For more than a month, Webb Ranch in Portola Valley has been dealing with its own pandemic lockdown due to an outbreak of equine herpesvirus that has led to one horse being euthanized and sickened dozens more.

With no new cases reported by the California Department of Food and Agriculture (CDFA) since Feb. 17, the quarantine at the 300-horse facility at Highway 280 and Alpine Road is loosening up. An employee at its riding lessons office said they hope to reopen to the public in another week or so, and that boarders and people who lease school horses have been able to return to riding on the property.

CDFA issues regular updates on the website: equinediseasecc.org/alerts.

According to CDFA, the first sign of trouble started with two feverish horses and confirmed positive tests for a strain of equine herpesvirus called EHV-1 on Jan. 24. One of the horses was taken to a hospital. The other one had traveled to an equine event the day prior.

The most serious case at Webb involved a 22-year-old paint gelding "with acute neurological signs." He was not feverish, was isolated, and then euthanized in late January "due to poor prognosis," CDFA reported.

Monitoring at Webb Ranch is ongoing with temperatures being taken twice a day to see if any additional cases occur.

EHV-1 is common in horses around the world, and like human herpes, can lie dormant. There is a vaccine and treatments available, but no proven cure.

It can cause respiratory and/or neurologic disease, mares to abort and foals to die. The neurological form (EHM for myeloencephalopathy) may be caused by blood vessel damage in the brain and spinal cord brought on by EHV-1 infection. Symptoms include a fever over 102 degrees, nasal discharge, and poor coordination, especially in the back end.

A recent report confirmed two EHM cases (EHV-1 positive with neurologic signs) and 17 EHV-1 febrile only cases at Webb, saying that the quarantine will be lifted "when all positive horses have had two consecutive negative tests seven days apart."

The virus is easily spread via nasal secretions or aerosol droplets, and can contaminate shared water supplies, surfaces and equipment.

To avoid acting as carriers, people are advised to disinfect shoes, wash hands and clean clothes with hot water, detergent and a dryer.