Is it unusual for an HIV-infected person to progress to AIDS quickly -- in less than a week, for example? The information I've read indicates the disease develops slowly, but I have witnessed a case in which the patient progressed from HIV status to AIDS to death in less than two months.

N.J.

Let's define some terms. HIV (which stands for human immunodeficiency virus) is the virus that causes AIDS. AIDS (acquired immune deficiency syndrome) is really just the name for a variety of severe medical manifestations of HIV infection.

On average, without treatment, a person progresses from infection to AIDS in about seven to 10 years. This is a rough estimate that varies somewhat depending on how the patient contracted HIV. In general, the rate of progression seems to be higher for those who are infected through blood contact, rather than through sex. Transfusion recipients may be the fastest to progress, on average in about seven years. Hemophiliacs and injection drug users are next fastest. Homosexual men tend to progress a little more slowly. These are generalizations, of course, and an individual's rate of progression may be quite different.

The average time from HIV infection to death is 10-12 years. The most rapid rate of progression from HIV infection to death from AIDS has been about six months. There may have been undocumented cases of somewhat faster progression, but that would be very rare.

I have a possible explanation for the case you witnessed. Perhaps the patient you describe was infected with HIV for quite a while but did not know he or she had it. The person was eventually diagnosed with HIV infection and, soon thereafter, AIDS.

If the patient you described had recently tested negative for HIV, then maybe the negative test result was false. That would make the infection appear to have occurred more recently than it really did. There are various causes of a false-negative test result, but fortunately they are rare. First, infection with a few rare strains of HIV can cause the test to remain negative. Second, in some patients with advanced immune dysfunction, the HIV test becomes negative because the body is not producing the disease-fighting antibodies that most HIV tests measure. Other extremely rare causes of a false-negative result include congenital diseases that cause antibody deficiencies and infection with HIV-2, a variant of HIV that is found mostly in Africa.