You've got 100-year-old TB married to 25-year-old HIV and the honeymoon is causing havoc.”
That's how Kenyan activist Lucy Chesire described the impact when people are infected with both mycobacterium tuberculosis and the human immunodeficiency virus.
Tuberculosis, a preventable and treatable disease, is now the leading cause of death for people infected with HIV.
While the incidence of TB is declining in most of the world, there has been a 4% to 5% annual increase in Africa in recent years, Dr. Paul Nunn of the World Health Organization told the XVIth International AIDS conference in Toronto in mid-August. And the appearance of multidrug-resistant TB is causing alarm in public health circles.
About one-third of people infected with HIV are also infected with the tuberculosis bacillus, and the latter causes the deaths, each year, of a quarter of a million people living with HIV, said Dr. Helene Gayle, president of the International AIDS Society.
TB is “a direct threat to the scale-up of access to HIV treatment,” said Dr. Kevin De Cock, head of the WHO program for HIV/AIDS. That scale-up, agreed to by members of the G8 nations last year, aims to provide near-universal access to antiretroviral (ARV) treatment for HIV by 2010. Currently, about 1.3 million people in the developing world have access to ARV treatment, while an estimated 5 million in need do not have access. An estimated 40 million people now live with HIV.
But De Cock warned that TB may be the “Achilles heel” of such a scale-up, and the spectre of multidrug-resistance to both TB and HIV looms if there is not urgent attention paid to the co-infection issue.
New research presented at the conference included both promising and disturbing results, the latter focusing on the emergence of TB strains, called XDR-TB, in South Africa that are resistant to both first-and second-line drugs.
People with HIV have an “exquisite vulnerability” to TB because of their weakened immune systems, De Cock noted. Among HIV-positive people with latent TB, the chance of developing active TB increases by 6 times in the first year after HIV infection, and continues to increase over the years. When someone living with HIV develops active TB, the likelihood of progressing to full-blown AIDS increases by 100 times.
Chesire told conference participants that she had been infected with HIV for 10 years and was managing well. “But getting TB took me almost to my deathbed … I had 3 surgeries and spent 7 months in a hospital bed.”
Yet TB is preventable. A 6-month course of isoniazid preventive therapy, which has been around for 20 years, costs just pennies and is highly effective, says Dr. Richard Chaisson, a professor of medicine, epidemiology and international health at Johns Hopkins University and the principal investigator with CREATE, the Consortium to Respond Effectively to the AIDS/TB epidemic. CREATE was funded by the Bill and Melinda Gates Foundation and launched by Nelson Mandela at the XVth International AIDS conference in Bangkok 2 years ago.
People living with HIV face a 4% annual risk of developing active TB, Chaisson said. But prescribing isoniazid is a “tough sell, perhaps because there is an emphasis on treatment but not prevention,” Chaisson told a press conference. “There seems to be a fear of developing resistance and of toxicity, but these are not warranted. Isoniazid has been studied perhaps more than any other treatment in medicine.”
TB prevention, diagnostic and treatment services must become core functions of all HIV services in countries with a high prevalence of TB, De Cock said. People with HIV need to be screened for TB and get prophylaxis and people with TB need to be screened for HIV: “We need one-stop shopping.” — Ann Silversides, Toronto
Figure. The face of HIV/TB: Vuyolwethu Tshambuluku, 8, is a patient at St. Joseph's Home for Chronic Invalid Children, Cape Town, South Africa. Photo by: WHO/STB/Colors Magazine/M. Shoul