SHIC Updates Pork Industry on HP-PRRS and Ebola Viruses
From high path porcine reproductive and respiratory (HP-PRRS) virus to Ebola virus, are you aware of the latest facts and information about swine disease threats?
The Swine Health Information Center (SHIC) is continually updating its Swine Disease Fact Sheet Library. This process, part of SHIC’s mission to protect the health of the U.S. swine herd, provides guidance and resources for producers, practitioners, and diagnosticians who are on the front lines of swine health concerns. Most recently, the HP-PRRSV and Ebola sheets were updated, particularly in the taxonomy and epidemiology sections.
HP-PRRSV
When PRRS first emerged in the U.S. and Germany in the late 1980s, it caused severe illness in pigs. Since then, PRRS has become an economically devastating disease and occurs in many parts of the world. Countries thought to be PRRS-free include Sweden, Norway, Finland, Switzerland, New Zealand, Australia, Argentina, Brazil and Cuba, SHIC reports.
HP-PRRS was first identified and described in China in 2006 and circulates in China with new variants continuing to appear, SHIC reports. While to date Chinese HP-PRRS virus variants have not been detected in the U.S., there is ongoing concern about transboundary spread. For example, the virus has spread to other countries in Asia, including Vietnam, Bhutan, Cambodia, Laos, Malaysia, Myanmar, the Philippines, Thailand, Singapore and India.
Clinical presentation of HP-PRRS is variable but infections with highly virulent strains are characterized by increased disease severity. In the 2006 Chinese outbreak, morbidity rates ranging from 50% to 100% were noted. An overall mortality rate of nearly 20% was observed, with up to 100% mortality in individual herds. Mortality rates were highest in suckling pigs (100%), followed by nursery pigs (70%), finishers (20%), and pregnant sows (10%), SHIC reports.
In breeding animals, anorexia, fever, lethargy, depression, respiratory distress, and vomiting can be seen, as well as cyanosis of the ears, abdomen and vulva. Transplacental transmission results in reproductive failure (stillborn, autolyzed and/or mummified fetuses) or birth of viremic piglets. In young, growing and finishing pigs, acute viremia is followed by respiratory disease including pneumonia, sneezing and expiratory dyspnea. Fever, lethargy and depression can also be seen.
Neurological signs have also been associated with HP-PRRS virus, as well as an erythematous blanching rash. HP-PRRS virus causes clinical disease and death in all ages, including adult pigs and pregnant sows.
Ebola
There are six Ebola virus species, each known by species name (common name): Bombali Ebola virus (Bombali virus), Bundibugyo Ebola virus (Bundibugyo virus), Reston Ebola virus (Reston virus), Sudan Ebola virus (Sudan virus), Taï Forest Ebola virus (Taï Forest virus), and Zaire Ebola virus (Ebola virus). “Ebola virus” refers specifically to the species Zaire Ebola virus. Ebola viruses occur mainly in regions of Africa. Bats are thought to be the primary reservoir hosts, SHIC reports. Reston virus is the only known Ebola virus that occurs in Asia.
Clinical illness due to Ebola virus has not been reported in pigs. However, serosurveys indicate pigs in some regions have been exposed to Ebola virus. The prevalence of Reston virus in pigs is unknown, SHIC notes.
Natural infection with Ebola virus has not been described, but young pigs experimentally infected with Ebola virus develop non-specific respiratory disease. Clinical signs and lesions in pigs co-infected with Reston virus and PRRS virus were consistent with severe, atypical PRRS (i.e., fever, respiratory distress, diarrhea, lameness, blue ears, petechiae and elevated mortality).
In one experimental study, five-week-old pigs inoculated with Reston virus remained asymptomatic, SHIC reports. However, it was recently shown that piglets aged three, five or seven weeks developed respiratory distress following oronasal inoculation with this virus.
Reston virus is not known to cause disease in humans; however, concern about spillover events and changes in pathogenicity remain, SHIC reports.
SHIC is focused on being prepared with a fact sheet for those diseases that are on their list of risks.
“We want to make sure we are prepared with information should we get them,” he says. “I hope we never use them. I hope we never have to use a nipah virus outbreak in the U.S. pork industry. But boy, if we do, we've got it and that's what SHIC’s supposed to do.”
For more information, visit swinehealth.org.
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