Why is a person with AIDS less able to combat infections than who does not have AIDS?

A person with AIDS (acquired immunodeficiency syndrome) is less able to combat infections than someone without AIDS because HIV (human immunodeficiency virus), the virus that causes AIDS, attacks and weakens the immune system. The immune system is the body's defense mechanism against infections and diseases. It consists of various cells, tissues, and organs that work together to protect the body from harmful microorganisms such as bacteria, viruses, and fungi.

Here's how HIV affects the immune system, leading to reduced ability to combat infections:

1. CD4+ T Cell Depletion:

- HIV primarily infects a type of white blood cell called CD4+ T cells, also known as helper T cells.

- These cells play a crucial role in coordinating the immune response by identifying and eliminating infected cells and triggering other immune system components.

- As HIV replicates within CD4+ T cells, it destroys them, leading to a decline in their numbers.

2. Impaired Immune Response:

- The depletion of CD4+ T cells weakens the body's ability to recognize and mount an effective immune response against invading pathogens.

- Without a sufficient number of CD4+ T cells, the immune system becomes less efficient in detecting and eliminating infections.

**3. Reduced Antibody Production:

- CD4+ T cells are essential for activating B cells, which produce antibodies.

- Antibodies are proteins that bind to specific antigens (foreign substances) and help neutralize them.

- With fewer CD4+ T cells, the production of antibodies is reduced, further weakening the immune response.

4. Opportunistic Infections:

- The weakened immune system in individuals with AIDS makes them more susceptible to a wide range of opportunistic infections.

- Opportunistic infections are illnesses caused by microorganisms that usually do not cause disease in individuals with a healthy immune system.

- Common opportunistic infections in people with AIDS include Pneumocystis jirovecii pneumonia (PCP), candidiasis, cryptococcal meningitis, and cytomegalovirus (CMV) retinitis.

5. Increased Viral Replication:

- HIV also affects the replication of other viruses, leading to increased viral loads in the body.

- This increased viral load further compromises immune function and makes the person more vulnerable to infections.

In summary, a person with AIDS has a weakened immune system due to the depletion of CD4+ T cells and impaired immune responses. As a result, they are less able to combat infections and are more prone to opportunistic infections, leading to increased morbidity and mortality.