Vesicular Stomatitis, United States , May 21, 2004

Impact Worksheet

Summary:

An outbreak of Vesicular Stomatitis  (VS) was confirmed on May 19 on a premises near Balmorhea, in Reeves County in west Texas.  Three of 9 horses on the premises exhibited clinical signs and were seropositive for the New Jersey strain.  A quarantine has been placed on the premises by the Texas Animal Health Commission (TAHC).  TAHC is beginning a public information and education campaign regarding VS and are in the process of performing an area surveillance evaluation. 

Reeves County is located in an area with low numbers of livestock, accounting for only 0.1% of farms with horses and 0.2% of horses in Texas.  Similarly, Reeves County had minor numbers of cattle, with less than 0.1% of Texas’ farms with cattle and 0.3% of the state’s cattle.  Pig inventories in Reeves County were negligible.

Texas exported significant numbers of pigs in 2003, mostly to Mexico .  Texas exported smaller numbers of cattle and horses.  In 2003, the primary destination country for exported cattle was Mexico .  Horses exported in 2003 went to 28 destination countries; however, the majority went to Mexico .   

How extensive is vesicular stomatitis (VS) in the US , and what was the US ’ disease status prior to the outbreak?

An outbreak of Vesicular Stomatitis  (VS) was confirmed on May 19 on a premises near Balmorhea, in Reeves County in west Texas.  The premises is a roping facility with 9 horses and 8 steers.  Three of the horses exhibited clinical signs (2 with tongue erosions, 1 with nares erosions) and were seropositive for the New Jersey strain.  The steers are both clinically and serologically negative.  A quarantine has been placed on the premises by the Texas Animal Health Commission.  TAHC is beginning a public information and education campaign regarding VS and are in the process of performing an area surveillance evaluation. 

The last reported outbreak of VS in the US occurred in 1998.  The US has experienced sporadic outbreaks of VS since 1916.  VS is endemic on Ossabaw Island, Georgia .  Both the New Jersey and Indiana serotypes have been identified in the US . VS outbreaks have occurred in two distinct regions of the US :  1) outbreaks associated with the New Jersey serotype have occurred in the southeastern states of Georgia , Alabama, North Carolina and South Carolina, and 2) outbreaks associated with both the New Jersey and Indiana serotypes have occurred in the southwestern states, mainly New Mexico, Arizona, Utah, Colorado.  No VS outbreaks have occurred in livestock in the southeastern states since the mid 1970s.  In the southwestern states, however, outbreaks have occurred in livestock at approximately 10 year intervals.  The 1998 US outbreak included 130 positive premises in four southwestern states: Arizona, Colorado, New Mexico and Texas.  Texas had only one premises affected by VS in the 1998 outbreak, and this premises was in Reeves County.

Source: Vesicular Stomatitis (VS) confirmed in west Texas,; first US case since 1998, Texas Animal Health Commission News Release, May 19, 2004, www.tahc.state.tx.us; OIE disease report; Rodriquez LL, Emergence and re-emergence of vesicular stomatitis in the United States . 2002. Virus Research, 85:211-219;  Bridges VE, McCluskey BJ, Salman M.D, Hurd HS, Dick J.  Review of the 1995 vesicular stomatitis outbreak in the western United States . 1997. J Am Vet Med Assoc. 211:556-560.

What is VS and where does it occur?

VS is caused by a virus (family Rhabdoviridae, genus Vesiculovirus) and there are two major serotypes, New Jersey and Indiana.  VS has a wide host range, primarily affecting horses, cattle, and swine.  In addition, sheep, goats, camilids and various species of wild animals (deer, bobcats, raccoons, monkeys) can become infected with VS.  VS is considered a minor zoonosis, as humans can become infected, but human cases are rare even during an animal epidemic.  In humans, VS infection may produce a flu-like illness lasting 3-4 days.

The incubation period ranges from 2 to 8 days.  Clinical signs include excess salivation, fever, and vesicular lesions of the mouth, hooves, and teats (in dairy cows).  These clinical signs can lead to decreased food and water intake, and lameness.  Generally, the proportion of animals in a herd that show clinical signs varies from 5 to 10 percent of animals, however, up to 80 percent of dairy cattle herds have become affected.  Affected animals recover in around 2 weeks and death is rare.

