Five variables were identified as important factors for WSSV
infection, however one of them was excluded in the final analysis
because of its similarity in its effect to WSSV with another variable
which was more strongly correlated. Using commercial pellets was
identified as a risk factor in polyculture farms, and feeding live
molluscs in the analysis that included either both farm types or
monoculture farms only. Feeding planktons to the shrimp was
included in the final models for the entire dataset and for monoculture
as a protective factor.