Tuberculosis is the leading infectious killer of people living with HIV. According to the World Health Organization (WHO), TB accounts for an estimated 13% of AIDS deaths worldwide. Research has shown that people who are co-infected with both HIV and latent TB have an up to 800 times greater risk of developing active tuberculosis disease and becoming infectious, compared to people not infected with HIV.
Moreover, a person who has both HIV and ‘active tuberculosis’ is considered as having an AIDS defining illness.
Referred to as co-epidemics or dual epidemics, they drive and reinforce one another: HIV activates latent TB in a person who then becomes infectious and is able to spread the TB bacillus to others.
Where normally a person can live with latent TB infection even for a lifetime, never developing into a disease, contracting HIV can very quickly change that status into active TB disease.  Once the person becomes infected, he is able to infect others.  Untreated, someone with active tuberculosis or TB disease will infect an estimated 10 to 15 people per year.
Increasingly, people with latent tuberculosis are becoming infected with HIV, ultimately triggering active TB; hence it is very important for such persons to heed the message of HIV Prevention. If they don’t, given that their immune system would have become weakened after contracting HIV, they are now at risk for developing active TB.
HOW IS TB SPREAD?
Tuberculosis is spread through the air when a person with untreated pulmonary TB coughs or sneezes. Prolonged exposure to a person with untreated TB usually is necessary for infection to occur.  The TB bacillus is easily spread from person to person in hot and congested or overcrowded places.
Therefore, with greater numbers of persons with active TB in our midst, the end result will be:
* more transmission of the tuberculosis bacteria
* more people with latent tuberculosis
* and a population with an overwhelming incidence of more TB disease
A person with TB disease may remain contagious until he/she has been on appropriate treatment for several weeks. However, a person with latent TB infection, but not disease, cannot spread the infection to others, since there are no TB germs in the sputum.
WWW.avert cites several important associations between the epidemics of HIV and tuberculosis, namely:
* Tuberculosis is harder to diagnose in HIV positive people
* Tuberculosis progresses faster in HIV-infected people
* Tuberculosis in HIV positive people is more likely to be fatal if undiagnosed or left untreated
* Tuberculosis occurs earlier in the course of HIV infection than other opportunistic infections
* Tuberculosis is the only major AIDS-related opportunistic infection that poses a risk to HIV-negative people.
The global TB epidemic
Globally, an estimated 2 million people die of TB each year, and of the 1.8 million deaths in 2008 alone, half a million were co-infected with HIV. That apart, in 2008, there was an estimated 9.4 million new cases of TB globally, the majority of which were in Asia and Africa.
When someone is infected with tuberculosis, the likelihood of them becoming sick with the disease is dramatically increased if they are also HIV positive.  Both TB and HIV affect people in the most productive period of their lives, impacting national economies and health systems, and contributing to the cycle of poverty.
The currently available TB vaccine – Bacille Calmette Guerin (BCG) – was developed in 1921 and has not been improved upon since.  Its ability to prevent TB is limited and unreliable and it is not safe for infants with HIV, according to Peg Willingham, the Senior Director of External Affairs, Aeras Global Vaccine Foundation.
In a report coinciding with a meeting of World Leaders at the United Nations in New York last month, Ms. Willingham alluded to TB as “a devastating disease of poverty that continues to kill nearly 2 million men, women and children every year.”  The purpose of the meeting was to discuss ‘ambitious global poverty reduction agenda’ set forth in the Millennium Development Goals (MDGs),
Registering a passionate call for resources and support needed to continue research for the development a TB vaccine, Ms. Willingham, who noted that there is an urgent need to address such issues as would cut across the Millenium Development Goals (MDGs), stressed: “New tools to fight TB are urgently needed, and momentum in TB vaccine research provides an opportunity for optimism.”
There was heightened momentum as researchers met too, to assess ‘a decade of progress in the search for more effective TB vaccines and to chart a path forward to sustain the momentum over the next decade.’
The Senior Director of the Vaccine Foundation noted that developing these new weapons against TB is critical, adding that no infectious disease has ever been eliminated without vaccines.  “Yet this important fight has been hampered by the lack of funding for a disease that is too often overlooked by policymakers,” she chided.
Willingham observed : “Despite its devastating impact, people who suffer from TB garner far less attention and resources than they deserve.”  She called on  policymakers and opinion leaders to recognize TB as a growing global threat, and to marshal significantly greater resources to support vaccine research and the ambitious plan to save millions of lives with them.
Meanwhile, until a vaccine can be found to combat TB, the best must be made of the available tuberculosis treatment. In our next publication of the HIV/AIDS Mailbox, we will look at “Tuberculosis Treatment and HIV”