Fungi are everywhere. Sometimes, they are too small to see with the naked eye. Fungi live:

There are millions of fungal species, but only a few hundred of them can make people sick. Molds, yeasts, and mushrooms are all types of fungi.

Fungi can cause many different types of illnesses, including:

• Asthma or allergies. Learn more about mold and how it can affect your health.
• Rashes or infections on the skin and nails
• Lung infections (pneumonia), with symptoms similar to the flu or tuberculosis
• Bloodstream infections
• Meningitis

If you have ever had athlete's foot or a yeast infection, you can blame a fungus. A fungus is a primitive organism. Mushrooms, mold and mildew are examples. Fungi live in air, in soil, on plants and in water. Some live in the human body. Only about half of all types of fungi are harmful.

Some fungi reproduce through tiny spores in the air. You can inhale the spores or they can land on you. As a result, fungal infections often start in the lungs or on the skin. You are more likely to get a fungal infection if you have a weakened immune system or take antibiotics.

Fungi can be difficult to kill. For skin and nail infections, you can apply medicine directly to the infected area. Oral antifungal medicines are also available for serious infections.

Most common fungal diseases

Fungal diseases that affect people who live in or travel to certain areas

Fungal diseases that affect people with weakened immune systems

Weakened immune systems can’t fight off infections as well, due to conditions such as HIV, cancer, organ transplants, or certain medications.

Other diseases and health problems caused by fungi

Anyone can get a fungal infection, even people who are otherwise healthy. Fungi are common in the environment, and people breathe in or come in contact with fungal spores every day without getting sick. However, in people with weakened immune systems, these fungi are more likely to cause an infection.

People with weakened immune systems

Opportunistic infections are infections that happen because a person’s immune system is weakened. These illnesses can be caused by bacteria, viruses, or fungi. Many fungal infections are opportunistic infections.

Fungal infections can also happen in people without weakened immune systems

Fungal infections that are not life-threatening, such as skin, nail, or vaginal yeast infections, are common.

Some infections can be more serious. Lung infections like Valley fever or histoplasmosis can happen in people who live in or visit certain areas.

What weakens an immune system?

Some people are born with a weakened immune system. Others may have an illness that attacks the immune system such as HIV.  Some medicines, like corticosteroids or cancer chemotherapy, can also lower the body’s ability to fight infections.

If you have a weakened immune system, you should be aware that fungal infections can happen. Learning about fungal infections can help you and your doctor recognize them early. This may help prevent serious complications.

As a person living with HIV/AIDS, you have many opportunities for a healthy and full life. You may also have some health challenges. One of those challenges is avoiding infections.

Many fungal infections are called opportunistic infections, which means that they usually affect people with weak immune systems. Because HIV weakens the immune system, you have a greater chance of getting some types of fungal infections, like cryptococcosis, coccidioidomycosis, histoplasmosis, and pneumocystis pneumonia (PCP).

What you need to know about fungal infections

Your CD4 count is important. You’re at greatest risk for fungal infection when your CD4 count is less than 200. Keeping your CD4 count above 200 may help you avoid serious illness.

Anti-retroviral therapy (ART) is important. Starting ART helps slow the progress of HIV and can reduce your chances of getting a fungal infection.

Fungal infections can range from mild to life-threatening. Some fungal infections are mild skin rashes, but others can be deadly, like fungal meningitis. Because of this, it’s important to seek treatment as soon as possible to try to avoid serious infection.

Fungal infections can look like bacterial or viral infections. If you’re taking medicine to fight an infection and you aren’t getting better, ask your doctor about testing you for a fungal infection.

Where you live (geography) matters. Some disease-causing fungi are more common in certain parts of the world. If you have HIV/AIDS and live in or visit these areas, you’re more likely to get these infections than the general population.

Your activities matter. Disease-causing fungi can be found in air, dust, and soil, especially soil that contains bird or bat droppings. Doing activities that disturb the soil, like gardening, cleaning chicken coops, construction, demolition, and visiting caves can cause you to inhale more fungi and increases your chance of infection.

Some fungal infections can interfere with taking your medications. Thrush, an infection in the mouth and throat, is sometimes seen among people living with HIV/AIDS. This infection is not usually life-threatening, but can be painful, make it difficult to eat, or interfere with taking your medications. Your nutrition is an important part of staying healthy, so it’s important to seek care for this infection.

Preventing fungal infections in people living with HIV/AIDS

Fungi are difficult to avoid because they are a natural part of the environment. Fungi live outdoors in soil, on plants, trees, and other vegetation. They are also on many indoor surfaces and on your skin. However, there may be some ways for you to lower your chances of getting a serious fungal infection.

Learn about fungal infections. There are different types of fungal infections. Learning about them can help you and your healthcare provider recognize the symptoms early, which may prevent serious illness.

Find out about your risk. The danger of getting a fungal infection can change depending on your location and your CD4 count. Learning what things can put you at risk may prevent serious illness.

