Interventions for Tuberculosis Control and Elimination 2002

makes it impossible to reduce the minimum duration of six months. In
the United States, US Public Health Service trial 21 evaluated the same
regimen, but without the supplement of ethambutol or streptomycin (except
for those with a high probability of initial resistance) in the intensive phase
and showed it to be efficacious. 490,491 However, given the possibility of
drug resistance among new cases of tuberculosis in many locations, the recommendation
for a four-drug initial treatment is preferred, at least in areas
where drug resistance is frequent or unknown. In the United Kingdom, a
four-drug intensive phase is always recommended. 518 The IUATLD and
WHO also recommend a four-drug intensive phase in new sputum smearpositive
cases of pulmonary tuberculosis and other severe cases of tuberculosis
where this regimen is being used. 8,13
Non-rifampicin-containing continuation phase
Current options for a non-rifampicin-containing continuation phase are isoniazid
plus thioacetazone or isoniazid plus ethambutol.
A four-drug, two-month intensive phase followed by six months of
isoniazid plus thioacetazone has been found to be highly efficacious in East
Africa. 519,520
No critical evaluation of an ethambutol-containing continuation phase
has been carried out extensively. One trial in India evaluated the effectiveness
of a fully unsupervised eight-month regimen with isoniazid and
ethambutol throughout, supplemented by rifampicin and pyrazinamide in the
two-month intensive phase. 521,522 The entire treatment was self-administered
and compared to a six-month regimen using rifampicin throughout, given
twice-weekly, and at least partially supervised. The results during chemotherapy
were encouraging with the eight-month regimen. Four per cent had an
unfavorable response during chemotherapy and five per cent relapsed; the
relapse rate was only half that in the directly observed control arms.
Intermittent regimens
To facilitate directly observed therapy, various intermittent regimens have
been studied extensively. 122,521 In Chennai (formerly Madras), India, all
parameters were superior in patients receiving twice-weekly isoniazid plus
para-aminosalicylic acid, supplemented by streptomycin during the intensive
phase, as compared with patients receiving once-weekly isoniazid plus
para-aminosalicylic acid for self-administered treatment. 523 This study rep-
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