Mycoplasmal pneumonia is commonly referred to as “enzootic pneumonia,” meaning that the disease is widespread and common among a population of animals.
There have been many estimates of prevalence within the U.S. swine industry, but most would agree that well over 90% of swine herds are positive for this organism.
The mycoplasma organism is a very small bacterium without a cell wall. It is a unique pathogen in that it does not invade the body, but instead colonizes the mucosal surfaces of the respiratory tract, destroying the surface cells (epithelium) and villi of the respiratory tract. This process makes the pig more susceptible to other bacterial pathogens such as Pasteurella multocida and allows viruses to replicate more easily.
In turn, the body does not mount an immune response in the same manner as when confronted with other bacterial pathogens.
The cell structure and the way it causes disease makes mycoplasma difficult to treat with many of the commonly used antibiotics.
Enzootic pneumonia, associated with mycoplasma and complicated with pasteurella, is likely the most costly swine respiratory disease.
Depending upon the prevalence and severity of the infection, this disease can reduce feed consumption and weight gain, resulting in reduced overall growth performance and increased treatment costs.
Previous studies have shown that vaccination against mycoplasma reduces the severity of lung lesions and clinical signs including coughing, which leads to improved feed efficiency and average daily weight gain during the finishing phase.
Even with effective vaccines, however, the producer must still pay special attention to stocking density, ventilation, biosecurity and control of other diseases to be successful in the long-term control of mycoplasma.
Health technologies such as all-in-all-out (AIAO) pig flows and multi-site production of nursery and grow-finish pigs have improved rate of gain and shortened days to market in the face of mycoplasma infection.
Case Study No. 1
A 2,000-sow, conventional health, commercial farm had a known problem with mycoplasma, which later turned into porcine respiratory disease complex (PRDC). The farm weaned at 2 to 3 weeks of age and for various reasons decided to vaccinate with a single-dose mycoplasma vaccine at weaning.
About 7-10 months after beginning this vaccination protocol, the farm was still experiencing a lot of morbidity and mortality from PRDC. Problems occurred late in finishing, often at about 18 weeks of age. While these “breaks” were no worse than before, they certainly were no better than prior to vaccination.
We reassessed the vaccination protocol and decided that while it was very convenient to vaccinate at weaning, it was just too early in this case. Also, perhaps for reasons of maternal antibodies, the pigs were just not developing protective immunity for mycoplasma throughout finishing.
Therefore, it was decided to shift the single-dose mycoplasma vaccine to about four weeks after weaning. Theoretically, this would allow enough time for the maternal antibodies to wane, while still allowing enough time to develop an active immunity to the vaccine before the challenge begins in the finishing phase. Time will tell if our strategy will be successful.
Case Study No. 2
A seedstock supplier was establishing a new, 500-sow nucleus herd and wanted to stock it with females from more than one source to assure the correct combination of genetic lines. The producer was concerned, since some of the potential sources were not free of mycoplasma.
The location for this new herd was very isolated. Since health was such an important component of future sales, it was decided to attempt disease elimination upon startup of this herd.
The various sources for the new farm were contacted to request that all of the animals targeted for this repopulation were within a two-month age window at the time of stocking. It was imperative to the producer that there be no animals under 10 months of age residing in the population at the time of the first farrowing on this new farm.
For added assurance of successful elimination of mycoplasma, all of the breeding animals (regardless of source and mycoplasma status) were given mycoplasma vaccine twice, once on arrival and again one month later.
Also, as the time approached for the first sows to farrow, the entire herd was medicated for two weeks with an antimicrobial known to be effective against mycoplasma.
By the time the first gilts farrowed, the youngest animal on the farm was at least 10 months old.
Now after almost four years, this farm is still producing mycoplasma-naïve seedstock.