Fungal Diseases and COVID-19

Overview

COVID-19-associated fungal infections can lead to severe illness and death.^{1, 3, 4, 7, 8, 28, 29, 30} Symptoms of certain fungal diseases can be similar to those of COVID-19, including fever, cough, and shortness of breath.^{1, 31} 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.³² The most commonly reported fungal infections in patients with COVID-19 include aspergillosis, invasive candidiasis, and mucormycosis (sometimes called by the misnomer ”black fungusexternal icon.”^1–6 Fungal infections resistant to antifungal treatment have also been described in patients with severe COVID-19.^{19, 20}

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).^{1, 3, 6, 9,10-14, 33}

Available information indicates that CAPA:

• Usually occurs in patients with severe COVID-19 (e.g., patients on ventilators in ICUs)^{1 ,6, 11-14}
• Can be difficult to diagnose because patients often have non-specific symptoms and testing typically requires a specimen from deep in the lungs^11, 14
• Can cause severe illness and death^{8 ,9, 11-14}

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.¹⁶ 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.^{34, 35}

COVID-19-associated mucormycosis

Often called by the misnomer ”black fungusexternal icon,” COVID-19-associated mucormycosis is a major public health problem in India.^{30, 36} 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.^{28, 29, 37}

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.²⁷ Providers should consider therapeutic drug monitoring during COVID-19-associated mucormycosis treatment.^{34, 35}

The risk of COVID-19-associated mucormycosis may be decreased by encouraging vaccination against COVID-19, prescribing steroids for COVID-19 treatment based on guidelinesexternal icon, and controlling the blood sugar of patients with diabetes who have COVID-19.^{28, 29} 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.³⁸ 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.^{7, 17–19} 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.²¹ 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.^{22, 23}