Serological patterns of Actinobacillus pleuropneumoniae, Mycoplasma hyopneumoniae, Pasteurella multocida and Streptococcus suis in pig herds affected by pleuritis

Abstract

BackgroundRespiratory illness is traditionally regarded as the disease of the growing pig, and has historically mainly been associated to bacterial infections with focus on Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae. These bacteria still are of great importance, but continuously increasing herd sizes have complicated the scenario and the influence of secondary invaders may have been increased. The aim of this study was to evaluate the presence of A. pleuropneumoniae and M. hyopneumoniae, as well as that of the secondary invaders Pasteurella multocida and Streptococcus suis by serology in four pig herds (A–D) using age segregated rearing systems with high incidences of pleuritic lesions at slaughter.ResultsPleuritic lesions registered at slaughter ranged from 20.5 to 33.1 % in the four herds. In herd A, the levels of serum antibodies to A. pleuropneumoniae exceeded A450 > 1.5, but not to any other microbe searched for. The seroconversion took place early during the fattening period. Similar levels of serum antibodies to A. pleuropneumoniae were also recorded in herd B, with a subsequent increase in levels of antibodies to P. multocida. Pigs seroconverted to both agents during the early phase of the fattening period. In herd C, pigs seroconverted to P. multocida during the early phase of the fattening period and thereafter to A. pleuropneumoniae. In herd D, the levels of antibodies to P. multocida exceeded A450 > 1.0 in absence (A450 < 0.5) of antibodies to A. pleuropneumoniae. The levels of serum antibodies to M. hyopneumoniae and to S. suis remained below A450 < 1.0 in all four herds. Pigs seroconverted to M. hyopneumoniae late during the rearing period (herd B–D), or not at all (herd A).ConclusionDifferent serological patterns were found in the four herds with high levels of serum antibodies to A. pleuropneumoniae and P. multocida, either alone or in combination with each other. Seroconversion to M. hyopneumoniae late during the rearing period or not at all, confirmed the positive effect of age segregated rearing in preventing or delaying infections with M. hyopneumoniae. The results obtained highlight the necessity of diagnostic investigations to define the true disease pattern in herds with a high incidence of pleuritic lesions.

Herd-level risk factors for chronic pleuritis in finishing pigs: a case-control study

“…The present study agrees with the previously described debilitating effect of growing herd size on prevalence of pleuritis [5,6,7,14,16]. This effect could be related to infection pressure because bigger herds are more likely to need to purchase more animals, which is accompanied by an increased risk of introducing pathogens or naïve animals into the herd.…”

“…Also, the timing of the infection remains unknown in our study, as we are dealing with endemic disease. For example, Wallgren et al [5] found different serological patterns during the growing time of pigs in four herds. They showed that repetitive sampling helped to pinpoint the actual causative agent and disease pattern in different herds.…”

“…The registration of pleuritis has continuously increased also in a neighbouring country of Finland, Sweden, since the year 2000 [5].…”

Associations between animal and herd management factors, serological response to three respiratory pathogens and pluck lesions in finisher pigs on a farrow-to-finish farm

“…This facilitated recirculation of disease and a higher and earlier risk of exposure to pathogens [34] compared with pigs in ow 1, due to contact between animals of different ages and mixed immune status [40]. Actinobacillus pleuropneumonia circulates in the herd for long periods of time [5], with antibody levels increasing with age [41]. Therefore, the higher antibody levels for App from pigs in ow 2 and ow 3 could be associated with direct and prolonged exposure to recovered sick pigs [27] that could still be carrying and shedding pathogens [42].…”

Herd-level risk factors for chronic pleurisy in finishing pigs: a case-control study

“…Also, swine in uenza virus (SIV) has been noted to have an association with pleurisy [10]. Especially dorsocaudal pleurisy has been reported to be strongly associated with APP [1,6,10,11].…”