New TB test
CIH researcher, Tehmina Mustafa, has developed a new robust, rapid, sensitive, and specific test for TB, implementable in low-resource settings!
Professor Mustafa, from the Centre for International Health (CIH) and the Department of Thoracic Medicine at Haukeland University Hospital, leads multi-national research efforts into improved diagnosis of tuberculosis (TB). TB is a leading cause of death globally (see the Fact Box for more information). It is considered an endemic disease in large parts of Africa and Asia. Key challenges include correct diagnosis and treatment in low- and middle-income countries, where there are significant issues due to lack of sufficient medical infrastructures and low-cost, timely approaches.
Mustafa explains that in Norway the number of cases of TB diagnosed per year is 300-400, or 6-9 per 100 000 citizens. However, in low- and middle-income countries, such as Pakistan, for example, this number can be as high as nearly 300 people per 100 000 citizens: a much higher health burden. Incidences of extrapulmonary TB are often under-reported, as these are more difficult to detect. It is estimated that at least 18-20% of all TB cases are extrapulmonary. This proportion may be as high as 50% in children and in those who are HIV co-infected.
At a project meeting held in Bergen spring 2017, Mustafa explained that there are a number of challenges associated with correct diagnosis of extrapulmonary TB, particularly in low- and middle-income countries, where treatment is usually started on clinical suspicion without laboratory support. This can easily result in either over- or under-diagnosis leading to increased morbidity, mortality with significant socioeconomic consequences. TB affects mainly adults, constituting the most economically productive and care-givers age group in the society. Due to the nature of disease and the fact that it has a lower bacterial burden, routine methods may miss out many cases. The PCR-based methods can detect more cases but these methods require advanced lab technology, closed facilities to avoid contamination, qualified personnel and time. This is beyond the health system infrastructure of many low- and middle-income countries.
In 2006 Mustafa published the findings describing the immunohistochemistry-based analyses which detect an antigen, MPT64. This is a protein that is secreted by the pathogenic mycobacteria causing TB. This protein accumulates in TB-infected host cells during the disease process. She has since shown that identification of MPT64 in cells is a test that is both sensitive and specific for the presence of TB. Since 2007 Mustafa has led a series of studies in Norway, Zanzibar, Tanzania, India and Pakistan, that have shown that MPT64 is effective in different types of extrapulmonary TB including, tuberculous lymphadenitis, pleural TB, abdominal TB, and TB meningitis.
In addition to being robust, sensitive, and specific, the MPT64 test is relatively rapid, requiring about 1 day to carry out as compared to the conventional culture method which requires 4-8 weeks. Mustafa and her research partners feel that implementation of their MPT64 test in routine diagnostic settings will improve the TB diagnosis, for extrapulmonary TB in particular, in a cost- and time-effective way in the vulnerable populations of low- and middle-income countries.