Tuberculosis Disease

Tuberculosis Disease

Abstract

The leading cause of death amongst the infectious diseases is tuberculosis. Tuberculosis is caused by Mycobacterium tuberculosis, and once inside the host body, it forms an active TB or latent TB. The disease is contagious as it is transmitted through the air. When nearby individuals breathe in a load of bacteria, they become infected. In the lungs, the bacteria begin to propagate and spread to the other body parts, such as the spine, kidney, and brain. Habitually, M. tuberculosis grows in the lungs resulting in pulmonary TB. Symptoms caused by pulmonary disease include a bad cough that lasts for weeks, fever, weight loss, chest pain, and chills. On spreading to the other body parts, different symptoms are portrayed depending on the anatomical structure. Types of TB under the extra-pulmonary sites are military TB, gastrointestinal TB, central nervous system TB, TB pericarditis, among others. Treatment of TB is through multiple antibiotics in at least six months.

Keywords: Tuberculosis, Latent Tuberculosis, active tuberculosis, physiology, anatomy, organ, lungs, Mycobacterium tuberculosis, risk factors, clinical manifestation, prognosis, and diagnosis

 

Annotated Bibliography

Heemskerk, D., Caws, M., Marais, B., & Farrar, J. (2015). Clinical Manifestations. In Tuberculosis in Adults and Children (pp. 17-26). Springer, Cham.

This article reviews the clinical manifestation of variants of TB. This source is reliable and very strong, due to that the four authors work in distinct sectors – The corresponding author works at a research institute, the other three are in a university, children hospital, and Wellcome Trust, respectively. In their article, the authors broadly classify Tb into three types; primary TB, extra-pulmonary TB (EBTB), and other forms of EBTB.  The first type consists of endobronchial tuberculosis, parenchymal disease, and intra-thoracic lymph node disease. The forms of Tb under the extra-pulmonary type are less prevalent than the ones in the pulmonary TB type. Nonetheless, the forms are multiple and include pleural TB, Miliary TB, central nervous system tuberculosis, and TB pericarditis. In the last type, it comprises of TB forms like gastrointestinal TB, urogenital TB, and Laryngeal TB. The authors provide the clinical manifestations of all these TB forms concisely and coherently and even go further to provide chest X-ray images of a patient with military TB.

Additionally, they analyze the global prevalence of EBTB. Their article supports the work of Mayo clinic concerning the diagnosis examination as they indicate the importance of tuberculin skin tests and imaging diagnosis.

Narasimhan, P., Wood, J., MacIntyre, C. R., & Mathai, D. (2013). Risk factors for tuberculosis. Pulmonary medicine, 2013.

In 2012, scholars from the University of New South Wales, Australia, embarked on a study to focus on the risk factor of tuberculosis. They argued that exogenous and endogenous factors govern the progress of active TB in a person. They define exogenous risk factors as the elements that accelerate the exposure of an individual to a bacillary load. On the other hand, endogenous factors entail elements that are involved in the infection to progress to active TB. In achieving their objectives, their strategy involved searching for articles and journals which were related to the risk factors of TB. They obtained articles from multiple databases like PubMed, EMBASE, and Medline, whereas tuberculosis journals include Bulletin of the World Health Organization, International Journal of Tuberculosis and Lung Disease, and the Indian Journal of Medical Research. In the exogenous category, they were able to infer that a substantial bacillary load and proximity to an infectious event escalates the risk of infection. In regards to the factors related to individuals, they highlighted that immunosuppressive conditions (like HIV/AIDS and immune-mediated inflammatory disorders), malnutrition, diabetes, young age, and social-economic factors (like smoking and alcohol abuse) increase the risks of being infected. This article by Narasimhan et al. is relevant because it helps in the discussion of the risk factors in the present paper.

Bauer, M., Ahmed, S., Benedetti, A., Greenaway, C., Lalli, M., Leavens, A., … & Schwartzman, K. (2015). Health-related quality of life and tuberculosis: a longitudinal cohort study. Health and quality of life outcomes, 13(1), 65.

In 2015, Bauer et al. did a cohort study to compare the health-related quality of life (HRQOL) to individuals diagnosed and treated for TB. From the background of their report, people diagnosed with TB show to have a decline in their psychological and physical well-being. From this concept, they set objectives of measuring the HRQOL in both treated and untreated patients. In their findings, they reveal that individuals diagnosed and treated with TB have impaired well-being, though it improves slowly with time. For those patients with latent TB infection, their psychological aspect was negligibly impaired. This write-up is significant as it shows the need for psychosocial support involvements for people cured for TB disease and aids in the discussion of the quality of life prognosis in the present paper.

