Legionella refers to a genus of pathogenic bacteria which can cause diseases such as legionellosis, Pontiac fever and Legionnaires' disease. Their symptoms are similar to pneumonia. Complicated cases might also lead to issues related to the gastrointestinal tract and nervous system. The infections generally spread by the inhalation of water droplets from a source in which the bacteria has spread. It has not been observed to spread from person-to-person. The incubation period of these bacteria inside a host organism is up to two weeks. It usually causes severe complications in individuals who are aged or immunocompromised. This book contains some path-breaking studies in the research of legionella. Also included herein is a detailed explanation of the various infections and pathology of these bacteria. The extensive content of this book provides the readers with a thorough understanding of the subject.