Transmission electron microscopy image of L. pneumophila, responsible for over 90% of<unk>  cases Over 90% of cases of<unk>  are caused by Legionella pneumophila. Other types include L. longbeachae, L. feeleii, L. micdadei, and L. anisa. Transmission<unk>  is usually spread by the breathing in of aerosolized water or soil contaminated with the Legionella bacteria. Experts have stated that<unk>  is not transmitted from person to person. In 2014, one case of possible spread from someone sick to the caregiver occurred. Rarely, it has been transmitted by direct contact between contaminated water and surgical wounds. The bacteria grow best at warm temperatures and thrive at water temperatures between , with an optimum temperature of . Temperatures above kill the bacteria. Sources where temperatures allow the bacteria to thrive include hot water tanks, cooling towers, and evaporative condensers of large air conditioning systems, such as those commonly found in hotels and large office buildings. Though the first known outbreak was in Philadelphia, cases of legionellosis have occurred throughout the world. Reservoirs L. pneumophila thrives in aquatic systems, where it is established within amoebae in a symbiotic relationship. Legionella bacteria survive in water as intracellular parasites of water-dwelling protozoa, such as amoebae. Amoebae are often part of biofilms, and once Legionella and infected amoebae are protected within a biofilm, they are particularly difficult to destroy. In the built environment, central air conditioning systems in office buildings, hotels, and hospitals are sources of contaminated water. Other places the bacteria can dwell include cooling towers used in industrial cooling systems, evaporative coolers, nebulizers, humidifiers, whirlpool spas, hot water systems, showers, windshield washers, fountains, room-air humidifiers, ice-making machines, and misting systems typically found in grocery-store produce sections. The bacteria may also be transmitted from contaminated aerosols generated in hot tubs if the disinfection and maintenance programs are not followed rigorously. Freshwater ponds, creeks, and ornamental fountains are potential sources of Legionella. The<unk>  is particularly associated with hotels, fountains, cruise ships, and hospitals with complex potable water systems and cooling systems. Respiratory-care devices such as humidifiers and nebulizers used with contaminated tap water may contain Legionella species, so using sterile water is very important. Other sources include exposure to potting mix and compost.
Legionnaires' disease
Freshers' flu
Lemierre's syndrome
Boutonneuse fever
Scarlet fever
Bartonellosis
Listeriosis
Metal fume fever