Specialists prevent, diagnose, and treat conditions caused by bacteria, viruses, fungi, or parasites. Conditions Treated AIDS Autoimmune diseases COVID-19 Cellulitis Chickenpox Diphtheria Ebola Endocarditis Enteroviruses Fifth disease Gangrene Giardiasis HIV Hand-foot-mouth disease Hepatitis Herpes simplex virus Human parainfluenza viruses Infectious diseases Lyme disease MRSA Malaria Measles Osteomyelitis Pneumonia Pulmonary disease Rocky mountain spotted fever Sexually transmitted diseases Shingles Thrush Tuberculosis