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From: aberno@questor.wimsey.bc.ca (Anthony Berno)
Newsgroups: sci.med.aids
Subject: Time to illness
Message-ID: <1991Jan19.230925.5335@cs.ucla.edu>
Date: 19 Jan 91 17:31:47 GMT
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liz@ai.mit.edu (Liz A. Highleyman) writes:

> I was under the impression that the time between infection with HIV and
> the development of illness was somewhere in the area of 5 years.  Yet
> I have also heard that people who received transfusions of infected
> blood (early in the epidemic) were known to get sick within a few months.
> How can this be?  Is it taking longer and longer for people to develop
> OIs?  Does this indicate that HIV is perhaps becoming less virulent?
> 
> -Liz

Actually, the time from infection to the onset of noticeable symptoms 
averages almost 8-10 years! I read a number of articles on the
subject that discussed the onset time of the disease - for a person
infected "today", symptoms will take an average of about 10 years to
appear. The typical scenario is that nothing happens for two years, then
T-cell counts drop from their normal 1000 by about 100  per year. When the
counts hit about 200, you start to get sick.

Curiously, there is a little statistical anomaly in that the average person
developing AIDS today was infected only 6-7 years ago. This is due to the
skewed profile of the epidemic (well, ALL epidemics are like that...) i.e.
most people infected with HIV were infected recently, so that those
that deveop the disease early are disproportionatly represented.

Keep in mind that HIV is not a carefully timed clock - as always, some
people will develop the disease immediately, others will take many many 
years. I have heard of no difference correlated with the mode of infection,
but then I have been a little out of touch.

Sorry, I can never remember my sources for my statistics. I think the 
above ones were from a March issue of Science?