 Current Case Definition for Surveillance
The current clinical case definition of diphtheria
for surveillance purposes is: "An upper respiratory
tract illness characterized by sore throat, low-grade
fever, and an adherent membrane of the tonsils(s),
pharynx, and/or nose." Beginning in 1980, cutaneous
diphtheria was excluded from reporting in the United
States. A laboratory criterion for diagnosis involves
either isolation of the organism from a clinical specimen
or a histopathologic diagnosis of diphtheria. A confirmed
case is one that is clinically compatible and either
laboratory confirmed or epidemiologically linked to
a laboratory-confirmed case.
Photo Courtesy
of the Centers for Disease Control
Immunization
The diphtheria toxoid was developed in 1921, came
into use in the early 1930's, and into widespread
use in the United States in diphtheria-pertussis-tetanus
vaccine (DTP) from the mid 1940's. While adequate
studies of clinical efficacy are lacking, a protective
level of antitoxin is reached in over 95% of young
children following the primary series of four toxoid
doses.
Most individuals have antitoxin levels below optimal
levels ten years after the last dose. Immunization
is required by Maryland law for children in preschool
programs and in kindergarten through the twelfth grade,
and booster doses are recommended every ten years.
Based on the 1998/99 retrospective kindergarten survey,
an estimated 78% of children in Maryland had received
four doses of DTP by 24 months of age (60% in the
1988/89 survey).
Historical Trends (see
graphs below)
At one time, respiratory diphtheria was common, occurred
primarily in children, and was one of the major causes
of infant and child mortality in the United States.
In the 1920's approximately 150,000 cases of diphtheria
were reported annually (140 cases per 100,000 population).
Only 33 cases of diphtheria were reported in the United
States between 1981 and 1990. From the time data collection
began, the case fatality rate of approximately 9%
overall, and nearly 20% in those under five or over
40 years of age, has remained essentially unchanged.
The last reported case of diphtheria in Maryland
occurred in 1973. In 1970, there were 13 reported
cases in Maryland. There was a fairly steady decline
in the number of cases reported (and in attack rates)
in Maryland from a maximum of 2,743 in 1919, to 1962,
the first year in which no cases were reported. This
trend in Maryland reflected what was happening in
the United States as a whole. This period of decline
appears to have been interrupted by epidemics in Maryland
in 1927/28, 1931, and in 1945/46.
Rate
in Maryland from 1909 to 1989
| 
are PDF. Download