PRRS and PCV2 dominate IPVS congress in South Korea

Tuesday, February 5, 2013

A record number of attendees also heard numerous papers on Mycoplasma hyopneumoniae, swine influenza, ileitis, Actinobacillus pleuropneumonia and salmonella. Here are some key
take-homes

by ERNEST SANFORD


The 22nd IPVS (International Pig Veterinary Society) Congress was held in Jeju Island, South Korea last June, the second time that it has been held in Asia, the first being in Bangkok, Thailand in 1994. Once again, the IPVS was every bit as much of a success as any of the previous congresses, with 3,093 registered attendees from 60 countries, a new record.

Some 1,008 abstracts were accepted for the published proceedings of the congress. Of these, 277 were accepted as oral presentations and 731 as posters. Another 11 papers were presented by keynote and lead speakers invited to present updates on the major topics affecting the swine industry, such as PRRS, PCV2, emerging diseases, nutrition and welfare.

PRRS and PCV2, with 149 and 136 papers respectively, were the topics with the highest number of presentations. Mycoplasma hyopneumoniae (51), swine influenza (45), ileitis (32), Actinobacillus pleuropneumonia (30) and salmonella (26) were well represented, along with topics such as reproduction, nutrition, welfare, animal behaviour, classical swine fever (hog cholera), porcine epidemic diarrhea, foot-and-mouth disease, lameness and analgesia/anaesthesia for pain control.

I have written previously about oral fluid (saliva) sampling technology (Better Pork, October 2006, June 2009 and June 2010) as a substitute for blood (serum) for diagnostics for various swine pathogens (PRRS virus, influenza,  Mycoplasma hyopneumoniae, etc.). At this congress, there were 20 papers on use of oral fluids technology. As would be expected, most (15 of the 20) were from the United States, with one each from the Netherlands, Spain, Denmark, France and Poland.

This technology has now gone global and is being embraced by the swine industry worldwide.
The following are "take-homes" from some of the oral presentations.

Novel insights into pathogenesis of highly virulent PRRS virus strains, Frydas I. et al.,
pg 66-67
Background. A review of extremely aggressive PRRS virus (PRRSV) strain Lena (EU type 1, subtype 3 strain) and highly virulent Chinese strains.
Take-Home. Highly virulent European and Chinese strains are similar pathologically in producing marked viremia and extensive fibrino-hemorrhagic systemic lesions. They share identical deletions of 29-30 amino acids (AAs) in the nonstructural Nsp2 protein. Although tempting to ascribe virulence significance, this deletion sequence is not a PRRSV virulence factor.

Causes of sow lameness in group housing, Nielsen E.O. et al., pg 99
Background. This study was conducted on lameness in sows in two Danish herds (A & B) with major sow lameness problems. The sows are housed in groups of 60-90 and fed by an electronic sow feeder.
Results and Take-Home. One week after placement in group housing, 8.2 per cent and 31.5 per cent of sows showed signs of mild lameness in herds A and B, respectively. Later, after placement in gestation, 26 per cent and 48 per cent showed lameness in herds A and B. Lameness was mild to moderate and usually lasted two to eight weeks. No fevers were observed.
Causes of lameness were: arthrosis/osteochondrosis, 45 per cent; arthritis/osteomyelitis, 33 per cent; claw infections, 14 per cent; back problems, 2 per cent.

Prevalence and phylogenetic analysis of the current PCV2 genotypes five years after implementation of widespread U.S. vaccination programs, Opriessnig T. et al., pg 105
Background.  PCV2 vaccination has been widespread in the United States since 2006. This study aimed to determine if vaccination had changed the predominant genotype of PCV2 in the field.
Results.  In PCVAD pigs, the prevalence of PCV2a was 13 per cent and PCV2b was 65 per cent. Unvaccinated pigs had higher prevalence and higher DNA loads of PCV2a than vaccinated pigs. A surprising finding was that vaccinated herds had a higher level of PCV2b viremia than unvaccinated herds. The results suggest there might be a need for both PCV2a and PCV2b vaccines, or a PCV2b-specific vaccine.
Take-Home. There might be a need for a PCV2b-based vaccine in the future.

Thoracic fluids from stillborn pigs for identification of PCV2 DNA by PCR, Misener M, et al., pg 235
Background. This paper by our own Dr. Marty Misener consisted of a two-part study: part 1 – thoracic fluids from stillborn pigs analyzed for PCV2 by qPCR; part 2 – breeding herd performance after side-by-side PCV2 vaccination.
Take-Homes. Thoracic fluids were positive for PCV2 in clusters of two to three weeks of stillborns after three to four months of negative PCV2 tests. After a cluster of PCV2-positives, thoracic fluids were again negative over the next several months.
CircoFLEX-vaccinated sows and gilts had a six per cent higher farrowing rate than the unvaccinated sows and gilts (84.59 per cent versus 90.6 per cent for unvaccinateds compared to vaccinates, P<0.05).

Relationship between treatment for lameness during suckling and fattening period, Ehlorson C.J. et al., pg 96
Take-Home. Pigs treated for lameness during the suckling period were 2.5 times more likely to be treated for lameness again in the finishing period.
 
Severe lameness in weaner pigs caused by methicillin-resistant Staphylococcus aureus (MRSA) infection, Wendt M. et al., pg 128
Background. Severe lameness occurred in just-weaned, three-to-four-week-old piglets, in five different German herds. From six to 25 per cent of piglets were lame two to three weeks after purchase. All piglets were from the same sow herd source. Pigs purchased from another source did not have the lesions.
Findings and Take-Home. Lameness was caused by claw lesions associated with MRSA (sequence type ST 398). Small wounds at the coronary band during transport or in pens after arrival may have allowed MRSA infection. The pigs responded well to treatment with trimethaprim-sulfa.

Genotypic heterogenicity of Mycoplasma hyopneumoniae isolates from different epidemiological sources, Nathues H. et al., pg 174
Background. In this study, the researchers compared various Mycoplasma hyopneumoniae isolates from different herds and from several pigs in the same herd. Pigs were sampled from 109 herds in northwest Germany.
Take-Home. More than one Mhyo strain was found in a herd and even in a single pig.

In the next issue of Better Pork, I'll cover additional topics, including antibiotic resistance, castration and animal welfare. BP

S. Ernest Sanford, DVM, Dip. Path., Diplomate ACVP, is a swine specialist with Boehringer Ingelheim Vetmedica (Canada) in Burlington. Email: ernest.sanford@boehringer-ingelheim.com