New Research Released on Common Childhood Virus

SEATTLE -- Human herpesvirus 6 (HHV-6), a common infection seen in children under the age of two, is usually symptomatic, often results in medical evaluation and appears to be contracted from older siblings, according to a new study from Children's Hospital and Regional Medical Center in Seattle and published in the February 24 edition of The New England Journal of Medicine.

HHV-6 was discovered in 1986 and is believed to be the cause of most cases of roseola since the early 1900's. An ever-present virus that establishes a dormant, lifelong infection in the host, HHV-6 is thought to be present in more than 95 percent of the human population and most commonly infects infants and young children. Most cases of HHV-6 are benign and require only supportive therapy. The most common symptoms associated with infection were fever and fussiness. HHV-6 can be particularly dangerous for immuno-compromised people often resulting in encephalitis, rash, fever, and even death.

Prior to this study, little was known about the acquisition, virological course and clinical manifestations of the infection. Researchers at Children's Hospital and the University of Washington School of Medicine studied 277 children from birth through the first two years of life to define the pattern of acquisition of HHV-6. Each child's saliva was tested weekly for HHV-6 and parents maintained a daily log of signs and symptoms of illness in their children.

Approximately 77 percent of study participants acquired HHV-6 in the first 24 months with the peak age of acquisition between 9 and 21 months of age. Among the children who acquired the virus 93 percent had symptoms and 39 percent were seen by a physician.

"Many in the medical community theorized that most children with HHV-6 did not end up in a physician's office or emergency room and would run the course of the virus at home. So it was surprising when our study showed 39 percent of children with the virus did seek medical attention," said Danielle Zerr, MD, MPH, medical director of infection control at Children's Hospital and Regional Medical Center, assistant professor of Pediatrics at the University of Washington School of Medicine and lead author of the study. "This implies that the virus has a more significant impact on our healthcare systems than originally thought."

Another interesting finding of the study was that older siblings appeared to serve as a source of transmission for the virus and the virus continued to be present in saliva for up to 12 months after infection.

Source: Children's Hospital and Regional Medical Center