Immunization, Vaccines and Biologicals

WHO-recommended surveillance standard of rubella and congenital rubella syndrome

Rationale for surveillance

Rubella is a mild illness but rubella in a pregnant woman can lead to congenital rubella syndrome (CRS) in the infant. The birth defects associated with CRS include heart disease, blindness, deafness and mental retardation. By 2002 123 countries/territories had introduced rubella vaccine into their routine immunization services. Additional countries, especially those in the elimination phase of measles control, are considering the introduction of rubella vaccine. All countries that include rubella vaccine in their immunization services should conduct surveillance for CRS and rubella. In the CRS prevention stage, disease surveillance should focus on detecting cases of CRS. In the CRS/rubella elimination phase (usually conducted in conjunction with measles elimination), case-based surveillance of febrile rash illness is necessary


Recommended case definitions

Case definitions for rubella and CRS are provisional, pending field-testing

Rubella

Suspected rubella case: Any patient of any age in whom a health worker suspects rubella. A health worker should suspect rubella when a patient presents with: fever, maculopapular rash; and cervical, suboccipital or postauricular adenopathy or arthralgia/arthritis

Clinical confirmation: Rubella cannot be confirmed clinically: laboratory confirmation is required

Laboratory-confirmed rubella case: Because of the difficulty of clinical diagnosis of rubella, laboratory confirmation is required. A laboratory-confirmed case is a suspected case with a positive blood test for rubella-specific IgM. The blood specimen should be obtained within 28 days after the onset of rash

Epidemiologically confirmed rubella case: A patient with a febrile rash illness that is linked epidemiologically to a laboratory-confirmed rubella case

Congenital rubella syndrome (CRS)

Suspected CRS case: Any infant less than one year of age in whom a health worker suspects CRS. A health worker should suspect CRS when an infant aged 0-11 months 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 (microphthalmus), or larger eye ball (congenital glaucoma). A health worker should also suspect CRS when an infantís mother has a history of suspected or confirmed rubella during pregnancy, even when the infant shows no signs of CRS

Clinically confirmed CRS case: An infant in whom a qualified physician detects at least two of the complications listed in (a) below or one in (a) and one in (b):
(a) Cataract(s), congenital glaucoma, congenital heart disease, loss of hearing, pigmentary retinopathy
(b) Purpura, splenomegaly, microcephaly, mental retardation, meningocephalitis, radiolucent bone disease, jaundice that begins within 24 hours after birth

Laboratory confirmed CRS case: An infant with clinically-confirmed CRS who has a positive blood test for rubella-specific IgM (100% of such infants are positive at the age of 0-5 months; 60% are positive at 6-11 months). Where special laboratory resources are available the detection of rubella virus in specimens from the pharynx or urine of an infant with suspected CRS provides laboratory confirmation of CRS (60% of such infants shed rubella virus at the age of 1-4 months; 30% at 5-8 months: 10% at 9-11 months)

Congenital rubella infection (CRI): If a mother has suspected or confirmed rubella in pregnancy her infant should have a rubella-specific IgM blood test. An infant who does not have clinical signs of CRS but who has a positive rubella-specific IgM test is classified as having congenital rubella infection (CRI)


Recommended types of surveillance

CRS prevention sate

minimum requirements:

  • Routine monthly reporting of the number of suspected CRS cases; zero reporting should be required. All suspected CRS cases in infants aged under 1 year should be investigated. The investigation should include clinical and laboratory analysis Routine monthly reporting of the number of suspected rubella cases
  • All febrile rash illnesses in pregnant women should be investigated
  • If a rubella outbreak is detected a limited number of suspected rubella cases should be investigated with rubella-specific IgM tests periodically during the outbreak (5 to 10 cases investigated per outbreak). Active surveillance (defined as regular visits to selected reporting sites to look for unreported cases) should be initiated to improve detection of suspected CRS in infants aged under 1 year and continued for nine months after the last reported case of rubella

CRS/rubella elimination stage

minimum requirements:

  • Same as CRS prevention stage, plus
  • Routine monthly reporting of the number of confirmed rubella cases; zero reporting should be required
  • All febrile rash cases, regardless of age, should be investigated. The investigation should include laboratory analysis of each case for measles and, if the result is negative, for rubella (see section of this document on measles). Priority should be given to the investigation of febrile rash illnesses in pregnant women Regardless of the type of surveillance, designated reporting sites at all levels should report at a specified frequency (e.g. weekly or monthly) even if there are zero cases (often referred to as "zero reporting")

Recommended minimum data elements

Routine surveillance data

  • The number of suspected CRS cases in each health facility by month
  • For countries with surveillance for febrile rash illnesses, the number of these reported in each health facility by month
  • For other countries, the number of suspected rubella cases in each health facility by month

Routine immunization coverage data

  • Rubella vaccine coverage (%) for each target group (women of childbearing age, schoolgirls, infants, preschool children) in each health facility by month

