The outbreak of vesicular stomatitis that affected hundreds of horses across Colorado and Texas is considered over, American authorities have reported to the World Organisation for Animal Health (OIE).
No new cases of of the disease have been reported since early December 2014, according to Dr John Clifford, who is deputy administrator for Animal and Plant Health Inspection Service (APHIS), which is part of the US Department of Agriculture.
Clifford told the OIE in the 28th and final report to the OIE on the outbreak, dated December 29, that a comprehensive epidemiological investigation into the outbreak had been completed.
“All premises previously under quarantine in Nebraska and Texas have been released,” he said. “All the remaining premises under quarantine in Colorado will be released 21 days after lesions of all affected animals on the premises have healed.
“This VSV event is considered closed.”
The report officially brings to an end the worst recorded outbreak of the disease, which has symptoms similar to foot and mouth disease, in the United States.
The latest situation report on the APHIS website, dated December 24, shows that 433 premises were affected in the outbreak, with 370 of them in Colorado, 62 of them in Texas and one in Nebraska.
In all, 644 horses and cattle were affected in the outbreak.
A total of 584 horses were infected, all of them in either Colorado (495) or Texas (89). November’s four positive cases in Nebraska involved cattle.
Colorado had 48 cases involving cattle and Texas had 8.
APHIS said cases had been reported in the following counties since the outbreak began in May:
- Colorado: Adams, Arapahoe, Boulder, Broomfield, Douglas, Elbert, El Paso, Fremont, Huerfano, Jefferson, Larimer, Logan, Morgan, Otero, Pueblo, Sedgwick, and Weld counties.
- Texas: Bastrop, Falls, Guadalupe, Hidalgo, Jim Wells, Kinney, Lee, McLennan, Nueces, San Patricio, Travis, Val Verde, and Williamson counties.
- Nebraska: Wheeler County.
Of the 433 premises across the states that were positive for the disease, 403 were positive equine premises, 27 were cattle premises, and three housed both cattle and horses.
By Christmas, just 15 premises, all in Colorado, remained under quarantine. No premises in Texas have been under quarantine since October 13.
Positive premises are eligible for quarantine release 21 days after lesions have healed in all affected animals.
Vesicular stomatitis is a viral disease which primarily affects horses, cattle, and pigs.
The virus has a wide host range and can occasionally infect sheep and goats.
It causes blister-like lesions to form in the mouth and on the dental pad, tongue, lips, nostrils, hooves, and teats. These blisters swell and break, leaving raw tissue that is so painful that infected animals generally refuse to eat and drink and show signs of lameness. Severe weight loss usually follows, and in dairy cows a severe drop in milk production commonly occurs. Affected dairy cattle can appear to be normal and will continue to eat about half of their feed intake.