Get additional medical care if necessary. Fungal infections often resemble other illnesses. Visiting your healthcare provider may help with faster diagnosis and may prevent serious illness.

Antifungal medication. Your healthcare provider may prescribe medication to prevent fungal infections. For example, they may recommend medication (TMP-SMX, also called Bactrim, Septra, or Cotrim) to prevent a type of fungal pneumonia called Pneumocystis jirovecii pneumonia (PCP).

Protect yourself from the environment. There may be some ways to lower your chances of getting a serious fungal infection by trying to avoid disease-causing fungi in the environment. It’s important to note that although these actions are recommended, they have not been proven to prevent fungal infections.

• Try to avoid areas with a lot of dust like construction or excavation sites.
• Stay inside during dust storms.
• Stay away from areas with bird and bat droppings. This includes places like chicken coops and caves.
• Wear gloves when handling materials such as soil, moss, or manure.
• Wear shoes, long pants, and a long-sleeved shirt when doing outdoor activities such as gardening, yard work, or visiting wooded areas.

Testing for early fungal infection. In areas of the world with high rates of HIV/AIDS and where cryptococcosis is common, high-risk HIV patients can be tested for this infection before symptoms appear. If the test detects early cryptococcal infection, treatment can prevent it from becoming deadly.

As an organ transplant patient, you have new opportunities for a healthy and full life. You may also have some new health challenges. One of those challenges is avoiding infections. While anti-rejection medication helps you accept the new organ by lowering your body’s immune system response, it can also put you at greater risk for fungal infections.

What you need to know about fungal infections

Fungal infections can range from mild to life-threatening. Some fungal infections are mild skin rashes, but others can be deadly, like fungal pneumonia. Because of this, it’s important to seek treatment as soon as possible to try to avoid serious infection.

Fungal infections can look like bacterial or viral infections. If you’re taking medicine to fight a bacterial or viral infection and you aren’t getting better, ask your doctor about testing you for a fungal infection.

Fungal infections may be more common in certain types of transplants. Some experts think that fungal infections may be most common in small bowel transplant patients, followed by lung, liver, and heart transplant patients.

Where you live (geography) matters. Some disease-causing fungi are more common in certain parts of the world. If you have had an organ transplant and live in or visit these areas, you’re more likely to get these infections than the general population.

Your hospital stay matters. After your transplant, you may need to stay in the hospital for a long time. While there, you may need procedures that can increase your chance of getting a fungal infection.

Fungal infections can happen any time after your surgery. Fungal infections can happen days, weeks, months, or years after the transplant surgery.

Some types of fungal infections are more common than others in solid organ transplant patients. In the United States, invasive candidiasis is most common, followed by aspergillosis and cryptococcosis, but other types of fungal infections are also possible. For lung transplant patients, aspergillosis is most common.

Indoor mold. You may be at higher risk for getting sick from indoor mold.

Preventing fungal infections in organ transplant patients

Fungi are difficult to avoid because they are a natural part of the environment. Fungi live outdoors in soil, on plants, trees, and other vegetation. They are also on many indoor surfaces and on your skin. However, there may be some ways you to lower your chance of getting a serious fungal infection.

Learn about fungal infections. There are different types of fungal infections. Learning about them can help you and your healthcare provider recognize the symptoms early, which may prevent serious illness.

Get additional medical care if necessary. Fungal infections often resemble other illnesses. Visiting your healthcare provider may help with faster diagnosis and may prevent serious illness.

Antifungal medication. Your healthcare provider may prescribe medication to prevent fungal infections. Scientists are still learning about which transplant patients are at highest risk and how to best prevent fungal infections.

Protect yourself from the environment. As you recover from your surgery and start doing your normal activities again, there may be some ways to lower your chances of getting a serious fungal infection by trying to avoid disease-causing fungi in the environment. It’s important to note that although these actions are recommended, they have not been proven to prevent fungal infections.

• Try to avoid areas with a lot of dust like construction or excavation sites.
• Stay inside during dust storms.
• Stay away from areas with bird and bat droppings. This includes places like chicken coops and caves.
• Wear gloves when handling materials such as soil, moss, or manure.
• Wear shoes, long pants, and a long-sleeved shirt when doing outdoor activities such as gardening, yard work, or visiting wooded areas.

As a cancer patient, you may have received a lot of information about your treatment and your journey to recovery. Chemotherapy and radiation cause many changes in the body as they destroy cancer cells. One major change is that these treatments weaken your immune system, which can increase your chances of getting an infection, including a fungal infection.

Stem cell transplant patients or those who have a blood (hematologic) cancer such as leukemia, lymphoma, or myeloma may have different risks for fungal infections.

What you need to know about fungal infections

Chemotherapy and radiation lower your white blood cell count. As you receive your cancer treatment, your white blood cell count can become very low, also known as neutropenia. During this time, your body will have trouble fighting infections, including fungal infections.

Fungal infections can range from mild to life-threatening. Some fungal infections are mild skin rashes, but others can be deadly, like fungal pneumonia. Because of this, it’s important to seek treatment as soon as possible to try to avoid serious infection.

