Research studies show that people with HIV who are on antiretroviral (ARV) treatment now live almost as long as their HIV-negative peers.
But this gain in life years also has a downside: it has put HIV-infected people at risk of developing non-communicable diseases (NCDs) such as diabetes, heart disease and high cholesterol, which normally only appear in older people.
There is an "extra epidemic" on the horizon, according to the health department's head of noncommunicable diseases, Melvyn Freeman.
"People over the age of 45 have a higher risk of developing these conditions and many people with HIV now live far beyond that age."
According to Freeman, if NCDs are not addressed properly, the financial cost to the health system will be "massive".
A 2011 paper, published in the medical journal Aids, estimated that HIV prevalence (the proportion of a population with HIV at a designated time) in people over 50 will "nearly double in the next 30 years, whereas the fraction of HIV-infected patients aged over 50 years will triple in the same period".
Freeman said it's expensive to treat chronic conditions such as NCDs.
"For example, once you need hypertensive medication, you're probably going to need it for the rest of your life. One pill may be cheap but a lifetime of medication is extremely expensive."
The longevity of HIV-infected people may be compromised by the generally unhealthy lifestyles of South Africans, resulting in them getting fat, said Francois Venter from the Reproductive Health and HIV Institute at the University of the Witwatersrand. "We have some of the highest rates of obesity in the world," he said.
Obesity, especially a disproportionate accumulation of fat around the abdomen, places one at a much higher risk of developing a number of medical conditions, including diabetes and cardiovascular disease, according to Jeffery Wing, a medical doctor and diabetes expert working at Charlotte Maxeke Hospital.
He said that this is often more pronounced in people living with HIV as they are very "weight sensitive" because being underweight is a well-documented side effect of being infected with the virus.
"They tend to push the calories more than patients without HIV."
The Human Sciences Research Council's 2013 health and nutrition survey revealed that almost half of South African women are obese (40.1%) and 11.6% of men.
Apart from the fact that people with HIV are living longer and therefore may develop age-related illnesses, there is also a body of research emerging that suggests that HIV medication, as well as the virus itself, may put HIV-positive individuals at a higher risk of developing some chronic conditions than the general population and at a younger age.
According to a Chris Hani Baragwanath doctor and researcher, Colin Menezes, the ARV drug, Stavudine, is associated with the early onset of several NCDs.
"What I saw [in my study] was the metabolic consequences – things we're concerned about – like diabetes and dislipidemia [high cholesterol]," he said.
Stavudine, also known as d4T, was part of the state's first-line regimen until 2010, when the country adopted the World Health Organisation's guidelines to substitute it for the less toxic drug Tenofovir.
However, when public-sector clinics run out of Tenofovir – there have been many documented stock-outs this year – patients receive Stavudine as a replacement, Menezes said. According to him, patients with kidney failure are also switched to Stavudine.
Menezes said, although he is seeing fewer cases of opportunistic infections like tuberculosis (TB), he's seeing more patients as a result of "the side effects of ARVs, and clinicians and patients should be aware of this".
Thandi Nyawo, a secretary from Mpumalanga, took Stavudine for six years and developed a common side effect – fat in the body is redistributed largely around the waist, making it disproportionately large. After four years on Stavudine, she was diagnosed with diabetes but doesn't know what caused it.
"[The doctors] don't know [what caused my diabetes]; they say maybe it's a family thing but at home no one has got diabetes. Just me," she said.
According to Wing, "about 30% of patients on ARVs get it [fat redistribution], which we know is a very strong risk factor for developing diabetes."
Because Nyawo does not have a family history of diabetes, which would make her more vulnerable to the condition, Stavudine could "very possibly" have caused her diabetes, Menezes said.
Although Stavudine has been associated with much of the weight redistribution side effect, Wing said other ARVs, particularly protease inhibitors that are used in second-line treatment, can also cause it. Patients go on second-line treatment once they have become resistant to the initial regimen.
HIV itself, because it is an inflammatory condition, can also place one at risk of developing diabetes, according to Wing.
"Inflammation produces inflammatory molecules, which cause insulin resistance in the various tissues, so poorly controlled HIV is also associated with a higher diabetes risk."
However, Venter cautions that this is a "theoretical area" of research.
"It's possible [that HIV, ARVs or a combination of the two can elevate the risk of developing NCDs] but we don't know for certain what the impact of HIV is going to be on these diseases, other than the fact that people are living longer and are, therefore, more likely to get them."
According to Freeman, diseases lower the body's resistance to fight off other illnesses. "So diseases in themselves are mechanisms which change the body's way of dealing with other sicknesses."
For example, studies have shown that diabetic patients are three times more likely to contract TB but the "exact mechanism" through which this happens is still not clear. A TB patient is also at a higher risk of developing diabetes.
According to the World Health Organisation, South Africa has the third-highest TB burden in the world, with more than 70% of TB patients also living with HIV.
But, said Venter, being HIV positive and on treatment could also be an advantage regarding NCDs. He said there is an "absolutely fascinating development": where people living with HIV are actually living longer in some countries because they are managing all of their conditions better than the general population.
"There are studies in the Unites States, Europe and Uganda which show that patients are actually getting [their NCDs] sorted out earlier rather than later and are doing very well."
According to Venter, the average HIV-negative person doesn't access health services often enough to detect these conditions at an early stage before complications arise.
"Personally, I never get my cholesterol or blood pressure checked when I'm supposed to but, once you're in the healthcare system getting your ARVs, checking these things is really easy."
Wing said that, because HIV-infected individuals will soon qualify for drugs when their CD4 count (a measure of the strength of the immune system) is below 500 (unlike the current threshold of 350), many more patients will be on treatment, which will significantly increase the costs to the health system.
"The same concept is being applied to diabetes so young prediabetic patients may qualify for drug treatment earlier rather than just be advised to change their lifestyles."
Freeman said that the government can only do so much and that patients need to take some responsibility for their health.
"The minister has said that, if the National Health Insurance system is going to work, we need a healthy population. HIV is a massive burden on the fiscus. You don't give antiretroviral therapy for a year or two; you give it for life, the same is true for NCDs. You can just imagine the burden chronic diseases place on the health system."