Cerebral palsy linked to perinatal viral exposure.(News)

Newborns whose blood samples showed exposure to potentially neurotropic viral infections were significantly more likely to be diagnosed as having cerebral palsy than were those with no such exposure, reported Catherine S. Gibson, Ph.D., of the University of Adelaide, Australia, and her associates.

In particular, neonates whose blood contained the nucleic acids of varicella zoster virus, human herpes virus 6, or human herpes virus 7 had nearly twice the rate of cerebral palsy (CP) as did nonexposed neonates in a retrospective case-control study that screened all children with CP who were born between 1986 and 1999 to white mothers in South Australia.

The researchers obtained newborn screening cards from 443 neonates who were later diagnosed as having CP and from 883 control neonates. The cards contained dried blood samples collected by heel prick at 3-5 days of life. Punches of these blood samples were extracted and tested for the presence of viral DNA.

The stored blood samples yielded readable results from 414 of the children with CP and 856 of the controls. The results indicated only intrauterine or early neonatal exposure to the viruses and could not conclusively demonstrate active congenital or neonatal infection. However, given the small size of the blood sample and the limit of detection of 1-10 viral copies, "it could be inferred that true viremic infection was occurring," the researchers said (http://bmj.bmjjournals.com; doi 10.1136/bmj.38668.616806.3A).

"The primary analyses showed a significant association between any viral exposure and cerebral palsy at all gestational ages," they noted.

The risk of developing CP was 1.5-2.5 times greater after exposure to varicella zoster, herpes type 6, or herpes type 7 viruses, compared with controls. The prevalence of exposure to these viruses was 12.1% for babies with CP, compared with 7.6% for controls, "giving a potential attributable risk of 4.5% of all cases of cerebral palsy if a causal relation exists," Dr. Gibson and her associates said.

In addition, the risk of preterm birth was significantly higher in babies exposed to cytomegalovirus, herpes simplex virus 1, herpes simplex ...