Transmission of VS can occur in several ways.  The virus can be transmitted by insect vectors such as black flies and sand flies.  Transmission can also occur by direct contact with saliva or fluid from ruptured vesicles.  Mechanical transmission from contaminated objects is also possible.  Control measures include quarantine of affected premises, isolation of affected animals from healthy animals, insect control, stabling of animals, use of protective measures such as gloves when handling affected animals, and disinfection of equipment.

Worldwide, VS is limited to North, Central, and South America.  VS is endemic from northern South America to southern Mexico and outbreaks occur yearly in these areas. VS outbreaks occur seasonally and are usually more frequent in the rainy season in tropical areas, however, in some countries, outbreaks are associated with the dry season.  In temperate areas, outbreaks typically occur in the spring or summer and generally disappear at the first frost.

VS is considered an economically important livestock disease.  Livestock producers may experience production losses and restrictions on animal movement.  VS causes additional concern because the clinical signs of VS are similar to two other important foreign animal diseases, foot-and-mouth disease and swine vesicular disease.

Sources: OIE Animal Diseases Data: Vesicular Stomatitis, 2002; USDA, APHIS, VS Factsheet for Vesicular Stomatitis, http://www.aphis.usda.gov/lpa/pubs/fsheet_faq_notice/fs_ahvs.html; Rodriquez LL, Emergence and re-emergence of vesicular stomatitis in the United States . 2002. Virus Research, 85:211-219; Bridges VE, McCluskey BJ, Salman M.D, Hurd HS, Dick J.  Review of the 1995 vesicular stomatitis outbreak in the western United States . 1997. J Am Vet Med Assoc. 211:556-560. 

What are inventories of susceptible livestock in Texas and the affected county?

In 1997, Reeves County had 61 farms with a total of 433 horses and ponies, accounting for only 0.1% of farms with horses and 0.2% of horses in Texas.  Similarly, Reeves County had minor numbers of cattle, with less than 0.1% of Texas’ farms with cattle and 0.3% of the state’s cattle.  Pig inventories in Reeves County were negligible.

Table 1.  Inventories of horses, cattle, and pigs

Inventory, 1997

Number farms

Number animals
 

Texas

Reeves Co.

Texas

Reeves Co.

Horses & ponies

44,203

61

241,981

433

Cattle

144,354

95

14,532,814

44,390

Pigs

5,428

4

578,664

18

Source:  USDA NASS, 1997 Census of Agriculture

Most of Texas’ horses are located in the eastern part of the state.  Cattle are concentrated in the northern panhandle and also in the eastern part of the state.  Reeves County is located in an area with low numbers of livestock. 

Horses and Ponies, Inventory, 1997

Source:  USDA, NASS, 1997 Census of Agriculture

Note:  The data for these maps are at the county level.  The dots are randomly placed in the county and do not indicate locations of specific premises.


Cattle and Calves, Inventory, 1997
Hogs and Pigs, Inventory, 1997

What are exports of susceptible livestock from Texas?

By far the largest numbers of livestock exported from Texas are pigs, with over 200,000 head exported in 2003.  These went almost exclusively to Mexico .  Almost 16,000 cattle were exported from Texas in 2003 and the primary destination country was Mexico .  Horses exported in 2003 went to 28 destination countries; however, the majority went to Mexico .

Table 2.  Exports of horse, cattle, and pigs from Texas

 

2003

Horses

4,737

Cattle

15,919

Pigs

206,289

Source:  VS Export Tracking System

(Note: It should be noted that the VS Export Tracking System only tracks certificates issued for animal exports, it does not track if the animals actually leave the country.) 

CEI’s plans for follow up:

CEI will monitor the situation.  If you need more information or if you’d like to comment on this worksheet, you may reply to this message, or contact Judy Akkina at (970) 494-7324 or Chris Kopral at (970) 494-7325.