Clinical Characteristics of Primary HHV-6B Infection in Children Visiting the Emergency Room

• Published in: The Pediatric infectious disease journal Vol. 38; no. 10; pp. e248 - e253
• Main Authors: Hattori, Fumihiko, Kawamura, Yoshiki, Kozawa, Kei, Miura, Hiroki, Miyake, Misa, Yoshikawa, Akiko, Ihira, Masaru, Yoshikawa, Tetsushi
• Format: Journal Article
• Language: English
• Published: United States Copyright Wolters Kluwer Health, Inc. All rights reserved 01-10-2019
• Subjects: Age Distribution; Child, Preschool; Cohort Studies; Emergency Service, Hospital; Female; Herpesvirus 6, Human - isolation & purification; Humans; Incidence; Infant; Infant, Newborn; Male; Roseolovirus Infections - epidemiology; Roseolovirus Infections - pathology; United States - epidemiology; United States
• ISSN: 0891-3668; 1532-0987
• DOI: 10.1097/INF.0000000000002379

OBJECTIVE:This cohort study, based on the design of a prior study in the United States, was conducted to elucidate the clinical features of primary human herpesvirus-6B (HHV-6B) infection.
METHODS:Between June 2014 and May 2016, febrile children younger than 5 years who visited the emergency room (ER) and underwent blood examination were enrolled in this study.
RESULTS:Fifty-nine (12%) of the 491 patients were diagnosed with primary HHV-6B infection. The rates of both simple and complex febrile seizure were significantly higher in patients with primary HHV-6B infection than in those without (P < 0.001 and P = 0.008, respectively). The median age at primary HHV-6B infection was 15 months. Forty-seven (79.7%) of the 59 patients with primary HHV-6B infection were younger than 2-year-old. Clinical features were compared between HHV-6B–infected patients older and younger than 2 years. The frequency of apparent infection (exanthema subitum) was significantly higher in the younger patients (P = 0.01). The median leukocyte (P = 0.01) and lymphocyte (P < 0.001) counts in the patients older than 2 years were significantly lower than those in the younger patients.
CONCLUSIONS:Primary HHV-6B infection accounted for 12% of ER visits. Secondary febrile seizures, in particular the complex type, were considered to be a major contributor to the disease burden of primary HHV-6B infection. The timing of primary HHV-6B infection occurred at older ages than in past reports, and the frequency of inapparent infection was higher in older patients.