domingo, 22 de maio de 2016
When the drugs don’t work / How to combat the dangerous rise of antibiotic resistance
When the drugs don’t work
How to combat the dangerous rise of antibiotic resistance
May 21st 2016 | From the print edition
SOME people describe Darwinian evolution as “only a theory”. Try explaining that to the friends and relatives of the 700,000 people killed each year by drug-resistant infections. Resistance to antimicrobial medicines, such as antibiotics and antimalarials, is caused by the survival of the fittest. Unfortunately, fit microbes mean unfit human beings. Drug-resistance is not only one of the clearest examples of evolution in action, it is also the one with the biggest immediate human cost. And it is getting worse. Stretching today’s trends out to 2050, the 700,000 deaths could reach 10m.
Cynics might be forgiven for thinking that they have heard this argument before. People have fretted about resistance since antibiotics began being used in large quantities during the late 1940s. Their conclusion that bacterial diseases might again become epidemic as a result has proved false and will remain so. That is because the decline of common 19th-century infections such as tuberculosis and cholera was thanks to better housing, drains and clean water, not penicillin.
The real danger is more subtle—but grave nonetheless. The fact that improvements in public health like those the Victorians pioneered should eventually drive down tuberculosis rates in India hardly makes up for the loss of 60,000 newborn children every year to drug-resistant infections. Wherever there is endemic infection, there is resistance to its treatment. This is true in the rich world, too. Drug-resistant versions of organisms such as Staphylococcus aureus are increasing the risk of post-operative infection. The day could come when elective surgery is unwise and organ transplants, which stop rejection with immunosuppression, are downright dangerous. Imagine that everyone in the tropics was vulnerable once again to malaria and that every pin prick could lead to a fatal infection. It is old diseases, not new ones, that need to be feared.
The spread of resistance is an example of the tragedy of the commons; the costs of what is being lost are not seen by the people who are responsible. You keep cattle? Add antibiotics to their feed to enhance growth. The cost in terms of increased resistance is borne by society as a whole. You have a sore throat? Take antibiotics in case it is bacterial. If it is viral, and hence untreatable by drugs, no harm done—except to someone else who later catches a resistant infection.
The lack of an incentive to do the right thing is hard to correct. In some health-care systems, doctors are rewarded for writing prescriptions. Patients suffer no immediate harm when they neglect to complete drug courses after their symptoms have cleared up, leaving the most drug-resistant bugs alive. Because many people mistakenly believe that human beings, not bacteria, develop resistance, they do not realise that they are doing anything wrong.
If you cannot easily change behaviour, can you create new drugs instead? Perversely, the market fails here, too. Doctors want to save the best drugs for the hardest cases that are resistant to everything else. It makes no sense to prescribe an expensive patented medicine for the sniffles when something that costs cents will do the job.
Reserving new drugs for emergencies is sensible public policy. But it keeps sales low, and therefore discourages drug firms from research and development. Artemisinin, a malaria treatment which has replaced earlier therapies to which the parasite became resistant—and which now faces resistance problems itself—was brought to the world not by a Western pharmaceutical company, but by Chinese academics.
Sugar the pill
Because antimicrobial resistance has no single solution, it must be fought on many fronts (see article). Start with consumption. The use of antibiotics to accelerate growth in farm animals can be banned by agriculture ministries, as it has in the European Union. All the better if governments jointly agree to enforce such rules widely. In both people and animals, policy should be to vaccinate more so as to stop infections before they start. That should appeal to cash-strapped health systems, because prophylaxis is cheaper than treatment. By the same logic, hospitals and other breeding grounds for resistant bugs should prevent infections by practising better hygiene. Governments should educate the public about how antibiotics work and how they can help halt the spread of resistance. Such policies cannot reverse the tragedy of the commons, but they can make it a lot less tragic.
Policy can also sharpen the incentives to innovate. In a declaration in January, 85 pharmaceutical and diagnostic companies pledged to act against drug resistance. The small print reveals that the declaration is, in part, a plea for money. But it also recognises the need for “new commercial models” to encourage innovation by decoupling payments from sales.
That thought is taken up this week in the last of a series of reports commissioned by the British government and the Wellcome Trust, a medical charity. Among the many recommendations from its author, Jim O’Neill, an economist, is the payment of what he calls “market-entry rewards” to firms that shepherd new antibiotics to the point of usability. This would guarantee prizes of $800m-1.3 billion for new drugs, on top of revenues from sales.
Another of Lord O’Neill’s suggestions is to expand a basic-research fund set up by the British and Chinese governments in order to sponsor the development of cheap diagnostic techniques. If doctors could tell instantaneously whether an infection was viral or bacterial, they would no longer be tempted to administer antibiotics just in case. If they knew which antibiotics would eradicate an infection, they could avoid prescribing a drug that suffers from partial resistance, and thereby limit the further selection of resistant strains.
Combining policies to accomplish many things at once demands political leadership, but recent global campaigns against HIV/AIDS and malaria show that it is possible. Enough time has been wasted issuing warnings about antibiotic resistance. The moment has come to do something about it.