Learn more about HIV :: What is HIV disease?

What is HIV disease?

We tend to think of "disease" in simple terms: infection equals illness. It's a little different with HIV since the virus can cause slow, subtle damage to the immune system long before an infected person will feel ill. Most health care providers use the term "HIV disease" to identify the variety of changes a person may experience, from initial infection to more advanced stages of serious, life-threatening illness. The term describes the medical condition of anyone infected with the virus, regardless of his or her symptoms.

HIV reproduces continuously in the body from the first day of infection. A person who is infected with HIV will typically produce about 10 billion new HIV particles each day, and about 2 billion virus-fighting immune system cells (CD4 T cells) are produced and destroyed.

A person's immune system attacks HIV soon after infection, and at first is able to clear a large amount of virus from the body. However, for each virus particle cleared, at least one new one is created. The body's initial, vigorous anti-HIV response creates a temporary equilibrium between immune cells and the virus that may last for months or years.

Typically, a person will show no outward signs of illness during this time, except for severe flu-like symptoms after the initial infection as a sign that the immune system is kicking-in to fight off HIV. This first stage of HIV disease is called 'acute infection', which includes symptoms such as fever, fatigue, rash, headache, swollen lymph glands, sore throat, nausea and vomiting and may last for one or two weeks. Preliminary research suggests that treatment during acute infection might protect the immune system enough so that it can control HIV without drugs.

Following acute infection the body enters the asymptomatic period, where a person looks and feels well for anywhere from 6 months to over 10 years. If left untreated most people lose approximately 70-100 CD4 cells a year after infection. Some people can live 10 or more years after infection with very little loss of CD4 cells.

Over time the virus can gain the upper hand on the body's immune system. The amount of HIV in the body (viral load) increases and the CD4+ cell count declines. This is the symptomatic period, characterized by enlarged lymph glands, tiredness, weight loss, fever, chronic diarrhea, yeast infections and other conditions that may last several years.

The immune system cannot work properly under constant attack from HIV. Eventually, the virus overwhelms the defenses of the immune system, which then can no longer ward off other illness-causing infections, some of which can be life threatening. When the CD4+ cell count is less than 200 (a healthy immune system has a CD4+ cell count of 800 – 1200) or there has been an opportunistic infection, a person is diagnosed with AIDS. This diagnosis is somewhat arbitrary since someone's cell count can improve and rise, and/or overcome the opportunistic infection, but medically they still carry an AIDS diagnosis.

Opportunistic infections are infectious diseases and cancers that make people with low immunity sick. For people with healthy immune systems, exposure to these diseases would cause no problems. The most common Opportunistic Infections (OI's) are pneumocystis carinii pneumonia (PCP), Mycobacterium Avium complex (MAC), Cytomegalovirus (CMV), Kaposi's sarcoma (KS), chronic yeast infections, and invasive cervical cancer.

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