The history of tuberculosis (TB), a social disease that has caused thousands of million deaths in the last two centuries, is old and complex. The first historical records of the disease claim that Mycobacterium tuberculosis originated more than 150 million years ago (Barberis et al., 2017, p. 9). The first signs of this infection were found in East Africa three million years ago, and 3300 and 2300 years ago, the cases of TB were described in Indian and Chinese documents (Barberis et al., 2017, p. 9). However, according to Churchyard et al. (2017), “Robert Koch discovered M. tuberculosis in 1882” (p. 630). After that, scientists and researchers began to search for medicines against this infection.
TB is a serious infectious disease that remains a global health problem and mostly affects young adults, but senior people and children are also affected. If people do not receive any treatment, they will die. Sometimes, people may suffer from long-lasting effects of TB, such as permanent lung damage and focal neurologic deficits (Shah & Reed, 2014, p. 403). Sub-Saharan Africa is affected the most, but other countries have many cases of TB. This term paper will examine the history and pathophysiology of TB, transmission and risk factors, signs/symptoms and diagnosis, treatment, and prevention of the disease.
History and Pathophysiology of Tuberculosis
As it was already mentioned, TB originated many million years ago. The classic theory of its origin claimed that the disease emerged as a zoonotic infection, but recent research showed that TB’s ancestor appeared about 73,000 years before the common era (BCE) and originated in Homo sapiens from an environmental mycobacterium (Cardona et al., 2020, p. 1). However, short life expectancy and low population density did not allow researchers to examine the impact of the infection on human lives fully. Thus, the first TB genes vanished, and the disease progressed to an active form later. The modern version of Mycobacterium TB (MTB) kills about 5,000 people per day, or more than any other epidemic infection (Hunter, 2018, p. 1). The research on TB began more than 200 years ago and stopped in the 1950s, but later it started again in the 1990s, although a lack of information was available (Hunter, 2018, p. 2). First, scientists studied the pre-antibiotic era of the disease and humans with untreated infection. The second phase continues today, and researchers use advanced technologies to scan the pathology and clinical course of untreated TB and understand how the infection occurs in human lungs.
Pathophysiology of pulmonary tuberculosis begins when a person inhales MTB. After that, four possible outcomes may occur: organism may be purified immediately; latent infection may occur; the onset of active (primary) disease may begin; and the condition may be reactivated many years later (Wani, 2013, p. 10). For people with latent infection and no serious medical problem, the disease may be reactivated in 5 to 10 percent of cases (Wani, 2013, p. 10). People with HIV are at risk of infection reactivation due to the suppression of the immune response.
Primary disease is developed when the tubercle bacilli reach the alveolar spaces and establish infection in the human lungs. If a person has a weak defense system, these bacilli began to kill healthy cells. If the bacterial replication is not controlled, lymphadenopathy will occur, and lung destruction will start (Wani, 2013, p. 10). After that, tuberculosis lesion leads to bacilli spread into the lung airways, and a person becomes infectious. Eighty percent of people without treatment will die at this stage (Wani, 2013, p. 10). Reactivation disease may occur when some factors trigger the latent infection. However, it is not clear now which factors become the triggers.
Transmission and Risk Factors
TB is a droplet or respiratory infection, and it can be transmitted from one person to another during the active stage of the primary disease. According to Shimeles et al. (2019), more than 90 percent of people infected with TB will not develop the disease (p. 2). Those who develop TB belong to the risk groups, such as poorly nourished people and those with weak immune systems, including people with diabetes, HIV, leukemia, alcoholics, and patients receiving immunosuppressive treatment (Shimeles et al., 2019, p. 2). The researchers conducted a case-control study to evaluate the risk factors contributing to TB development. They found out that more than 45 percent of people infected with TB were 25-45 years old (Shimeles et al., 2019, p. 12). The majority of them were males, and most participants lived in poor housing conditions.
Research showed that the main risk factor contributing to the disease spread is close contact between people (Shimeles et al., 2019, p. 12). Other risk factors include tobacco smoking, alcohol consumption, illiteracy, and chronic illnesses. People who live in houses with one window or no windows were twice more likely to develop TB than those who lived in places with good ventilation systems (Shimeles et al., 2019, p. 13). People who are often admitted to hospitals in Ethiopia are more likely to get infected than those who had no history of hospital admission (Shimeles et al., 2019, p. 13). One can see that socio-demographic factors have a great impact on the development of TB.
Signs/Symptoms and Diagnosis
Since TB mostly affects adults, the signs and symptoms of adult TB will be discussed further. The clinical symptoms of pulmonary TB are chronic cough, appetite loss, sputum production, hemoptysis, night sweats, fever, and weight loss (Loddenkemper et al., 2016, p. 2). The signs of post-primary disease may include blood-stained sputum, anorexia, localized thoracic pain, and breathlessness (Loddenkemper et al., 2016, p. 4). Patients with MTB may have a normal chest X-ray, but the radiograph will show a possible diagnosis in most cases. Traditional diagnostics include symptom screening, chest X-ray, microscopy, solid media culture, and drug sensitivity testing (Cudahy & Shenoi, 2016). Modern diagnostics involve interferon-gamma release assays, fluorescence, liquid media culture, polymerase chain reaction, line probe assay, and other technologies (Cudahy & Shenoi, 2016). New technologies allow diagnosing 63 percent of patients with TB (Cudahy & Shenoi, 2016, p. 9). Those who remain undiagnosed require a novel multifaceted approach and a stronger health care system.
The effectiveness of TB treatment depends on several factors, including social and economic factors. First, patient-related factors should be considered, such as age, immune status, genetic characteristics, addictions, nutritional status, drug tolerance, and adherence to treatment (Rebahi et al., 2017, p. 473). In addition, the virulence of the organism and the radiological extent of TB should not be ignored. Such care-related factors as a motivation of healthcare practitioners, patients’ access to the care system, and monitoring and supervision of patients are also important (Rebahi et al., 2017, p. 473). Finally, treatment-related factors, such as drugs administration, absorption, clearance, metabolism, and availability, are crucial for TB treatment.
TB treatment in adults usually includes standardized treatment regimens with the use of antituberculosis drugs. Treatment must consist of an intensive phase to reduce the bacterial burden and a “sterilizing” stage that continues for about six months (Sulis et al., 2016, p. 3). During the intensive phase, such drugs as “isoniazid, rifampicin, pyrazinamide and ethambutol” are used for two months (Sulis et al., 2016, p. 3). The consolidation phase uses only two drugs – isoniazid and rifampicin (p. 3). If a patient with TB has other chronic diseases, treatment should be adjusted accordingly.
Methods of Prevention
Nowadays, there are many ways to prevent TB infection. The first and main method is administering a BCG vaccine to neonates and people at the highest risk of disease (Sotgiu et al., 2019, p. 2). Preventive therapy should be considered in high-risk populations and other groups of people who live in unfavorable conditions. Suppose people live in regions with high rates of TB. In that case, they should try to minimize contact with other people, avoid using public transportation, open windows and always wash hands after coughing or squeezing. Having healthy lifestyles and breaking bad habits will also help to prevent the disease.
Tuberculosis is a global public health problem because it leads to thousands of deaths yearly. Current diagnostic and therapeutic practices are aimed to prevent the spread of the disease and minimize its adverse health outcomes. Still, humanity did not fully eradicate the disease, so new methods of treatment and prevention should be developed in the nearest future. Although the BCG vaccine is used in many countries, it is ineffective in preventing global epidemics, so more effective vaccines should be developed to improve efficiency and decrease mortality.
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