Tuberculosis – an Old Scourge of Human Kind
Tuberculosis, better known as TB, is an infectious disease caused by Mycobaterium tuberculosis. It is a disease that mainly affects the lungs but can and does present with symptoms in other parts of the body. Evidence is present that the oldest known case of TB occurred some 9000 years ago and it may truly have been the first disease known to man.
In 2010, according to the World Health Organization (WHO), there were 8.8 million new cases of TB with approximately 1.5 million deaths. More than 80% of these cases come from 22 countries with India and China representing the bulk of the cases. Pakistan lies 6th on that list.
TB is a slow growing infection but a very debilitating disease. One third of the world’s population is thought to be infected with this bacterium. There is a distinction between infection and disease. Disease occurs only in 10-15 percent of those infected. Although, this percentage can drastically change depending on the HIV status of the population
Diagnosis presents the largest hurdle to the control of the disease. All cases need to be identified and treated to break the transmission chain and spread of the disease as an effective vaccine doesn’t exist.
Noncompliance or defaulting after being enrolled in the treatment program also poses a challenge and can lead to the development of drug resistance in the bacteria.
The other challenges that have arisen in recent years include the Human Immune-deficiency Virus (HIV) epidemic and the emergence of drug resistance.
HIV infected individuals develop TB more readily with the initial disease rate (primary TB) jumping from 10 % to 40 % and with yearly incremental development of cases.
The emergence of Multi and Extremely Drug Resistant Strains of TB has further complicated the control efforts in place. Multi Drug Resistant (MDR) TB strains are resistant to the most potent first line drugs and require treatment by second line drug which result in a longer course and more toxicity.
Directly Observed Treatment Strategy (DOTS) is a program implemented worldwide by the World Health Organization (WHO) to fight TB epidemic.
Sputum culture is the most common laboratory test used for the diagnosis for TB. However, state of art laboratories for the diagnosis of the disease, employ cutting edge technology like the GeneXpert test. The advantage of using GeneXpert over the conventional microscopy is that it diagnoses over 90 % of cases with a single sputum sample as compared to 50% and it also notifies about the resistance status of the strain to Rifampicin, a first-line drug against the bug. The advantage over culture is that it gives you the results within 2 hours as compared to almost 6 weeks with the conventional culture. Although it is a relatively expensive test to perform, in a high burden setting such as ours the cost may be justified because of the increase in diagnosis.
Pakistan has an escalating HIV epidemic and with increase in HIV patients, this disease would become harder to control. Hence, it is imperative that the case finding should be escalated and it be made sure that all patients complete their treatment successfully. Investing in better diagnostic methods and in educating the health workers in techniques for proper dispersion of instructions for sputum collection and treatment needs to the patient might be a worthwhile undertaking.
About the author: Dr. Amyn A. Malik is a graduate of Aga Khan University (2010), Karachi, Pakistan and is currently pursuing his MPH at Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. He has worked on TB REACH Wave 2 at Interactive Research and Development in Karachi and is interested in control of TB and other infectious diseases. He can be reached at [email protected]