Tuberculosis Disease Outline

1. Introduction

– Tuberculosis (TB) is a severe granulomatous, and contagious disease that usually attacks the lungs. However, it spreads to other regions of the body for example spine and brain

–           TB is categorized based on the potency of the infection or the body part that is affected. Based on potency, there is Latent Tb and active TB.

–  In the last two centuries, TB causes a significant number of deaths among communicable diseases.

1. Normal physiology of Organ System Involved; Lungs

–           The lungs are the first line of infection

– Lungs are the prime structures of the respiratory system

III.       Clinical Manifestation

–           Different types of TB portray different signs and symptoms

–           Typical symptoms of Pulmonary TB

–           Specific symptoms of forms of TB in extra-pulmonary type

1. Etiology and pathogenesis

–           The causative agent of TB is the Mycobacterium tuberculosis complex.

–           Infection initiates when the M. tuberculosis are dispersed in the air

–           Spread from the lungs

1. Risk factors and prevention

– Factors that intensify the risk of TB; Intrinsic factors, environmental factors, and socioeconomic status.

1. Diagnostic procedures, including lab, imaging, and biopsy

–           Effective diagnosis of active and latent TB involves multiple examinations. Initiates with the basic tests, then followed by imaging tests.

VII.     Potential treatments and their costs

– Treatment of any kind of TB is a lengthy process and involves taking multiple antibiotics.

VIII.    Prognosis and potential sequelae

–           Environmental factors affect the prognosis of TB

–           TB infection can lead to severe and mild complications

1. Potential for self-management

–           Patients play a significant role in the managing of TB

1. Prognosis & quality of life issues for the patient, family, and community

–           Aftermath of individuals treated for Tuberculosis

 

Tuberculosis Disease

Introduction

Tuberculosis (TB) is a severe granulomatous, and contagious disease that usually attacks the lungs. Nonetheless, it can spread to other anatomical parts like the spine and brain. Mycobacterium tuberculosis is the primary cause of TB, however at rare instances, other bacteria of these families- M. microti, M. africanum, M.bovis, and M. canetti- can be the causation of the disease. Due to the consumptive or “wasting” impact of the disease, it was termed as tubercle in the 17^th century by a Dutch anatomist, Fransiscus de la Boe. The disease was known by different names before the identification of its pathogen. The names include phtisis (Greek), balasa (Hindu), yaksma (Sanskrit), and shaky oncay (Incan). In the epidemic of Europe of the 17^th century, it was referred to as the white plague (Heemskerk et al., 2015).

TB is categorized based on the potency of the infection or the body part that is affected. Concerning potency, there exist two types, latent TB and active TB. In both instances, the bacteria are present in the body, but in the former, the immune system manages them from spreading. Therefore, no symptoms and not contagious. Nonetheless, the infection can be re-activated when the host is exposed to high-risk factors. Whereas, in active TB, the microbes multiply and cause consumptive effects. Over 90% of adult cases with active TB result from reactivation from the Latent infection (CDC, 2020). Grounded on the tissue or organ affected, TB is broadly grouped into three; pulmonary TB (parenchymal disease, endobronchial TB, and Intra-thoracic lymph node TB), and extra-pulmonary TB (Pleural TB, Miliary TB, central Nervous system TB, gastrointestinal TB, genitourinary TB among others) (Heemskerk et al., 2015).

In the last 200 years, TB has caused more death than any other infectious disease. The incidence rate of TB in 2012 globally was 8.6 million cases, with deaths amounting to 1.3 million. The high prevalence rate is attributed to the numerous risk factors and the drug-resistant Tb variant (CDC, 2020).

Normal physiology of Organ System Involved

TB mostly infects the lungs before spreading to other body parts. The lungs are the principal organs of the respiratory system.  Their physiology entails the oxygenation of the body through the exchange of oxygen and carbon dioxide. They have paired organs with a pyramid-like shape and connected to the trachea through the bronchi. The cage enclosing the lungs is known as pleurae and is attached to the mediastinum. The lungs are divided into lobes, the superior lobe (at the apex), the middle lobe (present in the right lung only), and the inferior lobe (close to the diaphragm). There is a cardiac notch which an indentation on the left lung’s surface, for housing the heart. Fissures separate the lobes, and each region has bronchopulmonary segments.

