Page 192 of articles about health

Serological diagnosis of PRRS
A definitive diagnostic evaluation of PRRS with respect to clinical disease requires that serological information be interpreted in combination with results from other virus assays.
Argentina: progress in cooperation with China on Animal Health

Interaction between PRRSV and Streptococcus suis
PRRSV favours the appearance of secondary infections like the one caused by S. suis due to the impairment of the alveolar macrophages cleaning functions.