Drug-resistant TB must be elevated as a priority
22 September 2011
BY GUY MARKS
PAPUA NEW GUINEA is currently in a battle with potentially preventable and treatable tuberculosis, a disease that has increased by 42% over the past decade.
TB is an infectious disease that’s passed on when a person with tuberculosis of the lungs coughs and another person inhales the organism.
About a third of the world’s population is infected with the organism that causes TB. But only 10% of these people will go on to develop the disease. Once you’re infected, you can develop the disease at any time but it’s most likely to occur within two years.
The common forms of TB are treatable by antibiotics but this can be quite complicated. A standard course of treatment requires four different drugs (daily or three times a week) over a two month period, and then two of those drugs to continue for a total of six months.
Unless the treatment is closely supervised, people to tend take only a partial course of these drugs. This is because the symptoms of the disease usually disappear quite quickly but the drugs can be difficult to access and may cause side-effects.
Unfortunately, taking a partial course of treatment means that the disease is likely to relapse and, worse still, may relapse in a drug resistant form. The organism mutates to develop a resistance to one antibiotic; the multiple antibiotics are used to prevent those mutations from surviving.
Drug resistant TB can be transmitted to others, just like drug-susceptible TB. Drug resistant TB is much more difficult to treat than the usual, drug-susceptible disease and it can’t be treated with the standard drugs.
The drugs that can treat it are less effective, more toxic and more expensive. And because they’re less effective, treatment is required for much longer. So it’s much more difficult to treat.
I don’t think anybody really knows how serious the situation is in PNG because there’s very little data. In many countries, including PNG, the organisms are not routinely tested for drug resistance. In this situation the only way you know you’re dealing with multi-drug resistant TB is when the standard treatments fail.
We do have data from clinics in the Torres Strait Islands, which test for drug susceptibility. Visiting clinicians have found a very high proportion of patients have multi-drug resistant tuberculosis. So we can assume it’s also common in PNG.
There are many factors why TB is so prevalent in PNG. Much of it has to do with living conditions in crowded houses – this promotes the spread of the disease. Also, the prevalence of other illnesses increases the likelihood of latent TB infection progressing to TB disease.
But the biggest problem is when the disease takes hold in an area and there’s no effective program for controlling the disease, then tends to spread.
You control the spread of tuberculosis by finding people with active tuberculosis early (soon after developing symptoms), putting them on effective medications and making sure they continue their treatment until completion.
Australia has a very good TB control program. Everybody who comes to Australia from countries with high rates of tuberculosis is screened for active TB. If they have the disease, they can’t come until they’re clear.
But the issue with tuberculosis is that the disease is latent in many people and the screening process doesn’t pick this up. And if it did, I’m not sure what we’d do with that information – it’s so common and affects a third of the world’s population.
Australia’s role is to assist PNG and other countries to increase their capacity to deal with this problem themselves. This requires a substantial investment of funds, training, and, in some cases, the supply of health professionals.
PNG needs laboratories to make diagnoses, it needs skilled clinicians and supervisors to treat the disease, and it needs funds to purchase the drugs. These are the necessary steps to effectively manage contain the disease.
PNG has enormous problems, of which tuberculosis is only one. But containing TB requires that this disease be elevated as a priority.
Professor Guy Marks is Head of Epidemiology at the University of Sydney’s Woolcock Institute
Source: Science Alert, The Conversation, 12 September
http://www.sciencealert.com.au/opinions/20111109-22598.html
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