How does the tuberculosis infection invade and attack body?

The tuberculosis (TB) infection, caused by the bacterium *Mycobacterium tuberculosis*, has a complex mechanism of invading and attacking the human body. Here's a step-by-step overview of how TB typically progresses:

1. Initial Infection:

- The TB bacteria usually enter the body through the respiratory tract when someone breathes in tiny droplets or aerosols containing the bacteria.

- These droplets are often released when an infected person coughs, sneezes, or talks.

2. Primary Complex Formation:

- Once inside the lungs, the bacteria can cause a primary infection known as the primary complex. This complex consists of:

- A focus of infection in the lung tissue called a Ghon focus.

- Swollen lymph nodes near the affected lung, known as hilar lymph nodes.

- A connection between the Ghon focus and the hilar lymph nodes through lymphatic channels.

3. Latent TB Infection:

- In many cases, the primary TB infection can become latent. During this stage, the bacteria remain dormant within the body without causing any symptoms or active disease.

- Individuals with latent TB are not contagious and can carry the bacteria for years without knowing it.

4. Reactivation of Latent TB:

- In some cases, the latent TB infection can reactivate and cause active TB disease. This reactivation can occur due to various factors, including:

- Weakened immune system, such as in individuals with HIV/AIDS, diabetes, or certain medications

- Old age

- Malnutrition

- Substance abuse

- Stressful conditions

5. Active TB Disease:

- When TB reactivates, it can spread to different parts of the lungs and other organs. The most common form is pulmonary TB, affecting the lungs.

- Active TB can cause symptoms such as persistent cough, chest pain, fever, night sweats, weight loss, and fatigue.

- Untreated active TB can lead to severe lung damage, spread to other organs (extrapulmonary TB), and even be fatal.

6. Transmission and Contagion:

- People with active TB can transmit the infection through respiratory droplets when they cough, sneeze, or talk.

- Prolonged close contact with an infected individual increases the risk of infection for others.

It's important to note that not all individuals exposed to TB will develop an infection or active disease. The risk depends on factors such as the person's immune status, the strain of bacteria, and the extent of exposure. Early diagnosis, treatment, and infection control measures are crucial for managing and preventing the spread of tuberculosis.