CRS case investigation data

  • Patient's date of birth
  • Sex: 1 = male; 2 = female; 9 = unknown
  • Date of notification
  • Date of investigation
  • Date of collection of blood specimen
  • Date blood specimen received by laboratory
  • Date rubella serology results reported
  • Results of rubella-specific IgM test: 1 = positive; 2 = negative; 3 = not tested; 4=indeterminate; 9 = unknown
  • Collection of specimen for viral identification: 1 = yes; 2 = no; 9 = unknown
  • Specimen type: 1 = nasopharyngeal; 2 = other, 9 = unknown
  • Results of rubella virus identification: 1 = positive; 2 = negative; 3 = not tested; 9 = unknown
  • Mother's history of febrile rash illness or exposure to febrile rash illness during this pregnancy 1=had febrile rash illness during pregnancy (but no known exposure to others with febrile rash illness); 2=no history of febrile rash illness during pregnancy but was exposed .; 3=no febrile rash illness during pregnancy and no known exposure; 9=unknown history or exposure to febrile rash illness
  • Mother's history of rubella immunization 0 = never immunized against rubella; 1 = 1 dose; 2 = 2 doses; 3 = 3 or more doses; 9 = unknown
  • Mother's rubella immunization history determined by card or history? 1 = card; 2 = verbal history; 3 = some doses by card and some by history; 9 = unknown
  • Patient's date of birth or age Sex: 1 = male; 2 = female; 9 = unknown
  • Date of onset of rash
  • Date of investigation
  • Date of collection of blood specimen
  • Date blood specimen received by laboratory
  • Date rubella serology results reported
  • Results of rubella-specific IgM test: 1 = positive; 2 = negative; 3 = not tested; 4 = indeterminate; 9 = unknown
  • Collection of specimen for virus identification: 1 = yes; 2 = no, 9 = unknown
  • Results of rubella virus culture/identification: 1 = positive; 2 = negative; 3 = not tested; 9 = unknown
  • Specimen type: 1 = nasopharyngeal; 2 = other
  • Results of rubella virus identification: 1 = positive; 2 = negative; 9 = unknown
  • History of rubella immunization through routine services or SIAs: 0 = never immunized against rubella; 1 = 1 dose; 2 = 2 doses; 3 = 3 or more doses; 9 = unknown
  • Rubella vaccination history determined by card or history? 1 = card; 2 = verbal history; 3 = some doses by card and some by history; 9 = unknown
  • History of rubella immunizations through routine services or SIAs: 0 = never immunized against rubella; 1 = 1 dose; 2 = 2 doses; 3 = 3 or more doses; 9 = unknown

Recommended data analyses, presentations, reports

Aggregated data (i.e. from routine reporting)

  • Number of CRS cases and incidence rate per 1000 live births by month, year, and geographic area
  • CRS cases per 1000 live births per year
  • Number of rubella cases and incidence rates by month, year, and geographical area
  • Age-specific, sex-specific, and district-specific rubella incidence rates
  • Rubella vaccine coverage rate by target group and geographical area per year
  • For CRS and rubella cases, completeness/timeliness of monthly reporting
  • Proportion of known outbreaks confirmed by the laboratory

Case-based data (i.e. from case investigations only)

  • Number of CRS cases by sex, month, year, and geographic area
  • Sex-specific, district-specific CRS incidence rates per 1000 live births per year
  • Age-specific, sex-specific and district-specific rubella incidence rates
  • Final classification of all suspected cases of CRS and rubella
  • Rubella immunization status of mothers of CRS cases
  • Proportion of all cases of febrile rash illness with laboratory investigation which are rubella-specific IgM-positive

Note: This should be linked with investigations described in the measles section

Surveillance quality

  • Completeness and timeliness of routine reporting, notification clinical investigation, and laboratory investigation. In the low-incidence or elimination phase, performance indicators for rubella case investigation should be linked to those for measles case investigation

Principal uses of data for decision-making
  • Understand the epidemiology of CRS and its burden in the population to guide rubella immunization strategies. Because children with CRS may be blind, deaf, retarded or have major heart disease, CRS creates a long-term burden on health, social and educational systems
  • Use rubella outbreak investigation as a tool for activating CRS surveillance
  • Investigate rash illness in pregnancy and provide culturally appropriate follow-up to women who have rubella, including follow-up of their infants
  • Investigate febrile rash illnesses in the measles/rubella elimination phase to determine the proportion of such illnesses attributable to rubella. This allows the identification of high-risk areas, age groups and/or populations

Special aspects
  • Outbreaks of rubella and measles have occurred simultaneously
  • CRS cases are likely to be underreported in areas and among populations where a high proportion of births occur at home and where infant deaths may not be reported
  • Infants with CRS are likely to be seen at specialty facilities that do not normally participate in the immunization service or the routine communicable disease surveillance system, e.g. eye hospitals and hospitals specializing in cardiac surgery. For comprehensive CRS surveillance these facilities should be included in CRS detection, investigation and reporting activities
  • Infants with CRS and CRI shed rubella virus for long periods (60% for the first 4 months of life) and appropriate infection control measures should be applied. It is particularly important that pregnant women who are not rubella-immune should not be exposed to infants with CRS or CRI
  • Serological monitoring of rubella susceptibility in women attending selected antenatal clinics can be used to monitor the performance of rubella immunization services. However, serological monitoring requires a different laboratory test, e.g. rubella-specific IgG. If serological screening is conducted, arrangements should be made to provide postpartum rubella vaccination to women found to be seronegative

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