Timeline of Tuberculosis
TB, an ancient and evergreen disease has plagued human world throughout human history and prehistory. Humans are known to be suffering even before the discovery of the causal agent of the disease. Approximately 4000 years ago, skeletal deformities typical of tuberculosis were seen in ancient Egyptian mummies showing the first evidence of TB (Daniel 2006). By staining the sputum of the infected people with a new staining method, Prussian physician, Dr. Robert Koch in the year 1882 discovered the causative organism of TB as Mycobacterium tuberculosis (M. tb). He termed it as Koch Bacilli. Numerous developments and theories by different scientists and physicians were in the field until in 1882, tubercle bacillus was found to be the actual cause of tuberculosis. Tubercles are present in the lung tuberculosis was stated in the year 1689 by Richard Morton, an English physician (Konti? et al. 2009). A percussion method for diagnosing tuberculosis was developed by an Austrain physician in the year 1761 (H. K. Walker, 1990), tuberculous meningitis clinical description was given for the first time in 1768 (Breathnach 2014) and arthritic tuberculosis was named as Pott disease by English surgeon (1779). Historically, TB was known by variety of names including Phthisis (Greek word, to decay), Consumption, Wasting disease, White Plague (TB epidemic in Europe during 18th century), scrofula (swellings of lymph nodes of the neck), white swelling (Tuberculosis infection of the bones), Lupus Vulgaris (TB of skin), King’s Evil (due the belief that king’s touch would heal scrofula), Lung Sickness, Tabes mesenterica (TB of the abdomen) and Pott’s disease (Tuberculosis infection of spine). In the year 1839, disease tuberculosis was named by German naturalist Johann Lukas Schonlein followed by Jean Antoine Villemin demonstrating the transmissibility of Mycobacterium tuberculosis (Daniel 2006).
Scientists from University of Tubingen say that humans first acquired tuberculosis in Africa about 5000 years ago (Zimmer 2014) but there is an evidence that first tuberculosis infection happened some 9000 years ago (Hershkovitz et al. 2008). Back then trade routes were the main source of the spread of infection. Human tuberculosis is 6000 years old, newer than ever thought was suggested by the new DNA study from remains in the south Peru. The strain of tuberculosis found in both seals and humans were closely related posing animals as the main mode of transmission from East to West. The seals contracted the disease from the domesticated goats and cows of the infected humans when they came to the beaches of Africa for breeding (Zimmer 2014).
In the 18th and 19th centuries, TB had surged as great epidemics when population densities increased in Europe and North America before receding, thus behaving like one of many infectious diseases.
Despite our familiarity with TB for centuries, it continues to cause high morbidity and mortality. Vigorous and continuous actions are required to be taken in order to decrease the mortality rate. While TB was never fully eradicated, the development of a live attenuated vaccine, Bacillus Calmette-Guérin (BCG), by Albert Calmette and Camille – Guérin in 1921, and the discovery of the first antibiotic against TB, streptomycin, by Selman Waksman in 1943 led to the significant drop in the mortality rates which led to the opinion that appropriate control measures had become available for fighting TB.
TB-control programs were established between 1950 and 1965. However, these initiatives in developing countries showed limited success. As compared to the industrialized countries which showed pronounced reduction of infection and death rates. Consequently, TB programs became a lower priority because the disease was considered close to elimination.
In the early 1980s, with the emergence if drug resistant strains, TB re-emerged more violently that ever before. The prevalence increased to worrying level. By 1993 increasing TB could no longer be ignored so the World Health Organization (WHO) declared the disease a global health emergency (Daniel 2006) and subsequently developed End TB Strategy, with the aim to end global TB epidemic by 2035.
Statistical data and epidemiology
With the increasing awareness, progress has been made in reducing TB related deaths and infection spread. According to the Global TB Report 2017, 53 million lives have been saved and TB mortality rate have been reduced by 37% since 2000. Despite all the efforts, the disease continues to take millions of lives and is ninth leading cause of death worldwide which is quite upsetting. It ranks above HIV/AIDs as one of the leading causes of death by an infectious disease.
Though claimed to be completely curable and preventable, according to the WHO TB report 2017, 10.4 million people (1million children) fell ill with TB (10% of which are HIV infected) of which 1.7 million (250000 children) died from the disease (including 0.4 million among people with HIV) in 2016 alone (Figure1.1). It is important to note that over 95% of the TB deaths occur in underdeveloped and developing countries. Theoretically, it occurs in every corner of the world. In 2016, largest number of new TB cases occurred in Asia, with 45% of the new cases, followed by 25% in Africa. 87% of new TB cases occurred in the 30 high TB burden countries. Seven countries account for 64% of the global deaths with India leading the count followed by Indonesia, China, Philippines, Pakistan, Nigeria and South Africa (Figure1.2). TB is the second largest death causing disease from any single infectious agent after HIV-AIDS (Acquired Immunodeficiency Syndrome). It is the leading killer of HIV positive people: in 2016 alone, 40% deaths are due to TB (World Health Organization 2017). Apart from the HIV coinfection, increasing resistance of M.tb. to anti-TB drugs poses another great challenge and has become a matter of health threat. In 2016 alone, 60000 new cases were identified showing resistance to first line anti-TB drug- rifampicin of which 490000 showed MDR-TB (Figure1.3). Nearly 47% of these cases were accounted from India, China and Russian federation. A more severe drug resistance XDR-TB, extensively drug resistance form of Tb in which bacteria does not respond to the most effective second line of anti-TB drugs was seen in about 6.2% of the MDR-TB cases. Global progress depends on advances in TB prevention and care in these endemic countries.t 2017, According to WHO TB report, in order to reach the first milestone of End TB strategy 2020, TB mortality rate and TB incidence rate needs to fall to 4-5% and Case Fatality Report (CFR) to 10% per year.