of the fetus, typically those kinds of infections are fatal. However, research suggests that primary or reactivation of infection in mothers with inflammation so close to the womb is the cause of the neurodevelopment outcomes.
About one in five American women has HSV-2, also known as genital herpes. HSV-2 is a highly contagious and lifelong infection, usually spread through sex. After an initial outbreak, HSV-2 virus lives in nerve cells and is often inactive, with flare-ups occurring with diminishing frequency as the body builds up immunity to the virus.
Researchers focused on five pathogens which when exposed to women during pregnancy can lead to miscarriage and birth defects. Blood samples from 412 mothers of children diagnosed with ASD and 463 mothers of children without ASD were examined. The samples were taken at around 18 weeks of pregnancy and at birth.
Scientist found high levels of antibodies to HSV-2 correlated with risk for ASD. No other pathogen studied showed a similar connection. This link was only evident in blood samples taken at a time point reflecting exposure during early pregnancy when the fetal nervous system undergoes rapid development, not at birth.
In all, 13-percent of mothers in the study tested positive for anti-HSV-2 antibodies at mid-pregnancy. Of these, only 12 percent reported having HSV lesions before pregnancy or during the first trimester, a likely indication that most women did not show signs or symptoms (asymptomatic).
Scientist say further study is needed to determine if screening and suppression of HSV-2 infection during pregnancy is needed.
"The cause or causes of most cases of autism are unknown," says senior author W. Ian Lipkin, director of the Center for Infection and Immunity.
"But evidence suggests a role for both genetic and environmental factors. Our work suggests that inflammation and immune activation may contribute to risk. Herpes simplex virus-2 could be one of any number of infectious agents involved."
To read the full study, click here.
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