Fungal infections can look like bacterial or viral infections. If you’re taking medicine to fight an infection and you aren’t getting better, ask your doctor about testing you for a fungal infection.

The type of cancer you have can affect your risk. If you have a blood cancer like leukemia or myeloma, you may be at greater risk for getting a fungal infection than people with other types of cancer.

Your risk of infection can change based on the strength of your chemotherapy. Some types of cancer may require stronger chemotherapy medication than others, especially the blood cancers. This is sometimes known as aggressive chemotherapy. Aggressive chemotherapy weakens your immune system and can put you at risk for getting a fungal infection.

Your hospital stay matters. After your transplant, you may need to stay in the hospital for a long time. While there, you may need to have procedures that can increase your chance of getting a fungal infection.

Where you live (geography) matters. Some disease-causing fungi are more common in certain parts of the world. If you live in or visit these areas and have cancer, you may be more likely to get these infections than the general population.

Preventing fungal infections in cancer patients

Fungi are difficult to avoid because they are a natural part of the environment. Fungi live outdoors in soil, on plants, trees, and other vegetation. They are also on many indoor surfaces and on your skin. However, there may be some ways for you to lower the chances of getting an infection, including a serious fungal infection.

Learn about fungal infections. There are different types of fungal infections. Learning about them can help you and your healthcare provider recognize the symptoms early, which may prevent serious illness.

Know if your white blood cell count is low. Having a very low white blood cell count (neutropenia) can put you at greater risk of infection.

Get additional medical care if necessary. Fungal infections often resemble other illnesses. Visiting your healthcare provider may help with faster diagnosis and may prevent serious illness.

Antifungal medication. Your healthcare provider may prescribe medication to prevent fungal infections. Scientists are still learning about which patients are at highest risk and how to best prevent fungal infections.

Protect yourself from the environment. As you recover from chemotherapy and start doing your normal activities again, there may be some ways to lower the chances of getting a serious fungal infection by trying to avoid disease-causing fungi in the environment. It’s important to note that although these actions are recommended, they have not been proven to prevent fungal infections.

• Try to avoid areas with a lot of dust like construction or excavation sites.
• Stay inside during dust storms.
• Stay away from areas with bird and bat droppings. This includes places like chicken coops and caves.
• Wear gloves when handling materials such as soil, moss, or manure.
• Wear shoes, long pants, and a long-sleeved shirt when doing outdoor activities such as gardening, yard work, or visiting wooded areas.

Even though you’re staying in the hospital to get better, it’s possible to get an infection while you’re there. If you’re staying in the hospital for an injury or an illness, you may be at risk for getting a fungal infection, especially if you’re very sick or have a weak immune system. These types of infections are called healthcare-associated infections (HAIs).

Hospital staff and healthcare providers do everything they can to prevent HAIs, but some procedures and situations can increase your risk for fungal HAIs. The information provided below can help you understand your risk and help you be a safe patient while hospitalized.

What you need to know about fungal infections

Fungal infections can range from mild to life-threatening. Some fungal infections are mild skin rashes, but others can be deadly, like fungal pneumonia. Because of this, it’s important to get treatment as soon as possible to try to avoid serious infection.

Life-saving devices like central venous catheters (a special kind of IV tube) can increase your risk for fungal infection. During your hospital stay you may need a central venous catheter, which is a tube placed into a vein to give medications or liquids. This can make it easier for fungi to enter your body and increase your chances of getting a fungal bloodstream infection such as candidemia.

Disease-causing fungi can enter your body through cuts, wounds, and burns. Fungi naturally live on your skin and on healthcare workers’ hands. These fungi can enter your body through cuts and wounds and cause infection during a hospital stay, especially if your wounds are severe.

Staying in the intensive care unit (ICU). If you’re in the ICU because you’re critically ill or injured, you’re likely to need life-saving devices or procedures that can put you at risk for fungal infections, particularly Candida and Aspergillus infections.

Surgery can lead to infection. If you’ve had surgery, it’s possible to get a fungal infection in in the part of the body where the surgery took place. Surgical site infections are often caused by bacteria, but can also be caused by fungi.

Hospital construction. Hospital staff do everything they can to prevent fungal infections. Despite this, outbreaks of aspergillosis have happened among very sick patients staying at hospitals where there is ongoing construction or renovation.This is thought to be because construction stirs up the amount of fungal spores in the air.

Preventing fungal infections in hospitalized patients

Fungi are difficult to avoid because they are a natural part of the environment. Fungi live outdoors in soil, on plants, trees, and other vegetation. They are also on many indoor surfaces and on your skin. However, there may be some ways for you to lower your chances of getting a serious fungal infection.

Learn about fungal infections. There are different types of fungal infections. Learning about them can help you and your healthcare provider recognize the symptoms early, which may prevent serious illness.

