Opportunistic Infection

An opportunistic infection happens when pathogens (germs) affect people whose immune systems aren’t working as well as they should (immunocompromised). If your immune system was healthy, the infection would be mild, or you wouldn’t have one at all. Examples of opportunistic pathogens include:

• Bacteria
• Fungi
• Parasites
• Viruses

You may have a weakened immune system for many reasons. Some conditions you have at birth (congenital conditions) may affect your immune system. But medications/therapies or conditions you get later in life can also harm it.

Opportunistic infections (OIs) are serious and even life-threatening. If you have a compromised immune system and show symptoms of an OI, don’t wait — get in touch with a healthcare provider.

What is an example of an opportunistic infection?

Common examples of opportunistic infections include:

Bacterial infections

• Mycobacterium avium complex (MAC)
• Salmonella
• Tuberculosis (TB)

Fungal infections

• Candidiasis
• Histoplasmosis
• Valley fever (coccidioidomycosis)

Parasitic infections

• Cryptosporidiosis
• Cystoisosporiasis
• Toxoplasmosis

Viral infections

• Cytomegalovirus (CMV)
• Herpes simplex virus 1 (HSV-1)
• Kaposi’s sarcoma (caused by the Kaposi’s sarcoma herpesvirus or human herpesvirus 8)

What are the symptoms of opportunistic infections?

There is a wide range of opportunistic infections, so symptoms vary. But some of the most common opportunistic infection symptoms include:

• Body aches
• Chills
• Fever
• Headache
• Loss of appetite
• Night sweats
• Swollen lymph nodes
• Unexplained weight loss

How does a person get an opportunistic disease?

There are many ways in which you can come across germs that cause opportunistic infections. You might inhale germs from the air around you, or eat or drink a contaminated food or drink. Some of the most common sources of opportunistic germs include:

• Drinking unpasteurized juices or dairy
• Drinking untreated water
• Eating unwashed fruits and vegetables
• Eating undercooked eggs and meat
• Encountering animal poop (feces)
• Encountering the bodily fluids (blood, pee, saliva) of an infected person

Risk factors

You’re at greater risk of an opportunistic infection if you:

• Have cancer or a personal history of cancer. Some types of cancer, like leukemia and lymphoma, can affect your white blood cells (lymphocytes). These cells help your immune system fight viruses and bacteria.
• Have HIV or AIDS. These conditions infect and destroy T cells in your immune system, increasing the risk of opportunistic infections.
• Have primary immunodeficiency. This is when you have a genetic variation at birth that weakens your immune system. It may also occur later in life, when your immune system gets weaker with age.
• Take certain medications or use certain therapies. A weakened immune system is a side effect of chemotherapy, corticosteroids, immunomodulators, immunosuppressants and radiation therapy.

How doctors diagnose opportunistic infections

A healthcare provider will ask about your symptoms and medical history, then do a physical exam. To help confirm their diagnosis, they may recommend testing. These tests may include:

• Analysis of the fluid around your brain and spinal cord (lumbar puncture)
• Blood tests
• Imaging tests, including a CT scan, MRI or X-ray
• Sputum culture
• Throat culture
• Pee tests (urinalysis)

How do you treat opportunistic infections?

It depends on the type of infection you have. Possible treatments include:

• Antibiotics
• Antifungals
• Antiparasitic drugs
• Antivirals
• Antiretroviral therapy

Even after you feel better, a healthcare provider may recommend staying on the same medicine or taking something else to keep the infection from coming back (prophylaxis).

When should I see my healthcare provider?

Contact a healthcare provider right away if you have a compromised immune system and develop symptoms of an infection. Let them know:

• About any animal exposure, including animal poop
• About any recent bug bites or stings
• If you ate or drank anything that may have been contaminated
• Of any recent travels

You may also wish to ask a provider questions to help understand your condition and learn how to get and stay healthy. These may include:

• What type of opportunistic infection do I have?
• What treatment do you recommend?
• How long will it take to feel better?
• What should I do if my symptoms don’t get better?
• What new symptoms should I be aware of?
• What can I do to protect myself from future infections?
• How often should I schedule follow-up appointments?
• How do I prevent spreading an infection to someone with a compromised immune system?

What can I expect if I have an opportunistic infection?

Opportunistic infections are serious and can be hard to treat. But healthcare providers can help you stay healthy with regular checkups and preventive care.

Can opportunistic infections be prevented?

The following tips can help you prevent OIs:

• Prevent infections
• Food and water safety
• General wellness
• Reduce risks

Prevent infections

• Avoid bodily fluids
• Avoid others who are sick
• Regularly wash your hands, especially after using the bathroom and encountering animals
• Wear a mask in crowded areas

Food and water safety

• Don’t consume undercooked eggs or meat, raw seed sprouts and unpasteurized dairy products and juices
• Drink bottled water or boil water before drinking it in areas where the water supply may not be safe
• Eat healthy food every day
• Thoroughly wash fruits and veggies before you eat them

General wellness

• Get regular physical activity
• Schedule regular visits with a healthcare provider
• Talk to a provider about what medications and vaccines they recommend to help keep you healthy
• Talk to a provider about whether you should take vitamins

Reduce risks

• Manage anxiety and stress
• Use condoms every time you have sexual intercourse
• Never share needles, syringes or other equipment that can inject drugs
• Wear long sleeves and pants, and use bug spray to protect yourself from insect bites

Is pneumonia an opportunistic infection?

Healthcare providers don’t usually consider pneumonia an opportunistic infection because anyone can get it. Many kinds of bacteria and viruses can cause pneumonia. But certain fungi — like Cryptococcus, Pneumocystis jirovecii and Coccidioides — are more likely to cause pneumonia in people with compromised immune systems. Healthcare providers consider pneumonia from these causes to be opportunistic infections.