World's greatest epidemics collide

The scenario is all too familiar. In a rural town in Tanzania, a young woman is diagnosed with HIV. Although she will receive antiretroviral treatment to keep her healthy, what she doesn't know is that HIV's silent partner, tuberculosis, may quickly kill her.

That woman is not alone. Today, two of the world's deadliest infectious diseases, HIV/AIDS and TB, have collided, creating a condition that is more lethal and more difficult to diagnose and treat than either disease individually. Without intervention, TB kills people with HIV with merciless speed. It is the single-greatest killer of people with HIV, causing more than 50 percent of AIDS deaths in some countries. Yet only a paltry number of people with TB worldwide are being tested for HIV, and even fewer people with HIV are screened for TB. This represents a colossal failure of policy, health systems and science, translating into immeasurable human suffering, substantial economic losses and political instability in places hardest hit by the dual epidemic.

Global estimates of extensively drug-resistant (XDR) TB are steadily increasing. As of October 2007, XDR-TB has been confirmed in 41 countries, up from 17 countries in March 2006. While TB has never completely gone away, why has this ancient scourge returned with a vengeance? The answer: HIV/AIDS. Despite the well-known and deadly synergy between the two epidemics, the world is still doing much too little to address the complicated issues of the intertwining diseases, a matter of life and death for the 40 million people living with HIV/AIDS.

Until now, HIV and TB research and funding have proceeded along largely independent tracks, but that needs to change. Developing better diagnostic and screening tools, expanding laboratory testing for drug-resistant TB, scaling up crucial infection control measures, and developing effective medications are challenges that must be met by a more well-funded and coordinated research response.

Consider that the most widely used diagnostic tool for TB is 120 years old and detects as little as one-fifth of TB infections in people co-infected with HIV. Waiting times to confirm a TB diagnosis are more than six weeks in some countries, if the diagnosis can be made at all. The last new TB drug was developed more than four decades ago. Within sub-Saharan Africa, only South Africa has the capacity to diagnose XDR-TB. An outbreak there recently caused the deaths of 98 percent of those with XDR-TB within weeks, all of whom had HIV.

With additional research, we can find solutions. The Bill & Melinda Gates Foundation, the Global Fund to Fight AIDS, TB and Malaria, the U.S. government and other donors are stepping up their support. But addressing the dual epidemic of TB and HIV requires a multipronged approach that optimizes current health care practices, reduces pervasive societal discrimination against people with HIV and TB and coordinates investment and action with an ambitious research strategy.

While we wait for new diagnostics and drugs, much can still be done to improve the chances of survival for many of the world's co-infected people. Strengthening laboratory systems, improving access to and use of essential supplies and drugs and educating communities to reduce the dual stigma that keeps so many people with HIV and TB from seeking timely care all must be pursued vigorously. Universal access to TB testing for HIV-positive individuals and HIV counseling and testing for people with TB must be implemented worldwide.

In Tanzania, where PATH (Program for Appropriate Technology in Health) is supporting TB/HIV service integration, more than 90 percent of TB patients are screened for HIV at project sites, giving them a greater chance for early diagnosis and treatment or for HIV prevention if they test negative. Providing TB and HIV services within the same health care facility also improves co-infected people's access to those important services.

The World Health Organization's Global Plan to Stop TB 2006-2015 calls for $6.7 billion in funding for TB/HIV control in affected countries over the next 10 years. Let's hope that the money is found to support both the research of new tools and the bolstering of current practices. "If not," says Dr. Mohammed Makame, PATH's TB/HIV project director in Tanzania, "defeating TB and TB/HIV will be a dream that will take ages to realize."