Tuberculosis (TB) is a contagious disease that kills around 2 million people each year. One-third of the world’s population is currently infected with TB and someone is newly infected every few seconds.
TB is caused by an organism called mycobacterium tuberculosis. These bacteria can attack any part of the body, but they most commonly attack the lungs.
What is the relationship between TB and HIV ?
-TB is the leading cause of death among HIV infected people; the WHO estimates that TB accounts for up to a third of AIDS deaths worldwide. When someone is infected with TB, the likelihood of them becoming sick with the disease is increased many times if they are also HIV positive.
Because TB can spread through the air, the increase in active TB among people infected with both TB and HIV results in:
-more transmission of the TB bacteria
-more people with latent TB
-more TB disease in the whole population
The HIV/AIDS epidemic is reviving an old problem in well resourced countries and greatly worsening an existing problem in resource poor countries. There are several important associations between epidemics of HIV and TB:
- *TB is harder to diagnose in HIV positive people
*TB progresses faster in HIV-infected people
*TB in HIV positive people is more likely to be fatal if undiagnosed or left untreated
*TB occurs earlier in the course of HIV infection than other opportunistic infections
*TB is the only major AIDS-related opportunistic infection that poses a risk to HIV-negative people.
What are the symptoms of TB?
Symptoms of TB depend on where in the body the TB bacteria are growing. TB bacteria often grow in the lungs, causing pulmonary tuberculosis. Pulmonary TB may cause a bad cough that lasts longer than 2 weeks, pain in the chest and coughing up of blood or sputum. Other symptoms of TB disease include weakness or fatigue, weight loss, lack of appetite, chills, fever and night sweats.
Inactive TB has no symptoms.
Can TB be prevented?
There is a vaccine against TB called BCG, but the vaccine is now very old (it was first used in the 1920s), and tests have found it to be very variable in its ability to protect people from infection in modern settings. When it does provide protection, this generally only lasts for around 15 years. The BCG can also cause false-positive readings on the tuberculin skin test, and if given to HIV+ adults or children with very weak immune systems, it can occasionally cause disseminated BCG disease. This is often fatal.
A drug called isoniazid (INH) can be used as a preventative therapy for those who are at high risk of becoming infected with TB or for those who have inactive TB. People who have inactive TB but are not yet sick can take a course of isoniazid for several months to stop them developing active TB.
The WHO recommends that HIV positive people who have latent TB (but definitely not active TB) should be offered isoniazid preventive therapy as needed.
TB treatment and HIV
It is vitally important for people with HIV to have treatment if they have active TB. This will cure them and prevent transmission to others. Even in settings where antiretroviral drugs are unavailable or inaccessible, it is crucial that the health system is able to offer HIV positive people the simple antibiotics needed for DOTS.
For some people it can be difficult to take drugs for both TB and HIV at the same time. Some anti-HIV drugs can also interact with some TB drugs making the treatment more difficult. It is important that the TB treatment is taken regularly and exactly as the health care provider has advised. If the drugs are not taken regularly, the bacteria can become resistant to the drugs and this can be dangerous.
As one of the first opportunistic infections to appear in HIV-infected people, TB may be one of the earlier signs of HIV infection. Addressing TB offers the opportunity for early HIV intervention. Although treatment of TB can improve the quality of life of HIV positive people and prolong their life, it cannot stop them from dying of AIDS. This is why access to antiretroviral treatment is also vitally important.