Deadly duo

An astonishing one-third of the world’s population is infected with the bacterium that causes tuberculosis (TB), Mycobacterium tuberculosis. In most people it remains inactive or latent but in about 10% of people an active case of TB disease will develop within their lifetime. Simple antibiotics can prevent and treat most of these cases, yet 8-10 million people develop an active TB infection annually and two million die from it. In recent decades the risk posed by TB and its consequences have been far greater due to the relentless spread of the HIV/AIDS pandemic. Stephen Lewis, the former United Nations Special Envoy for HIV/AIDS in Africa, has called the two diseases a “combination made in hell.” HIV-infected individuals have a 20-fold greater risk of developing active disease, and TB is now the leading cause of death among HIV-infected people around the world. The TB bacterium and HIV are a deadly combination because both pathogens attack the immune system. “Both diseases suppress the immune system independently,” says Jerald Sadoff, president and chief executive officer at the Aeras Global TB Vaccine Foundation, an organization developing improved TB vaccines. This compounds the damage to the body’s defense system. The relentless spread of the HIV epidemic is also making it impossible to continue to confront TB through traditional approaches. In response, the global health community is changing how it confronts these two diseases, incorporating more collaboration between historically separate TB and HIV/AIDS programs. A major goal of the World Health Organization’s (WHO) new Stop TB Strategy, launched in 2005, is to decrease the burden of TB and HIV in populations affected by both diseases, and the plan is endorsed by a coalition of organizations involved in TB and HIV care. This new initiative combines the traditional approach to TB therapy, known as directly observed therapy short-course or DOTS where individuals are observed taking their medications, with a greater awareness of the interaction between HIV and TB. The Stop TB policy recommends more thorough surveillance and prevention, both of HIV among TB patients and of TB in people living with HIV/AIDS. “TB prevention, diagnosis, and treatment services need to be core functions of HIV prevention, treatment, and care services, and vice versa,” says Haileyesus Getahun, secretary of the TB/HIV working group at the WHO.