Man with a mission
Despite some setbacks, Keertan Dheda remains committed to the fight against TB, writes Tamar Kahn
WHEN Keertan Dheda grew up in Durban’s Casbah suburb in the 1970s, dinner table conversations were dominated by the numerous doctors in his extended family. The son of a tailor and a housewife, he longed to join the ranks of the medical fraternity, driven by the noble idea of healing broken bodies.
He realised his dream, qualifying as a doctor in the early 1990s and went to work at the King Edward Hospital in Durban, where he was confronted by a population riven by the disease of poverty: tuberculosis (TB) was rife and its evil twin HIV raged virtually unchecked, as the government refused to provide access to lifesaving antiretroviral medicines. Since HIV weakens the immune system, the most common killer among these patients was TB.
It was a turning point in his career, prompting his decision to specialise in respiratory medicine and propelling him along the path that led to the position he holds today — head of the pulmonology division at the University of Cape Town. He defines himself as a “clinician scientist”, combining work at the bedside with medical research. In SA his ilk is “as rare as the rhino”, he laments, explaining that the paucity of government funding means there are few posts available for specialists who wish to both treat patients and “go and think in dark corners” about scientific problems.
Dheda is not a man with a carefully polished script, and he volunteers few anecdotes or details about his personal life. He rattles off his achievements rapid-fire, in an almost offhand manner, downplaying his extensive academic accomplishments: he was SA’s top matriculant in 1986, won the Suzman Gold Medal when he was admitted to the South African College of Physicians, and won a British Lung Foundation fellowship to study for a PhD at University College London. He won a prestigious scientific award from the International Union Against Tuberculosis and Lung Disease, has published over 145 peerreviewed research papers, and earlier this year won the highly sought-after Harry Oppenheimer Fellowship Award that is “granted to scholars of the highest calibre who are engaged in cutting-edge, internationally significant work”.
Like many scientists, he is most animated when talking about his work, which ranges from probing the mysteries of how the body’s immune system attempts to fend off TB’s attack to trying to figure out why some patients are so much more efficient than others at spreading this deadly disease.
The many failed TB vaccines show that scientists still don’t have a good handle on the way the immune system responds to the Mycobacterium tuberculosis bacteria, an understanding that is vital if they are to design a vaccine that can teach the body how to fend it off, says Dheda.
“We just don’t have adequate knowledge about TB
The numbers are starting to overwhelm us and we are magnifying the problem by sending people home to die. We need a new strategy, combining home-based care, longterm community stay facilities, and palliative care facilities
to select a good vaccine. So we have gone back to study the immunology of TB in the lung,” he says. One of the areas his team is looking at is an apparent paradox in which the body’s own immune system appears to sabotage itself when confronted with TB.
His group found that some kinds of regulatory T-cells in the lungs, which “stop the body from overreacting to all the gunk we breathe in every day”, subvert the immune system’s response to TB and stop it from containing the bacteria.
TB is one of the oldest diseases known to man, and over the centuries it has evolved with an extensive bag of tricks to enable it survive in its human host, including the ability to lie dormant for years before rearing up to cause full-blown infection. Throughout history it has cut a swathe through humankind, killing four out of five people it infects. That changed dramatically in the 1940s and 1950s when powerful new antibiotics were developed that turned the disease from an almost certain killer into one that almost everyone survived.
For a brief period, it seemed as if modern medicine had won. Sadly, that optimism has long since evaporated, as tuberculosis has continued to evolve in ways that have provided it with resistance to one drug after another.
Today the number of patients with multidrugresistant TB is soaring, and in a completely new way: it used to be a relatively small problem, largely confined to patients who had for one reason or another failed to continue to take their six-month cocktail of antibiotics.
Now 80% of drug-resistant TB is spread from person to person. Healthcare workers are at particularly high risk, due to their occupational exposure to the disease: in SA they are six times more likely to become infected with drug-resistant TB than people in the general population, according to a study co-authored by Dheda.
So is he worried that he too might be at risk?
“The short answer is I don’t think about it”, says Dheda. “No one comes into your office with a sign on their head saying ‘I’ve got TB’, so we are constantly being exposed to it,” he says.
The sheer numbers of people with drug-resistant TB in SA — an estimated 15,000 were diagnosed last year alone — mean isolating patients until they recover is no longer feasible, says Dheda.
At the moment, many patients who don’t respond to treatment are sent home once it becomes clear the hospital can no longer help: since they are still infectious, they put their friends, family and people in their community at risk. Dheda made this point in a paper published earlier this year in The Lancet, in which he urged the government to rethink its approach.
“The numbers are starting to overwhelm us and we are magnifying the problem by sending people home to die,” Dheda says. “We need a new strategy, combining home-based care, long-term community stay facilities, and palliative care facilities.”
By analysing patients’ coughs, Dheda’s team has shown that about 80% of TB is transmitted by a minority of patients dubbed “superspreaders”. If these patients can be identified, then perhaps precious resources can be channelled towards them, while those at low risk of spreading TB can be treated at home. The team is now trying to understand the genetic blueprint of both the host and the bug in the high-risk patients in the hope of finding better ways to contain outbreaks.
Dheda has also pushed hard to bring cutting-edge technology to South African patients with respiratory diseases: Groote Schuur is the only hospital in Africa to offer a heat treatment called bronchial thermoplasty to severe asthmatics, the first nonpharmaceutical treatment approved by the US Food and Drug Administration. The procedure uses heat to burn off a thin layer of muscle cells inside the lung’s airways, which reduces the incidence of lifethreatening asthma attacks.
“It’s been a major benefit to the healthcare system, because a small group of severe asthma patients consume probably two- thirds of the medical costs of asthma control,” says Dheda.
Some of his youthful idealism may have been displaced by the pragmatism that comes with age, but Dheda remains deeply committed to the fight against TB.
“As a junior doctor I was intrigued and appalled by this infamous disease that has been the biggest killer of mankind. We still haven’t got on top of the problem,” he says.