Source: Swine Health Information Center
Swine acute diarrhea syndrome coronavirus, a coronavirus variant emerging in China, has been on the Swine Health Information Center’s radar and, based on information directly from China, new actions are being taken. Affected piglets show morbidity and mortality similar to the effects of porcine epidemic diarrhea, which reemerged in China in 2010.
A recent letter to Nature reported on research about a 2017 SADS-CoV outbreak associated with neonatal piglet diarrhea and death in four Guangdong Province farms. In October 2017, the SHIC Monitoring and Analysis Working Group reviewed virus and outbreak information and advised continued monitoring of this virus to track spread. Communication with sources in China report the virus is continuing to move between farms and provinces, so SHIC is initiating preparedness research.
What SHIC did to first assess and communicate SADS-CoV risk in 2017
SADS-CoV was first identified in 2004 then again in 2006 in bats. First clinical signs in pigs were observed in late-December 2016 and was associated with SADS-CoV in the first half of 2017. When this information was received, SHIC communicated the potential emergence of SADS-CoV in China to the U.S. pork industry and asked the SHIC Monitoring and Analysis Working Group to review the outbreak information and advise on risk.
The SHIC Working Group arrived at a consensus that SHIC should closely monitor the situation but not devote resources for diagnostics or to further investigate this virus unless there develops evidence of interregional spread in China, indicating this is more than an isolated incident. When contacts in China recently reported spread of SADS-CoV to three provinces, SHIC followed the Working Group’s recommendation to devote resources to evaluate need and, if necessary, develop diagnostics to increase U.S. readiness.
What SHIC Is doing now to ensure North American readiness for SADS-Cov
The SHIC Preparedness and Response Working Group recently outlined a research strategy. An urgent call for proposals is being prepared. The call will focus on the development of diagnostic tools to facilitate the detection of this emerging virus should it travel to the United States. The ability to detect this virus in clinical samples and in diagnostic tissues, and to detect antibodies to the virus in various tissues, including oral fluid samples, are priorities. SHIC also continues to research common inputs to U.S. production with the objective of identifying potential pathways and preventing the entry of viruses, such as SADS-CoV.
What you can do now
SHIC is encouraging swine veterinarians to increase awareness and understanding of SADS-CoV to help monitoring. The Chinese experience indicated a PED-like outbreak that continued and worsened with negative PED tests. Continue to be vigilant for unresolved high impact neonatal diarrhea and mortality that may warrant further investigation.
In incidents of high or ongoing morbidity or mortality, where an etiology is either not identified or there is a strong suspicion that the identified etiology is not the likely cause of the outbreak, SHIC continues to offer diagnostic fee support after the initial diagnostic workup is completed and paid for by the owner. In these cases, additional support for the fees of further diagnostic workup may help to identify newly introduced or emerging swine diseases. Find a description of the requirements, submission and review process for the Support for Diagnostic Fees program on the SHIC website.
Why this virus got the attention and research funds of international human emerging disease experts
There were several reasons the 2017 bat-to-pig transmission caught the attention of human emerging disease investigation teams. First, the virus has a viral ancestor similar to human severe acute respiratory syndrome, which transmitted from horseshoe bats to humans and caused over 8,000 infections and 774 human deaths in 2002. Of note, no further human SARS cases have been detected since 2004. To date, six CoVs are known to infect humans, but only two have been linked to large fatal outbreaks: SARS and Middle East respiratory syndrome coronavirus.
Second, like SARS, it is suspected the SAD-CoV infecting pigs has the same horseshoe bat reservoir. And lastly, the pig outbreak was within 62 miles of where the SARS index case-patient lived.
It is important to note researchers did evaluate the potential zoonotic transmission of the virus. They found no evidence of enhanced infection or entry for SADS-CoV in cells expressing known human coronavirus receptors, suggesting that none of these receptors functions as a receptor for virus entry for SADS-CoV. Also, to further help determine the risk of SADS-CoV to humans, all 35 employees exposed to the virus were tested and none were positive for SADS-CoV exposure.
The work was a collaboration among scientists from EcoHealth Alliance, Duke-NUS Medical School, Wuhan Institute of Virology and other organizations, and was funded by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health. The research is published in the journal Nature.