Take medications as directed. Your healthcare provider may prescribe antifungal medications to prevent fungal infections. Scientists are still learning about which patients are at highest risk and how best to prevent fungal infections.

Be a safe patient. There are some actions that you can take to help protect yourself from infections, including:

• Speak up. Talk to your doctor about any worries you have about your safety and ask them what they are doing to protect you.
• Keep hands clean. If you do not see your providers clean their hands, please ask them to do so. Also remind your loved ones and visitors. Washing hands can prevent the spread of germs.

What to do after leaving the hospital. If you have a weakened immune system, you may still be at risk for getting a fungal infection after you leave the hospital.

As a stem cell transplant patient, you have new opportunities for a healthy and full life. Stem cell transplants have many benefits, but they also have risks. Because stem cell transplants destroy and rebuild your immune system, they increase your risk for fungal infections.

There are two main types of stem cell transplants:

• Stem cells from your own body (also called an autologous transplant).
• Stem cells from a donor (also called an allogeneic transplant). The donor can be a family member or someone unrelated to you.

There are different reasons for receiving either type of transplant. You and your healthcare provider will discuss your options and choose the treatment that’s best for you.

What you need to know about fungal infections

A transplant using stem cells from a donor increases your risk for fungal infection more than a transplant that uses stem cells from your own body. If your stem cells come from another person, you will need to take anti-rejection medication. This medication weakens your immune system.

Chemotherapy and radiation lower your white blood cell count. As you recover from your transplant, your white blood cell count can become very low, also known as neutropenia [PDF – 4 pages].  During this time, your body will have trouble fighting infections, including fungal infections.

Graft-versus-host disease (GVHD). If you receive stem cells from a donor, the transplanted stem cells may attack your body. This is known as graft-versus-host disease, which can increase your risk for fungal infection. The steroid medications given to treat graft-versus-host disease can also increase the chance of getting a fungal infection.

Fungal infections can range from mild to life-threatening. Some fungal infections are mild skin rashes, but others can be deadly, like fungal pneumonia. Because of this, it’s important to seek treatment as soon as possible to try to avoid serious infection.

Fungal infections can look like bacterial or viral infections. If you’re taking medicine to fight an infection and you aren’t getting better, ask your doctor about testing you for a fungal infection.

Fungal infections can happen any time after your transplant. Fungal infections can happen days, weeks, or months after the stem cell transplant. If you develop GVHD, you’re at risk for a longer period of time.

Some types of fungal infections are more common than others in stem cell transplant patients. Aspergillosis is the most common type of fungal infection in stem cell transplant patients, followed by Candida infection and mucormycosis, but other types of fungal infections are also possible.

Your hospital stay matters. After your transplant, you may need to stay in the hospital for a long time. While there, you may need to have procedures that can increase your chance of getting a fungal infection. Please see the following sites for more information:

• Types of healthcare-associated infections
• Hospitalized patients and fungal infections

Where you live (geography) matters. Some disease-causing fungi are more common in certain parts of the world. If you live in or visit these areas, you may be more likely to get these infections than the general population.

Indoor mold. You may be at higher risk for getting sick from indoor mold.

Preventing fungal infections in stem cell transplant patients

Fungi are difficult to avoid because they are a natural part of the environment. Fungi live outdoors in soil, on plants, trees, and other vegetation. They are also on many indoor surfaces and on your skin. However, there may be some ways for you to lower the chances of getting a serious fungal infection.

Learn about fungal infections. There are different types of fungal infections. Learning about them can help you and your healthcare provider recognize the symptoms early, which may prevent serious illness.

Get additional medical care if necessary. Fungal infections often resemble other illnesses. Visiting your healthcare provider may help with faster diagnosis and may prevent serious illness.

Testing for early infection can help lower your risk for some types of fungal infection. Some patients may benefit from blood tests to detect fungal infections like aspergillosis before symptoms appear. Talk to your doctor to determine if this type of test is right for you.

Antifungal medication. Your healthcare provider may prescribe medication to prevent fungal infections. Scientists are still learning about which transplant patients are at highest risk and how to best prevent fungal infections.

Protect yourself from the environment. As you recover after surgery and start doing your normal activities again, there may be some ways to lower your chances of getting a serious fungal infection by trying to avoid disease-causing fungi in the environment. It’s important to note that although these actions are recommended, they have not been proven to prevent fungal infections.

• Try to avoid areas with a lot of dust like construction or excavation sites.
• Stay inside during dust storms.
• Stay away from areas with bird and bat droppings. This includes places like chicken coops and caves.
• Wear gloves when handling materials such as soil, moss, or manure.
• Wear shoes, long pants, and a long-sleeved shirt when doing outdoor activities such as gardening, yard work, or visiting wooded areas.

Overall, most serious fungal infections are rare, but they do happen. They are most common among people with weak immune systems. People with certain health conditions may need to take medications with side effects that can weaken your immune system and put you at risk for fungal infections.

Specifically, corticosteroids and TNF (tumor necrosis factor) inhibitors are two types of medications that can increase your chances of getting a fungal infection.

