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The Oxford Dictionary defines evolution as "The process by which different kinds of living organisms are believed to have developed from earlier forms during the history of the Earth." Mycobacterium tuberculosis, a pathogen belonging to the ‘Mycobacteriaceae‘ family, is notorious for causing tuberculosis. The question at hand is how Mycobacterium tuberculosis evolved into the bacterium we see today. Did it solely evolve in humans, or did it first emerge from another biological organism? Could environmental factors like climate and temperature change have played a role in this evolution?
The quest for answers involves the evaluation of various aspects: the historical development of Mycobacterium tuberculosis worldwide, its relationship with humankind (and other organisms), the insights offered by technology on its evolution, and the current state of the bacterium as we move towards the future. Understanding these facets will be crucial in formulating a response to the fundamental question concerning the origin and climate's impact on Mycobacterium tuberculosis.
The origin of Mycobacterium tuberculosis in relation to humans and other biological organisms is pivotal in comprehending how we might potentially "control and eliminate this lethal disease." Ever since Dr. Robert Koch's groundbreaking discovery of Mycobacterium tuberculosis in 1882, researchers have explored ways to combat the bacterium effectively. To gain comprehensive knowledge, it is essential to deduce its historical and present relationships and origins, enabling us to assess its development and mitigate its effects.
The History of Tuberculosis and the Global Spread of Mycobacterium Tuberculosis
Around 70,000 years ago, the tuberculosis bacterium is believed to have originated from early humans in the African region. As noted by Sarah Pruitt (2018, p.3) in a History article, research indicates that Mycobacterium Tuberculosis emerged during the Neolithic Revolution. Some scientists argue that it originated in animals and was later transmitted to humans due to increased animal domestication during that period. However, alternative research conducted by Sebastien Gagneux and the Swiss Tropical and Public Health Institute (2018) suggests that the bacterium actually originated in early humans in Africa and subsequently spread due to human migration and population growth.
To survive for millennia, Mycobacterium tuberculosis remained dormant within hosts for approximately 20,000 to 30,000 years, re-emerging later as a survival mechanism. Evidence of its spread through migration is evident in discoveries such as Ancient Egyptian mummies dating back to approximately 5000 BCE, which showed signs of tuberculosis. The disease can spread through the air, as infectious bacteria are expelled through coughs or sneezes, infecting susceptible hosts who inhale these particles.
Mycobacterium Tuberculosis and Humankind
Mycobacterium tuberculosis causes tuberculosis in humans, primarily affecting the lungs. As a pathogen, it relies on a living host to survive. Tuberculosis can manifest in two ways: Latent TB, where the bacteria remain alive but dormant and cannot be transmitted to others, and Active TB, where the bacteria multiply and spread, making transmission possible. Zoonotic tuberculosis affects animals and research suggests that it can contaminate food supplies, such as cheese and milk, and spread through direct contact between domestic livestock and humans.
Notably, people with weakened immune systems, such as those with HIV/AIDS and children, are more vulnerable to contracting Mycobacterium tuberculosis. In 2017, tuberculosis caused one million infections and 230,000 deaths among children, making it one of the top 10 causes of human mortality worldwide.
According to the World Health Organization (2018), the global spread of tuberculosis has been declining at a rate of 2% per year, thanks to better understanding, increased resources, and improved technology. One significant technological development is genotyping, coined by Wilhelm Johannsen, which allows researchers to identify different strains of the bacterium, including drug-resistant ones. "Beijing" is the name given to the genotype that encompasses multiple strains of Mycobacterium Tuberculosis. Genotyping is crucial for understanding the bacterium's evolution and its genetic connections to humans, which have allowed it to persist for generations after its origination.
CRISPR (Clusters of Regularly Interspaced Short Palindromic Repeats) is another revolutionary technology that aids in exploring drug resistance adaptations within Mycobacterium tuberculosis. By studying the adaption of the bacterium, researchers are better equipped to address the challenges posed by tuberculosis effectively. Ongoing research in this area holds promise for the future.
Addressing Drug-Resistant Tuberculosis
Drug-resistant tuberculosis poses a significant challenge today. As bacteria evolve and adapt, Mycobacterium tuberculosis has developed resistance to certain drugs. According to the UN Interagency Coordination Group on Antimicrobial Resistance (Pai.M, 2019), drug-resistant tuberculosis accounts for 230,000 deaths worldwide each year.
Current prevention strategies and treatments include the use of respirators and masks to limit disease spread, the BCG vaccine, education about tuberculosis, chemoprophylaxis, and isoniazid. However, continuous research aims to identify better ways to combat drug-resistant tuberculosis. Leveraging technology, such as genotyping and CRISPR, offers hope in finding effective solutions.
Climate Change and Mycobacterium Tuberculosis
Studies suggest that Mycobacterium tuberculosis can withstand temperatures below 100 degrees Celsius, and global warming, indicated by an average temperature rise of 70 degrees Celsius, has little effect on the bacterium. Interestingly, research by The Brazilian Journal of Infectious Diseases (2015) indicates that tuberculosis is more widespread during winter, with people being more susceptible to the bacterium during colder periods.
Eliminating Mycobacterium Tuberculosis
Scientists aspire to eliminate Mycobacterium tuberculosis. Research on the genome connection between the bacterium and humans has led to the study of gene silencing for its eradication. However, complete eradication might not be feasible, given the widespread nature of the bacterium. Nonetheless, ongoing efforts, such as those proposed by Richard E. Chaisson, MD, Center for AIDS Research, Johns Hopkins University, aim to decrease tuberculosis spread and improve the evolutionary success of the human population.
In conclusion, the journey of Mycobacterium tuberculosis is intertwined with human history and the world's evolution. Through comprehensive research and the application of cutting-edge technologies, we hope to better understand this ancient bacterium and devise effective strategies to combat its impact on human health. By embracing scientific advancements and recognizing the influence of climate change, we strive to pave the way for a healthier future.
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