The congenital human herpesvirus-6 has long been associated with a wide range of conditions and illnesses. And now a researcher at the University of Rochester Medical Center says that HHV-6 could play a role in slowing children's mental development.
Dr. Mary Caserta, a URMC professor of pediatrics and infectious diseases, recently completed a study showing that infants with HHV-6 scored lower on mental development tests than uninfected infants.
The study, which was recently published in the journal Pediatrics, showed that the scores of infected infants are on par with those of infants exposed to toxins such as lead or cocaine in the womb.
It's too early to tell if the delays go away as the child ages, Caserta says, or if they grow worse with time.
Every human is infected with HHV-6, usually by age 2, she says. In some people, however, the virus is actually part of their genetic makeup, Caserta says.
"It's inherited," she says. "It's in the human chromosome."
Roughly 1 percent of newborns are infected with the virus congenitally. And it's this group that most concerns Caserta.
Her study looked at nearly 300 newborns during their first 12 months. The infants were given three tests to measure intellectual development; the tests examine an infant's visual recognition and the ability to form expectations about what they're seeing.
The scores for the first two tests are about the same for the infected and uninfected infants. But in a third commonly used comprehensive test, Caserta says, the infected infants scored lower. The scores are not dramatically lower, she says, but they are statistically significant.
Caserta says that she became interested in HHV-6 because it has some troubling similarities to the cytomegalovirus, which is much more menacing. In adults with compromised immune systems, CMV can cause blindness. In newborns, it can cause deafness and developmental disorders.
The next step in understanding HHV-6 should involve a much larger study that looks at older children with learning disabilities to determine if congenital HHV-6 is somehow involved, Caserta says. Even taking a second look at the children in her own study would be interesting, she says.
"They're 5 or 6 now and we'd like to know how they're doing," she says. She would like to have followed them to see if they developed learning disabilities, she says.
While Caserta says that she's hopeful she'll find the necessary funding for future work on HHV-6, she can't predict when it will happen because of the overall reduction in research funding.
"The funding for HHV-6 hasn't been so generous," she says.