Tuberculosis (TB)

 Key facts 

• A total of 1.3 million people died from TB in 2022 (including 167,000 people with HIV). Worldwide, TB is the second leading infectious killer after COVID-19 (above HIV and AIDS).
• In 2022, an estimated 10.6 million people fell ill with tuberculosis (TB) worldwide, including 5.8 million men, 3.5 million women and 1.3 million children. TB is present in all countries and age groups.  TB is curable and preventable. 
• Multidrug-resistant TB (MDR-TB) remains a public health crisis and a health security threat. Only about 2 in 5 people with drug resistant TB accessed treatment in 2022.
• Global efforts to combat TB have saved an estimated 75 million lives since the year 2000.
• US$ 13 billion in needed annually for TB prevention, diagnosis, treatment and care to achieve the the global target agreed at the 2018 UN high level-meeting on TB.
• Ending the TB epidemic by 2030 is among the health targets of the United Nations Sustainable Development Goals (SDGs).

Overview 

Tuberculosis (TB) is an infectious disease that most often affects the lungs and is caused by a type of bacteria.  It spreads through the air when infected people cough, sneeze or spit.

Tuberculosis is preventable and curable.

About a quarter of the global population is estimated to have been infected with TB bacteria.  About 5 - 10% of people infected with TB will eventually get symptoms and develop TB disease. 

Those who are infected but not (yet) ill with the disease cannot transmit it.  TB disease is usually treated with antibiotics and can be fatal without treatment. 

In certain countries, the Bacille Calmette-Guerin (BCG) vaccine is given to babies or small children to prevent TB. The vaccine prevents TB outside of the lungs but not in the lungs. 

Symptoms 

People with latent TB infection don't feel sick and aren't contagious. Only a small proportion of people who get infected with disease and symptoms.  Babies and children are at higher risk. 

Certain conditions can increase a person's risk for tuberculosis disease: 

• Diabetes (high blood sugar).
• Weakened immune system (for example, HIV or AIDS).
• Being malnourished.
• Tobacco use.

Unlike TB infection, when a person gets TB disease, they will have symptoms. These may be mild for many months, so it is easy to spread TB to others without knowing it. 

Common symptoms of TB:

• Prolonged cough (sometimes with blood).
• Chest pain 
• Weakness 
• Fatigue 
• Weight loss
• Fever 
• Night sweats. 

The symptoms people get depend on where in the body TB becomes active. While TB usually affects lungs, it also affects the kidneys, brain, spine and skin. 

Prevention 

Follow these steps to help prevent tuberculosis infection and spread: 

• Seek medical attention if you have symptoms like prolonged cough, fever and unexplained weight loss loss as early treatment for TB can help stop the spread of disease and improve your chances of recovery. 
• Get tested for TB infection if you are at increased risk, such as if you have HIV or are in contact with people who have TB in your household or your workplace. 
• If prescribed treatment to prevent TB, complete the full course. 
• If you have TB, practice good hygiene when coughing, including avoiding contact with other people and wearing a mask, covering your mouth and nose when coughing or sneezing, and disposing of sputum and used tissues properly. 

Special measures like respirators and ventilation are important to reduce infection in healthcare and other institutions. 

Diagnosis 

• Tuberculin Skin Tests (TST): Also known as the mantoux test, involves injecting a small amount of tuberculin into the skin and measuring the reaction after 48 - 72 hours. 
• Interferon-Gamma Release Assays (IGRA): blood tests that measure the immune response to TB bacteria. 
• Chest X-Ray: Used to detect lung abnormalities indicative of TB.
• Sputum Smear Microscopy: Examining sputum samples under a microscope for the presence of TB bacteria. 
• Sputum Culture: Growing TB bacteria from sputum samples in a lab to confirm the diagnosis. 
• Molecular Tests: Such as the GeneXpert MTB/RIF, which can detect TB bacteria and rifampicin resistance with a few hours. 

Treatment 

Tuberculosis disease is treated with antibiotics. Recommended for both TB infection and disease. 

The most common antibiotics used are: 

• Isoniazid
• Rifampin
• Pyrazinamide
• Ethambutal
• Streptomycin

To be effective , these medications need to be taken daily for 4 - 6 months.  It's dangerous to stop the medications easily or without medical advice.  This can allow TB that is still alive to become resistant to the drugs.

Tuberculosis that doesn't respond to standard drugs is called drug-resistant TB and requires more toxic treatment with different medicines.

Prevalence and Mortality 

• Prevalence: TB is one of the top 10 causes of death worldwide. In 2022, an estimated 10.6 million people fell ill with TB. 
• Mortality: TB is the leading cause of death from a single infectious agent, ranking above HIV/Aids.  In 2022, TB caused around 1.4 million deaths, including 187,000 people with HIV. 

Geographic Distribution 

• High-Burden Continues: The majority of TB cases are concentrated in a small number of countries. Eight countries account for two-thirds of the total: India, China, Indonesia, the Philippines, Pakistan, Nigeria, Bangladesh, and South Africa. 
• Low-Burden Countries: In many high-income countries, TB is less common but remains a significant public health challenge, particularly among vulnerable populations such as immigrants, refugees, and the homeless. 

Drug-Resistant TB 

1. Multidrug-resistant TB (MDR-TB): MDR-TB is a form of TB that is resistant to at least isoniazid and rifampicin, the two most powerful first-line treatment anti-TB drugs. In 2022, there were around 465,000 new cases of MDR-TB. 
2. Extensively Drug-Resistant (XDR-TB): XDR-TB is resistant to at least four of the core anti-TB drugs and is even more challenging to treat. 

Economic Impacts 

• Health Costs: TB imposes significant Costs on health systems, especially in low- and middle-income counties where resources are already limited. 
• Loss of Productivity: Individuals with TB often experience prolonged illness and absence from work, leading to substantial economic losses for families and communities. 
• Poverty Cycle: TB disproportionately affects the poor, and the economic burden of the disease can exacerbate poverty, creating a vicious cycle. 

Social Impact 

• Stigma and Discrimination: TB patients often face stigma and discrimination, which can discourage them from seeking diagnosis and treatment. 
• Family Impact: The disease can have a profound impact on families, particularly when the main breadwinner is affected, leading to financial and social instability. 

Public health Response 

1. WHO's End TB Strategy: The World Health Organisation (WHO) has set ambitious targets to reduce TB incidence by 90% and TB deaths by 2035, compared with 2015 levels. 
2. Vaccination: The Bacillus Calmette-Guerin (BCG) vaccine is widely used in countries with a high prevalence TB to protect against severe forms of the disease in children. 
3. Global Funding and Initiatives: Efforts such as the Global Fund to Fight Aids, Tuberculosis, and Malaria, and various national TB programs, are critical in funding TB prevention, diagnosis, and treatment efforts. 

Research and Development 

• New Diagnostic: Advances in diagnostic tools, such as GeneXpert, have improved the speed and accuracy of TB diagnosis. 
• Treatment Regimens: Research is ongoing to develop shorter, more effective treatment Regimens for both drug-susceptible and drug-resistant TB. 
• Vaccine: Efforts are also underway to develop more effective vaccines to prevent TB, with several candidates in various stages of clinical trials.