PhD-candidate Guilherme Milanez Preis, working with Drs. Cesar Corzo and Fabio Vannucci on the epidemiology of Senecavirus A. In an article for the National Hog Farmer, Preis shares the latest results of his work on Senecavirus A prevalence in the USA.
Senecavirus A (SVA) is a virus that induces vesicular lesions that resemble high impact diseases such as Foot and Mouth Disease (FMD). This virus belongs to the Picornaviridae family, and has been associated with vesicular disease and neonatal mortality in breeding herds in different countries. Clinically, it is indistinguishable from FMD.
Currently there are many unanswered questions with regards to the occurrence of SVA and yet, outbreaks of the disease continue to occur sporadically in breeding and finishing sites but also in pigs that have recently arrived at the slaughter plant. Data on the proportion of pig farms exposed to SVA is scarce in the United States. Therefore, this National Pork Board-funded study aims to estimate the proportion of SVA-exposed breeding and finishing sites by collecting blood samples from 100 sow and 100 growing pig farms.
Production companies and swine clinics were invited to participate in this national SVA prevalence study. Within each herd, 30 blood samples have been collected randomly across parities in sow farms and from pigs 20-weeks old or older in growing pig farms. Samples collected were tested with an indirect immunofluorescence assay for SVA antibodies at the University of Minnesota Veterinary Diagnostic Laboratory. Participating practitioners were also being asked to fill out a farm characteristics survey that will allow us to determine herd-level risk factors associated with the presence of SVA antibodies.
The sample collection phase is reaching the end as samples originating from 186 pig farms located in 16 different states have been collected and tested for SVA antibodies. Preliminary serologic test results show that out of 5,583 samples, 268 (4.8%) have tested positive. Positive samples are clustered in 17 out of 91 (18.7%) sow herds and seven out of 95 (7.4%) growing pig herds. The proportion of animals with SVA antibodies within each farm ranged from 3.3% to 100%, with an average of 37.2% among all farms with positive samples. Out of the 16 represented states, seven had at least one farm with positive samples.
This study contributes to the understanding of the epidemiology of SVA in the country. The virus appears to be present in the U.S. swine industry at a low level; however, at a low prevalence the virus continues to be a source of concern as SVA cases continue to occur and generate stress and production disruptions on production systems and packers as every time there is a case a disease investigation is conducted to rule out foreign animal diseases.