In performing a gas exchange, the pulmonary artery supplies deoxygenated blood, and through its subsequent branching into pulmonary capillary networks, oxygenated blood draining happens by way of the pulmonary vein. The sympathetic and parasympathetic nervous systems accomplish the constriction (bronchoconstriction) and dilation (bronchodilation) of the airway. The sensory nerve fibers enter the lungs at the hilum and extend from the vagus nerve at the second to fifth ganglia. In the lungs, the nerves closely follow the bronchi and branch into the glands, blood vessels, and muscle fibers. The pleura encompasses the visceral pleural –the superficial layer to the lungs- and parietal pleural –the outer layer that connects to the diaphragm, mediastinum, and thoracic wall. The primary function of the pleura is to form the pleural cavity and produce pleural fluid. These two features, in turn, protect the lung during expansion.

Clinical Manifestation

Different types of TB portray different signs and symptoms. The classical clinical manifestations linked with active pulmonary TB are coughing, fever, fatigue, chest pains, weight loss, and hemoptysis. For extra-pulmonary Tb, the manifestations are highly likely to be non-specific. The release of antidiuretic hormone by the lung tissue that is affected leads to issues of leukocytosis, hyponatremia, and leukocytosis (Heemskerk et al., 2015).

Genitourinary TB is mostly characterized by frequent urination, flank pain, and dysuria. In women, the infection is comparable to pelvic inflammatory disease, while in men, this genital TB may manifest as orchitis, prostatitis, epididymitis, or scrotal mass.

Gastrointestinal TB affects any site of the gut, and symptoms are dependent on the location. They include non-healing ulcers (mouth), difficulty in swallowing (esophageal infection), pain in the abdomen (duodenal and stomach), and hematochezia or diarrhea (colon). Lastly, skeletal TB shows back pain, lower extremity paralysis, and tuberculosis arthritis.

It is worth noting that the general clinical manifestations of TB disease in elderly individuals may not be displayed.  It is due to that their immune response is weak, and they manifest pneumonitis that is non-resolving (Mayo Clinic, 2019).

Etiology and pathogenesis

The causative agent of TB is the Mycobacterium tuberculosis complex, primarily M. tuberculosis. This family of bacteria is non-spore forming, non-motile, and aerobic. Their cell wall is filled with lipids, which enhances their survival by resisting antibiotics and disinfectants. The species M. tuberculosis is non-pigmented, slow-growing, and rod-shaped with a length of 2-4 micrometers.

Infection initiates when loads of M. tuberculosis are dispersed in the air and enter the human body. Once in the lungs, phagocytosis happens to the bacilli through the action of alveolar macrophage cells. The compound cells then enter the underlying epithelium. In eradicating the disease, a response, granuloma, commences. The infected macrophage is engulfed with lymphocytes and mononuclear phagocytes within the granuloma. It, in turn, forms caseous debris in the tissue mass. Contrary to containing the issue, the caseous center liquefies and cavitates, thus emptying the bacilli into the airway. Completion of the cycle occurs when the destroyed lungs produce a cough, which releases a highly infectious agent.

From the lungs, the macrophages that are infected spread to the kidneys, lymph nodes, epiphyses of skeletal bones, and other body areas via the lymphatic system. However, due to certain immunocompromised conditions of the host like AIDS, the plague-ridden macrophages may be distributed in the body through the blood (Narasimhan et al., 2013).

Risk factors

TB infects individuals of all races, ages, and gender. Nevertheless, specific factors increase the disease’s risk. The determinants involved are both intrinsic and environmental related. Usually, a healthy immune system effectively eliminates the TB bacteria. However, if the defensive mechanism of the body is low, the elimination process will be unsuccessful. The immune system is weakened by a substantial number of diseases, medications, and conditions. The diseases include HIV/AIDs, specific cancers, diabetes, and critical kidney illnesses. The conditions entail malnutrition and very advanced or young age.

Environments where the rates of tuberculosis are high, increase the risks of contracting the disease. The renowned areas are Africa, Asia, Latin America, Eastern Europe, and the Caribbean Islands. Additionally, individuals who are in frequent contact with TB patients, be it in healthcare or homes and reside in poorly ventilated or overcrowded structures like prisons, and nursing homes are at a higher risk of contracting.

