Basics
Description
- Exanthem subitum
- Incubation period of 5 " 15 days
- Mode of acquisition unknown:
- Horizontal spread by oral shedding suggested
- It is spread person to person but is not very contagious.
- Human is the only host.
- Pathophysiology:
- Complex immune response (cytokines, antibody responses, T-cell reactivity)
Etiology
- Human herpesvirus 6 (HHV-6):
- Large, double-stranded DNA
- Closely related to human cytomegalovirus
- Peak incidence at 6 " 12 mo; 90% occurrence within 1st 2 yr
- Highest incidence in late spring and early summer
Diagnosis
Signs and Symptoms
- Usually self-limited
- Diarrhea
- Irritability
- Rarely causes severe or fatal disseminating diseases:
- Infectious mononucleosis syndrome of hepatitis
- Complications
- Febrile seizures in 5 " 35%
- Aseptic meningitis/encephalopathy
- Thrombocytopenic purpura
- Reactivation in immunocompromised individuals. Manifestations are fever, rash, hepatitis, bone marrow suppression, pneumonia, and encephalitis
- Most newborns are seropositive for HHV-6 due to transplacental antibodies.
- By age 1 " 2 yr, >90% of infants are seropositive.
History
- Classic history is the onset of sudden, high fever 39.4 " 41.2 °C (103 " 106 °F) commonly followed by defervescence and the appearance of rash
- Absence of physical findings:
- Child looks well
- Temperature normalizes in 3 " 4 days
- Irritability and anorexia may be present
- Bulging fontanelle may be noted
Physical Exam
- Enlarged lymph nodes
- Maculopapular eruption from trunk to arms and neck after temperature normalizes
- Rash fades within 3 days.
- Erythematous papules in pharynx (Nagayama spots)
- Otitis media is common
- Cervical and postoccipital lymphadenopathy
Essential Workup
Clinical diagnosis:
- High fever in well-appearing child
Diagnosis Tests & Interpretation
Lab
- CBC:
- Initial increase in WBC, then normalization with lymphocytosis; WBC may decrease 3 " 5 days after onset of illness
- Platelets may be decreased
- HHV-6 DNA:
- Detected by polymerase chain reaction
- Available at research level
- IgM appears early and declines as IgG is produced
- May be done on blood and CSF
- CSF if concern about meningitis
Differential Diagnosis
- Fever of unknown origin
- Scarlet fever:
- "Sandpaper " rash, Pastia lines, and strawberry tongue
- Measles (rubeola):
- Koplik spots, cough, coryza, conjunctivitis, and fever
- Rocky Mountain spotted fever:
- Rash begins at ankles and wrists.
- Rubella:
- "Fifth disease " (erythema infectiosum)
- Dengue fever
- Pneumococcal bacteremia
- Meningitis, especially with bulging fontanelle
Treatment
Pre-Hospital
None
Initial Stabilization/Therapy
ABC management
Ed Treatment/Procedures
Medication
- Acetaminophen: 500 mg (peds: 15 mg/kg/dose) PO q4h; do not exceed 5 doses/24 h or 4 g/24 h
- Ibuprofen: 200 " 600 mg (peds: 5 " 10 mg/kg PO q6 " 8h); suspension 100 mg/5 mL; oral drops 40 mg/mL
Follow-Up
Disposition
Admission Criteria
Fever in child who is toxic and does not respond to initial supportive care
Discharge Criteria
Usually, all patients may be discharged. Usually may not return to daycare until rash has resolved
Followup Recommendations
Re-evaluate if persistent fever after 3 " 4 days
Pearls and Pitfalls
- Child looks well
- Antivirals are not recommended in the immunocompetent child.
- Febrile seizures need appropriate evaluation.
Additional Reading
- American Academy of Pediatrics. Report of the Committee on Infectious Diseases. 29th ed. Elk Grove, IL: American Academy of Pediatrics; 2012.
- Laina I, Syriopoulou VP, Daikos GL, et al. Febrile seizures and primary human herpesvirus 6 infection. Pediatr Neurol. 2010;42:28 " 31.
- Leach CT. Human herpesviruses 6 and 7. In: Hutto C, ed. Congenital and Perinatal Infections: A Concise Guide to Diagnosis. Totowa, NJ: Humana Press; 2006:101 " 109.
- Leach CT. Roseola (human herpesviruses 6 and 7). In: Kliegman R, Behrman R, Jenson H, et al., eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, PA: WB Saunders; 2007:1380 " 1383.
- Prober CG. Human herpesvirus 6. In: Hot Topics in Infection and Immunity in Children VII. Advances in Experimental Medicine and Biology. New York, NY: Springer; 2011:87 " 90.
See Also (Topic, Algorithm, Electronic Media Element)
- Fever, Pediatric
- Rash, Pediatric
- Seizures, Febrile
Codes
ICD9
- 058.10 Roseola infantum, unspecified
- 058.11 Roseola infantum due to human herpesvirus 6
ICD10
- B08.20 Exanthema subitum [sixth disease], unspecified
- B08.21 Exanthema subitum [sixth disease] due to human herpesvirus 6
SNOMED
- 54385001 Exanthema subitum
- 402902002 Roseola infantum (HHV 6)