Occurrence of pathogenic Legionella and Amoebae spp. from source (groundwater) to exposure (taps and cooling towers) in a complex water system

Legionella species are gram-negative bacteria that are known to cause a severe lung infection,which is known as Legionnaires' Disease and a less severe illness called Pontiac Fever. Legionella species can be aerosolized from showers, faucets, cooling towers, and decorative fountains. Once aerosolized, individuals can contract both diseases via inhalation of these pathogenic bacteria. Legionnaires Disease is of particular concern because the incidence of Legionnaires Disease is rising in the United States. Chapter one will review known information about specific Legionella species associated with human disease. The discussion will focus on the history of Legionnaires Disease, the taxonomy of Legionella species, specific pathogens associated with the disease, epidemiology cases of the disease, and environmental occurrence in premise plumbing systems. Chapter two will confirm that Legionella species associated with human disease are present in different types of buildings from the influent to the taps, all utilizing the same water system. I will also compare physiochemical parameters (water temperature, turbidity, pH, conductivity, and residual chlorine) that affect the concentrations and species of Legionella in cold and hot water taps. Chapter three will demonstrate that water age plays a role in the occurrence and concentration of Legionella species in the water distribution and premise plumbing system. In this chapter, I present data on the concentration of Legionella spp. in the influent and effluent of the reservoir, two buildings, and cooling towers. Examining Legionella species throughout the MSU campus from the water source to the taps, and thecooling towers provide a wholistic view of the MSU water system. Chapter four will confirm the co-occurrence of pathogenic Legionella species and Acanthamoeba spp. Naegleria fowleri in the drinking water supply system on the MSU campus. I show that Naegleria fowleri co-occurs with Legionella bozemanii and Legionella longbeachae in two buildings (F and ERC) on the MSU campus. In chapter five, I conclude by addressing future research trajectories needed to better understand how to manage the risk from the various other pathogenic Legionella species besides the primary water-related bacterium, L. pneumophila. In addition, there is a critical need to develop better methods for the detection of Legionella species in water systems to improve primary prevention strategies instead of reactive approaches. A proactive approach of monitoring for specific Legionella species in a building water system is the best approach to control Legionnaires' disease outbreaks in large buildings.