CSTE POSITION STATEMENT 1999-ID 4

COMMITTEE: Infectious Diseases

TITLE:  Intensifying surveillance and updating of Congenital Rubella Syndrome (CRS) case definition.

ISSUE: Rubella vaccines were licensed in the United States in 1969.  At that time, an expert panel on rubella and CRS met to establish case definitions and classification for a national CRS registry.  Many changes in rubella vaccination policies and epidemiology have occurred since 1969, including high coverage with MMR among children, implementation of a routine second dose schedule of MMR for prevention of measles, record low levels of reported rubella and CRS cases, and development of new laboratory methods for rubella.  As part of Healthy People 2000, a goal for the elimination of indigenous CRS was established for the year 2000.  

POSITION TO BE ADOPTED:

States and territories should be provided with additional resources for vaccine-preventable disease surveillance in order to carry out intensified surveillance for congenital rubella surveillance activities.

States and territories should intensify surveillance for CRS.  Efforts should be focused on providing educational information to health care providers who are responsible for the diagnosis and care of these infants (e.g. cardiologists, audiologists, ophthamologists and neonatologists).  Because hearing impairment is one of the most common manifestations of CRS, states that have newborn hearing screening programs in place may wish to develop partnerships with these programs to enhance ascertainment of infants with CRS.

CDC will provide a package with educational materials that can be distributed.  This package would include information on newborn hearing testing, signs/symptoms associated with CRS and the appropriate laboratory work-up.

The following case definition for CRS is adopted:

Clinical case definition

  • An illness, usually manifesting in infancy, resulting from rubella infection in utero and characterized by signs or symptoms from the following categories:

  • Cataracts/congenital glaucoma, congenital heart disease (most commonly patent ductus arteriosus or peripheral pulmonary artery stenosis), hearing impairment, pigmentary retinopathy.

  • Purpura, hepatosplenomegaly, jaundice, microcephaly,  developmental delay, meningoencephalitis, radiolucent bone disease.

Laboratory criteria for diagnosis

  • Isolation of rubella virus, or

  • Demonstration of rubella-specific immunoglobulin M (IgM) antibody, or

  • Infant rubella antibody level that persists at a higher level and for a longer period than expected from passive transfer of maternal antibody (i.e., rubella titer that does not drop at the expected rate of a twofold dilution per month).  

  • PCR positive for rubella virus

Clinical description

Presence of any defect(s) or laboratory data consistent with congenital rubella infection.  Infants with CRS usually present with more than one sign or symptom consistent with congenital rubella infection.  However, infants may present with a single defect.   Deafness is most common single defect.

Case classification  

  • Suspected:  A case with some compatible clinical findings but not meeting the criteria for a probable case.

  • Probable:  A case that is not laboratory confirmed and that has any two complications listed in first paragraph of the clinical description or one complication from first paragraph and one from second paragraph, and lacks evidence of any other etiology.

  • Confirmed:  A clinically consistent case that is laboratory confirmed.

  • Infection only:  A case that demonstrates laboratory evidence of infection, but without any clinical symptoms or signs.

Note:    

In probable cases, either or both of the eye-related findings (cataracts and congenital glaucoma) count as a single complication.  In cases classified as infection only, if any compatible signs or symptoms (e.g., hearing impairment) are identified later, the case is reclassified as confirmed.

BACKGROUND AND JUSTIFICATION:

The elimination of indigenous rubella and CRS in the United States has been targeted for the year 2000.  To document that elimination has been achieved, improved surveillance is needed.  Moreover, extensive evaluation of reported cases and new methods of case diagnosis support revisions of the case definition.  In a meeting of experts on May 11, an analysis of the prospective and retrospective studies evaluating the clinical manifestations of CRS was presented and an update of the CRS case definition was proposed.   The revisions in the CRS case definition are included in the clinical description and clinical case definition to more clearly describe and update the spectrum of CRS clinical presentation.  Laboratory criteria for diagnosis was expanded to include PCR.

With record low levels of CRS cases, intensifying surveillance is critical to document the elimination of CRS.  In a retrospective chart review of infants hospitalized between 1994-1996 in a hospital at the U.S.-Mexico border, 9 infants were identified in having signs/symptoms that met the probable or confirmed case classification for CRS (unpublished data, CDC).   Of those 9, two infants had confirmed CRS and only one CRS case had been reported to the state health dept.  None of the 7 other cases had appropriate laboratory evaluation for CRS.  The incidence of CRS in that hospital was >400 times that of the national incidence of CRS.  These findings emphasize the need to educate health care providers about the signs/symptoms and diagnostic evaluation of infants with CRS and reporting requirements.

As noted in the previous example, infants with CRS are being missed.  Identifying mechanisms to identify possible cases is important.  In 1999, the American Academy of Pediatrics (AAP) recommended universal newborn hearing screening.  With hearing impairment being one of the most common defects in CRS, this recommendation provides a new opportunity to improve ascertainment of less severely affected cases. 

COORDINATION WITH OTHER ORGANIZATIONS:

Agency for Response:       

Centers for Disease Control and Prevention (CDC)

Institute of Medicine Immunization Committee

Agency for Information:       

Association of State and Territorial Health Officials, ASTHO

CONTACTS:

Stephen Waterman, MD, MPH
State Epidemiologist
California Department of Health Services
2151 Berkeley Way, Room 707
Berkeley, CA 94704
Phone: (510) 540-3503
Wate101w@cdc.gov

David Fleming, MD
State Epidemiologist
Oregon Health Department
800 NE Oregon
Portland, OR 97232
Phone:(503) 731-4023
david.w.fleming@state.or.us