HIV infection progresses through several stages, each characterized by specific clinical and immunological features.

The stages are typically categorized into three main phases: acute HIV infection, chronic or clinical latency, and acquired immunodeficiency syndrome (AIDS).

Acute HIV Infection:

Initial Exposure: The virus enters the bloodstream through contact with infected bodily fluids, most commonly through unprotected sexual intercourse, sharing of needles, or from an infected mother to her child during childbirth or breastfeeding.
Flu-Like Symptoms: Within 2 to 4 weeks post-exposure, individuals may experience flu-like symptoms such as fever, fatigue, swollen lymph nodes, and rash. This phase is known as acute retroviral syndrome (ARS).
High Viral Load: The virus replicates rapidly during this stage, resulting in a high viral load in the blood.

Chronic or Clinical Latency:

Asymptomatic Stage: After the acute phase, the virus enters a prolonged period of clinical latency. During this stage, individuals may not experience any noticeable symptoms.
Viral Replication Continues: Although the immune system is actively fighting the virus, HIV continues to replicate at lower levels.
CD4 Cell Decline: Over time, the virus gradually depletes the CD4 T cells, which are crucial for the immune system’s proper functioning.

Acquired Immunodeficiency Syndrome (AIDS):

Criteria for AIDS Diagnosis: AIDS is diagnosed when the immune system is severely compromised, and the CD4 cell count drops below a critical level. Additionally, the person may develop opportunistic infections or certain cancers.
Opportunistic Infections: Individuals with AIDS are susceptible to opportunistic infections that the immune system would typically control. Examples include pneumonia, tuberculosis, and certain types of cancers.
Severe Immunodeficiency: The immune system becomes severely compromised, and the individual is more vulnerable to life-threatening illnesses.

It’s important to note that the progression of HIV infection can vary from person to person. With proper medical care, antiretroviral therapy (ART), and support, individuals with HIV can live for many years without progressing to AIDS. Early detection, regular medical monitoring, and adherence to prescribed medications are crucial in managing HIV infection and preventing the progression to severe immunodeficiency. Regular testing and access to healthcare services are essential for timely intervention and effective management of HIV.