• Corticosteroids are medications that treat conditions including arthritis, asthma, allergic reactions, and autoimmune diseases such as lupus, sarcoidosis, or inflammatory bowel disease.
• TNF inhibitors are medications that treat autoimmune diseases such as rheumatoid arthritis, psoriasis, and inflammatory bowel disease.

Some fungal infections can be serious, such as:

• Coccidioidomycosis (Valley fever)
• Cryptococcosis (neoformans and gattii)
• Histoplasmosis
• Pneumocystis pneumonia (PCP)
• Invasive Candida infection
• Invasive aspergillosis

Other fungal infections, such as oral candidiasis (thrush), are usually not life threatening.

What you need to know about fungal infections

Fungal infections can range from mild to life-threatening. Some fungal infections are mild skin rashes, but others can have serious complications. Because of this, it’s important for you to seek treatment as soon as possible to avoid serious infection.

Fungal infections can look like bacterial or viral infections. If you’re taking medicine to fight an infection and you aren’t getting better, ask your doctor about testing you for a fungal infection.

Where you live (geography) matters. Some disease-causing fungi are more common in certain parts of the world. If you live in or visit these areas and are taking medications that weaken the immune system, you’re more likely to get these infections than the general population.

The length of your treatment matters. Your healthcare provider can prescribe corticosteroids for short-term use (days to weeks) or long-term use (weeks to months). Long-term corticosteroid use is more likely to increase your chance of getting a fungal infection.

Amount of medication (dose). Higher doses of medications that weaken your immune system are more likely to increase your risk of getting a fungal infection.

Click on the sections below to see lists of corticosteroids and TNF inhibitors that can increase the chances of getting a fungal infection.

Medications that can increase the chances of getting a fungal infection

Oral Corticosteroids

Corticosteroids taken by mouth can increase your chance of getting a serious fungal infection. Oral corticosteroids include the following:

• Budesonide (Entocort EC)
• Cortisone (Cortone)
• Dexamethasone (Decadron)
• Hydrocortisone (Cortef)
• Methylprednisolone (Medrol)
• Prednisolone (Prelone)
• Prednisone (Deltasone)
• Triamcinolone

Inhaled Corticosteroids

Inhaled corticosteroids used to treat asthma can increase your chance of developing oral candidiasis (thrush). Inhaled corticosteroids include the following:

• Beclomethasone (QVAR®)
• Budesonide (Pulmicort®, Symbicort®*)
• Ciclesonide (Alvesco®)
• Flunisolide (AeroBid®)
• Fluticasone (Flovent®, Advair®*)
• Mometasone (Asmanex Twisthaler®, Dulera®*)
• Triamcinolone (Azmacort®)

*a combination medication that also includes a bronchodilator

TNF Inhibitors

TNF inhibitors can increase your chance of getting a serious fungal infection, particularly histoplasmosis. TNF inhibitors include the following:

• Adalimumab (Humira®)
• Certolizumab pegol (Cimzia®)
• Etanercept (Enbrel®)
• Golimumab (Simponi®)
• Infliximab (Remicade®)

Preventing fungal infections while taking corticosteroids or TNF inhibitors

Fungi are difficult to avoid because they are a natural part of the environment. Fungi live outdoors in soil, on plants, trees, and other vegetation. They are also on many indoor surfaces and on your skin. However, there may be some ways for you to lower your chances of getting a serious fungal infection.

Learn about fungal infections. There are different types of fungal infections. Learning about them can help you and your healthcare provider recognize the symptoms early, which may prevent serious illness.

Get additional medical care if necessary. Fungal infections often resemble other illnesses. Visiting your healthcare provider may help with faster diagnosis and may prevent serious illness.

Protect yourself from the environment. While using these medications, there may be some ways to lower your chances of getting a serious fungal infection by trying to avoid disease-causing fungi in the environment. It’s important to note that although these actions are recommended, they have not been proven to prevent fungal infections.

• Try to avoid areas with a lot of dust like construction or excavation sites.
• Stay inside during dust storms.
• Stay away from areas with bird and bat droppings. This includes places like chicken coops and caves.
• Wear gloves when handling materials such as soil, moss, or manure.
• Wear shoes, long pants, and a long-sleeved shirt when doing outdoor activities such as gardening, yard work, or visiting wooded areas.

Here are 10 questions you can use to understand fungal infections and know what you need to do to stay healthy.

Fungi are everywhere. Sometimes, they are too small to see with the naked eye. Fungi can live outdoors in soil and on plants, indoors on surfaces and in the air, and on people’s skin and inside the body. There are millions of fungal species, but only a few hundred of them can make people sick.

Mild fungal skin infections can look like a rash and are very common. For example, ringworm is a skin infection caused by a fungus—not a worm. Fungal infections in the lungs can be more serious and often cause symptoms that are similar to other illnesses, such as bacterial pneumonia or tuberculosis. Finding the correct diagnosis can be difficult and cause delays in getting the right treatment. Fungal infections like meningitis and bloodstream infections are less common than skin and lung infections but can be life-threatening.

