Tuberculosis is a global health emergency that should keep you up at night. It is the second deadliest infectious disease after AIDS–in 2010, 8.8 million people fell ill with TB and 1.4 million died from it. It is very much a disease of our era: as mega-cities pop up in the developing world, more and more people live in cramped conditions, making it easy to spread a disease like TB.
TB is treatable, but not easily. For the most part, patients must take one pill a day for six months. The thing is, patients must be observed taking the pill. This is a key recommendation by the World Health Organization; people are generally going to stop taking pills once they start feeling better, but if the patient stops taking her TB medicine before the disease is fully gone, it could mutate and develop resistance to the treatment. This poses a risk to the patient and to the entire health system of a poorer country that may not be able to afford the more expensive second line treatment.
The first step to treating TB is diagnosing it correctly. This is rather difficult in poorer countries, particularly in rural settings. Last year, I visited a village in Bangladesh that was part of a national TB screening program. Diagnosis was a protracted process with many moving parts:
At a small health clinic, trained workers collect sputum samples from people who are symptomatic. Someone from a nearby hospital regularly visits the village to pick up samples for testing. There, a lab technician examines the sample under a microscope to make a diagnosis. If the test is positive, a doctor on site prescribes a treatment regime of anti-retroviral therapy.
This is kind of an ordeal. It is also burdensome on the health system because it requires a microscope and it someone who knows how to read the slides. In resources straped places like rural Bangladesh, this means that there can be long lag times between diagnosis and treatment. Also, this system cannot quickly identify Multi-Drug Resistant TB, which is really scary and must be quickly contained before it spreads.
This onerous diagnosis process may soon change for the better. Earlier this week a co-hort of global health organizations including UNITAID, PEPFAR, The Gates Foundation and USAID banded together to sharply reduce the cost of a new kind of rapid diagnostic test for TB and MDR-TB. The test is approved by the World Health Organization and can reliably diagnose TB (including an HIV/TB co-infection) within two hours. It also doesn’t require any special training, like reading a slide.
The problem was, this system was very expensive–much to expensive for resource strapped heath ministries. That’s where that group of health organizations comes in.
Funds provided by this partnership will reduce the cost of Xpert MTB/RIF cartridges from $16.86 to $9.98, a price which will not increase until 2022. The effective date of this price decrease is August 6, 2012.
To date, the high unit cost of Xpert® MTB/RIF cartridges produced by the medical device manufacturer Cepheid has proven a barrier to their introduction and widespread use in low- and middle-income countries. The new agreement will immediately reduce the cost of cartridges used to diagnose TB by more than 40 percent.
In December 2010, the World Health Organization (WHO) recommended the Cepheid product, known as Xpert MTB/RIF assay, which is run on Cepheid’s GeneXpert platform. Until Cepheid developed the Xpert MTB/RIF assay, the only method used in most laboratories in developing countries was smear microscopy, a technique first developed in the 1880s by the German bacteriologist Robert Koch that requires visual detection of the TB bacterium under a microscope.
Smear microscopy is particularly insensitive for diagnosing TB in patients who are co-infected with HIV. It also does not help clinicians detect the presence of drug-resistant strains of TB. The limitations of traditional smear microscopy, along with the cost and long delays to receive culture results, have limited the ability to diagnose and treat TB and drug-resistant forms of the disease.
Cepheid’s GeneXpert is a molecular diagnostic system that can detect TB disease in patients co-infected with HIV and resistance to the antibiotic rifampicin – a widely accepted indicator of the presence of multi-drug resistant TB – in less than two hours. The system also can be used outside of conventional laboratories because it is self-contained and does not require specialized training.
Because TB is the leading cause of death among people living with HIV in Africa, greater access to this test offers a significant advance in the capacity of health care workers to diagnose TB quickly and help reduce TB transmission, the development of TB disease, and premature TB deaths.
The capacity of the Xpert MTB/RIF assay to yield a rapid and accurate diagnosis has the potential to improve TB diagnosis and treatment in rural clinical settings. A large percentage of people with TB disease fail to start treatment promptly because of the long wait for results of older conventional tests and the need for them to return to the clinic, which may be far from where they live. Using the GeneXpert system, clinics in poor and rural settings can deliver rapid diagnosis and immediately start patients on appropriate treatment, including second-line drugs in cases of drug-resistant.
Research suggests that the incremental scale up of GeneXpert in countries with high TB burdens could allow for the rapid diagnosis of 700,000 cases of TB disease and save health systems in low- and middle-income countries more than U.S. $18 million in direct health costs.
Rapid diagnosis of TB could be a big game changer in the global fight against this disease. This announcement means more people will be treated more quickly and reliably, which will reduce new infections. Well done.