Tuberculosis: Let us end it together!
14 February 2022
Tuberculosis (TB) has haunted mankind since 400 BCE. It is a bacterial pulmonary (affecting lungs) and extra-pulmonary disease (affecting lymph nodes, brain, kidneys, etc.) which is highly contagious and fatal if not treated. Even though it is treatable and curable, it is one of the top 10 causes of death worldwide.
‘TB knows no borders as it can affect anyone and everyone irrespective of their age, caste, religion, etc.’
What is the causative agent?
It is caused by a bacterium known as Mycobacterium tuberculosis which is an aerobic, acid-fast bacillus (based on Acid-fast staining technique), non-sporing and has slow growth rate. The cell membrane contains mycolic acid which gives it property of virulence. Other predisposing factors that contributes are presence of poverty, malnutrition, overcrowding and incomplete health care system.
There are two different types of TB:
(i) Active TB- people incubate the bacteria and display symptoms and can spread the disease.
(ii) Latent TB- people incubate the bacteria BUT do not show any symptoms and CANNOT spread the disease. But since the bacteria are present, it can be reversed to active TB anytime in their lifetime.
It is a worldwide spread disease. Today, half of the global cases are contributed by countries such as India, Russia and China. The prevalence rate now is 2 billion people which accounts for 1/4th of the world’s population and the incidence rate is 10 million. In 2019, globally 7.1 million people with TB were newly diagnosed and 1.4 million people succumbed to death. However, according to WHO reports in 2017, very few active cases are observed in developed countries such as UK and USA but with many people having latent TB.
How is it transmitted?
The bacteria are transmitted from person to person through air droplets expelled in air while sneezing, coughing, speaking or singing. The contraction of disease depends on several factors such as infectiousness of the TB patient (mild v/s severe), environment (open v/s closed), frequency of exposure (once v/s multiple times), duration of exposure, and the immune status of the exposed individual.
Signs and Symptoms to look out for:
Persistent cough and coughing up blood, fever, chest pain, chills, weight loss, night sweats, fatigue, no appetite.
Different Diagnostic Methods:
1. Mantoux Tuberculin skin test (TST)- tuberculin is injected into the forearm and waited for 48-72hrs. A wheal and flare reaction shows hypersensitivity. It is however not a fool-proof method and cannot distinguish between active and latent TB.
2. TB blood tests- detection of interferon gamma (cytokine) secreted by T cells which are involved in immunity.
3. Chest X-rays- for pulmonary TB. It may show infiltrates or cavities in lungs which can suspect TB.
4. Culture of sputum-TB is confirmed by culturing the sputum and detecting the presence of bacteria in the sample.
5. Sputum smear microscopy- Using acid-fast staining technique and then examining smears for acid-fast bacilli.
1st line drugs- Isoniazid, rifampicin, ethambutol, pyrazinamide, streptomycin.
2nd line drugs- Para-aminosalicylic acid, ethionamide, cycloserine, linezolid, fluoroquinolones, aminoglycosides
We can take certain measures stop the transmission of TB:
Vaccination: BCG vaccine is only vaccine available currently. It is extremely safe. Every child must take it in their infancy to develop immunity. School-based vaccination for those who missed it and Supplementary immunisation programmes for vaccination of close contacts of diagnosed TB individual should also be initiated.
Break the chain: Isolate the patient to avoid transmission from one adult to another.
Take your medicine timely: TB drugs should be taken exactly as prescribed by the health care provider.
Chemoprophylaxis: WHO recommends TB Preventive Treatment (TPT) for health workers and family members residing with patient.
TB education: Spread awareness on etiquettes to be followed by TB patients and community on how to identify case of TB and what should be done if detected.
Several Global plans by organisations such as WHO, CDC are in progress to control & eradicate TB globally. However, we all must come together and support them by detecting symptoms, taking treatment properly and necessary precautions to eradicate this disease!