Temporal patterns of colonization and infection with Mycoplasma hyorhinis in two swine production systems in the USA

Control of Mycoplasma hyorhinis (M. hyorhinis) associated disease is currently hindered by limited knowledge of the epidemiology and ecology of this organism. A prospective longitudinal investigation was conducted to determine the dynamics of M. hyorhinis colonization in two swine production systems. In each system (A, B), 51 young sows (parities 1, 2) and 56 older sows (>parity 2) were selected at farrowing and tested by qPCR of nasal swabs and for antibodies by serum ELISA. From each sow, a piglet was randomly selected, and nasal and serum samples were collected at birth, weaning, and 10 days post-weaning. Two further samplings were performed in the nursery and finishing stages during the high-risk periods for M. hyorhinis-associated disease, and 12 pigs were euthanized and necropsied at these later sampling events. The prevalence of M. hyorhinis colonization in sows was low (<5%). No associations were found between sow parity or sow serum titer and piglet nasal colonization at either birth or weaning. In contrast to the low prevalence (0.95–2.70%) observed in piglets pre-weaning, most pigs became colonized during the first four weeks after weaning and remained positive throughout the nursery and finishing stages. The detection of M. hyorhinis in oral fluids followed similar patterns as those observed using nasal swabs. ELISA results showed decreased detection of maternal antibodies at around 3 weeks of age and a subsequent increase after natural exposure. The role of M. hyorhinis in polyserositis and arthritis was demonstrated in these two herds. Establishing the temporal dynamics of exposure and infection with M. hyorhinis in pigs will enable more strategic implementation of intervention strategies in affected herds.