There are good reasons why you should still consider having safer sex even if you are HIV-positive.

First of all, you might infect somebody else with HIV. In England, there have been cases of men being sent to prison for infecting their sexual partners with HIV, and two men have also been imprisoned in Scotland for this.

Then there’s the issue of sexually transmitted infections, which at the very least can be unpleasant and inconvenient, and can also make it more likely that you can pass on HIV during sex. If left untreated, some sexually transmitted infections can cause serious health problems, particularly if your immune system is very weak.

There is some evidence that unsafe sex might damage the health of people with HIV and several cases of reinfection or superinfection with drug-resistant strains of HIV have now been recorded.

For more information see the chapter Sex and HIV.

Reinfection/superinfection

Although it is clearly established that drug-resistant HIV can be transmitted to previously uninfected people, it is less clear if it can be transmitted to people already infected with HIV. There have, however, been over 20 case reports from around the world of HIV-positive people being reinfected with another strain of HIV after having unprotected sex – and doing less well on their HIV treatment as a consequence.

It seems that reinfection is, however, rare. All but one of the cases reported so far were in people who had had HIV for less than four years and none of these recently-infected people were taking HIV treatment. However, one case of reinfection has been reported in a gay man with long-term HIV infection. He had a lot of unsafe sex and had resistance to most of the available anti-HIV drugs.

Reinfection is quite a controversial subject. It is being looked at very closely by doctors around the world, and more information is being published on it all the time.

Co-factors

Although there are these doubts about the importance of re-infection with HIV, there are reasons to believe that other virus infections and sexually transmitted infections may speed up disease progression.

In the first place, many infections are likely to cause HIV to reproduce simply because they stimulate the immune system. That immune response will include the activation of latent HIV in immune cells, leading to the production of new HIV and the infection of further cells.

For instance, after being infected with cytomegalovirus (CMV), people with HIV infection have been shown to experience increases in HIV viral load. But CMV and some other viruses can also assist HIV in the infection of new cells, and speed up HIV replication in cells which are infected with both HIV and CMV. The same goes for other herpes viruses, Epstein-Barr virus (which causes glandular fever) and hepatitis B virus. All these viruses have the potential to provide `keys' to cells which HIV would otherwise be unable to infect. Almost all of these viruses are transmitted through sexual or body fluid contact.

Sexually transmitted infections

For most people with HIV, standard treatments for sexually transmitted infections work just as well as they do in HIV-negative people.

However, if your immune system is very weak, you might need a longer course of antibiotics to treat infections such as gonorrhoea and syphilis.

Viral sexually transmitted infections can also be more serious and harder to treat if you have HIV. For example, people with HIV may be at greater risk of having more frequent and more painful attacks of genital herpes.

In people with HIV, it can also be harder for the immune system to clear infection with HPV, the virus that causes genital and anal warts. Some strains of this virus can cause cervical and anal cancer, and even after the introduction of anti-HIV treatments, doctors have seen an increase in the incidence of these cancers in people with HIV.

Hepatitis B virus is also sexually transmittable, and people with HIV are recommended to be vaccinated against it. There's evidence that hepatitis C virus can also be sexually transmitted.

Oral-anal contact, or rimming, can lead to gut infections.

It is up to each individual to decide what sex practices they want to keep up, which they want to modify, and which they want to stop. For instance, one might still make the choice not to use condoms for penetrative sex with a regular HIV-positive partner. At the other end of the spectrum, one might decide to begin to use condoms for oral sex.