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Seven horses dead from EHV-1, 33 confirmed cases

May 21, 2011


Equine Herpesvirus 1 (EHV-1) has been confirmed in 33 horses across eight states, with 12 of those animals showing neurological signs from the disease. Seven have died or been euthanized.

Death toll

As at 21.5.2011, 09.42am NZT

Data is now being collated by the Animal and Plant Health Inspection Service (APHIS) of the US Department of Agriculture, meaning a clearer picture is emerging of the outbreak, which appears centred on the National Cutting Horse Association's Western National Championship in Ogden, Utah, held from April 30 to May 8.

The latest information lists 308 horses across 18 states that were exposed at Ogden.

It lists, in total, 689 horses as secondarily exposed to the potentially deadly virus, and the number of suspected EHV-1 cases stood at 41.

To date, 21 horses had tested positive for the virus but were not showing neurological signs. Another 12 had the virus and showed neurological signs, known as Equine Herpes Myeloencephalopathy (EHM), bringing the total number of cases to 33.

Of the 33 confirmed cases, 32 of the horses were at the Ogden event.

In total, 12 horses are suspected of showing neurological symptoms as a result of the disease, but test results were awaited. Not all horses infected with the virus will show neurological signs.

In its summary, APHIS said owners of horses known to have been exposed have been contacted by state animal health officials.

Horses with suspected or confirmed cases are reported to be under voluntary or state quarantine.

The charts below, supplied by APHIS, provide state by state analysis.

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