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Chapter 27 : Epidemiology
Category: Environmental Microbiology
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This chapter summarizes available information on the epidemiology of major clinically significant Vibrio species, including Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus with an especial emphasis on cholera. Hallmarks of the epidemiology of cholera include a high degree of clustering of cases by location and season, with highest rates of infection in children 1 to 5 years of age in endemic areas, and protection against the disease being afforded by improved sanitation/hygiene and preexisting immunity. V. cholerae strains associated with epidemics also undergo frequent genetic and phenotypic changes. Surveillance of cholera in Bangladesh has provided important information regarding the epidemiology and seasonality of the disease. Developments in DNA analysis techniques led to the introduction of several new typing methods that have enabled the study of the epidemiology of V. cholerae on a global scale. Subsequently, it was proposed that, in addition to other possible seasonal factors causing a bloom of diverse V. cholerae in the environment, epidemics may be preceded by a gradual enrichment of pathogenic strains through passage in human beings who consume surface water. Diarrheal disease due to V. parahaemolyticus is toxin-mediated. At least two toxins have been identified as potential virulence factors, thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH). Preventive measures to interrupt transmission of pathogenic vibrios and thus reduce the disease burden are possibly the most effective disruption to the emergence or rapid evolution of Vibrio species toward enhanced virulence.
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- Restriction Fragment Length Polymorphism