Interventions for Tuberculosis Control and Elimination 2002

Logistical problems may, however, impose substantial impediments in some
settings in low-income countries. Of critical importance is the capability
to exclude the presence of active tuberculosis. This is particularly the case
in adults, where the bacterial load of unrecognized tuberculosis might be
sufficiently high to favor selection of isoniazid-resistant mutants if monotherapy
is being given. In the Uganda study, 905 a sizeable portion of HIVinfected
patients who were examined had active pulmonary tuberculosis,
and not all had positive sputum smears on direct microscopic examination.
For good reasons, WHO has thus recommended that both sputum smear
microscopy and chest radiography are mandatory in HIV-infected patients
before commencing preventive chemotherapy. 907
The IUATLD limits the recommendations for preventive chemotherapy
in low-income countries to asymptomatic children under the age of five
years who live in the same household as a newly discovered sputum smearpositive
case. 8 This is a group of persons with a high risk of becoming
infected because of the closeness of contact. Preventive chemotherapy (or
prophylactic treatment in the portion of children who have escaped infection)
can be administered without prior investigation except for a clinical
assessment of health. Even in the presence of an asymptomatic primary
complex, the bacillary load will be too small in such children to pose the
problem of selecting isoniazid-resistant bacilli. The drug of choice is isoniazid
(5 mg/kg body weight), as it is the least expensive and the drug with
which there is most experience. The duration of treatment might be pragmatically
adjusted to the length of the tuberculosis treatment regimen prescribed
for the index person, i.e., between six and twelve months.
For national programs wishing to expand their preventive chemotherapy
program to other risk groups, the above measures to exclude active
tuberculosis before initiating preventive chemotherapy should be strictly
enforced.
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