Infections at birth substantially increase the risk of autism and intellectual disability, study finds
Sarah BodenToday at 2:28 p.m.
Public Health
Rubella
Kids born with certain congenital infections are approximately three times more likely to be diagnosed as having autism, according to a study out of the Karolinska Institutet in Stockholm, Sweden. These children were also more likely to have an intellectual disability compared to those born without an infection, with the risk of severe to profound intellectual disability being up to 30 times higher than the general population.
The study, published last week in JAMA Pediatrics, included 3.7 million people born in Sweden from 1987 through 2021. Of this group, 975 had congenital infections caused by pathogens that can cross the placenta, leading to maternal-fetal transmission, though spread can also happen during or after birth. Collectively, these are called TORCH infections, standing for toxoplasmosis, other infections, rubella, cytomegalovirus (CMV), and herpes simplex virus.
Researchers compared kids born with a TORCH infection to their siblings, as well as the general population, finding similar results in the frequency and severity of poor neurodevelopmental outcomes. The authors say this suggests these outcomes cannot be explained solely by genetic factors shared within families.
“In contrast to studies of common maternal infections, where associations with autism are largely explained by familial confounding, our findings persisted after sibling adjustment,” the study authors wrote. “Nevertheless, absolute risk estimates indicate that these exposures accounted for only a small proportion of autism cases in the population.” This is because TORCH infections remained rare in the children studied.
Another important finding is that TORCH infections are associated with poorer academic performance later in life. The authors said this indicates that TORCH illness might cause more subtle cognitive differences. Though they note that the study's results on sibling academic performance were imprecise, limiting any conclusions that can be drawn.
TORCH vaccines could prevent autism
The magnitude of the association between a TORCH infection and adverse neurodevelopmental outcomes was striking, said Megan Pesch, MD, MS, the medical director of the Center for Autism and Developmental Disabilities at Henry Ford Health, a Michigan-based medical system.Pesch, who did not contribute to the study, praised its overall design. But she noted that the researchers focused on clinically identified TORCH infection. In some cases, that parameter may exclude kids with asymptomatic infections, so Pesch cautioned that the risk estimates in the study's findings may not apply to every TORCH-affected infant.
CMV was responsible for roughly half of all observed cases of a TORCH infection in the study. This isn't too surprising, as an association between autism and the virus, which belongs to the herpes family, has been suspected for decades.
But previous studies exploring that relationship were small and uncontrolled, said Mark Schleiss, MD, pediatric infectious disease physician at the University of Minnesota School of Medicine.
Schleiss did not contribute to the study but wrote an editorial to accompany its publication.
Now that the association between CMV and autism has been "rigorously proven," Schleiss told CIDRAP News in an email that the results highlight the need for a CMV vaccine—and that people should also get vaccinated for rubella, another TORCH infection.
"We need to acknowledge that one solution (for at least a subset of autism spectrum disorders) is to administer more vaccines," he said.
Swedish findings have implications in US
Given that Sweden's demographics and newborn screening policies can differ widely from other countries, similar studies are needed to determine if the results are translatable, said Lisa Croen, PhD, an epidemiologist specializing in autism and other neurodevelopmental disorders at Kaiser Permanente's Division of Research. Croen likewise was not involved in the study.The population impact of TORCH infections may be even greater in the United States, Pesch said, noting that CMV epidemiology in the States differs from Scandinavia because of variations in public-health practices.
In general, Schleiss said awareness of CMV is "disturbingly low," which is why he wants Congress to pass the Stop CMV Act of 2025. The bill, which has bipartisan support in the House and Senate, would require screening newborns for the virus.
"Two states, Minnesota and Connecticut, currently screen for congenital CMV infection in all newborns," said Schleiss. "This should become a national standard of care."