The present study demonstrates that there is a seasonal influence
of water temperature, salinity, and turbidity on V. cholerae
non-O1/non-O139 chxAþ density, showing the seasonal variability
of virulence determinants and indicating that these water parameters
may help to predict the V. cholerae pathogenic occurrence in
the oyster. Thus, monitoring programs are crucial to enhance the
safety of raw oyster harvested from polluted areas, within the
context of public health. To the best of our knowledge, the present
study reports for the first time the evidence of the presence of chxA
gene among an important number (100 and 19.8%) of V. cholerae
non-O1/non-O139 strains in oysters harvested from the MLS on the
Mexico's Gulf coast. Based on our findings, the seasonal dynamics
of V. cholerae non-O1/non-O139 harboring pathogenic genes would
vary with seasonal changes in environmental conditions. Thus, the
isolation of pathogenic strains in environmental oysters during the
annual cycle should be considered a health concern as they may
increase in the future due to global warming. Unlike other areas of
the world, the variation of water temperature in tropical zones is
less pronounced throughout the seasons and it might explain,
considering the interaction with turbidity, and salinity e chlorophyll,
the presence of pathogenic V. cholerae non-O1/non-O139
chAþ in oysters harvested from the MLS that cannot be ignored
in public health planning and response. Hence, the monitoring of
key environmental factors that influence the pathogenic V. cholerae
non-O1/non-O139 occurrence may be an effective tool for better
seasonal predictability of their presence within oysters, mitigating
human exposure due to oyster consumption harvested from
contaminated marine and estuarine environments, and to assess
the possible public health risks in coastal areas.
Additional research and efforts are needed to understand the
effects of the climate changes and variability of environmental
factors over the V. cholerae dynamics in estuaries that contribute to
disease epidemiology. Consequently, the presence of these pathogenic
V. cholerae non-O1/non-O139 chxAþ strains raises important
health issues and may be indicative of a risk of gastrointestinal
illness in the usual consumers of oysters. Hence, the monitoring of
pathogenic strains in the oyster is crucial to determine seafood
safety and to predict the possible risks of infection given the public
health risk.