Occurrence and Inactivation of Emerging Pathogens in the Environment.
AdvisorGerba, Charles P.
Committee ChairGerba, Charles P.
MetadataShow full item record
PublisherThe University of Arizona.
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AbstractEmerging pathogens are organisms whose incidence has increased within the past two decades. In the last 40 years, several pathogens have emerged to cause infectious waterborne and foodborne diseases, thus causing a significant public health concern. Enterobacter sakazakii and Naegleria fowleri are emerging pathogens that have been documented to cause fatal infections. E. sakazakii is an emerging foodborne pathogen that represents a significant health risk by causing infections resulting in septicemia, meningitis and necrotizing enterocolitis in neonates, premature infants and also elderly immunocompromised individuals. Naegleria fowleri is a water-based protozoan flagellate that is the cause of primary amoebic meningoencephalitis; a fatal disease that mostly infects children and young adults through water-related recreational activities. The focus of this dissertation is to identify environmental reservoirs of Enterobacter sakazakii and to determine inactivation strategies to control Naegleria fowleri by chlorine and ultraviolet disinfection. In Appendix A, samples from various household kitchens were collected to determine the presence of E.sakazakii. The highest percentage of E.sakazakii was isolated from kitchen sponges (8%; n=50) and dishrags (10%; n=50). This study provided information on the presence of E.sakazakii on environmental surfaces in the kitchen. In Appendix B, our recent research has determined that N. fowleri is present in 8% (n=143) of municipal drinking water wells in central and southern Arizona. Therefore, guidelines need to be established for treatment of water with various disinfectants to control the growth and proliferation of N.fowleri. In Appendix C, the Ct values (concentration (mg/l) × exposure time) for chlorine inactivation of N. fowleri trophozoites and cysts were determined using the Efficiency Hom Kinetic Model (EHM). The Ct values for 99% inactivation of trophozoites and cysts were estimated to be 9 and 31, respectively. The ultraviolet light dose required for the 99% inactivation of N.fowleri trophozoites and cysts was determined to be 63 mW.sec/cm² and 13 mW.sec/cm², respectively.
Degree ProgramMicrobiology & Immunology