By the age of 2 most children have become infected with a form of herpes virus that frequently causes symptoms severe enough to require a doctor’s attention.
Findings from one of the first studies to take a close look at human herpesvirus 6 (search) (HHV-6) are at once reassuring and a cause for concern.
The study shows that a high percentage of children get sick enough to require a trip to the doctor when they are infected with the virus. But the rate of serious illness was much lower than has been reported in studies that included only children who got sick enough to end up in hospital emergency rooms.
Fever, fussiness, and runny nose were common symptoms among children with herpesvirus 6 infection in the newly reported study published in the Feb. 24 issue of The New England Journal of Medicine.
“This paints a kinder, gentler picture of HHV-6 than we have seen when we looked only at kids who ended up in emergency departments,” says Ohio pediatrician Keith Powell, MD, who is a spokesman for the American Academy of Pediatrics. “This shows that most kids have much milder illness.”
First discovered in 1986, HHV-6 is one of eight known members of the human herpesvirus family. It does not cause cold sores, chicken pox, shingles, or genital infections, as other herpes viruses do. But it has been believed to be a major cause of childhood rash and has also been implicated as a cause of childhood seizures.
How Common Is the Infection?
In an effort to learn more about herpesvirus 6, Danielle Zerr, MD, MPH, and colleagues from Seattle’s Children’s Hospital and Regional Medical Center closely followed 277 children from birth through the first two years of life.
Weekly tests of the children’s saliva were conducted to look for evidence of HHV-6. Parents also kept daily logs detailing signs and symptoms of any illnesses.
By age 2, roughly 77 percent of the children in the study had been infected with herpesvirus 6. Most infections occurred between age 9 and 21 months. More than nine out of 10 children had symptoms. The symptoms were severe enough to require a doctor’s visit in 39 percent.
Having older siblings doubled the risk of HHV-6 infection. Girls became infected slightly more often than boys. But attending daycare did not appear to increase the risk of infection, and infection was not associated with a particular season.
“The fact that such a large proportion of children sought medical care shows the public health implications of becoming infected with this virus,” Zerr tells WebMD.
Rash Common, Seizures Not
Herpes virus 6 infection is a major cause of roseola (search), a common childhood condition that usually starts as a high fever and progresses to a rash on the face and body. But only about one-quarter of the children in the study with a well-defined time of HHV-6 acquisition developed roseola.
And none of the children in the study ended up having seizures. Seizures and high fevers are not uncommon among young children with HHV-6 infection who are treated in hospital ERs.
“It appears from this study that seizures are not as frequent as previously thought,” Zerr says.
“The average kid in the first three years of life has eight respiratory infections a year,” Powell tells WebMD. “Most kids that age either have a cold or are getting over one or are in the process of getting another one.”
Currently, there is no rapid test to diagnose herpesvirus 6. Zerr says a rapid test for HHV-6 could help doctors rule out potentially serious bacterial infections earlier.
“If we knew that a child had this particular virus or some other virus we wouldn’t necessarily need to do the diagnostic tests for bacterial infection,” she says.
SOURCES: Zerr, D. The New England Journal of Medicine, Feb. 24, 2005; vol 352: online edition. Danielle M. Zerr, MD, MPH, Children’s Hospital and Regional Medical Center, Seattle. Keith Powell, MD, Noah Miller Chair of Pediatrics, Akron Children’s Hospital, Akron, Ohio; and spokesman, American Academy of Pediatrics.