The more you know about fungal infections and your chances of getting one, the better you can protect your health.

Find Out If You’re At Risk Of Getting A Fungal Infection

1. Where do you live and travel? Fungi that can cause infections are more common in some parts of the United States and world. For example, in the United States, the fungus that causes Valley fever is found mainly in the Southwest and parts of the Pacific Northwest. Histoplasmosis and blastomycosis occur most often in the eastern United States.

2. What types of activities are you doing? Harmful fungi can be found in air, dust, and soil. You could inhale fungi during activities like digging, gardening, cleaning chicken coops, and visiting caves. Histoplasma grows especially well in soil that contains bird or bat droppings.

3. Do you have a dog or cat? People can get some fungal infections from their pets, including ringworm, which causes skin rashes. In South America, people can get infections from a fungus called Sporothrix brasiliensis from cats, and this fungus might arrive in the United States. If you think your pet might be sick, talk to your veterinarian.

4. Have you recently taken antibiotics? Antibiotics can make women more likely to get a vaginal yeast infection, also known as vulvovaginal candidiasis. Women who are pregnant or those who have weakened immune systems also are more likely to get this condition. Men also can get genital candidiasis.

5. Are you taking any medicine that affects your immune system? Medicine that weakens your immune system, like steroids, biologics, or chemotherapy, may increase the chance of getting a fungal infection.

6. Are you receiving chemotherapy or radiation treatments? Cancer treatment, such as chemotherapy and radiation, weakens your immune system. These treatments may increase the chance you will get a fungal infection.

7. Are you living with HIV? People living with HIV (particularly those with CD4 counts less than 200) may be more likely to get fungal infections. Two well-known fungal infections associated with HIV in the United States are oral candidiasis (thrush) and Pneumocystis pneumonia. Worldwide, cryptococcal meningitis and histoplasmosis are major causes of illness in people living with HIV.

8. Are you going to be hospitalized? In the United States, one of the most common bloodstream infections acquired in the hospital is caused by a fungus called Candida. Candida normally lives in the gastrointestinal tract and on skin without causing any problems, but it can enter the bloodstream and cause infection. A type of Candida called Candida auris is often resistant to antifungal medicines and can spread between patients in healthcare settings.

9. Have you recently had a transplant? People who recently had an organ transplant or a stem cell transplant have weakened immune systems. That means they have a greater chance of developing a fungal infection. Doctors prescribe antifungal medicine for some transplant patients to prevent fungal infections.

10. Do you have symptoms of pneumonia that are not getting better with antibiotics? Fungal infections, especially lung infections like Valley fever, histoplasmosis, and blastomycosis, can have similar symptoms as bacterial infections. However, antibiotics don’t work for fungal infections. Early testing for fungal infections reduces unnecessary antibiotic use and allows people to start treatment with antifungal medicine, if necessary.

Anyone can get a fungal infection, even people who are otherwise healthy. People breathe in or come in contact with fungal spores every day without getting sick. However, in people with weakened immune systems, these fungi are more likely to cause an infection. 

Fungal infections that resist treatment are a challenge to the public’s health.

The problem

Antifungal drugs treat fungal infections by killing or stopping the growth of dangerous fungi in the body. Fungi can develop resistance to antifungal drugs the same way bacteria can develop resistance to antibiotics. Resistance happens when germs develop the ability to defeat the drugs designed to kill them. That means the germs are not killed and continue to grow.

Currently, only a small number of antifungal drug types exist, so resistance can severely limit treatment options. Some types of fungi, like Candida auris, can become resistant to all the antifungal drugs normally used to treat these infections. Resistance is especially concerning for patients with invasive fungal infections—severe infections that affect the blood, heart, brain, eyes, or other parts of the body.

What causes antimicrobial-resistant fungi

Some species of fungi are naturally resistant to certain types of antifungal drugs. For example, the drug fluconazole does not work against infections caused by the fungus Aspergillus, a type of mold found throughout the environment. Resistance can also develop over time when fungi are exposed to antifungal drugs. This resistance can occur when antifungal drugs are used to treat sick people, especially if the drugs are used improperly (for example, when dosages are too low or when treatment courses are not long enough).

Use of fungicides in agriculture to prevent and treat fungal diseases in crops can also contribute to resistant disease in people. For example, when Aspergillus found in the environment is exposed to fungicides, which are similar to medical antifungal drugs, the Aspergillus can become resistant to the drugs used to treat infections in people. People can then breathe in those resistant Aspergillus spores from the environment and become sick.

Types of antimicrobial-resistant fungi

Resistant fungi include Aspergillus, certain Candida species, and certain dermatophytes. Candida auris is a newer species of Candida that is particularly resistant to antifungal drugs and can spread quickly in healthcare settings.

