Fifth and Sixth Diseases: More Than a Fever and a Rash

Complications. Fifteen percent of infected children have febrile seizures.¹ Based on several case reports, HHV-6 infection has been associated with meningoencephalitis, acute disseminated demyelination, hepatitis, and myocarditis.¹⁷ It is unknown whether seizures increase the risk of these complications. Long-term sequelae from these manifestations of HHV-6 infection include developmental disorders and autism-spectrum disorders.^18,19

Treat supportively

Patients with primary HHV-6 infection usually require antipyretics and frequent hydration. Reserve antivirals such as ganciclovir, foscarnet, and cidofovir for immunocompromised patients or those with HHV-6 encephalitis.²⁰

Clinical recommendations

Most patients infected with HHV-6 have fever and rhinorrhea,
 and are fussy. Only 20% exhibit the rash of roseola. Treat seizures associated with HHV-6 infection as you would any other febrile seizure, giving an antiepileptic (diazepam, lorazepam, or midazolam) if the seizure lasts >5 minutes. Risk of seizure recurrence with HHV-6 is equivalent to that seen with other causes of febrile seizure.¹

Because of the ubiquitous prevalence of HHV-6 infection, there are no effective preventive measures. Little is known about the effect of HHV-6 exposure during pregnancy because most pregnant mothers are immune to the virus.²¹ Exclusion from school or child care is not recommended because of the prolonged shedding of the virus.^16,22

CORRESPONDENCE
Jason S. O’Grady, MD, Department of Family Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905; ogrady.jason@mayo.edu

ACKNOWLEDGEMENT
The author thanks Anne Mounsey, MD, Department of Family Medicine, University of North Carolina at Chapel Hill, for her invaluable assistance in editing this manuscript.