Current Case Definition for Surveillance
The clinical case definition is: "An illness with
all of the following characteristics: (a) acute onset
of generalized maculopapular rash, (b) temperature greater
than 37.2 C (99 F), if measured, and (c) arthralgia/arthritis,
or lymphadenopathy, or conjunctivitis." Cases meeting
the measles case definition, or with serology compatible
with recent measles infection, are excluded. The laboratory
criteria for diagnosis is "isolation of rubella virus,
or a significant rise between acute- and convalescent-phase
titers in serum rubella immunoglobulin G antibody level
by any standard serologic assay, or positive serologic
test for rubella IgM antibody." Probable cases must
meet the clinical case definition. Confirmed cases must
either be laboratory confirmed, or meet the clinical case
definition and be epidemiologically linked to a laboratory-confirmed
case. Congenital rubella syndrome (CRS) is also reportable.
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Centers for Disease Control and Prevention
Immunization
The first rubella vaccines were licensed in the United
States in 1969. In 1979, the current RA 27/3 vaccine was
licensed and other vaccine removed from the market. The
rubella vaccine is usually given combined with the measles
and mumps vaccines as MMR. For the rubella vaccine, seroconversion
occurs in about 95% of vaccinees after one dose. No significant
waning immunity has been demonstrated to date. Immunization
is currently required by Maryland law for children entering
pre-school programs, kindergarten, and all grades, one
through twelve. Based on the 1998/99 retrospective kindergarten
survey, an estimated 90% of children in Maryland had received
one dose of MMR by 24 months of age (compared to 78% in
the 1988/89 survey).
Historical Trends (see
graphs below)
Rubella can be a disastrous disease in early gestation,
leading to fetal death, premature delivery, and an array
of congenital defects in up to 85% of infants infected
in the first trimester. In the pre-vaccine era, epidemics
of rubella occurred every six to nine years in the United
States, with the last major epidemic in 1964-1965 resulting
in 12.5 million cases of rubella and 20,000 cases of CRS.
The estimated lifetime cost of one case of CRS today is
in excess of $200,000.
In Maryland, the last epidemic of rubella involving thousands
of cases was also during 1964, when 3,583 cases were reported.
Over 10,000 cases were reported in 1941, the largest epidemic
recorded in the state. In contrast, no more than six cases
have been reported in any one-year since 1983. Only one
case has been reported since the last publication of this
report, with onset in 1995.
The last case of CRS in Maryland was reported in 1976.
Between 1966 and 1976, 24 cases of CRS were reported in
Maryland (but were not included in the numbers of rubella
cases reported during these years). CRS was not nationally
notifiable prior to 1966, and no data on CRS in Maryland
could be found in the EDCP files before 1966.
Figure
1. Reported Cases of Rubella in Maryland, 1970-1998.
Figure
2. Reported Cases of Rubella in Maryland, 1923-Present
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