Transmission of porcine reproductive and respiratory syndrome virus (PRRSV) to age-matched sentinel pigs
Robert W. Wills, DVM, PhD; Alan R. Doster, DVM, PhD; Fernando A. Osorio, PhD
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Objectives: To determine how long PRRSV-infected pigs remain contagious to age-matched sentinel pigs and whether the infected pigs are intermittently or continuously contagious.
Methods: In each of two trials, five 4- to 6-week-old pigs (Principals) housed in one isolation room were inoculated with PRRSV. Pairs of age-matched sentinel pigs (Sentinels) were sequentially placed in direct contact with the Principals for 2-week periods, with 1-week intervals between pairs. Serum samples collected from Sentinels were tested by virus isolation and serology (ELISA) to determine whether transmission had occurred. Eight pairs of Sentinels were rotated through the Principals' rooms over a 165- or 167-day period.
Results: The Principals were contagious through Day 62 but not after Day 69 in the first trial and through Day 60 but not after Day 67 in the second trial.
Implications: This study demonstrated that seropositive, non-viremic, grower-aged pigs may be the source of spread of PRRSV in grow-finish units. The results also suggest that infected grower-aged pigs used as a source of PRRSV for natural infection of gilts of similar age in young-gilt acclimation programs may only be relied upon to transmit PRRSV for a maximum of 60 days.
Keywords: PRRS, transmission, epidemiology
Cite as: Wills RW, Doster AR, Osorio FA. Transmission of porcine reproductive and respiratory syndrome virus (PRRSV) to age-matched sentinel pigs. J Swine Health Prod 2002;10(4):161-165.
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