On July 13, 2020, the National Veterinary Services Laboratories in Ames, Iowa, confirmed a finding of vesicular stomatitis virus (VSV) infection (Indiana serotype) on an equine premises in Newton County, Missouri.
Two horses on the premises have met the confirmed case definition for a new infected state with compatible clinical signs and virus isolation positive results. This is the 2020 VSV Index Case for Missouri.
One other horse on the same premises has met subsequent case definition with compatible clinical signs and real-time reverse transcription polymerase chain reaction (RT-PCR)-positive results for VSV (Indiana serotype).
The Missouri index premises has nine horses present, of which three are showing clinical signs of VSV infection (ear lesions in two horses and oral lesions in one horse), which were first noted on July 7 and July 8. There are no other susceptible species on the premises and the epidemiological investigation is ongoing.
Known competent vectors for transmission of VSV include black flies, sand flies and biting midges (Culicoides spp.). Biosecurity measures and vector mitigation have been instituted to reduce the within-herd spread of the virus.
The animals are being monitored and the premises will remain under state quarantine until 14 days from the onset of lesions in the last affected animal on the premises.
Additionally, since the last situation report (7/7/2020), there have been 24 new VSV-affected premises identified (16 confirmed positive, 8 suspect) in 3 states.
Updates are as follows:
Kansas (12 new confirmed positive, 8 new suspect premises)
- Butler County – 3 new confirmed positive equine premises
- Chase County (New Infected County) – 1 confirmed positive equine premises
- Cowley County – 2 new confirmed positive, 2 new suspect equine premises
- Miami County (New Infected County) – 1 confirmed positive equine premises
- Montgomery County – 3 confirmed positive, 5 new suspect equine premises
- Morris County (New Infected County) – 1 confirmed positive equine premises
- Sedgwick County – 1 new confirmed positive equine premises
- Sumner County – 1 new suspect equine premises
The following previously VSV-infected or suspect premises have been released from quarantine:
- 19 in Butler County
- 3 in Cowley County
- 1 in Marion County
- 2 in Sedgwick County, and
- 3 in Sumner County.
Nebraska (2 new confirmed positive premises)
- Buffalo County – 1 new confirmed positive equine premises
- Johnson County (New Infected County) – 1 confirmed positive equine premises
- Since the last situation report, 1 previously VSV-infected premises has been released from quarantine in Buffalo County.
Oklahoma (2 new confirmed positive premises)
- Washington County – 2 new confirmed positive equine premises
Summary of the Outbreak
The 2020 VSV outbreak began on April 13, 2020, when the National Veterinary Services Laboratories (NVSL) in Ames, Iowa, confirmed the first VSV-positive premises in Dona Ana County, New Mexico.
Arizona, Texas, Kansas, Nebraska, Oklahoma and Missouri subsequently broke with VSV cases, which were confirmed by NVSL on April 22, 2020 (Cochise County, Arizona), April 23, 2020 (Starr County, Texas), June 16, 2020 (Butler County, Kansas), June 24, 2020 (Buffalo County, Nebraska), July 7, 2020 (Washington County, Oklahoma), and July 13, 2020 (Newton County, Missouri).
Since the start of the outbreak, 147 VSV-affected premises have been identified (109 confirmed positive, 38 suspect). One hundred forty (140) of these premises had only equine species clinically affected and 7 premises had clinically affected cattle (McMullen, Starr, and Zapata Counties, Texas; Butler and Cowley Counties, Kansas).
Arizona has identified 19 affected premises (18 confirmed positive, 1 suspect) in 7 counties (Apache, Cochise, Gila, Maricopa, Pima, Pinal, and Santa Cruz Counties).
Kansas has identified 94 affected premises (60 confirmed positive, 34 suspect) in 10 counties (Butler, Chase, Cowley, Greenwood, Marion, Miami, Montgomery, Morris, Sedgwick, and Sumner Counties).
Missouri has identified 1 affected premises (1 confirmed positive) in 1 county (Newton County).
Nebraska has identified 4 affected premises (4 confirmed positive) in 2 counties (Buffalo and Johnson Counties).
New Mexico has identified 16 affected premises (13 confirmed positive, 3 suspect) in 6 counties (Bernalillo, De Baca, Dona Ana, Eddy, Grant and Sierra Counties).
Oklahoma has identified 3 affected premises (3 confirmed positive) in 1 county (Washington County).
Texas has identified 10 affected premises (10 confirmed positive, 0 suspect) in 6 counties (El Paso, Hudspeth, Kerr, McMullen, Starr, and Zapata Counties).
There have been a total of 97 previously VSV-infected or suspect premises that have completed the quarantine period and been released. To date, all VSV-quarantined premises have been released in New Mexico (since June 4, 2020) and Texas (since June 8, 2020).
Fifty (50) premises remain under VSV quarantine in Arizona, Kansas, Missouri, Nebraska and Oklahoma.