Rubella Virus

Diagnosis
Background
Lab Tests
References
Related Topics

Indications for Testing

Prenatal screening for presence of maternal antibodies
Typical rash in unvaccinated patient

Criteria for Diagnosis

WHO case definition for congenital rubella syndrome
WHO Case Definition for Congenital Rubella Syndrome (CRS)
Suspected case
Any infant <1 year in whom a health worker suspects CRS
A health worker should suspect CRS when an infant presents with heart disease and/or suspicion of deafness and/or one or more 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)

When an 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 two of the complications in section A or one from section A and one 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
An infant with rubella IgM antibody who has clinically confirmed CRS

Congenital rubella infection
An infant with rubella IgM antibody who does not have clinically confirmed CRS

Laboratory Testing

CDC - testing recommendations
Serology
- In primary rubella infection, the appearance of clinical symptoms is associated with the appearance of both IgG and IgM antibodies
  - IgM antibodies – detectable a few days after onset of symptoms; peak 7-10 days later
  - May consider fetal IgM serology if fetal infection suspected indicating previous infection and immunity
- Prenatal screening – test women prior to pregnancy to confirm presence of IgG antibodies indicating previous infection and immunity
PCR
- Usually throat or urine samples
- Amniotic fluid when fetus is at least 2 weeks of age to identify fetal infection
Congenital – see CDC testing recommendations above

Differential Diagnosis

The reported number of rubella cases in the U.S. over the last 5 years is low enough for the Centers for Disease Control (CDC) to state that the endemic disease has been eliminated.

Epidemiology

Incidence – <25 cases a year in the U.S.
- Congenital rubella syndrome – <2/100,000 births
Age – usually young 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 the 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 the following
  - 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
  - Insulin-dependent diabetes mellitus
  - Panencephalitis (rare)
  - Thyroid dysfunction
  - Behavioral disorders

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

Tests generally appear in the order most useful for common clinical situations. Click on number for test-specific information in the ARUP Laboratory Test Directory.

Rubella Antibodies, IgG and IgM 0050552
Method: Semi-Quantitative Chemiluminescent Immunoassay

Recommended Use

Diagnose rubella infection

Follow-up

If test results are equivocal, repeat testing in 10-14 days

Rubella Antibody, IgG 0050771
Method: Semi-quantitative Chemiluminescent Immunoassay

Recommended Use

Determine immune status of females prior to pregnancy or for vaccination status

Guidelines

U.S. Department of Health and Human Services, Centers for Disease Control and Prevention. Recommended Immunization Schedules for Persons Aged 0 Through 18 Years. United States, 2015. Centers for Disease Control and Prevention. Atlanta, GA [Last Updated Jul 2011; Accessed: Nov 2015]