Faster Tuberculosis Diagnosis with Low Cost Public Health Devices

Tuberculosis (TB) is a deadly infectious disease that usually affects the lungs, but may affect almost any tissue of the body. The primary symptoms of TB include cough of more than three weeks duration, weight loss, fever, blood-stained sputum, chest pain, and if left untreated, can result in death. In 2013 alone, nine million people fell ill with TB, and one point five million people died from the disease, making TB the second greatest killer worldwide as a single infectious agent. TB is both preventable by implementing appropriate infection control measures, and is treatable through the use of specific antibacterial drugs. A common method for detecting active tuberculosis and measuring its bacillary load is through the use of acid fast staining, such as Ziehl Neelsen (ZN) staining, which involves applying specific chemicals to a sputum sample or other smear from a patient, and analyzing the smear under a microscope. In the case of ZN staining, TB bacteria appear as pink rod-shaped objects against a bright blue background. By counting the number of bacteria visible in the stained smear, the examiner can deduce approximately how advanced the TB infection is, and act upon it appropriately. At this time, it is the norm for the bacteria to be counted manually by lab technicians working in TB clinics. The goal of this thesis is to identify the problem that is TB, and explain a set of methods and devices which can be used to further reduce the global impact of TB. Using a combination of image processing methods and image acquisition devices combined with microscopy, we are able to rapidly count the number of bacteria present in a ZN stained slide. The result is a portable, low cost, hand-held device that can perform hours of manual analysis in under a minute, while providing ivgreater consistency across individual tests. This has the potential to decrease the lead time on diagnosis and treatment of TB in the field from weeks to minutes, helping to reduce the impact of this deadly disease.