If HIV-positive people become infected with another sexually transmitted infection, this will often follow a worse clinical course and be more difficult to treat than in HIV-negative people. Furthermore the risk of HIV transmission is markedly higher.
Easier HIV transmission
In most STIs, the mucous membranes in the genital area become inflamed. This inflammation forms ideal entry and exit points for HIV. The transmission risk is up to 16 times higher in the case of acute genital herpes, for example, and 3 to 5 times higher with a syphilis infection. This is why HIV-positive people are markedly more infectious if they are additionally suffering from a sexually transmitted infection. Due to their weakened immune system, people with HIV are more prone to infection with sexually transmitted diseases.
Usually a more severe clinical course
Sexually transmitted infections often follow a different clinical course in HIV-positive people to that occurring in HIV-negative people. The repercussions are usually more serious. This applies particularly to herpes, human papilloma virus, syphilis and chlamydia.
Difficult to treat
Special challenges often arise as far as treating sexually transmitted infections is concerned: because of interactions, the treatments have to be adapted to the HIV therapy. Some STIs in HIV-positive people additionally require a longer treatment time (e.g. chlamydia, candida).
HIV and hepatitis C
Anyone infected with both HIV and the hepatitis C virus has a hepatitis C/HIV co-infection. Hepatitis literally means "inflammation of the liver". It can have a variety of causes, one being sharing needles when using drugs. While hepatitis A will cure itself, hepatitis B and C can become chronic conditions, i.e. they never go away. You can be vaccinated against both hepatitis A and hepatitis B.
A hepatitis C infection can be detected by a blood test, and is basically curable nowadays.
HIV and tuberculosis
Tuberculosis is the most common AIDS-defining illness around the world. People with HIV respond well to tuberculosis treatment. HIV and tuberculosis therapies can be very complex, however, so you should speak to your doctor about which is best for you.