Clinical
Features |
Respiratory diphtheria presents
as a sore throat with low-grade fever and an adherent membrane
of the tonsils, pharynx, or nose. Neck swelling is usually
present in severe disease. Cutaneous diphtheria presents as
infected skin lesions which lack a characteristic appearance.
|
Etiologic
Agent |
Toxin-producing strains of Corynebacterium
diphtheriae. |
Incidence |
Approximately 0.001 cases per 100,000
population in the U.S. since 1980; before the introduction
of vaccine in the 1920s incidence was 100-200 cases per 100,000
population. Diphtheria remains endemic in developing countries.
The countries of the former Soviet Union have reported >150,000
cases in an epidemic which began in 1990. |
Complications |
Myocarditis, polyneuritis, and
airway obstruction are common complications of respiratory
diphtheria; death occurs in 5%-10% of respiratory cases. Complications
and deaths are much less frequent in cutaneous diphtheria.
|
Transmission |
Direct person- to-person transmission
by intimate respiratory and physical contact. Cutaneous lesions
are important in transmission. |
Risk
Groups |
In the pre-vaccine era, children
were at highest risk for respiratory diphtheria. Recently,
diphtheria has primarily affected adults in the sporadic cases
reported in the U.S. and in the large outbreaks in Russia
and New Independent States of the Former Soviet Union. |
Surveillance |
National surveillance through the
National Electronic Telecommunications System for Surveillance
(NETSS). Cases also identified by requests for diphtheria
antitoxin (DAT); since 1997 DAT is available in the U.S. only
through CDC. |
Trends |
Respiratory diphtheria has become
a rare disease in the U.S. (0-5 cases per year.) An increasing
proportion of cases occurs among older children and adults;
in the prevaccination era, younger children were most often
affected. |
Challenges |
Circulation appears to continue in some settings even in
populations with >80% childhood immunization rates. An asymptomatic
carrier state exists even among immune individuals.
Immunity wanes over time; decennial booster doses are required
to maintain protective antibody levels. Large populations
of adults are susceptible to diphtheria in developed countries--appear
to be increasing in developing countries as well.
In countries with low incidence, the diagnosis may not
be considered by clinician and laboratory scientists. Prior
antibiotic treatment can prevent recovery of the organism.
Limited epidemiologic, clinical, and laboratory expertise
on diphtheria.
|
Opportunities |
New molecular typing methods allow for characterization
of strains and closely related groups (clones) of strains.
Will facilitate epidemiologic studies and possibly identification
of other virulence factors.
Recent identification of persistent foci in the U.S., Canada,
and Australia may allow studies to determine risk factors
for persistence and needed control measures.
Diphtheria antitoxin is available only in the United States
through CDC; this should improve the reporting of suspected
diphtheria cases.
|
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December 2003
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