| Clinical case definition | |
| An illness, usually manifesting in infancy, resulting from rubella infection in utero and characterized by clinical findings from the following categories: | |
| Category A: Cataracts/congenital glaucoma, congenital heart disease (most commonly, patent ductus arteriosus or peripheral pulmonary artery stenosis), hearing impairment, pigmentary retinopathy | |
| Category B: Purpura, hepatosplenomegaly, jaundice, microcephaly, developmental delay, meningoencephalitis, radiolucent bone disease | |
| Laboratory criteria (any 1 of the following) | |
| Demonstration of rubella-specific IgM | |
| Infant rubella antibody level (IgG) that persists at a higher level and for a longer time than expected from passive transfer of maternal antibody (ie, rubella titer that does not drop at the expected rate of a twofold dilution per month)* | |
| Isolation of rubella | |
| PCR positive for rubella virus | |
| Classification | Criteria |
| Suspected | An infant that does not meet the criteria for a probable or confirmed case but has 1 of more of the above clinical findings (category A or B) |
| Probable¶ | An infant without an alternative etiology that does not have laboratory confirmation of rubella infection but has either:
|
| Confirmed | An infant with at least 1 of the above clinical findings that is clinically consistent with congenital rubella syndrome (category A or B), and laboratory evidence of congenital rubella infection, as demonstrated by any of the above laboratory criteria |
| Infection onlyΔ | An infant without any clinical symptoms or signs but with laboratory evidence of infection, as demonstrated by any of the above laboratory criteria |
IgM: immunoglobulin M; IgG: immunoglobulin G; PCR: polymerase chain reaction; CRS: congenital rubella syndrome.
* Infants with symptoms consistent with CRS who test negative soon after birth should be retested at age 1 month. Approximately 20% of infected infants tested for rubella IgM may not have detectable titers before age 1 month.
¶ In probable cases, either or both of the eye-related findings (cataracts and congenital glaucoma) count as a single complication.
Δ If any compatible signs or symptoms (eg, hearing impairment) are identified later, the case is reclassified as confirmed.