In a time span of less than one year, December 2004 to October 2005, several natural disasters of extreme proportions struck different areas of the world, causing unparalleled destruction and loss of lives and property. In each of these instances, the potential existed for acquisition of infectious diseases caused by bacteria, viruses, mold, and mildew and demonstrated that such disasters represent a public health concern, which is exacerbated by the fact that many factors may work synergistically to increase the risk of morbidity and mortality caused by communicable diseases. This article reviews causes, symptoms, and treatments of various infectious diseases that pose a threat in the event of a natural disaster.