The Effect of High-Magnitude Precipitation Events on Vibrio Vulnificus Morbidity Cases in Estuarine Environments
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The geographic origin of infection involving morbidity cases resulting from Vibrio vulnificus is difficult to determine. V. vulnificus is a halophilic pathogen that exists year-round in the Texas Gulf Coast and requires moderate salinity (5-25 ppt) and water temperatures over 20 degrees Celsius to thrive and reproduce. From 1999-2003, the majority of reported culture-confirmed infections in Texas occurred in Harris, Matagorda, and Galveston counties. These data are recorded by the Texas Department of Health. By analyzing above-normal precipitation (high-magnitude) events in the separate counties and corresponding changes in salinity and temperature in large bay systems, temporal and spatial risk of infection may be inferred. Precipitation data for the study period from the National Climatic Data Center is compared with NOAA long-term precipitation data for rain gauges in Matagorda and Galveston counties in coastal Texas. Water quality data for the period of study is collected and catalogued by the Texas Parks and Wildlife department. Using a Kendall’s Tau-b correlation analysis, statistical relationships between water temperature (C°), salinity (0/00), and above normal precipitation events may be determined. The relationship between the occurrence of Vibrio vulnificus morbidity cases and above normal precipitation events is tested tested using a Phi test to determine correlation. The results of this study indicate that salinity levels in both bay systems are correlated with above normal precipitation events at the .05 alpha level, but water temperature is not directly correlated with these events in either system. Vibrio vulnificus morbidity cases reported in either bay system do not appear to be related to above normal precipitation events.