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  Discussion on Research Summary: Rapid identification of EHV-1 infection
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Moderator:
DrO

Posted on Wednesday, Sep 24, 2008 - 11:03 am:

Concern over the spread of the more serious neurogenic form of EHV-1 has lead to extreme measures taken when respiratory disease break outs occur in horse populations. Usually this involves quarantine sometimes of large numbers of horses that are traveling. Early identification of the cause of the respiratory disease would be helpful in the management of such outbreaks. In the last few years several polyemerase chain reation assays (PCR) have been developed that have been shown to be able to identify EHV-1 presence in as little as 24 hours and early in the infection. This is considerably quicker than virus isolation, which may take up to a week, or testing for antibody rise which requires paired samples 21 days apart. The PCR test used in this research was excellent at correctly identifying infected individuals (95% sensitivity) but did have a moderately high false positive rate (24% specificity). In spite of this the conclusion of the researchers have concluded this is a useful tool to identify possible EHV-1 infection early in the course of the disease. By testing large numbers of infected horses a pretty good conclusion about whether EHV-1 is causing the problem can be made. However for individuals a follow up with viral isolation and/or serology should be used to confirm the cause of the infection.

J Vet Intern Med. 2008 Aug 5;
Detection of Equine Herpesvirus-1 in Nasal Swabs of Horses by Quantitative Real-Time PCR.

Perkins GA, Goodman LB, Dubovi EJ, Kim SG, Osterrieder N.

Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.

Background: Early identification of inhalation-transmitted equine herpesvirus type 1 (EHV-1) infections has been facilitated by the availability of a number of real-time quantitative PCR (qPCR) tests. A direct comparison between nasal swab qPCR and traditional virus isolation (VI) requires a method for normalizing the qPCR samples and controlling for PCR inhibitors present in some clinical samples. Objectives: To quantify EHV-1 shedding in viral swabs using an internal control and to compare fast qPCR to VI for the detection of EHV-1 in nasal swabs from horses. Animals: Fifteen horses experimentally infected with EHV-1. Methods: Experimental study: Nasal swab samples were collected daily after experimental infection for up to 21 days. VI was performed by conventional methods. The DNA was prepared for qPCR with the addition of a known quantity DNA of Marek's disease virus as an internal control. qPCR was performed. Results: The qPCR method detected virus up to day 21 after challenge, whereas VI detected virus only to day 5. The median Kaplan-Meier estimates for EHV-1 detection were 12 days for qPCR and 2 days for VI (P < .0001). When compared with VI, the sensitivity and specificity of qPCR were 97 (95% CI: 86-100) and 27% (95% CI: 20-35). Conclusions and Clinical Importance: We conclude that fast qPCR of nasal swab samples should be chosen for diagnosis and monitoring of herpesvirus-induced disease in horses. Recommended reference ranges of C(T) values are provided as well as justification of a minimum 10-day quarantine period.
Member:
lsweeney

Posted on Tuesday, May 17, 2011 - 3:21 am:

EHV-1 Outbreak:

https://lbemc.com/category/news/
Member:
lsweeney

Posted on Tuesday, May 17, 2011 - 7:01 pm:

This is what a local vet hospital posted:

Equine Herpes Virus Alert
ALERT FOR HORSEOWNERS: A recent disease outbreak of Equine Herpes Virus has been traced to California horses who attended the National Cutting Horse Associations’ Western National Championships in Odgen, Utah on April 30 – May 8. A rectal temperature in excess of 102F commonly precedes other signs of the disease. We will provide updates as they are available.

Here are some general guidelines. Please call in with specific questions, and our doctors can help assess your horse’s risk level, etc.

*For at-risk horses (horses that travel, show, etc.) without known exposure, it would be prudent to boost their EHV (rhino) vaccine status with the available vaccines that are labeled for respiratory and abortion forms (the closest we have to the neurologic form).

*For horses with suspected exposure or extremely high risk, it would be prudent to stimulate their cell-mediated immunity by using products like Zylexis, as well as boosting their EHV (rhino) vaccine status.

*For horses with early clinical signs (fever), immediate treatment with anti-viral drugs and supportive care is essential to reduce severity of disease (i.e. neurologic symptoms).

