Infectious diseases are caused by pathogenic organisms. There are various types of infectious diseases that are caused by different organisms. Diseases caused by viruses include human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS), influenza, and hepatitis A, B, and C. Some of the diseases caused by bacteria include cholera, meningitis, pneumonia, anthrax, and tuberculosis. Fungal diseases include aspergillosis, candidiasis, and onychomycosis. Other organisms, such as parasites can cause cryptosporidiosis, amebiasis, and isosporiasis.