Figure 2A shows that the frequency of norovirus outbreaks has a highly nonlinear relationship with the normalized gage height (GH) and daily change in gage height (DCGH).
The data for gage height, temperature, and salinity were collected from USGS station 8211503, and rainfall data were collected from USGS station 8288570.
Changes in gage height and temperature had the greatest influence on model predictions, whereas salinity, rainfall, and wind also affected model predictions.
Environmental conditions that favored an outbreak in Area 7 on this date included an extremely low gage height (normalized value = 0.
2010), to our knowledge, this is the first time that gage height has been identified as an environmental factor associated with oyster norovirus outbreaks.
Our findings also suggest that norovirus outbreaks generally occur when extremely low gage height occurs in combination with low water temperature, low salinity, strong offshore wind, and heavy antecedent rainfall.
Gage height and temperature were the most important environmental predictors of oyster norovirus outbreaks, whereas wind, rainfall, and salinity also predicted norovirus outbreaks.