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第25号公告板 - Summer 2006
BacterologyMycoplasma hyopneumoniae
FANO E, PIJOAN C, DEE S
Dynamics and persistence of Mycoplasma hyopneumoniae infection in pigs.
Canadian Journal of Veterinary Research, 2005, Volume 69, N°3, 223-228
Two experiments were conducted in order to better define the shedding and transmissionof Mycoplasma hyopneumoniaeas well as the duration of the infection. The animals involved in this study (63 two-month-old gilts) were either inoculated with Mycoplasma hyopneumoniae by the intratracheal route (28/63), used as direct contact exposure pigs and placed together with the inoculated pigs (12/63), or used as indirect contact exposure pigs and housed separately in two pens of the same barn (20/63). Three animals were kept as controls in an independent room. Blood samples and nasal swabs were collected in each pen and tested periodically by ELISA and nested-PCR respectively, up to day 119 post-infection. Pigs were also clinically monitored for the onset and duration of coughing up to day 155 post-infection. In addition, bronchial swabs were collected in 15 animals (9 inoculated and 6 direct/indirect contact pigs) and tested by nested-PCR at days 155, 170 and 185 post-infection. Direct transmission between pen mates did occur as showed by PCR (28 DPI) and serology (35 DPI). However, under field conditions, the timing of infection is probably even slower. In the indirect contact pigs, seroconversion was detected at day 42 post-infection confirming that airborne transmission is involved in the spread of M. hyopneumoniae even if by a delayed and slow process. Interestingly, a prolonged persitence of M. hyopneumoniae was observed (100% of contact pigs resulted still positive for M. hyo at 185 DPI). These results clearly show that the duration of M. hyo infection is currently underestimated and that eradication programs should be modified so as to better suit the actual dynamics and persitence of M. hyo in pig production systems.
