What events occur when HIV enters the body?
When HIV enters the body, a series of events occur that can lead to the development of AIDS if left untreated. Here are the key events that take place:
1. Initial Infection: HIV typically enters the body through contact with infected blood, semen, vaginal fluids, or breast milk. After entering the body, the virus primarily infects certain types of white blood cells called CD4+ T cells, also known as helper T cells.
2. Acute HIV Infection (seroconversion illness): Within a few weeks to a few months after initial infection, some individuals experience a brief period of flu-like symptoms known as seroconversion illness. Symptoms may include fever, rash, sore throat, swollen lymph nodes, and fatigue. This stage usually lasts for a few days to a few weeks.
3. Establishment of Viral Replication: After the initial infection, HIV establishes itself and begins replicating inside CD4+ T cells. The virus uses the cellular machinery of the T cells to produce new copies of itself. As the virus replicates, it damages and destroys CD4+ T cells, weakening the body's immune system.
4. Chronic HIV Infection (clinical latency): This phase is characterized by a relatively low level of viral replication and minimal symptoms. It can last for several years, and during this time, individuals may not experience any noticeable signs of the disease. However, the virus continues to replicate and spread within the body.
5. Progression to AIDS: As HIV continues to replicate and destroy CD4+ T cells, the immune system becomes severely weakened, leading to a state known as acquired immunodeficiency syndrome (AIDS). AIDS is characterized by a CD4+ T cell count below 200 cells/mm³ (or a percentage of less than 14%). Individuals with AIDS are at an increased risk of developing severe infections and certain types of cancer.
6. Opportunistic Infections and other complications: In the advanced stages of HIV infection, the weakened immune system allows for the development of opportunistic infections and certain types of cancer that take advantage of the body's weakened defenses. Common opportunistic infections include Pneumocystis jirovecii pneumonia (PCP), candidiasis, cryptococcal meningitis, and Kaposi's sarcoma. These infections and complications can cause serious illness and even death if left untreated.
7. Treatment and Management: With the advent of effective antiretroviral therapy (ART), the course of HIV infection can be significantly altered. Early diagnosis, consistent adherence to ART, and regular monitoring of viral load and immune status can suppress viral replication, restore immune function, and prevent the development of AIDS-related complications. ART has made it possible for individuals with HIV to live long, healthy lives.