Other sexually transmitted infections (STIs)

Other STIs in either the HIV negative or HIV positive partner can increase the risk of HIV transmission.

STIs include:

  • Chlamydia.
  • Genital warts (HPV – human pappiloma virus).
  • Gonorrhea.
  • Syphilis.
  • Herpes.
  • LGV (lymphogranuloma venereum).
  • Hepatitis A and B.
  • Hepatitis C (for HIV positive gay men).
  • Trichomoniasis.

STIs can reduce immune protection against other infections in HIV negative people.

An HIV negative person with an STI has an activated immune system. This increases the number of cells that HIV needs to infect. So HIV has a better chance of finding one of these cells. See Fig 10 (c) in the section Skin, mucous membranes and HIV transmission.

With herpes, for example, HIV target cells stay at much higher levels even weeks after a sore has cleared up.

This is why HIV negative people with herpes, are at higher risk of catching HIV, even when they have no current sores.

Any STI that causes a sore makes an easy way for HIV to enter the body.

An HIV positive person with an STI may be more infectious for HIV. This may also cause their undetectable viral load in blood to be at higher levels in genital fluid.

HIV positive people may also be at greater risk of catching STIs. For example, hepatitis C (HCV) is sexually transmitted for HIV positive gay men but rarely from heterosexual sex. The reasons for this are not clear.

HCV is usually transmitted by contact with infected blood.

Last updated: 1 June 2016.