Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: November 14, 1995
Publication Date: N/A
Technical Abstract: We hypothesized that transmission of S. choleraesuis from infected to naive swine establishes a long-term carrier state. Forty pigs were divided into 3 groups. Group 1 (Chal; n=12) was challenged with 10**8 S. choleraesuis by intranasal inoculation. One day postinoculation (PI) group 2 naive pigs (Nav; n=24) were commingled with the Chal pigs. Group 3 (n=4) served as unexposed controls. Two pigs from the Chal group and 4 pigs from the Nav group were necropsied at 1, 2, 4, 6, 9 and 12 wk PI. One control pig was necropsied at 1, 4, 9 and 12 wk. Pigs from both Chal and Nav groups had moderate to severe clinical signs through 2 wk PI. Tonsil, nasal, rectal swabs and group fecal pools (composites collected from individual animals) indicated that Nav group pigs were shedding S. choleraesuis 1 day after commingling. Fecal shedding peaked at 4.5 x 10**3 for the Chal group and 3.3 x 10**1 for the Nav group. After 8 wk PI, shedding could not be detected in either group. At 1 wk PI, 32/32 Chal group and 29/64 Nav group tissues were positive for S. choleraesuis. At 2 wk PI, 26/32 and 29/64 tissues were positive for Chal and Nav groups, respectively. Between 4 and 12 wk PI, the number of positive tissues steadily decreased for both groups. At 12 wk PI, S. choleraesuis was recovered from the Nav group only (2/64 tissues). These data indicate 1) that naive swine exposed to swine with acute paratyphoid can become infected with and shed S. choleraesuis within 24 h of exposure, and 2) the level of S. choleraesuis can be significantly reduced in, or eliminated from, naturally exposed swine.