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Open Access Publications from the University of California

Occurrence of Aeromonas hydrophila in Southern California’s Coastal Waters and Virulence Factors Associated with Infections

  • Author(s): Ardi, Veronica
  • et al.

Recent epidemiological studies have shown that storm drain discharges into the coastal waters of Santa Monica Bay are associated with an increase in traditional waterborne (gastroenteritis) and nontraditional (nondiarrheal) diseases especially among children. A recent epidemiological study of surfers from Orange and Santa Cruz Counties showed higher rates of water related illness including nondiarrheal diseases amongst the OC surfers. Examples of emerging pathogens that cause nontraditional illness are Mycobacterium complex and Aeromonas hydrophila. These studies suggest research to understand newly recognized pathogens is important to the Coastal Environmental Quality Initiative.

A. hydrophila has been isolated from drinking and recreational waters and is associated with gastroenteritis, Aeromonas sepsis, and wound and ocular infections. Data on drinking and coastal waters from Europe and from our preliminary sampling suggest A. hydrophila and the genes associated with virulence including cytolytic enterotoxins, hemolysins/aerolysins, and other extracellular proteins are present in waters world-wide. For these reasons, A. hydrophila was recently placed on the candidate contaminant list for drinking water in the U.S. These findings and our preliminary data from OC coastal waters indicate that A. hydrophila is worthy of study due to its potential health threat to people using the OC beaches.

We propose to examine the frequency and density of A. hydrophila and the related virulence genes at the interfaces between fresh and coastal waters of major rivers in the LA, Ventura, OC, and San Diego Counties as well as the associated surf zones. Polymerase chain reaction (PCR) for the virulence factors as a measure of pathogencity will be utilized to screen all the organisms recovered by membrane filtration and grown on selective agar. Occurrence data obtained can be used in a risk assessment model to determine if the organism and associated pathogenic factors are at concentrations and frequencies likely to cause disease among bathers.

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