Socioeconomic status also plays a significant role in increasing the risks of the disease. Poverty causes infected persons to lack access to medical care required in the diagnosis and management of TB. Substance use, like tobacco, deteriorates the immune system, thus rendering individuals vulnerable to TB (Narasimhan et al., 2013).

Diagnostic procedure

The accurate diagnosis of TB involves multiple examinations. The basic ones are physical (TB skin test- TST) and blood tests. TST is conducted by injecting PPD tuberculin in the forearm skin. Then checking for swelling in the injected region by the physician, typically after 48-72 hours (Mayo Clinic, 2020). A bump that is hard and red is highly linked with TB infection. However, healthcare providers ought to be aware that the results can be a false positive or false negative. The former scenario happens when an individual has recently been vaccinated with bacillus Calmette-Guerin (BCG). Contrary, false-negative results occur due to that some people do not respond to the skin test, or due to that they have been recently infected with TB. According to CBC, both TST and TB blood, cannot confirm or rule out active or latent TB. They recommend further investigations; imaging and biopsy (2020).

The most preferred imaging test for confirmation of TB is an X-ray or a CT- scan. The images will reveal white spots in the lungs in places where the immune system formed granulomas in response to the bacteria invasion. In addition, changes in these organs are evident in active tuberculosis. A biopsy is a prerequisite for positive imaging results. Physicians sample the sputum for the presence of TB bacteria. The sampling also tests for drug-resistant TB strains. Therefore, aiding in the choosing of the appropriate treatment plan.

Treatment and Costs

The treatment plan for TB usually encompasses the taking of antibiotics for a lengthy time. TB is a critical condition that can lead to deaths if untreated. However, death is uncommon when the treatment is finalized. For active pulmonary TB, the plan takes at least six months. The project involves taking a set of antibiotics. Rifampicin and isoniazid for the whole span and complementing with ethambutol and pyrazinamide in the first two months of the treatment span (CDC, 2020). Extra-pulmonary TB follows the same regime as for pulmonary TB. Nevertheless, if the infection has spread to the pericardium of the heart or brain, the corticosteroid is first prescribed.

In many settings, TB treatment is freely provided. However, it leads to high economic burdens. Bestowing to CDC, treating a multi-drug resistant and extensively drug-resistant patient amounts to $134,000 and $430,000 correspondingly.

Prognosis and potential sequelae

Individuals residing in zones where diagnosis and treatment are readily available, there is a good prognosis if they finalize their treatment. The rate of recurrence of TB usually falls between 0-14% and is caused by reinfection (CDC, 2020). Poor prognosis happens when the TB is drug-resistant or the patient has a weak immune, or elderly.

TB infection may cause a range of complications and, at times, does not cause any difficulties. Severe complications include meningitis, cardiac tamponade, and kidney and liver malfunctions.

Potential of Self-Management

Management of TB is not only at the hands of the healthcare providers; patients need to play a role. Patients can manage the disease themselves by making sure they adhere to the treatment plan. They should be aware that skipping a dose or ceasing the treatment plan makes the antibiotic to be resistant.

Prognosis to quality of Life

From a report (Bauer et al., 2015), TB disease shows its negative effect on the health-related quality of life. In all the sampled subjects, the substantial impact was on mental health. However, it slowly improved as time passed. On the contrary, physical well-being improved.

 

 

 

 

 

 

 

References

Bauer, M., Ahmed, S., Benedetti, A., Greenaway, C., Lalli, M., Leavens, A., & Schwartzman, K. (2015). Health-related quality of life and tuberculosis: a longitudinal cohort study. Health and quality of life outcomes, 13(1), 65.

CDC. (2020, February 12). Tuberculosis. Centers for Disease Control and Prevention. https://www.cdc.gov/tb/default.htm

Heemskerk, D., Caws, M., Marais, B., & Farrar, J. (2015). Clinical Manifestations. In Tuberculosis in Adults and Children (pp. 17-26). Springer, Cham.

Mayo Clinic. (2019, January 30). Tuberculosis – Diagnosis and Treatment. Mayo Clinic – Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/tuberculosis/diagnosis-treatment/drc-20351256

Narasimhan, P., Wood, J., MacIntyre, C. R., & Mathai, D. (2013). Risk factors for tuberculosis. Pulmonary medicine, 2013.