HIV and TB have become a deadly combination
Tubercolosis or TB is killing thousands of South Africans who have HIV.
The combination is lethal.
TB tends to hide in people with Aids, making it difficult for doctors to diagnose.
So by the time a patient is diagnosed he is likely to be at an advanced stage of Aids and will die before treatment is completed.
National TB Programme head Lindiwe Mvusi says the rate of TB infection has increased dramatically as the HIV epidemic worsens .
"This is because people with HIV have a bigger chance of developing TB . When you are infected with the virus the immune system is weakened, meaning that you will be vulnerable to infection," Mvusi says. "But this does not mean people who are HIV negative are not at risk."
South Africa is the fifth-worst country in the world as far as TB is concerned. . About 550 000 people are infected, with 66,4 percent also having HIV.
Mvusi says one of the reasons this country has such a high number HIV-positive people with TB is that TB is triggered easily in them.
"Many people live with latent or sleeping TB and don't know about it." Mvusi says.
"When they have HIV the TB bacilli suddenly wakes up. By the time they come to a clinic or hospital the TB has already spread in the body."
Natalie Beylis, a pathologist at the National Health Laboratory Service's central TB laboratory, says testing for TB has become more difficult.
"HIV has not only increased the prevalence of TB but has also made it difficult to diagnose using the microscope," Beylis says.
"Many public clinics still use the 115-year-old microscopic test to diagnose TB, though there are more advanced testing instruments available.
"Liquid or solid culture testing is accurate and can also detect drug resistance.
"Microscopic diagnosis is where a sputum is prepared and placed on a slide. Culture, on the other hand, involves growing the sputum or organism in a laboratory on solid or liquid media.
"Organisms grown in liquid media take at least two weeks. In solid media it takes up to six weeks. Technology is easing the challenge of diagnosing TB in HIV-positive patients."
TB treatment varies with the type of infection. Normal TB treatment lasts six months, but the course of medicine for the more common multi-drug resistant form of the disease can last 18 to 24 months.
Patients with drug resistant TB are often hospitalised for the first few months of treatment.
The Treatment Action Campaign (TAC) says HIV and TB co-infection is creating a pandemic of its own.
"The government needs to put more effort into the fight against TB and HIV," says Regis Mtutu of the TAC.