Pediatrics #10 – MEHLMANMEDICAL

HY lecture notes:

Rubella (German measles; three-day measles)

Presentation¹

Classically pediatric viral illness, with peak incidence age 5-9.
Three-day prodrome of fever, malaise, and anorexia.
As the fever abates, a maculopapular rash starts at the head and descends to cover the whole body.
Suboccipital and/or postauricular lymphadenopathy (exceedingly HY)
Adults may present with arthritis

Vaccine

Rubella is rare in the United States because of the Mumps-Measles-Rubella (MMR) live-attenuated vaccine.¹
First dose given at age 12-15 months; second dose given age 4-6 years.²
MMR and varicella/zoster are the only live-attenuated vaccines approved for use in HIV patients (CD4 must be >200 cells/mm³).³

Congenital rubella¹

Disease occurs secondary to first-trimester in utero infection in non-immune mother.
As mentioned above, pregnant adult female may present with arthritis.
Neonatal deafness, meningoencephalitis, cataracts
Patent ductus arteriosus (PDA) in neonate (exceedingly HY)

Rubeola (measles)

High fever, cough, coryza, conjunctivitis (3Cs).⁴
Koplik spots 2-3 days after symptoms begin and are described as punctate white spots on an erythematous background on the buccal mucosa.⁵
As the fever abates, a maculopapular rash starts at the head and descends to cover the whole body (similar to rubella).⁴

Mumps⁶

Classically presents as parotitis; orchitis and meningitis may also be seen (POM).
Rash is not part of the classic disease presentation.

Roseola infantum (exanthem subitum; Sixth disease)⁷

Caused by HHV6 (human herpes virus 6)
High-grade fever (i.e., up to 104F) for 3-5 days.
This is followed by a rapid defervescence of the fever with an accompanying maculopapular rash.
For the USMLE, just remember: “spiking fever followed by a rash.”

Fifth disease (erythema infectiosum; Fifth disease)⁸

Characteristic facial rash described as a “slapped cheek” appearance
By the time the rash appears, the virus is no longer infectious (i.e., cleared by the immune system). For behavioral science USMLE questions, you can tell the worried parent that the child will be okay.
Can cause aplastic anemia (↓ RBCs + ↓ WBCs + ↓ platelets – i.e., all are decreased); more common in children with RBC conditions associated with shortened lifespan, i.e., sickle cell.
Associated with daycare centers.
Can present as arthritis and lacy rash in adult.

Pityriasis rosea is a self-limiting cutaneous eruption with a very characteristic presentation:

Begins as a herald patch, or mother patch, which is an erythematous, round to oval, scaly patch or plaque, 2-10 cm in diameter, with a depressed center and raised border.¹

This is followed by crops of smaller lesions that erupt on the trunk and proximal extremities in a “Christmas tree” distribution (i.e., the eruption on the trunk/back + proximal shoulders is apparently euphemized to resemble a Christmas tree).⁹^{, 10}
The rash lasts 1-8 weeks in 85% of patients, with an average duration of 5 weeks, before self-resolving.¹¹
About half of cases are preceded by a non-specific upper respiratory tract-like presentation.¹²
The rash is described as mildly to severely pruritic in 25% of patients.¹²
Greatest incidence is 20-29 years of age.¹²

The exact etiology of pityriasis rosea may be manifold, however viral infection with human herpes virus 6 and 7 (HHV6/7), particularly HHV7, is believed to be highly associated.^{13, 14, 15, 16}

“Although the detection of HHV7 DNA in peripheral blood mononuclear cells (PBMC) and tissues does not prove directly a causal role, HHV7 DNA in cell-free plasma corresponds to active replication which supports a causal relationship. We propose that pityriasis rosea is a clinical presentation of HHV7 reactivation.”¹³
“Light and electron microscopy findings suggest infection with human herpesviruses 6 and 7 (HHV6/7). These viral antigens have been detected in skin lesions by immunohistochemistry and their DNA has been isolated from non-lesional skin, peripheral blood mononuclear cells, serum, and saliva samples.”¹⁴
“Pityriasis rosea is an acute exanthem with many clinical and epidemiologic features of an infectious disease. To date, human herpesvirus (HHV)-6 and HHV-7 appear to be the most indicted culprits.”¹⁵
“Nested polymerase chain reaction and in situ hybridization enabled detection of human herpesvirus-7 and human herpesvirus-6 in skin and other tissues isolated from patients with pityriasis rosea. These results suggest that pityriasis rosea is associated with systemic active infection with both human herpesvirus-7 and human herpesvirus-6.”¹⁶

1) https://www.sciencedirect.com/science/article/pii/B9780323035064102895

2) https://www.cdc.gov/vaccines/vpd/rubella/index.html

3) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4117268/

4) https://www.cdc.gov/measles/symptoms/signs-symptoms.html

5) https://www.sciencedirect.com/science/article/pii/B9780323045797001520

6) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5215468/

7) https://www.ncbi.nlm.nih.gov/books/NBK448190/

8) https://www.aafp.org/afp/2007/0201/p373.html

9) https://www.ncbi.nlm.nih.gov/books/NBK513301/

10) https://www.ncbi.nlm.nih.gov/books/NBK448091/

11) https://www.ncbi.nlm.nih.gov/pubmed/2595391

12) https://www.aafp.org/afp/2004/0101/p87.html