The initial stage of HIV infection often manifests through flu-like symptoms that can easily be mistaken for common illnesses. During this phase, individuals may experience symptoms such as high fever, persistent headache, and nausea that last for several days. Some people might also encounter issues like vomiting, diarrhea, and general malaise. Often, these signs are mild and temporary, leading individuals to believe they are experiencing a regular flu or cold. Consequently, many do not seek medical attention or recognize the seriousness of their condition at this early point.

Following the initial symptoms, individuals typically enter a prolonged period known as the chronic or asymptomatic stage. During this phase, HIV continues to replicate at low levels but progressively damages the immune system by attacking CD4 cells, also known as T-helper cells. This ongoing destruction weakens the body's defenses, even though outward symptoms might be minimal or absent, making it possible for an infected person to remain unaware of their status for many years, often spanning a decade or more. Without intervention or treatment, the virus relentlessly destroys immune cells, setting the stage for severe complications.

When the immune system becomes severely compromised, the individual transitions into the final phase known as Acquired Immunodeficiency Syndrome (AIDS). This occurs typically when the CD4 cell count falls below 200 cells per cubic millimeter of blood. At this critical point, the body's ability to fight off infections is drastically diminished, leading to the emergence of severe and opportunistic illnesses. Symptoms such as persistent fatigue, unexplainable fever lasting over a week, profuse night sweats, and chronic diarrhea become evident. Additional signs include unexplained skin changes, bruising, or bleeding, and infections like yeast infections in reproductive organs. Patients may also experience swollen lymph nodes in the neck and groin. Common complications involve skin cancers like Kaposi's sarcoma and respiratory infections such as pneumonia. People living with AIDS are highly vulnerable to secondary infections due to their compromised immune system, which can ultimately lead to death if not managed with appropriate medical care.

It is important to note that with proper treatment, individuals diagnosed with AIDS can survive for several years, often more than four, maintaining a better quality of life. This emphasizes the crucial need for early testing, diagnosis, and initiation of antiretroviral therapy (ART) to prevent or delay the progression to AIDS. Regular screening and prompt medical intervention play vital roles in managing HIV effectively and prolonging survival. Awareness about the progression stages of HIV can empower at-risk populations to seek timely healthcare, ensuring early detection and better health outcomes.