There is a disease that has been identified in some poultry houses in South Mississippi that is easily transmitted from bird to bird and farm to farm and can leave growers with hundreds of dead birds in just days. It poses no risks to humans, researchers say, but can be catastrophic to growers’ financial health if unchecked.
However, scientists say the current “outbreak” should be a source of concern, not panic. The disease so far is limited to poultry houses in Wayne and Jones counties in South Mississippi. Officials are monitoring the situation, but so far have only recommended the first line of defense — quarantine. No large-scale vaccinations are being pushed, and the current cases, at least at press time, were contained.
The disease is called infectious laryngotracheitis, or L.T. The disorder causes respiratory distress among chickens as well as pheasant. The first symptom noticed is usually watery eyes. Affected birds remain quiet because breathing is difficult. Coughing, sneezing and shaking of the head to dislodge exudate plugs in the windpipe follow. Birds extend their head and neck to facilitate breathing (commonly referred to as “pump handle respiration”). Inhalation produces a wheezing and gurgling sound. Blood-tinged exudates and serum clots are expelled from the trachea of affected birds, sometimes leading to asphyxiation due to a blockage of the trachea.
L.T. can run rampant through poultry houses. Danny Thornton, poultry specialist with the Mississippi State University Extension Service, said, “Growers can wake up one day to find, say, 30 or 40 dead birds. The next day, it’s 200. The next, it can be 1,000.”
Fortunately, the disease usually runs its course in just a few days, Thornton said. Mortality rates nosedive thereafter.
Unfortunately, birds that are diseased but survive are carriers for life.
It can be a bottom line-killer for poultry growers. During a 2002-2003 outbreak, the last significant appearance of L.T. that affected a minimum of 70 farms in Mississippi, mortality rates among birds on some farms reached as much as 8 percent. Thornton said mortality rates historically are in the 2 to 3 percent range.
Officials recommended those dead birds should be incinerated to help block the disease’s spread.
The last large-scale L.T. outbreak in Mississippi occurred in 1981-1982. Thornton and Dr. Danny Magee, director of the Poultry Research and Diagnostic Laboratory at Mississippi State University’s College of Veterinary Medicine, both were involved in combating the 1981-1982 outbreak, and both said they believed that it was the only large-scale outbreak in state history. Thornton said that outbreak affected practically the entire state, much larger than either the 2002-2003 or current cases of L.T.
There was little documentation of the 1981-1982 outbreak, so the financial impact from the outbreak is not known.
Mississippi has been fortunate on the L.T. front. Neighboring states have seen numerous outbreaks over the years. In fact, the 1981-1982 outbreak was blamed on chickens from Alabama.
Both Thornton and Magee said they are puzzled as to why Mississippi’s poultry farms have largely escaped L.T.’s worst.
There were lessons learned from the outbreak in 1981-1982 and 2002-2003 that officials are currently applying. One of those is the inoculation of birds.
The Alabama birds at the root of the 2002-2003 had actually been treated for L.T. When the birds in Mississippi were identified with L.T., scientists began inoculating birds using a live virus vaccination.
The strategy was to inoculate birds to a certain point, then stop. When the vaccinations stopped, so did the L.T.
Thus, researchers realized that using live-virus vaccinations was inherently risky. So, birds infected with L.T. now are not treated with a live virus.
While current vaccines are safer, they are not free. Magee said vaccines run approximately $8 per 1,000 doses, which he called “pretty expensive.” Poultry companies, not the growers, would pick up that tab, but, as with all other input costs, would be eventually passed to the consumer.
Communication is key. Misinformation can lead to panic and/or possibly perpetuation of the disease.
One Jones County grower told the Mississippi Business Journal that she had been advised to eliminate any contact with growers who have infected farms. The farmer attends church with an affected grower, and she was told it might be wise to skip church until the L.T. had run its course.
Neither Thornton nor Magee would say that is overkill. The disease can easily be spread from shoes and clothing, and Magee said growers and their companies should be highly concerned about bio-security.
One piece of misinformation does have Magee concerned, however. When the current L.T. cases were first identified, state veterinarian Dr. Jim Watson issued a statewide ban on the movement of chicken litter in an effort to isolate the disease. When the disease was found to be only in the two South Mississippi counties, Watson allowed the movement of litter in the unaffected parts of the state.
Magee said he had one grower tell him recently that since Watson partially lifted the litter-moving ban, the threat of L.T. is over. Magee said that is not the case, and now is not the time for growers to let down their guard.
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