Isoniazid

[KAMPALA] A South African tuberculosis expert has called for a cheap and readily available drug for tuberculosis prevention to be given to all HIV-positive children not receiving antiretroviral treatment.

Speaking during the African launch of the Second Global Plan to Stop TB, Dr Enoch Kibunguchy, the Assistant Minister for Health, noted that TB cases had risen from about 10,000 cases a decade ago to more than 106,000 in 2004. He estimates that in 2004 about 80,000 people might have died of TB in Kenya.

TB drug development is to receive a major injection of cash and expertise, the Global Alliance for TB Drug Development announced yesterday.

A 3-month course of isoniazid (INH) plus rifampicin (RIF) is as effective a treatment of latent tuberculosis (TB) as the standard six to twelve month course of INH alone, according to review published in the March 1 issue of the journal Clinical Infectious Diseases. The review (actually an analysis of the combined data from five randomised controlled clinical trials) also concluded that severe side effects and mortality were similar on both regimens.

The publication of an international study shows that six months of continuation phase treatment with isoniazid and ethambutol results in higher rates of relapse after treatment when compared to a four month continuation phase using isoniazid and rifampicin. The International Union Against Tuberculosis and Lung Disease and the United Kingdom Medical Research Council designed the study.

Isoniazid treatment for prevention of active tuberculosis in children significantly reduces the risk of death in HIV-positive infants and small children according to results of a South African study presented as a late breaker on the final day of the Fifteenth International AIDS Conference in Bangkok.

Globally, tuberculosis (TB) is the single most important disease associated with HIV and AIDS. It is obviously desirable to prevent active TB among people with HIV and one strategy for this is to treat people who have been exposed to the tubercle bacilli (Mycobacterium tuberculosis or MTb) before it makes them ill. Treating latent TB is a proven strategy for preventing active TB but diagnostic methods and available treatments are far from ideal, which is why the subject remains controversial. In practice, daily 300mg isoniazid (INH) treatment for six months is the main option available now to achieve this - known as Isoniazid Preventive Therapy or IPT. Alternatives - rifampicin plus pyrazinamide or rifampicin only - have been proposed and tested in clinical trials and adopted e.g. in the USA, but require closer monitoring. Whether treatment for latent TB is safe and appropriate depends on the quality of the services provided to treat TB, the level of TB risk, and the resources available to HIV treatment services in a particular community. It may therefore not currently be appropriate in some settings. Nonetheless, given the scale of the public health need and the relatively low cost, it must be seriously considered.