Tackling antimicrobial-resistant fungi

Resistant fungi are a growing public health threat. Everyone—including CDC scientists, healthcare professionals, and the general public—has a role to play in preventing resistant fungal infections. This work complements CDC’s antimicrobial resistance investments, collectively known as CDC’s Antimicrobial Resistance Solutions Initiative. Through these investments, CDC is transforming how the nation combats and slows antimicrobial resistance at all levels.

CDC is:

• Conducting surveillance: Tracking antimicrobial resistance in Candida infections at 10 sites across the country through the Emerging Infections Program (EIP).
• Expanding lab capacity: Supporting a network of regional public health laboratories through the Antimicrobial Resistance Laboratory Network (AR Lab Network) to detect resistant fungi and perform antifungal susceptibility testing.
• Using state-of-the-art lab technology: Using genetic sequencing and developing new laboratory tests to identify and understand specific mutations associated with antimicrobial resistance (fungi and bacteria).
• Supporting surveillance globally: Through collaborations with the World Health Organization’s (WHO’s) Global Antimicrobial Resistance Surveillance System (GLASS), CDC continues to support increased detection and tracking of antimicrobial resistance to prevent illnesses and save lives.
• Using data for action: Analyzing antifungal prescribing patterns across healthcare facilities and promoting appropriate use of antifungal drugs.

Healthcare facility leadership and infection control staff can:

• Assess antifungal use as part of their antimicrobial stewardship programs.
• Ensure adherence to infection prevention and control guidelines, including proper hand hygiene and disinfection protocols.

Healthcare providers and other hospital personnel can:

• Prescribe antifungal drugs appropriately and document the dose, duration, and indication for every antifungal prescription.
• Test for resistant fungi in patients with fungal infections that are not improving with first-line antifungal drugs.
• Be aware of resistance patterns, including  resistant fungi, in their facility and community.

Hospital patients can:

• Clean their hands.
• Be sure everyone cleans their hands before entering the room.
• Ask each day if a catheter is necessary, if the patient has one.
• Talk to their healthcare provider about their risk for certain infections, especially if the patient has a weakened immune system.
• Take antifungal drugs only when needed and exactly as prescribed.
• Talk to their healthcare provider if they experience side effects or if they are not seeing their symptoms improve when taking antifungal drugs.

Overview

COVID-19-associated fungal infections can lead to severe illness and death. Symptoms of certain fungal diseases can be similar to those of COVID-19, including fever, cough, and shortness of breath. Some patients can have COVID-19 and a fungal infection at the same time. Laboratory testing is necessary to determine if a person has a fungal infection, COVID-19, or both.

COVID-19 likely increases the risk for fungal infections because of its effect on the immune system and because treatments for COVID-19 (like steroids and other drugs) can weaken the body’s defenses against fungi. The most commonly reported fungal infections in patients with COVID-19 include aspergillosis, invasive candidiasis, and mucormycosis (sometimes called by the misnomer ”black fungus.” Fungal infections resistant to antifungal treatment have also been described in patients with severe COVID-19.

Awareness of the possibility of fungal co-infection with COVID-19 is essential to reduce delays in diagnosis and treatment in order to help prevent severe illness and death from these infections.

COVID-19-associated pulmonary aspergillosis

Scientists are still learning about aspergillosis (infections caused by the fungus Aspergillus) in people with severe COVID-19. In the past, scientists thought aspergillosis occurred almost entirely in people with severely weakened immune systems. However, aspergillosis has been increasingly reported in patients without weakened immune systems but who have severe respiratory infections caused by viruses, including influenza. Several recent reports describe COVID-19-associated pulmonary aspergillosis (CAPA).

Available information indicates that CAPA:

• Usually occurs in patients with severe COVID-19 (e.g., patients on ventilators in ICUs)
• Can be difficult to diagnose because patients often have non-specific symptoms and testing typically requires a specimen from deep in the lungs
• Can cause severe illness and death

Clinicians should consider the possibility of aspergillosis in patients with severe COVID-19 who have worsening respiratory function or sepsis, even if they do not have classical risk factors for aspergillosis. Testing for CAPA usually involves obtaining specimens from patients’ lower respiratory tract, which are tested for Aspergillus galactomannan antigen and fungal culture. The treatment of CAPA includes antifungals like voriconazole, posaconazole, and isavuconazole. Therapeutic drug monitoring should be considered when using these antifungals in CAPA treatment.

COVID-19-associated mucormycosis

Often called by the misnomer ”black fungus,” COVID-19-associated mucormycosis is a major public health problem in India. COVID-19-associated mucormycosis cases have also been seen outside of India, including in the United States, although much less commonly. Uncontrolled diabetes and overuse of steroids for COVID-19 treatment are important risk factors.

Biomarkers for diagnosing invasive aspergillosis, such as beta-d-glucan and galactomannan, are typically negative in patients with mucormycosis. The treatment for mucormycosis frequently involves aggressive surgical intervention and treatment with antifungals, including amphotericin B, posaconazole, or isavuconazole. Voriconazole is not recommended for treating mucormycosis. Providers should consider therapeutic drug monitoring during COVID-19-associated mucormycosis treatment.

