CDC History of Tuberculosis Control - Medical and Public Health ...

source patient, and one other patient infected
the other 18 persons. In five, active disease
developed after only brief, casual exposure.
There was extensive transmission from the
three patients to both close and casual
contacts. Of 429 contacts, 311 (72%) had
positive skin tests, including 86 documented
skin test conversions. The growth
characteristics of the strain involved in the
outbreak greatly exceeded those of other
clinical isolates of M. tuberculosis. The
extensive transmission of TB in this outbreak
may have been due to the increased virulence
of the strain rather than to environmental
factors or patient characteristics.
A nosocomial outbreak of multidrugresistant
tuberculosis (Kenyon, Ridzon,
Luskin-Hawk, et al. Ann Intern Med
1997;127:32-36).
This article details an outbreak of seven cases
of MDR TB (in six patients and one health
care worker, all of whom had AIDS) that
occurred in a hospital in Chicago. The
hospital had a respirator fit-testing program
but no acid-fast bacilli isolation rooms. All
seven M. tuberculosis isolates had matching
DNA fingerprints. Of patients exposed to M.
tuberculosis, those who developed TB had
lower CD4+ T-lymphocyte counts and were
more likely to be ambulatory than those who
did not. Of 74 exposed health care workers,
the 11 who converted their skin tests were no
more likely than those who did not convert to
report that they always wore a respirator with
a HEPA filter. Transmission of M. tuberculosis
occurred in a hospital that did not have
recommended isolation rooms. A respirator
fit-testing program did not protect health care
workers in this setting.
Outbreak of drug-resistant tuberculosis
with second-generation transmission in a
high school in California (Ridzon, Kent,
Valway, et al. J Pediatr 1997;131:863-868).
In the spring of 1993 four students in a high
school were diagnosed with TB resistant to
isoniazid, streptomycin, and ethionamide. A
TB Control at the Millennium
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retrospective cohort study with case
investigation and skin test screening was
conducted in the school of approximately
1,400 students. DNA fingerprinting of
available isolates was performed. Eighteen
students with active TB were identified.
Through epidemiologic and laboratory
investigation, 13 cases were linked. Nine of the
13 had positive cultures for M. tuberculosis
with isoniazid, streptomycin, and ethionamide
resistance, and all eight available isolates had
identical DNA fingerprints. No staff member
at the school had TB. One student remained
infectious for 29 months and was the source
case of the outbreak. Another student was
infectious for 5 months before diagnosis and
was a treatment failure. This student
subsequently developed additional resistance
to rifampin and ethambutol. The initial skin
test screening found 292 of 1263 (23%)
students tested had a positive TST. Risk of
infection was highest among twelfth graders
and classroom contacts of the two students
with prolonged infectiousness. An additional
94 of 928 (10%) students tested later had a
positive TST; 22 were classroom contacts of
the student with treatment failure and 21 of
these were documented TST conversions.
This article documents extensive transmission
of drug-resistant TB along with missed
opportunities for prevention and control of
the outbreak. Prompt identification of TB
cases and timely interventions should help
reduce these problems.
Transmission of multi-drug resistant
Mycobacterium tuberculosis during a long
airplane flight (Kenyon, Valway, Ihle, et al.
N Engl J Med 1996;334:933-938).
In April 1994 a passenger with infectious
MDR TB traveled on commercial-airline
flights from Honolulu to Chicago and from
Chicago to Baltimore and returned one month
later. We sought to determine if this passenger
infected any of her contacts on this extensive
trip. Of 925 people on the airplanes, 802
responded to a request to complete a
questionnaire and be screened by tuberculin