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Vet College Helped Stop Big Outbreak
MISSISSIPPI STATE -- A severe infectious bronchitis virus outbreak among Mississippi broilers was quickly subdued last winter with the help of improved tests run by Mississippi State University's College of Veterinary Medicine.
Infectious bronchitis virus causes coughing and sneezing in broilers, slows the birds' growth and can kill the broiler or cause it to be condemned at the processing plant. This disease causes about $1.7 million annual losses in an industry valued at more than $1.2 billion in 1997.
Reagan Sadler, laboratory manager and poultry pathologist for Central Industries in Forest, sends all suspected virus samples he encounters to MSU for testing.
"It used to take weeks to get the results of the tests, but now we're able to diagnose the problem in about one week," Sadler said.
When an outbreak of infectious bronchitis virus strikes a company, between 3 and 8 percent of the broilers are condemned at the processing plant, Sadler said. Proper vaccination drops that number down to about 1 percent. Reducing the time it takes to identify the virus strain and vaccinate against it can mean a substantial savings for a broiler company.
Dr. Roy Montgomery, CVM associate professor, said the virus is an on-going problem, but appears periodically as an epidemic. This year was one of those years, and all Mississippi broiler companies were affected by it. To date, samples from more than 160 affected farms have been tested this year.
MSU's veterinary college helped Mississippi producers react quickly to the problem. Faculty used two different tests to quickly determine which strain of the virus was present. Once the particular strain of the infectious bronchitis virus was detected, growers could vaccinate incoming flocks against that strain.
Dr. Frank Austin, veterinary college diagnostic microbiologist, used monoclonal antibodies in the indirect flourescent antibody test to detect the presence of the virus by looking for proteins the virus produced. The test has a four-hour turnaround from receipt of the specimen to diagnosis.
"This has dramatically decreased the producers' response time to the virus," Austin said. "Within a few weeks we can change the course of an epidemic, where in the past problems might go on for months."
Dr. Chinling Wang, veterinary college researcher, used the reverse transcriptase polymerase chain reaction test to identify the virus. Previously, Wang found a way to shorten the time it takes to run the RT-PCR test from almost 10 days to 5 days.
"We were able to quickly identify what kind of virus was involved and give the poultry companies the information they needed," Wang said.
The fluorescent antibody test is quicker and cheaper to run than is the RT-PCR test, which is more sensitive. Both are performed for comparison and to confirm the results. In the height of the outbreak, the lab tested 12 to 15 cases a week, Wang said.
"This is the first time we've had these two new weapons during an outbreak," Montgomery said. "Everyone worked on this together to solve the problem quickly."
Not all states have diagnostic labs to support their poultry industry and Mississippi has only recently gained this ability, Montgomery said. The seven people who work to diagnose this virus in the state's poultry industry are Montgomery, Wang, Austin, Sadler, and Drs. Bob Keirs, Danny Magee and Dr. Sue Ann Hubbard, all with MSU's veterinary college.
Contact: Dr. Roy Montgomery, (601) 325-1279