Swine DiseasesPart I of III Julie Zimmerman Advanced Swine Production Spring 2008
What is in a name? • Porcine Reproductive and Respiratory Syndrome has been called by many names, but now is referred to as PRRS • Other names were/are: • Mystery Swine Disease (name first given to the disease) • Mystery Reproductive Syndrome • Swine Infertility and Respiratory Syndrome (SIRS) • Blue Ear Disease • Lelystad Virus (virus that causes PRRS)
PRRS was discovered in 1987 in the United States and 1991 in the Netherlands, soon spreading throughout all of Canada and Europe. There are so many different strains of PRRS that preventative vaccines are not 100% effective. PRRS is a virus that causes reproductive failure in breeding stock and respiratory tract failure in young pigs. PRRS costs the United States swine industry approximately $600 million yearly. What is PRRS?
Origination Researchers at the University of Minnesota hypothesized that: “A mutant of a closely related arterivirus of mice (lactate dehydrogenase-elevating virus) infected wild boars in central Europe. These wild boars functioned as intermediate hosts and spread the virus to North Carolina in imported, infected European wild boars in 1912; the virus then evolved independently on the two continents in the prevalent wild hog populations for approximately 70 years until independently entering the domestic pig population.” - Peter G.W. Plagemann
Symptoms/Problems in Females • Infertility • Lethargic behavior • Abortions • Loss of appetite • Encephalitis • Heart problems • Depression • Premature births • Sometimes the entire litter is stillborn or very weak • High fever
Symptoms/Problems in Boars • High fever • Depression • Infertility • Primary issues with boars are the spread of disease through their semen
Symptoms/Problems in Pigs PRRS is more severe in nursery pigs than in finishing pigs. • Severe pneumonia with coughing & labored breathing • Increased pre-weaning sickness & death • Pigs with PRRS will take longer to finish • High fever • Depression (shows in finishing pigs)
Transmission of PRRS • Introduction of infected hogs into the herd • Mucus • Urine • Feces • Semen (both artificial insemination and natural) • Air (very unlikely) • Blood
Many hogs die from secondary infection, due to the fact there is no vaccine for post infected animals. For this reason, vaccination is important to treat that secondary infection, once PRRS has been diagnosed.
A common misconception about PRRS is that if the hog acquires the virus and lives, it will then be immune for the rest of its life. This is not true, not only can the hog acquire the disease again, but could also recover and live out its days as carrier (showing no signs).
Prevention • PRRS vaccine (not 100% effective & consideration needs to be taken due to the fact it is a modified live virus) • Clean farrowing houses • Disinfection & drying of pens • Better management practices • Quarantine incoming hogs for 60 days • Realize facility’s limitations and do not overcrowd • Prevent infected stock from entering herd • Do “homework” on potential purchases, investigate the herd, herdsman and general management practices before committing to buy.
Sources • Benfield, D., J. Hennings, J. Collins, S. Dee, W. Mengeling, K. Rossow, J. Zimmerman. “Porcine Reproductive and Respiratory Syndrome (PRRS)”. Pork Industry Handbook. Nov. 2002: 1-8. • Dee, S. “Porcine Reproductive and Respiratory Syndrome”. The Merck Veterinary Manual. 2006. • http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/54100.htm • Epperson, B., D. Benfield, K. Rossow. “Porcine Reproductive and Respiratory Syndrome (PRRS)”. SDSU Extension Fact Sheets. • http://vetsci.sdstate.edu/xnews/eeprrs.html • Harper, A. “An Overview of Porcine Reproductive and Respiratory Syndrome”. Livestock Update. July 1996. • http://www.ext.vt.edu/news/periodicals/livestock/aps-96_07/aps-665.html • Lawhorn, B. “Porcine Reproductive and Respiratory Syndrome”. Texas AgriLife Extension Service Educational Materials. • http://animalscience.tamu.edu/main/academics/swine/L5137-prs.pdf
Sources, Continued • Norby, M. “Vet scientist leading the way in fight against devastating viral swine disease”. Research Nebraska. Sept. 1998. • http://ard.unl.edu/rn/0998/prrs.html • Plagemann, P. “Porcine reproductive and respiratory syndrome virus: origin hypothesis”. Emerging Infectious Diseases. Aug. 2003. • http://www.cdc.gov/ncidod/EID/vol9no8/03-0232.htm • South Dakota State University, Veterinary Science Department. “Porcine Reproductive and Respiratory Syndrome (PRRS)”. 2003. • Van Alstine, G., G. Stevenson, C. Kanitz. “Diagnosis of Porcine Reproductive and Respiratory Syndrome”. Animal Disease Diagnostic Laboratory. Newsletter 1993. • http://www.addl.purdue.edu/newsletters/1992-93/prrs.shtml