Research looks at economic impact of vaccinating for bluetongue
Riverton – When bluetongue hit in the Big Horn Basin in 2007, it had severe impacts on sheep producers.
“Our research looks at deciding if vaccinating for bluetongue virus in domestic sheep flocks in Wyoming is a viable option for the future,” said University of Wyoming graduate student Tris Munsick at Fremont County Farm and Ranch Days on Feb. 10. “Currently, we don’t vaccinate. We looked at the economic impacts of vaccinating, and examined the costs and benefits of vaccinating in the regions affected by bluetongue.”
Munsick partnered with producer Randall Jones of Otto to investigate the question, and his research is guided by UW Professors Dannele Peck and John Ritten in agricultural and applied economics and Myrna Miller in veterinary sciences.
The 2007 outbreak in the Big Horn Basin was devastating for producers.
“The Big Horn Basin has no history of bluetongue before, and producers like Randall Jones who got the disease in their herds were nearly devastated by it,” he commented.
Jones explained that the outbreak started in his herd at the end of September.
“I’ll remember that outbreak for my entire life,” Jones said. “I had no idea what bluetongue was prior to getting it. The first thing I noticed was a lamb that acted like it had something in its mouth. Its tongue was swollen.”
He continued, “Two days later, I cut over 100 head from the main herd that were showing symptoms.”
Because the disease is viral, Jones said supportive care was his only option. He fed hay and intubated the affected sheep to provide sustenance in the form of a gruel. They also gave the sheep a painkiller to attempt to influence them to eat.
“It took about 10 days before they died,” he said. “It was miserable and hard to watch.”
“Over the course of six weeks, we lost one in every six of our sheep,” Jones said. “It didn’t matter whether we were talking about the stoutest rams or the skinniest ewes.”
Jones also noted that the infections continued until late October when a hard freeze killed the midges.
During the 2007 outbreak, Jones mentioned vaccine wasn’t available at the time.
“The only place we could find vaccine was from the California Wool Growers, but federal laws prohibited it from coming across state lines,” he explained.
Current work to develop a vaccine is being conducted by Miller in the Wyoming State Vet Lab.
Jones added that insecticide is also useful for controlling midges, but using an insecticide dip is both time consuming and labor intensive. Insecticide must be re-applied every three weeks.
“We have to cover every area that the skin does not have wool with insecticide,” he said. “I’m convinced it will have an impact on controlling the midge, thus controlling the transmission of bluetongue, but I prefer vaccine.”
“Working with Randall and Dr. Jim Logan has been great,” Munsick said. “We looked at the economics of vaccinating based on the 2007 bluetongue outbreak.”
Munsick looked at Jones’ herd of 1,400 sheep, 500 of which were affected. Of the affected sheep, 275 died, for a mortality rate of nearly 20 percent.
Using four methods and four scenarios, Munsick looked at the economic impacts of vaccinating
“There are four scenarios that can happen with a bluetongue outbreak,” he said. “We can not vaccinate and not get the disease, not vaccinate and get the disease, vaccinate and not get the disease or vaccinate and get the disease.”
Additionally, in his research, Munsick looked at the worst-case scenario, assuming naïve sheep populations, 100 percent certainty of disease contraction and 84 percent efficacy of the vaccine.
Munsick also used a herd of 1,400 sheep for his calculations, reflecting Jones’ herd from 2007.
In the worse case scenario, Munsick totaled the cost of an outbreak at over $72,000. Costs included supportive care, pharmaceuticals, death loss, sickness and labor costs.
“These costs don’t count for intangible costs,” he said. “This number is also variable depending on lamb prices and feed costs. We used prices for 60- to 90-pound feeder lambs in Fort Collins, Colo. from November 2014.”
When looking at vaccines, Munsick considered both modified live virus (MLV) vaccine, at a cost of 32 cents per dose, and killed virus vaccine, at $1.20 per dose.
Total MLV vaccine cost would reach $497.51 for the herd, and killed vaccine cost would be $3,499.93.
“We looked at breakeven costs,” Munsick explained. “How much would the outbreak have to cost to justify vaccinating every other year?”
He continued, “If the outbreak hits every five years, an outbreak would need to cost $1,478.92 if we use MLV or $10,403.89 if we use killed vaccines. If an outbreak hits every 10 years, it would need to cost $3,553.18 for MLV and $24,995 if we used killed vaccines.”
Munsick added that the maximum time between outbreaks to justify the use of MLV vaccine and killed vaccine is 48 and 18 years, respectively.
“If we see outbreaks less than every 48 years, we can justify the cost of MLV vaccine, and we if we an outbreak less than every 18 years, we can justify the cost of killed vaccines,” Munsick commented.
Munsick’s research will be finalized within the next four months. The Wyoming Agriculture Producer Research Grant Program, UW Ag Experiment Station and two private UW College of Agriculture donors funded the project.
Saige Albert is managing editor of the Wyoming Livestock Roundup and can be reached at firstname.lastname@example.org.