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HIV and Opportunistic Infections, Coinfections, and Conditions

What is an Opportunistic Infection?

Last Reviewed: September 16, 2020

Key Points

  • Opportunistic infections (OIs) are infections that occur more often or are more severe in people with weakened immune systems than in people with healthy immune systems. People with weakened immune systems include people living with HIV.
  • HIV damages the immune system. A weakened immune system makes it harder for the body to fight off OIs.
  • HIV-related OIs include pneumonia, Salmonella infection, candidiasis, toxoplasmosis, and tuberculosis (TB).
  • For people with HIV, the best protection against OIs is to take HIV medicines every day. HIV medicines prevent HIV from damaging the immune system. Because HIV medicines are now widely used in the United States, fewer people with HIV get OIs.

 

Word cloud containing the names of various opportunistic infections. 

What is an opportunistic infection?

Opportunistic infections (OIs) are infections that occur more often or are more severe in people with weakened immune systems than in people with healthy immune systems. People with weakened immune systems include people living with HIV.

OIs are caused by a variety of germs (viruses, bacteria, fungi, and parasites). OI-causing germs spread in a variety of ways, for example in the air, in body fluids, or in contaminated food or water.

Some OIs that people with HIV may get include candidiasis, Salmonella infection, toxoplasmosis, and tuberculosis (TB). The Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents with HIV provide detailed information on HIV-related OIs.

Why do people with HIV get OIs?

Once a person has HIV, the virus begins to multiply and to damage the immune system. A weakened immune system makes it harder for the body to fight off OIs.

HIV medicines prevent HIV from damaging the immune system. But without treatment with HIV medicines, HIV can gradually destroy the immune system and advance to AIDS. Many OIs, for example, certain forms of pneumonia and TB, are considered AIDS-defining conditions. AIDS-defining conditions are infections and cancers that are life-threatening in people with HIV.

Are OIs common in people with HIV?

OIs are less common among people with HIV in the United States now than they were in the past. Because HIV medicines are now widely used in the United States, fewer people with HIV get OIs. By preventing HIV from damaging the immune system, HIV medicines reduce the risk of OIs.

However, OIs are still a problem for many people with HIV. Some people with HIV get OIs for the following reasons: 

  • They may not know that they have HIV. Because of this, they are not getting HIV treatment. An OI may be the first sign that they have HIV.
  • They may know that they have HIV, but they are not getting HIV treatment.
  • They may be getting HIV treatment, but the HIV medicines are not controlling their HIV.

What can people with HIV do to prevent getting an OI?

For people with HIV, the best protection against OIs is to take HIV medicines every day.

People living with HIV can also take the following steps to reduce their risk of getting an OI.

Avoid contact with the germs that can cause OIs.
The germs that can cause OIs can spread in a variety of ways, including in body fluids or in feces. To avoid sexually transmitted infections, use condoms every time you have sex. If you inject drugs, don’t share drug injection equipment. After any contact with human or animal feces, wash your hands thoroughly with warm, soapy water.

Ask your health care provider about other ways to avoid the germs that can cause OIs.

Be careful about what you eat and drink.
Food and water can be contaminated with OI-causing germs. To be safe, don’t eat certain foods, including undercooked eggs, unpasteurized dairy products or fruit juices, or raw seed sprouts.

In addition, do not drink water directly from a lake or river. For more information, read the ClinicalInfo HIV and Nutrition and Food Safety fact sheet.

Travel safely.
If you are visiting a country outside the United States, avoid eating food and drinking water that could make you sick. Before you travel, read the CDC fact sheet on Traveling with HIV.

Get vaccinated.
Talk to your health care provider about which vaccines you need. To learn more, read the ClinicalInfo fact sheet on HIV and Immunizations.

Can OIs be treated?

There are many medicines to treat HIV-related OIs, including antiviral, antibiotic, and antifungal drugs. The type of medicine used depends on the OI.

Once an OI is successfully treated, a person may continue to use the same medicine or an additional medicine to prevent the OI from coming back.

The Clinicalinfo Drug Database includes information on many of the medicines used to prevent and treat OIs.

This fact sheet is based on information from the following sources: