January 4, 2006

USDA: PMWS increasing in Sweden

Swedish media is currently reporting on a "new" disease threatening Swedish pigs--PMWS or post-weaning multisystemic wasting syndrome.

This disease, which was first observed in Canada in 1991, was not found in Sweden until 2003. PMWS has spread to most pig-producing countries of the world including Sweden's neighbors: Norway, Denmark, the United Kingdom, Ireland, The Netherlands and Germany. Belgium and Finland reported their first cases in 2005.       

PMWS has spread slowly in Sweden due mainly to the geographic isolation of hog operations, low density of animals, high animal welfare standards, transportation restrictions and a low pathogen load within the country.  

The mortality rate in affected herds in Sweden has increased from 1 percent to 8-12 percent. This is quite low when compared to the normal average mortality rate of about 20 percent. This higher rate is usually attributed to a parallel virus infection, PRRS (Porcine Reproductive and Respiratory Syndrome). 

While this disease causes impairment of reproductive function in sows and respiratory disease in growing pigs, Sweden is free of PRRS. It is feared that the rise in outbreaks of PMWS, which appears to compromise the immune system, will lead to the spread of PRRS in Sweden.  

However, PRRS is endemic in Denmark. For several years now, Sweden has tried to halt Danish plans to transport their pigs destined for the Baltics and Russia through Sweden, on the grounds that it would lead to the introduction of PRRS in Swedish herds.

To the dismay of the Swedish pig industry, the Swedish Court approved the transit of Danish pigs through Sweden, citing EU regulations on free movement within the union. Transshipments of Danish pigs through Sweden have begun.

For the full USDA report, click here.