Table 1.

Major issues underlying a more effective control of PRRS.

	Possible Aims	Constraints
Farm management	Biosafety. Reduction of environmental infectious pressure.	Lack of adequate facilities, type of farm (farrow-to finish), lack of validated markers.
Genetic selection	PRRSV-resistant pigs.	Limited knowledge of molecular basis, costs, unfavorable pig phenotypes (lean type).
Animal Welfare	Prevention of stress-related immunosuppression.	Poor housing and infrastructure, high animal densities, unfavorable pig phenotypes.
Immune control	Adequate innate and adaptive immune responses by means of vaccines and immunomodulators.	Effective PRRSV decoy strategies, poor recognition of “danger”.
Markers of risk	Early warning of possibly serious clinical outcomes and pathogenicity of PRRSV isolates.	Lack of large-scale validations, costs, lack of recognized sampling protocols and laboratory procedures.