Tuberculosis (TB) is a disease caused by bacteria called Mycobacterium tuberculosis. When these bacteria enter the body, typically through inhalation, they can settle in the lungs and start to multiply. From the lungs, TB bacteria can travel through the bloodstream to other parts of the body, including the kidneys, spine, and brain. Understanding how TB spreads is crucial for prevention and control.
TB exists in two states: inactive and active. Inactive TB, also known as latent TB infection, means the bacteria are present in the body but are not causing illness. People with inactive TB do not experience symptoms, are not contagious, and often don’t even know they are infected. However, without treatment, inactive TB can progress to active TB disease.
Active TB disease occurs when the immune system is unable to contain the TB bacteria, allowing them to multiply and cause illness. Individuals with active TB disease feel sick and, importantly, can spread the bacteria to others. If left untreated, active TB disease can be fatal.
How Tuberculosis Spreads: Airborne Transmission
TB is an airborne disease, meaning it primarily spreads through the air. When a person with active TB disease of the lungs or throat coughs, speaks, sings, or even sneezes, they release tiny droplets containing TB germs into the air. These microscopic droplets can remain suspended in the air for several hours, especially in poorly ventilated environments.
Transmission is more likely to occur in enclosed spaces with limited airflow, such as indoor rooms, crowded areas, or vehicles with closed windows. People who share the same air space as someone with active TB disease can inhale these droplets and become infected with TB bacteria.
It’s important to note that TB is not spread through casual contact. You cannot get TB from:
- Shaking hands
- Sharing food or drinks
- Touching surfaces like bed linens or toilet seats
- Sharing personal items like toothbrushes
- Kissing
Who is at Risk of Getting TB?
Anyone can get TB if they breathe in air containing TB germs. However, certain factors increase the risk of exposure and developing active TB disease.
Increased Risk of Exposure:
- Spending time with individuals who have active TB disease, especially in close and poorly ventilated environments.
- Living or working in high-risk settings such as hospitals, homeless shelters, correctional facilities, and nursing homes.
- Traveling to or living in countries where TB is common.
Increased Risk of Developing Active TB Disease After Infection:
- Recent TB infection: Individuals recently infected with TB bacteria have a higher chance of developing active disease soon after.
- Weakened immune system: Conditions and treatments that weaken the immune system significantly increase the risk of active TB. These include:
- HIV infection
- Diabetes
- Cancer
- Organ transplantation
- Certain medications like corticosteroids or TNF-alpha inhibitors
In some individuals, active TB disease develops shortly after infection, before the immune system can effectively fight the bacteria. In others, the infection remains inactive for years, and active disease may only develop later when the immune system weakens due to age, illness, or other factors.
Preventing TB Transmission and Disease
Prevention strategies target both preventing the spread of TB germs and preventing inactive TB infection from progressing to active TB disease.
Preventing Active TB Disease in People with Inactive TB:
- Treatment for Inactive TB: The most effective way to prevent active TB disease is to treat inactive TB infection. Treatment involves taking medication, usually antibiotics, for several months. This eliminates the TB bacteria and significantly reduces the risk of developing active TB in the future, especially for those with weakened immune systems.
Preventing the Spread of TB Germs from People with Active TB Disease:
- Medical Treatment: Prompt diagnosis and treatment of active TB disease are crucial in preventing further spread. Effective antibiotic treatment significantly reduces the amount of TB bacteria in the body and quickly makes individuals non-infectious.
- Respiratory Precautions: Individuals with active TB disease of the lungs or throat may need to take precautions to avoid spreading germs, especially before they start treatment and become non-infectious. These measures can include:
- Covering the mouth and nose with a tissue when coughing or sneezing.
- Proper disposal of used tissues.
- Ensuring good ventilation in living spaces.
- Staying home from work, school, or social gatherings, as advised by a healthcare provider.
What to Do If You Think You’ve Been Exposed to TB
If you believe you have been exposed to someone with active TB disease, it is important to contact your healthcare provider or local health department. They can advise you on getting tested for TB infection. TB tests, such as a TB skin test or TB blood test, can determine if you have been infected with TB bacteria. Early detection and, if necessary, treatment can prevent the development of active TB disease and further transmission.
Understanding how TB is transmitted is the first step in protecting yourself and your community. By being aware of the risks, practicing prevention methods, and seeking timely medical attention, we can work together to control and eliminate TB.
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