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Mycobacterium avium subsp. paratuberculosis Infection in Swine

Houser AK, Washburn KE, Collins M, Roussel A, Fosgate G

Andrew Houser

Objective – The objectives of this study were to determine if swine can be infected with Mycobacterium avium subsp. paratuberculosis (MAP) and if negative affects are noted.

Procedure – Four litters of pigs provided 4 separate treatment groups housed individually.  There were 5, 8, 8 and 6 pigs in litters A, B, C and D, respectively. All pigs in each litter were orally challenged at 12, 14, 16, & 18 days of age. Groups A, B, & C were challenged with whole milk containing a bovine origin MAP, a human origin MAP clinical strain, and a human origin MAP type strain, respectively. Group D received whole milk.  Following inoculation, weekly weights were recorded and fecal samples were collected for MAP culture and PCR analysis.  On days 10, 21 and every 3 weeks thereafter, blood samples were obtained.  Diagnostics included: hematology, serum chemistries with electrolytes and MAP serology (ELISA).

Results – Pigs in litters A and B began to shed MAP in their stool approximately 1 month following the last inoculation. Although results have not been statistically analyzed, there appeared to be a downward trend in average daily gain (ADG) and blood albumin (Alb) of litter B pigs as compared to the control group (litter D). While litter A pigs became infected they did not show similar decreases in average daily gains or albumin.
Preliminary results of this study indicate that we successfully infected at least two litters of pigs with MAP and that ADG and albumin were negatively affected in the litter inoculated with human MAP clinical strain. Our data will be formally analyzed to determine the significance of the differences noted between inoculated pigs and the control group.

Conclusions – The ability to infect pigs with MAP may lead to the establishment of an animal model for human Crohn’s disease which would enable therapeutic regimen testing.