07 Sep TB and HIV: why they’re no longer a death sentence
Issued by IPASA
When you consider that HIV/Aids only really came to the world’s attention 35 years ago, it’s truly amazing that it has gone from a certain death sentence to a chronic manageable disease in such a short time.
Similarly, effective treatment for tuberculosis (TB) has only been around since 1946, when the development of streptomycin, an antibiotic, made the effective treatment and cure of TB a reality for the first time.
Before that, 90% of TB patients died. And even though multidrug-resistant TB remains a concern, great strides have been made in treating this disease: in the ordinary course of events, provided patients are compliant, it can be stopped in its tracks.
“It feels as if HIV/Aids has been around forever, and that medical progress has been slow, but actually, the opposite is true,” says Dr Konji Sebati, CEO of the Innovative Pharmaceutical Association South Africa (Ipasa), an association of numerous research-based pharmaceutical companies that focuses on building an environment for sustainable access to innovative, research-based healthcare. “Thirty-five years represents a very short space of time in which to understand such a complex syndrome.”
The first HIV therapy was available just five years after HIV/Aids was identified – in 1986, the US Food and Drug Administration approved the first antiviral drug, zidovudine (ZDV or AZT, part of a class of drugs called nucleoside analogue reverse transcriptase inhibitors), according to TheBody.com, an online HIV resource.
That class of drugs grew after 1991, and gradually new classes of anti-HIV drugs were added in subsequent years, but for the most part HIV-positive patients were on standard monotherapy treatment – that is, they were treated with a single drug. These drugs were only partly effective and many patients became resistant to them over time.
However, as scientists studied how HIV functioned in the body and how viral replication worked – with billions of copies of HIV being produced and destroyed daily – they began to understand how HIV could quickly develop resistance to any one medication.
Because the number of distinct classes of antiviral medications was growing, patients could now be put on combination therapy, in which drugs from two or more classes were used simultaneously.
“This switch had a dramatic impact on HIV treatment because combination therapy basically suffocates mutated forms of HIV before they have a chance to flourish,” says Sebati. “It’s a great example of innovation in medicine – and millions of HIV-positive people have hope because of what is now known as high active antiretroviral therapy, or Haart.”
TB treatment has also made great strides since streptomycin was first identified as an effective treatment. Early studies showed that streptomycin combined with bed rest achieved greater clinical improvement, but only modest pathological improvement (as assessed by chest radiography), compared with bed rest alone. These studies also noted that improvement in TB was greatest in the first three months of therapy. After that, many patients began to deteriorate, partly because of streptomycin resistance.
In the 1950s, several other TB drugs with different mechanisms of action were discovered and developed, paving the way for combination therapy that had to be administered for 18 months or more.
It would take another four decades for the current short-course treatment for TB to emerge: a regimen comprising isoniazid, rifampicin, pyrazinamide and ethambutol. The introduction of rifampicin into clinical practice in the 1960s was a major breakthrough, allowing treatment duration to be shortened to nine months or, when used in a regimen that also contained pyrazinamide, to six months.
Treating HIV and TB in combination can be tricky. The two diseases often occur together, and there are important drug interactions that can have adverse effects on patients.
“However, delaying initiation of antiretroviral therapy (ART) until TB treatment is completed in HIV-infected people significantly increases mortality,” says Sebati.
“Three clinical trials have shown that early initiation of ART in TB patients co-infected with HIV reduces mortality. So the World Health Organisation recommends that ART should be started within the first eight weeks of initiating TB treatment.”
These trials were reported in The New England Journal of Medicine in October 2011.
She adds: “Getting the timing right to initiate ART in patients co-infected with HIV and TB in sub-Saharan Africa is an urgent research priority. In countries like South Africa, where TB and HIV are endemic, we need to reduce the high mortality rates caused by these co-infections.”
Of course, neither disease is close to being eradicated. Multidrug-resistant TB is a real concern, and an effective HIV vaccine is yet to be developed.
“Our members remain committed to the fight against both diseases,” says Sebati. “Hopefully in the very near future, new breakthroughs will be made that will see both HIV and TB becoming a thing of the past.”