Aspergillus is a fungus that is commonly found in the environment, both indoors and outdoors. This fungus species can cause aspergillosis—a respiratory infection affecting the lungs. A. fumigatus, A. nidulans, and A. niger are some of the common species within the Aspergillus genus that cause aspergillosis. In high-risk populations, such as immunocompromised individuals, aspergillosis can be life-threatening and lead to poor patient outcomes.