People diagnosed HIV+ have fewer sexual partners: down from one a week
to one every two weeks, but still have "unprotected sex" more often
than not.

<http://www.aidsmap.com/en/news/AEA1B5A5-CDDC-455B-8B8D-5C8E475FFA99.asp>:

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Investigators wished to know if individuals diagnosed with acute HIV
infection were selecting new sexual partners of the same HIV status.
The selection of partners of the same HIV status is often called
serosorting.

The study involved patients aged 18 years or older with laboratory
evidence of acute HIV infection. These individuals completed two
questionnaires, the first soon after their HIV diagnosis and the
second eight weeks later. These questionnaires were designed to obtain
demographic details, health history, sexual risk behaviour, use of
drugs and alcohol and mental health state.

In particular, individuals were asked to provide information on the
number of instances of anal or vaginal sex (with or without condoms)
in the eight weeks before diagnosis with primary HIV infection and in
the weeks that followed diagnosis. They were asked to say if their
partners were perceived to be HIV-positive, HIV-negative or of unknown
HIV infection status.

[...]

The mean number of sexual partners declined significantly after
diagnosis with primary HIV infection from a mean of approximately nine
in the eight weeks before diagnosis to a mean of three in the first
five weeks after diagnosis with a mean of a further three partners in
the next five weeks (reduction in the number of sexual partners, p <
0.05).

What’s more, the investigators noted that the number of partners who
were HIV-positive increased significantly after diagnosis with acute
HIV infection (p < 0.001). In the eight weeks before diagnosis, the
majority of new partners were perceived to be HIV-negative, but in the
ten weeks following diagnosis with acute HIV infection, individuals
reported a mean of one HIV-negative partner, one partner of unknown
HIV infection status, and a mean of 4.5 HIV-positive partners.

Condom use increased after diagnosis. In the eight weeks before
diagnosis with acute HIV infection, individuals reported a mean of
twelve acts of unprotected sex and three acts of protected sex. But in
the ten weeks after diagnosis, the patients reported a mean of 18 acts
of unprotected sex and eight instances of protected sex. This increase
in condom use was statistically significant (p < 0.001).

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