Overview of Tuberculosis
Tuberculosis is a highly infectious disease of the respiratory system in humans. It is one of the oldest diseases ever known to man, and has been associated with a high mortality rate in the absence of adequate treatment and in immunologically weakened persons. It is generally regarded as a disease of poverty due to its prevalence in low-resourced regions with inadequate medical treatment. Over the ages, tuberculosis has remained a major public health threat, with over 1.7 billion people infected globally, and is still one of the leading causes of deaths worldwide, with over one million deaths every year. The major factors that make tuberculosis difficult to eradicate is its prevalence in poverty burdened regions, association with HIV-positive individuals, and the trend of antibiotic resistance in drug treatment.
What causes Tuberculosis?
The disease is mainly caused by the bacterium Mycobacterium tuberculosis, which is also called the ‘tubercle bacilli’. It usually infects the lungs and causes damage (pulmonary tuberculosis), but can spread to other parts of the body as well (extrapulmonary tuberculosis). It is transmitted through the air (airborne) and can infect a healthy person who inhales droplets containing the tubercle bacilli from the cough or sneeze of an infected individual. Once inside the body, the bacteria invade the respiratory tract, where the immune system responds and numerous white blood cells gather at the site of infection to form a restrictive barrier around the bacteria called a ‘granuloma’. If the barrier formed by the immune cells is able to keep the tubercle bacilli under control, the infection will not spread and the bacteria will be trapped within the granuloma. This results in a ‘Latent Tuberculosis Infection’ (LTBI), hence, the individual is not infectious and there will be no damage or symptoms.
However, if the bacteria escape from the granuloma, the infection will spread to other parts of the Lungs, as well as other organs of the body through the bloodstream, resulting in a full-blown tuberculosis disease. At this point, symptoms begin to manifest and the individual becomes infectious. Note that persons with latent tuberculosis infection can still develop active tuberculosis later on, especially in HIV patients (weakened immune system), and children below 5 years of age (developing immune system).
What are the Signs and Symptoms of Tuberculosis?
In individuals with latent tuberculosis infection, there are no symptoms observed as the bacteria are trapped by the immune system and are not capable of causing damage. In cases of active tuberculosis, the damage caused by the bacteria in the lungs gives rise to symptoms such as persistent coughs with thick phlegm or blood (haemoptysis) lasting three weeks or more, chest pain, fever, weakness, night sweats, loss of appetite and rapid weight loss. If untreated, the bacterial infection can spread to other organs in the body (extrapulmonary tuberculosis), resulting in the development of swollen lymph nodes in the neck, along with other symptoms that depend on the site of infection. For example, if the Brain and Spinal cord are infected, the condition is called ‘Tuberculous meningitis’, and the individual will experience additional symptoms such as dizziness, headaches and neck stiffness.
How is Tuberculosis diagnosed?
There are various methods for the diagnosis of tuberculosis disease. Certain tests such as the Tuberculin skin test (Mantoux test) and a Blood test are commonly used for tuberculosis diagnosis, however, these tests cannot differentiate between a latent tuberculosis infection (LTBI) and an active tuberculosis disease, and may also yield false positives if the individual had earlier received a tuberculosis vaccine. For actual confirmation, the specific tests used are Chest X-Ray or CT scans, and laboratory culturing of sputum samples (phlegm from deep within the throat) for direct bacterial identification.
What is the burden of Tuberculosis in Africa?
Research studies have shown that a great percentage of global tuberculosis cases occur in developing countries and resource-limited regions, especially in Africa, where it is highly endemic due to the limited resources, poor medical attention and inadequate treatment of cases. As of 2016, the World Health Organization African region (WHO Afro) accounted for about 25% of the estimated number of tuberculosis cases worldwide. African countries such as Nigeria, Liberia and Sierra-Leone are among the top 30 countries with the highest burden of tuberculosis globally. In fact, in Nigeria alone, the incidence of tuberculosis in 2019 was estimated at 220 cases per 100,000 population, and every year, about 590,000 new cases occur in the country, leading to the death of over 245,000 Nigerians. The country alone accounts for about 4% of the tuberculosis incidence worldwide. The tuberculosis incidence rate in Liberia and Sierra Leone was about 308 and 304 cases per 100,000 population respectively, however, Nigeria still ranks as the country with the highest tuberculosis burden in Africa. Other African countries like Ghana, Guinea Bissau and Mali also have very high rates of tuberculosis incidence in the global index.
The major challenges that impede the reduction and eradication of tuberculosis in Africa include poverty, undernutrition, poor infection prevention and control (IPC) measures, high financial burden of tuberculosis treatment, late diagnosis and diagnostic errors, increased HIV burden, ineffective disease surveillance systems, poor political will to eradicate the disease, and the trend of antibiotic resistance in the region.
How can Tuberculosis be treated?
Tuberculosis is quite curable if treatment commences early enough. It can be treated by the use of specifically prescribed antibiotics, but the treatment has some disadvantages, such as the fact that the drugs are expensive, require months of consistent consumption, and could produce a few unpleasant side effects with time. The treatment regimen usually lasts about 6-12 months for either latent or active tuberculosis, depending on the severity of the disease, and involves the use of antibiotics like rifampin, isoniazid, pyrazinamide, etc.
How best can Tuberculosis be prevented?
The most effective way of preventing the disease is by vaccination with a special vaccine called ‘BCG Vaccine’ (Bacillus Calmette-Gurein), which will help protect the individual from future infections. As the disease is airborne, it is difficult to effectively prevent people from getting infected. Thus, it is important that people are aware of the symptoms of the disease, and individuals suspected of having the disease should be isolated, tested and treatment must be commenced immediately if positive to avoid spreading the infection to others. Tuberculosis patients on antibiotic treatment should ensure they strictly adhere to the prescriptions in order to ensure effective resolution of the disease and prevent the bacteria from developing drug resistance.
Reference
- World Health Organization (2020). Tuberculosis. https://bit.ly/3hLcdI5.
- Web MD (2020). Tuberculosis – Symptoms, Causes, Treatment and Prevention. https://wb.md/3esevKb.
- Adebisi YA, Agumage I, Sylvanus TD, Nawaila IJ, Ekwere WA, Nasiru M, et al. Burden of Tuberculosis and Challenges Facing Its Eradication in West Africa. Int J Infect. 2019;6(3):e92250.