Microbiological Coastal Risks and Monitoring Systems - Vulnerability of Coastal Ecosystems and Adaptation - page 106

[GEN 00]. In France, a hundred cases of infection by
V. parahaemolyticus were reported in 2001, following the
consumption of mussels imported from Ireland [HER 05]. Since then,
only sporadic cases of infection by V. parahaemolyticus have been
reported [QUI 05].
3.2.4.3. Ecology of the human Vibrio pathogens
The work of Rita Colwell has revealed the presence of V. cholerae
O1 in the waters of Chesapeake Bay, on the east coast of the United
States, although there has been no cholera epidemic in the United
States for a long time [COL 81]. Numerous studies have since enabled
the understanding of the ecology of V. cholerae , which is a bacterium
native to coastal zones, in particular to estuaries and deltas.
Temperature, salinity, phytoplankton and copepods are major factors
that explain the dynamic of V. cholerae . This understanding is
necessary to explain the epidemiology of the disease, which was only
considered in the light of human transmission during cholera
epidemics [COL 05].
Notably, these studies have shown that blooms of phytoplankton
lead to significant blooms of zooplankton, including copepods, which
are known to be a natural host for V. cholerae . In effect, V. cholerae
forms biofilms on the carapaces of copepods, in a symbiotic or
commensal relationship, which thus becomes an important reservoir
for these bacteria. The marshes cause the intrusion inland of coastal
waters filled with zooplankton in large delta zones like that of
Bangladesh, thus placing human populations and V. cholerae in
contact. This has enabled some triggers for cholera epidemics to be
identified [COL 05, VEZ 10].
The spatio-temporal distributions of non-choleric human
pathogenic vibrios have been linked to environmental factors
[JOH 12]. Temperature is the most important factor because it
explains the seasonal distributions in the coastal waters of temperate
zones, with maximal abundances in summer and autumn. Salinity is
also a major factor of the dynamic of the vibrios. A decrease in
salinity favors growth and proliferation in brackish systems at