This disease results from an infection involving Mycoplasma hyopneumoniae and with many producers still using continuous flow systems, UK farms have a high prevalence of Mycoplasma which builds up early in the nurseries and early finishing, says Prof Done.

“The main burden of infection occurs at around four to eight weeks of age when maternal antibodies have disappeared and pigs are moved, mixed and introduced to new sources of mycoplasma,” he says.

“Recent research has suggested that one infected pig during the nursery phase will infect at least one more pig during this period. These animals may then infect a large number of piglets during the finishing period. They are more than likely to remain infected throughout the finishing period and therefore remain a threat to the rest of the group of finishing pigs.”

Early infection is common in the UK but less so in other countries where all-in/all-out systems are more widely used. The infection is characteristically seen in young start-up herds with little or no gilt acclimatisation, herds with no vaccination or where there is a lot of sow movement.

Prof Done says that under most UK conditions it is best to avoid vaccinating sows as this may protect piglets for too long, preventing an early slow acquisition of Mycoplasma which is necessary to facilitate active immunity without clinical infection.

However, early vaccination of piglets at seven days facilitates this slow acquisition of Mycoplasma in the face of a rising local and cellular immune response, and prevents either early or late onset of disease. It is, he says, “the best option to prevent colonisation by large numbers of mycoplasmas in the nursery.”

Once acquired, mycoplasma is slow to be cleared as it is a surface-living agent. It may be present 180 days after infection, he says, and many weaned first litter sows still have clinical signs indicative of mycoplasma infection.

Staying free from infection is not a reality, particularly in pig-dense areas where infected herds may be as close as 400 metres to other farms, and the disease can spread by aerosol or contact with infected material. In the modern era, the continuous or even strategic use of antibiotics is not the option of choice.

He recommends using all-in/all-out systems, with complete cleaning of all organic matter before disinfection and, if possible, atmospheric disinfection with subsequent drying.

ThePigSite News Desk