A pilot study by a team of researchers from Bangladesh and the Netherlands has demonstrated the effectiveness of ‘electronic nose’ technology to diagnose tuberculosis (TB). The findings of the pilot study titled Diagnosis of Active Tuberculosis by E-nose Analysis of Exhaled Air have been published in the journal Tuberculosis 2012 (Nov 02). The study was jointly undertaken by researchers at icddr,b, Consultatie Implementatie Technisch Beheer B.V. (C-it BV) and Erasmus MC, Rotterdam.
In the pilot study, two sub-studies were conducted at icddr,b’s tuberculosis laboratory, in collaboration with the Government of Bangladesh’s National TB Control Programme. ‘Electronic nose’ technology was used to analyse exhaled lung air samples from 15 TB patients admitted to Dhaka’s National Institute of Diseases of the Chest and Hospital. The findings were compared with 15 healthy participants. The results demonstrated a robust difference between the TB patients and healthy participants. A validation study (with 194 participants) was also conducted to estimate the diagnostic accuracy of the sophisticated ‘electronic nose’ using exhaled air to detect tuberculosis. A sensitivity of 95.9% and specificity of 98.5% was found for the pilot study.
The ‘electronic nose’ used in the study, the DiagNose (manufactured by C-it BV, Zutphen) incorporates 12 metal-oxide sensors and a pump. Dispensing with the needs for sputum samples, this new tool analyses lung air samples from TB patients for diagnosis. Its portability and time effectiveness enables a proactive screening search for new TB cases in rural areas, without the need for highly skilled operators or a hospital center infrastructure.
Prevalence of Tuberculosis and challenges in detection
TB, a highly infectious airborne disease, remains a major global health problem. It is estimated that one third of the world’s population is infected with Mycobacterium tuberculosis, often leading to active tuberculosis (TB). In 2010, there was an estimated incident case count of 8.8 million active TB infections, resulting in 1.5 million deaths.
The primary detection technique for TB is the 125-year-old Ziehl-Neelsen (ZN) staining combined with microscopy. However, the major drawback of this method is that it only allows for detection of pulmonary disease cases in an advanced stage, meaning that often the disease has already been transmitted to close contacts.
Chest X-ray and microbiological culture are also used to diagnose TB in developing countries. Many of the new diagnostic techniques are not suited for operation in the highly endemic low-income countries. The need for a sensitive, fast, easy-to-operate and low-cost method prompted the researchers to undertake the pilot study in Bangladesh.
Simple, rapid, sensitive and specific tests are central to the global strategy of controlling TB. Currently available diagnostics are either insensitive, time-consuming, or require considerable advanced laboratory infrastructures often not available in the developing countries where TB burden is high. Therefore, there is an urgent need for a new TB diagnostic test that is simple, rapid, sensitive and specific and can be made widely available. This project is one of several undertaken by icddr,b to identify simple techniques to detect and diagnose TB. In 2010 icddr,b was issued its first patent from the Director of United States Patent and Trademark Office (United States Patent US7638271) for inventing a new diagnostic method for tuberculosis, called antibodies produced by peripheral blood lymphocytes in culture supernatant, or ALS.
For details please contact Nasmeen Ahmed