Bluetongue

1
Bluetongue

• Lindsey Foard
• Trends and Issues in Ag
• Fall 2007

2
Overview

• Who may become infected?
• Sheep, White-tail deer, antelope
• Cattle, goats, elk
• Humans not susceptible
• Viral disease
• Spread by biting gnats (or midges)
• Animal to animal?
• Seasonal (summer/fall)
• Where is it found?

3
Symptoms

• First signs (4-6 days after infection)
• Depression, heavy breathing/panting
• Fever
• Swelling (lips, nose, eyelids, face, throat,
  area, ears)
• 7-12 days after infection
• Congestion of nose, nasal cavity, mouth, eyes
• Loss of wool
• Lameness
• Coronary bands of feet swell and turn dark
  blue/red (make walking difficult)
• Swelling of the tongue is common (some cases, may
  protrude from mouth)
• Because of damage to blood vessels and a lack of
  oxygen The tongue turns a blue color
  (Bluetongue)

4
History and Cases

• Fairly new to United States
• South Africa in 1800s
• U.S. in 1950s
• UK was hit hard this year
• 100 new cases of Bluetongue every day

5
Closer to home

• Outbreak of Bluetongue in South-Central Montana
• Early September 2007
• Reported in Musselshell County near Melstone
• September 10
• State Veterinarian, Dr. Marty Zaluski, authorized
  hold order on Musselshell County sheep
• Sheep Producers in the county not allowed to move
  their sheep within or beyond their county lines
  until October 10
• About 100 sheep had already died of Bluetongue
  already
• September 18
• Lab results came back from Iowa positive
• Had been reports of sick sheep in other counties
• State vet expanded the hold order to 15 other
  counties in the area

6
..cont

• October 3 Hold order lifted
• Earlier than expected
• Already had hard frosts in central and eastern
  Montana
• Short fall days
• No need to delay Fall market season

7
Why Montana?

• Southern states.. Yes. Montana?
• Not normally.. Too cold up here
• What made this year different from other years?
• Incubation Period
• As described by MSU Extension Sheep Specialist,
  Rodney Kott, and Lisa Surber

8
The Incubation Period of the Virus in Gnats

• The time from when the gnats get the virus from
  an infected animal, develop the infection, and
  are then able to transmit it to healthy animals
• Takes about 12-14 days
• Gnats have to take 3 blood meals (from infected
  animals) and complete 3 egg cycles to be able to
  transmit the disease
• Takes females about 6 days to complete one egg
  cycle
• Researchers have dissected hundreds of females
• found that less that 1 actually completed the 3
  egg cycles
• In other words, many never actually get the
  required 3 blood meals

9
What this proves

• This proves that normally the gnats, or midges,
  hardly ever live long enough to transmit the
  disease
• Temperature directly influences the incubation
  period of the virus in the gnats
• Because this summer was not an average summer, a
  larger percentage of gnats were able to survive
  and complete the 3 egg cycles
• Another contributing factor
• Virus has to be present.
• Cattle are said to be possible reservoirs for
  the virus organism
• Cattle arent normally affected by the disease,
  but could be carriers

10
Prevention

• Keep livestock away from areas where the biting
  gnats are numerous during summer/fall months
• Not always possible
• Try to get rid of breeding areas
• Moving livestock to higher altitudes

11
Treatment

• No cure for Bluetongue yet
• Vaccines have been developed for a couple of the
  serotypes of the disease
• There are 24 serotypes
• Vaccination not widely available
• Normally takes 2-3 weeks before the vaccine does
  actually increase immunity to the disease
• Antibiotics have not been developed
• Basically all ranchers can do is to try to
  minimize stress, provide comfort
• Should be fed soft, palatable feed (Oral lesions
  and soreness of mouth)
• Shade and water

12
Statistics and Losses

• They say only 5 of infected sheep in the U.S.
  have actually died
• Have been cases outside of the U.S. where 179,000
  sheep were lost in 4 months
• Mortality rate does depend on condition and
  environment
• Some herds more susceptible than others
• The sheep that do survive
• Not in great shape
• Economic losses
• Loss of weight and wool
• Reduced herd fertility
• Production and value

13
Wrap Up

• Not limited to those southern states
• Serious issue and concern
• Major reason this is an important subject
• Dont know that much about it yet
• No vaccine
• Hard finding information
• Could become a big problem in the future
• As in the Musselshell County case this year
• All ranchers could do was to wait and hope for a
  hard frost
• The sooner we find a vaccine and solution to this
  problem, the better off well be