A disease that can be transmitted to other individuals. An infectious disease is a disease that is caused by the invasion of a host by agents whose activities harm the host’s tissues and cause disease. Diseases are spread by direct person-to-person contact, such as through coughing, sneezing, sweating or sexual interaction. Fleas, mosquitos, and other carriers (known as vectors) can spread disease when they bite animals with a disease and then bite humans.
