There is some really exciting news in the world of TB diagnostics. If you haven’t heard already, there is a new molecular diagnostic test developed by Cepheid that has the potential to transform how TB is detected. The GeneXpert MTB/RIF assay can detect TB and mutations associated with rifampicin resistance in less than two hours with far greater accuracy than smear microscopy. The MTB stands for the mycobacterium that causes the Tuberculosis infection. The RIF means Rifampicin resistance, one of the most potent and important of the drugs to fight TB. If the mycobacterium is resistant to Rifampicin, it is an indication that the person also has an infection that is resistant to the other most important drug to fight TB, this is then called multi-drug resistance. TB is an extremely difficult disease that requires 2 years of treatment with toxic drugs.
In addition, this new test will help to detect more people who are infected with both TB and HIV since most of these people cannot be detected by smear microscopy alone. Since undiagnosed and untreated TB is the greatest killer of people living with HIV, the Xpert test should help to save many lives, especially in Africa.
For those of you not in the TB world, this means more people with different types of TB will be treated quicker and better. We think that the use of this new test could increase the number of TB cases detected by as much as 30% — which could translate into more than a million new cases diagnosed and hundreds of thousands of lives saved. Although the promise of this test is great, there are many people who think we need to be thoughtful and cautious as we help countries roll-out Xpert. Every new tool or diagnostic requires a lot of effort on the part of governments to implement it throughout the country. With many of the endemic TB countries with limited resources, this is even more difficult. With more people diagnosed with TB and MDR-TB, we need to ensure that we have enough quality drugs to treat everyone. This is particularly a problem for many countries with high rates of MDR-TB.
I believe there are some key things that need to happen in the introduction of this new diagnostic at the country level. There needs to be a good understanding of the burden of disease in the country and how the test will best be used. We need to make sure there is a clear implementation plan for the country with clearly defined roles for the National TB Program and all other partners in the country. We need to ensure that all labs and testing sites are properly prepared with the equipment, supplies and infrastructure necessary to run the test. Adequate training and supervision must be put in place so we know that all staff – from the lab personnel to the physicians – understands how the test works and how it can benefit TB control in the county. There needs to be a strong monitoring and evaluation component developed for implementation. It needs to have a good baseline and the measurements need to be comprehensive. Finally, there needs to be adequate technical assistance to ensure best practices and global knowledge of the tool is brought to bear at the beginning of country implementation and throughout the process.
The U.S. Government agencies are working closely together on this effort at the global and country level. We all want to ensure that the U.S. Government resources are well coordinated around this new diagnostic. We have taken existing global recommendations and guidance and helped to translate them into a comprehensive technical approach for our USG teams and partners in country. We are systematically tracking the purchase and use of machines and supplies in countries. And we are providing technical assistance through our USG partners to help countries as they try to roll-out and scale-up the use of the test.
I hope there will be more new TB diagnostics in the near future, but after waiting so many years for this one, we don’t know when the next new test will be available. It is important to move forward with this Xpert test in a robust, comprehensive approach so that we can quickly diagnose the many people with TB who currently are not detected and put them on life-saving treatment.
