The patient's presentation is most consistent with roseola, caused by infection with human herpes virus 6 (HHV-6).
Roseola, also known as roseola infantum or exanthema subitum, is characterized by several days of high fevers, often accompanied by febrile seizures. After the fevers subside, patients develop a maculopapular rash that typically begins on the trunk and spreads to the extremities and neck while sparing most areas of the face. Roseola is caused by HHV-6, an enveloped DNA virus of the Herpesviridae family. HHV-6 is double stranded and linear, like most DNA viruses. Primary infection is most commonly seen in children younger than 3 years old.
McKinnon et al review the evaluation of the febrile patient with a rash. Clinical findings and serology are most helpful in diagnosing a patient with roseola. The characteristic timing of fever and subsequent development of the rash are useful in distinguishing roseola form other childhood maculopapular rashes.
Flamand et al. review the basic biology, diagnostic testing, and antiviral efficacy associated with HHV-6. Presently, no antiviral agents have been approved for the treatment of HHV-6 infection. The rash of primary infections is self limiting and frequently disappears within a few days.
Figure A is a clinical photo that shows a rash consistent with roseola infantum.
Answer 2: Variola is the virus that causes smallpox. It presents with flu-like symptoms followed by a rash beginning in the mouth.
Answer 3: Rubeola is the virus that causes measles. Remember the prodrome of measles: cough, coryza, and conjunctivitis. Measles prodrome is followed by Koplik spots (red spots with blue-white centers on the buccal mucosa) followed by a maculopapular rash.
Answer 4: Rubella is the virus that causes German measles. German measles presents as a mild measles-like illness, often with posterior lymphadenopathy. Congenital rubella presents with the classic triad of patent ductus arteriosus, cataracts, and deafness.
Answer 5: Mumps virus causes the disease mumps. Mumps presents with swollen parotid glands (parotitis) and sometimes swollen, inflammed testes (orchitis).
McKinnon HD Jr, Howard T. Evaluating the febrile patient with a rash. Am Fam Physician. 2000 Aug 15;62(4):804-16. Review. Erratum in: Am Fam Physician 2001 Jul 15;64(2):220.
PMID:10969859 (Link to Abstract)
Flamand L, Komaroff AL, Arbuckle JH, Medveczky PG, Ablashi DV. Review, part 1: Human herpesvirus-6-basic biology, diagnostic testing, and antiviral efficacy. J Med Virol. 2010 Sep;82(9):1560-8. Review
PMID:20648610 (Link to Abstract)