Tuberculosis continues to be the most common contagious killer and the ninth leading cause of death worldwide(1). Despite the development of vaccines, drugs and the formulation of various strategies by the WHO for its prevention and killing, the incidence of the disease persists. This essay will highlight the various reasons pertaining to the persistence of tuberculosis.
An infectious bacterial disease caused by bacterium (Mycobacterium tuberculosis), tuberculosis is usually spread by coughing and sneezing which results in its fast spread amongst individuals. It primarily affects the lungs, but can also spread to other organs such as the kidney, brain and spine. Early diagnosis is vital to prevent further transmission because it spreads at a rate of one person per second, according to the WHO. The diagnosis coverage of the disease has increased from 45%-66%, but the idea of 100% eradication still seems far-fetched due to various reasons(2).
Failure of elimination of the disease can be attributed to the ill-informed public, economic barriers to primary care access in low income countries along with negligence of the governments which might lead to underdiagnosis of Tuberculosis (TB). For Eg; Inadequate budgetary allocations ,lack of proper infrastructure, manpower, poor implementation of programs and private sector malpractices has led to the failure of the TB eradication program in India(3).
Another notable reason that restricts elimination of the disease is the issue of latent tuberculosis infection. According to WHO, Latent tuberculosis is defined as a state of persistent immune response to stimulation by mycobacterium tuberculosis antigens without evidence of clinically manifested active TB. In simple terms, patients who have latent TB infection although infected with TB bacterium do not show signs and symptoms of TB disease. It is therefore, extremely difficult to identify a person with latent TB because most of the time the patient doesn’t feel sick and has a normal chest X-ray, a negative sputum and only a positive skin test or blood test result indicative of TB infection which are not enough to differentiate between latent TB and TB disease. The patients with a weaker immune response, especially those with HIV infection have increased risk of developing the disease later if not identified and treated at an early stage. HIV associated TB was responsible for 374,000 deaths in 2016 indicative of a major public health threat and another reason for the increase in TB cases(4). Current research focuses on improving the diagnosis and positive predictive value of LTBI tests, an effective post exposure vaccine and tools, and drugs to detect and treat LTBI for the control and eventual elimination of TB(5).
The most significant challenge that hampers effective TB control is the emergence of drug resistant tuberculosis. When TB is resistant to at least one or more than one first line anti- TB drugs such as Rifampicin and Isoniazid it is known as drug resistant tuberculosis. Multi drug resistant Tuberculosis (MDR-TB) is present in 3.8% of new TB patients and 20% of patients who have a history of previous treatment, with the highest rates found in countries like India, China and the Russian federation(6,7).
The causes for the global spread of MDR and Extensive drug resistant tuberculosis (XDR-TB) are disorderly treatment, amplifier effect of short course chemotherapy, community transmission and facility based transmission(7). Although drug resistant TB poses a great challenge in the treatment of TB, proper course of treatment and early detection can be curative.
Since, the frequently changing epidemiological situation makes it difficult to control and eradicate the disease, it is imperative that global health policies must be curated keeping in mind the best epidemiological approaches. Governments must build and implement strategies to improve cost effectiveness and duration of treatment along with effective application of biomedical tools. Prioritizing, targeted LTBI testing, treatment of marginalized groups and development of new drugs to treat MDR- XDR TB will also help in reaching the TB elimination goals(8). Indeed, in this fight against Tuberculosis we must innovate to accelerate action.
Karthika M, Philip S, Prathibha MT, Varghese A, Rakesh PS. Why are people dying due to tuberculosis? A study from Alappuzha District, Kerala, India. Indian J Tuberc. 2019 Oct;66(4):443–7.
Harries AD, Lin Y, Kumar AMV, Satyanarayana S, Takarinda KC, Dlodlo RA, et al. What can National TB Control Programmes in low- and middle-income countries do to end tuberculosis by 2030? F1000Research. 2018 Jul 5;7:F1000 Faculty Rev-1011.
Muñoz L, Stagg HR, Abubakar I. Diagnosis and Management of Latent Tuberculosis Infection. Cold Spring Harb Perspect Med. 2015 Nov;5(11):a017830.
Seung KJ, Keshavjee S, Rich ML. Multidrug-Resistant Tuberculosis and Extensively Drug-Resistant Tuberculosis. Cold Spring Harb Perspect Med. 2015 Sep;5(9):a017863.
Kiazyk S, Ball T. Latent tuberculosis infection: An overview. Can Commun Dis Rep. 2017 Mar 2;43(3–4):62–6.