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TB Notes 4, 2004
No. 4, 2004
HIGHLIGHTS FROM STATE AND LOCAL PROGRAMS
TB Strain with Strong Persistence and with Highly
Efficient and Rapid Transmission to HIV-Infected Patients, Louisiana,
The Louisiana Office of Public Health TB Control Program detected
a cluster of TB cases caused by the same organism, identified through
restriction fragment length polymorphism (RFLP) fingerprinting.
These cases were highly infectious, with multiple failures of directly
observed therapy (DOT) for latent TB infection (LTBI) with isoniazid
(INH, sometimes abbreviated as H), and with extremely virulent and
rapidly transmissible organisms.
The source patient, Patient A, identified in November 1998, was
diagnosed with sputum smear–positive TB and started on a standard
adult treatment regimen of isoniazid, rifampin, pyrazinamide, and
ethambutol (HRZE). Treatment compliance was adequate, recovery was
satisfactory, sputum-smear conversion occurred within the first
2 months, and the patient was considered cured upon completion of
6 months of DOT. Six household contacts and five nonhousehold contacts
of Patient A were evaluated, using Mantoux tuberculin testing, with
infection rates of 100% (6/6) and 60% (3/5) respectively. In Louisiana,
two different regimens for the treatment of LTBI are used. For children
and HIV-infected persons, the recommended duration of LTBI treatment
is 9 months. For all others, the recommended treatment duration
is 6 months. All contacts with LTBI were treated with either the
6-month or the 9-month INH regimen, as appropriate.
In July 1999, Patient B, one of Patient A’s children and a member
of the household, was diagnosed with sputum smear–positive TB, with
the same organism. A standard adult treatment regimen (HRZE) was
used. Again, treatment compliance was adequate, recovery was satisfactory,
sputum-smear conversion occurred within the first 2 months, and
the patient was considered cured upon completion of 6 months of
In November 1999, Patient A was rediagnosed with sputum smear–positive
TB, once more with the same TB organism. It is not clear whether
the relapse was due to reactivation of previous disease or reinfection
from Patient B. Patient A was re-treated with PAS (A) and ciprofloxacin
(C) in addition to the standard drugs (HRZE). Once again, treatment
compliance was adequate, recovery was satisfactory, sputum-smear
conversion occurred within the first 2 months, and the patient was
considered cured upon completion of 8 months of DOT. Six additional
nonhousehold contacts of Patient A were investigated, with an infection
rate of 88% (5/6). All contacts with LTBI were treated with INH
for either 6 or 9 months.
In February 2004, Patient C, one of Patient A’s grandchildren living
in the same household, was diagnosed with sputum smear–positive
TB. The same organism was identified. Patient C is currently on
a directly observed regimen of INH, rifampin, pyrazinamide, and
streptomycin (HRZS), is recovering well, and had sputum smear conversion
within the first 2 months. Of the five household contacts of Patient
C who were investigated, all were infected (infection rate of 100%).
In addition, an infection rate of 55% (31/55) was found in high-risk
nonhousehold contacts. In low-risk nonhousehold contacts, however,
the infection rate was as low as 2% (1/52). Once again, all contacts
with LTBI were treated with INH for either 6 or 9 months.
Recently, three more cases were diagnosed with sputum smear–positive
or culture-positive TB, due to the same organism. They are summarized
- In February 2004, Patient D, a step-grandparent and household
contact of Patient C, was diagnosed with culture-positive TB.
- In May 2004, Patient E was diagnosed with sputum smear–positive
TB. Patient E was never named as a contact of Patient C. However,
after RFLP matching, both cases were linked, with less than 3
hours’ exposure. Patient E is known to be HIV infected.
- Also in May 2004, Patient F was diagnosed with culture-positive
TB. Again, Patient F was not named as a contact of Patient C.
After RFLP matching, however, Patient F was also linked to Patient
C, having had occasional exposures totaling less than 4 hours
per month. Patient F is also known to be HIV infected.
This case review shows that, in spite of prompt diagnosis and appropriate
treatment of the cases, thorough contact identification and investigation,
and adequate treatment for LTBI with INH, transmission of infection
and occurrence of disease persisted. Infection rates for Patients
A and C were 100% among high-risk household contacts, and were consistently
high, even among high-risk nonhousehold contacts. The failure of
INH treatment for LTBI to prevent disease, at least in Patient C,
and possibly in Patient B, is an unusual finding. INH treatment
for LTBI has been proven highly (at least 85%) effective at preventing
Of note, documented transmission to Patients E and F, both HIV
infected, was the result of very limited and short contact with
Patient C. Even with an extremely timely and thorough TB contact
investigation, this type of almost casual exposure usually will
be missed. A high index of suspicion for HIV-infected contacts is
obviously warranted, but in reality, the HIV status of contacts
is often not known or not disclosed. As a result, it is advisable
that all known HIV-infected persons, being highly susceptible to
TB infection, have routine and regular tests for LTBI and TB disease.
Treatment for LTBI is recommended for all coinfected persons. Timely
assessment of risk and adequate prevention of TB will unquestionably
improve the health and prolong the lives of HIV-infected persons.
—Reported by Peter Vranken, RN, DPH, MBA
EIS Officer, Office of Workforce and Career Development
Assigned to the Infectious Disease Epidemiology Section,
Louisiana Office of Public Health
and Carol Williams
Regional TB Manager, TB Control Section
Louisiana Office of Public Health