In 1982, the reported occurrence of measles reached its lowest
level since national reporting of measles began in 1912. A
provisional total of 1,697 cases was reported, for a record low
incidence rate of 0.7 cases per 100,000 population of all ages
(Figure
1). This is a 99.7% reduction from the 1950-1962 prevaccine era
when
an annual average of 525,730 cases was reported (315.2
cases/100,000),
and a 45.7% reduction from the 3,124 cases in 1981, the previous
year
of record low incidence (1.4 cases/100,000). Fewer than 100 cases
were reported each week during the entire year, and record low
weekly
numbers of cases were reported in 37 weeks. Most reporting areas
reported very few or no measles cases (Figure 2). Twenty-two
states
reported no indigenous cases all year, including 15 states that
reported no cases--indigenous or imported.* Ninety-four percent
(2,944) of the nation's 3,138 counties reported no measles cases
during the entire year, and only 0.7% (22) of the counties reported
measles during 5 or more weeks. Those 22 counties contained 14.4%
of
the U.S. population.
Of the 1,697 measles cases, 119 (7.0%) were imported, with
sources
in 32 different countries, for an average of 2.3 international
importations* per week. In addition, 498 cases within the United
States were epidemiologically linked to 19 international
importations. Thus, international importations and associated
cases
together accounted for 36.4% (617/1,697) of all measles cases
reported
in 1982.
*See CDC. Classification of measles cases and categorization of
measles elimination programs. MMWR 1983;31:707-11.
Of the 1,697 measles cases, 1,072 (63.2%) occurred in 14
separate
chains of transmission, each consisting of from two to 16
generations
of infection, and 625 (36.8%) occurred sporadically. Sources were
identified for 11 of the 14 chains of transmission. Of these,
eight
were international importations, two were out-of-state
importations,
and one was an indigenous case in a child with a medical exemption
to
vaccination.
Reported by Div of Immunization, Center for Prevention Svcs, CDC.
Editorial Note
Editorial Note: The measles elimination program is succeeding
because
of public health strategies** implemented to ensure immunization of
targeted populations with a safe and highly immunogenic vaccine.
However, as long as measles incidence rates are 10 to 10,000 times
higher outside the United States than within it, international
importations will remain potential sources of measles infection
(1).
Although relatively few imported cases are preventable (1,2),
transmission has been limited when immunity levels are high.
Because indigenous measles is extremely rare in the United
States,
a major challenge now exists to maintain what has been achieved
(3).
Measles and other vaccine-preventable diseases will return if the
imperative to vaccinate children is relaxed and immunization levels
are allowed to fall. Long-term success requires a sustained effort
to
vaccinate each new birth cohort every year, and to eliminate
remaining
foci of transmission. Communities that are already measles-free
can
best preserve that accomplishment by maintaining high immunization
levels in their children and intensifying surveillance for all
suspected cases of measles.
**Achievement and maintenance of high immunization levels,
maintenance
of strong and effective surveillance, and aggressive response to
the
occurrence of suspected cases.
References
Amler RW, Bloch AB, Orenstein WA, Bart KJ, Turner PM, Hinman
AR.
Imported measles in the United States. JAMA 1982;248:2129-33.
Turner PM, Amler RW, Orenstein WA. Measles surveillance: United
States, imported measles, first 26 weeks of 1982. EPI
Newsletter,
Pan-American Health Organization 1982;IV(6):4-5.
Kirby CD. Measles elimination--the final push and beyond.
Proceedings of the 17th Immunization Conference, May 18-19,
1982,
Atlanta: 7-9.
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