Chemoprophylaxis in tuberculosis and HIV infection

Is it feasible in developing countries?

Should chemoprophylaxis with a course of antituberculous drugs be given to people infected with Mycobacterium tuberculosis and HIV to prevent the reactivation of latent tuberculosis? The decision depends on three factors: the efficacy of the treatment, its cost effectiveness, and whether it is financially and organisationally feasible.

The World Health Organisation estimates that 1700 million people are infected with M tuberculosis—one third of the world's population. Symptomatic tuberculosis is becoming an increasing problem owing to population growth, poverty, multidrug resistance, and HIV infection. The risk of active tuberculosis in dually infected people is 3-8% a year, with a lifetime risk of about 50% or more.1 The WHO has calculated that the global incidence in 1990 of about 7.5 million cases of tuberculosis will increase to about 12 million by 2005 (M C Raviglione, personal communication). Already, worldwide, tuberculosis is the most common cause of death due to a single infectious agent.

Chemoprophylaxis with isoniazid has an efficacy of 25-92% in various risk groups not infected with HIV.2 Some data are available in people infected with HIV. In a controlled trial in Zambia patients with HIV infection and with Walter Reed stages III and IV disease who were given a B vitamin placebo had an incidence of tuberculosis of 11.2 per 100 person years, which was four times the rate in those receiving daily isoniazid (D Wahhawan et al, eighth international conference on AIDS and third world congress on sexually transmitted diseases, Amsterdam, 1992).

In Haiti a 12 month course of prophylaxis with isoniazid reduced …