Rubella is a contagious viral illness, which, prior to vaccination, was responsible for a significant number of fetal losses and congenital abnormalities. The reported number of rubella cases in the U.S. is low enough that the CDC considers it eliminated in 2004.
Tabs Content Clinical Overview Diagnosis
Indications for Testing
Prenatal screening for evidence of immunity (presence of maternal antibodies)
Typical symptoms in unvaccinated patient – rash, fever, headache, pink eye, malaise, lymphadenopathy, cough, rhinitis
Criteria for Diagnosis
World Health Organization (WHO) case definition for congenital rubella syndrome (CRS)
Suspected case – any infant <1 year in whom a health worker suspects CRS
Infant presents with heart disease and/or suspicion of deafness and/or ≥1 of the following eye signs – white pupil (cataract), diminished vision, pendular movement of the eyes (nystagmus), squint, smaller eye ball (microphthalmos), or larger eye ball (congenital glaucoma)
Infant’s mother has a history of suspected or confirmed rubella during pregnancy, even when the infant shows no signs of CRS
Clinically confirmed case – an infant in whom a qualified physician detects 2 of the complications in section A or 1 from section A and 1 from section B
Section A – cataracts, congenital glaucoma, congenital heart disease, hearing impairment , pigmentary retinopathy
Section B – purpura, splenomegaly, microcephaly, developmental delay , meningoencephalitis, radiolucent bone disease, jaundice with onset within 24 hours of birth
Laboratory-confirmed case – infant with rubella IgM antibody who has clinically confirmed CRS
Congenital rubella infection – infant with rubella IgM antibody who does not have clinically confirmed CRS
Rubella/German measles case definition (CDC, 2013)Laboratory Testing
Differential Diagnosis
Background
Epidemiology
Incidence – <10 cases per year in the U.S. (all contracted outside the country since 2012)
Age – usually children who are unvaccinated
Transmission
Via droplets, aerosol particles – close contact required
Organism
Rubella, an RNA virus, is a member of the Togaviridae family
Virus infects cells in the upper respiratory tract and replicates in the lymphoid system; virus then spreads to other organs
Clinical Presentation
Transmission can occur up to 7 days before and 7 days after onset of rash
In children and adults, infection usually results in mild, exanthematous disease
Adults are more likely to experience prodromal phase – fever, headache, sore throat, cough, conjunctivitis
Rare complications – arthralgias and arthritis, thrombocytopenia , hemorrhage, and encephalitis
In pregnant women, particularly during first trimester, infection can result in fetal death or congenital abnormalities
Disease can be asymptomatic
Congenital abnormalities include
Ophthalmologic – cataracts, glaucoma, iris hypoplasia, retinopathy
Otorhinolaryngologic – sensorineural or central deafness
Cardiac – patent ductus arteriosus, pulmonary stenosis, pulmonary arterial hypoplasias, myocarditis
Central nervous system – developmental delay with central nervous system calcifications, microcephaly
Dermatologic – petechia, purpura
10-20% of newborns infected in utero will die during the first year of life
Because complications in utero are so severe, diagnosis during first trimester may result in decision to terminate pregnancy
Delayed manifestations
Prevention
Vaccination programs have resulted in marked decrease in infections
Estimated >95% of children in U.S. are vaccinated (recommended between ages 12-15 months)
Vaccine is live, attenuated virus and contraindicated in pregnant women
ARUP Lab Tests
Aid in diagnosis of suspected rubella infection
If test results are equivocal, repeat testing in 10-14 days
Determine seroreactivity of women of childbearing age or provide evidence of vaccination/past infection
Not recommended as a stand-alone test
Panel that combines rubella IgG and IgM antibodies is preferred
Not recommended for diagnosing congenital infections in newborns; tests should be selected individually to target the most likely infectious agents
May be used in pregnant women to assess past exposure or immunization to Toxoplasma, rubella, cytomegalovirus (CMV), and herpes simplex virus (HSV)
Not recommended for diagnosing congenital infections in newborns; tests should be selected individually to target the most likely infectious agents
References Neu N, Duchon J, Zachariah P. TORCH infections . Clin Perinatol. 2015 Mar;42(1):77-103, viii. PubMed
Resources from the ARUP Institute for Clinical and Experimental Pathology® Related Topics Last Update: October 2019