We do not currently have any suspect or confirmed cases in the hospital, and we have made the decision to not accept these horses at our facility for the protection of our other hospitalized patients. We have assembled a separate team of …our veterinarians and staff that are available to help our clients with infected horses on their own premises only. As always, please call us if you have ANY questions regarding prevention or suspect cases… we are here to help all of our clients get through this scary situation.

https://lbemc.com/2011/05/16/equine-herpes-virus-alert/
Member:
lsweeney

Posted on Tuesday, May 17, 2011 - 7:02 pm:

From UC Davis

Horse Owners Alerted about Equine Herpesvirus Outbreak
The following statement was prepared by faculty of the Equine Medicine Service at the William R. Pritchard Veterinary Medical Teaching Hospital.

May 17, 2011

During the past week in Colorado, there have been at least two confirmed cases of equine herpes-1 infection in horses that competed at the National Cutting Horse Association Western National Championships in Ogden, Utah. Other horses that competed in Ogden, Utah were transported to the Kern Country Cutting Horse Association show in Bakersfield, California, and some of these horses became ill, with one horse being euthanized at the fairgrounds. One horse was transported from Bakersfield to the isolation facility at the William R. Pritchard Veterinary Medical Teaching Hospital. Another horse that attended the Ogden show was also sent to UC Davis. Both of these horses have been confirmed as positive for EHV-1. In addition, as of today, at least 4 additional horses in various areas of Northern California have been confirmed as positive for EHV-1.

William R. Pritchard Veterinary Medical Teaching Hospital (VMTH)

The VMTH operates an isolation facility that was designed specifically to allow us to provide the best possible care to horses with infectious diseases such as EHV-1, while completely segregating them from other hospitalized horses and outpatients. The isolation facility is located a substantial distance from the main hospital, utilizes a dedicated group of staff and employs rigid infectious disease control and containment protocols that prevent other horses from becoming exposed. Currently, the two horses mentioned above are being treated under maximum isolation. These horses have no contact with other horses at the hospital. Because of the presence of EHV-1 in the community, the VMTH is taking every precaution to prevent EHV-1 entry into the general hospital. Every horse admitted to the hospital is being tested for EHV-1 and full biosecurity precautions are in force during the next few weeks as necessary.

Equine Herpesvirus

Equine herpesvirus is a common virus of horses world wide, and can cause respiratory disease, abortions, and less commonly neurologic signs as it has in these cases. It is transmitted by aerosol and close contact between horses, including fomites such as shared tack, equipment and by human hands. Though there are vaccines available for prevention of respiratory disease and abortions caused by equine herpesvirus, there are currently none that are labeled for prevention of the neurologic form of the disease.

Precautions

Please contact your veterinarian if your horse may have been exposed to EHV-1 at one of these shows or through contact with a horse that has returned from one of these events. In general, exposed horses should be isolated and have their temperatures monitored twice daily. If an exposed horse develops a fever, diagnostic testing of nasal swabs and blood should be performed. Consideration should be given to vaccination of resident, non-exposed horses on premises where potentially exposed horses are returning to, as per your veterinarian’s guidelines.

Resources -- Links and fact sheets (PDF)

California Animal Health and Food Safety Laboratory
https://www.cahfs.ucdavis.edu/
This laboratory performs testing services.

UC Davis Real Time PCR Research and Diagnostics Core Facility (PCR test)
https://www.vetmed.ucdavis.edu/vme/taqmanservice/

UC Davis Center for Equine Health Fact Sheet
https://www.vetmed.ucdavis.edu/ceh/ehv1_general.cfm

USDA Animal and Plant Health Inspection Service 2009 brochure about equine herpes myeloencephalopathy
https://www.aphis.usda.gov/vs/nahss/equine/ehv

California Department of Food and Agriculture Equine Herpes Myeloencephalopathy Fact Sheet
https://www.cdfa.ca.gov/AHFSS/Animal_Health/pdfs/EHV-1FactSheetSept2010.pdf

CDFA Equine Herpes May 13th update
https://cdfa.ca.gov/ahfss/Animal_Health/equine_herpes_virus.html

American Association of Equine Practitioners Fact Sheet
https://www.aaep.org/ehv.htm

American Association of Equine Practitioners Fact Sheet
https://www.aaep.org/pdfs/control_guidelines/Equine%20Herpes%20Virus.pdf
Member:
lsweeney

Posted on Tuesday, May 17, 2011 - 7:31 pm:

https://www.sacbee.com/2011/05/17/3634256/10-california-horses-test-positive.html

Ten horses in California have a highly contagious and potentially fatal disease, state agricultural officials said Tuesday.

The horses tested positive for Equine Herpes Virus, or EHV-1, and have been found in five counties: Kern, Placer, Stanislaus, Amador and Napa.
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