The risk of COVID-19-associated mucormycosis may be decreased by encouraging vaccination against COVID-19, prescribing steroids for COVID-19 treatment based on guidelines, and controlling the blood sugar of patients with diabetes who have COVID-19. Early diagnosis and treatment are key to improving outcomes for patients with COVID-19-associated mucormycosis. Clinicians should consider the possibility of mucormycosis in patients with COVID-19 even when patients lack classic risk factors for this disease.

Increased spread of Candida auris during COVID-19 pandemic

Candida auris (C. auris) is an emerging fungus that can cause outbreaks of severe infections in healthcare facilities. In the United States, it has most commonly spread in long-term care facilities caring for people with severe medical conditions. However, since the start of the COVID-19 pandemic, outbreaks of C. auris have been reported in COVID-19 units of acute care hospitals. These outbreaks may be related to changes in routine infection control practices during the COVID-19 pandemic, including limited availability of gloves and gowns, reuse or extended use of these items, and changes in cleaning and disinfection practices. Screening for C. auris colonization, an important part of containment efforts, has been more limited as healthcare facilities and health departments have been responding to COVID-19.

Invasive candidiasis in patients with COVID-19

Patients hospitalized for COVID-19 are at risk for healthcare-associated infections (HAIs), including candidemia, or bloodstream infections caused by Candida. Patients with COVID-19 who developed candidemia were less likely to have certain underlying conditions and procedures commonly associated with candidemia and more likely to have acute risk factors linked to COVID-19 care, including medicines that suppress the immune system.

Fungal pneumonias can resemble COVID-19

Other fungal diseases, such as Valley fever (coccidioidomycosis), histoplasmosis, and blastomycosis, can cause fever, cough, and shortness of breath, similar to COVID-19 and bacterial pneumonias.These fungi live in soil. People become infected by breathing in fungi present in the air. Clinicians should consider fungal pneumonias as a possible cause of respiratory illness, particularly if COVID-19 testing is negative. It is important to note that these fungal diseases can occur at the same time as COVID-19.

One Health is an approach that recognizes that the health of people is closely connected to the health of animals and our shared environment. One Health involves experts in various fields working together at the local, regional, national, and global levels to improve health. Disease spread by fungi are a One Health issue—fungi that cause human diseases live in the environment and some can spread between animals and people.

Fungi are everywhere. There are millions of fungal species, but only a few hundred of them are known to make people sick. Some fungal diseases, such as ringworm, are zoonotic—meaning that the disease can spread from animals and people. Other fungal diseases, like histoplasmosis, can’t spread from animals and people, but can infect both animals and humans who are exposed to fungi in the environment. Exposure to fungi can also cause other health problems, like asthma and allergies. Natural disasters like flooding can cause fungi to grow quickly. Changes in the environment caused by urban growth and intensive farming practices can also affect fungi and their spread. A One Health approach is important for the prevention and control of fungi that can spread through the environment and between animals and people.

We are only beginning to understand how the interconnections between people, animals, and the environment affect fungal diseases. The following examples show these connections:

• Ringworm is a common fungal skin infection that affects humans and animals. People can get ringworm from contact with infected animals or the environment.
  • Over half of outpatient doctor visits for fungal diseases are for ringworm.

• The use of antifungal drugs in the environment may be causing antifungal resistance. Antifungal resistance happens when fungi develop the ability to defeat the drugs meant to kill them. Resistant fungi can make infections harder to treat in both people and animals.
  • Triazole antifungal drugs are the main treatment for Aspergillus infections in animals and people. Triazole fungicide use in plant agriculture may lead to triazole-resistant Aspergillus infections, which are difficult to treat.
• Because of climate change, the environments where disease-causing fungi might live are expanding.
  • In the United States, environmental fungal diseases that may become more common because of climate change include blastomycosis, Valley Fever, histoplasmosis, Cryptococcus gattii infection, mold-related illnesses, and Candida auris.
  • Climate change is increasing the frequency, intensity, and duration of extreme weather events, such as drought and wildfires. These events can encourage the production and spread of fungal spores that cause disease.
• New zoonotic disease-causing fungi, such as Sporothrix brasiliensis, are becoming more common.
  • Sporotrichosis, caused by Sporothrix brasiliensis, is a zoonotic disease that can spread among cats and from cats to humans. This disease is rapidly expanding to new regions in South America.
• Fungi can impact human and animal health in other ways.
  • Toxins produced by fungi associated with agriculture can affect human and animal health when consumed.
    • Contamination of food crops with aflatoxins, produced by Aspergillus, has led to pet aflatoxin poisonings and pet food recalls in the United States. Aflatoxins can also cause sickness in humans.
  • Eating poisonous mushrooms can serious illness and death in humans and animals.
  • Damp and moldy environments can lead to allergy symptoms in people and animals. During and after severe weather events, flooding can lead to excess moisture and mold growth. Preventing excess moisture in your home can help prevent mold.