What egg producers need to know about infectious coryza

Infectious coryza affects commercial layer and broiler flocks. Learn what producers should look for and what methods of treatment may be valuable.

As coryza outbreaks affect commercial layers and broilers, veterinarians are working to better understand the disease and how to treat it. (kaninstudio | Adobe Stock)
As coryza outbreaks affect commercial layers and broilers, veterinarians are working to better understand the disease and how to treat it. (kaninstudio | Adobe Stock)

Infectious coryza is a bacterial disease caused by Avibacterium paragallinarum that affects chickens' respiratory systems.

“You need to know that not all of the Avibacterium are pathogenic; some of them are, in fact, normal flora,” said Sherrill Davison, DVM, avian medicine and pathology professor at Pennsylvania State University, during the presentation of her findings during the pullet and layer health workshop in Minneapolis on March 12 during the Midwest Poultry Federation Convention. Chickens are the natural host of the disease, she said.

“Turkey coryza and infectious coryza are two separate diseases caused by different organisms (Bordatella avium vs. Avibacterium paragallinarum, respectively) and (require) different control measures," said Eric Gingerich, DVM, technical services specialist with Diamond V, in a separate interview. "Improved biosecurity is always a common denominator in these infectious disease outbreaks, however."

Outbreaks

Since the start of 2019, the coryza outbreak has affected 22 premises in southeastern Pennsylvania, Davison said in a follow-up interview. These outbreaks affect commercial layers and broilers.

"Some premises have more than one flock affected,” she said.

In a specific layer flock Davison worked with, she saw as much as a 43 percent decrease in egg production, which may have been impacted by additional factors. A broiler flock she worked with saw a 12 percent mortality rate; this resulted in 1,500 dead birds in one day, she said. Another layer flock experienced 16 percent mortality.

Signs of coryza and susceptibility

Clinically, the disease presents itself with signs of respiratory disease. The birds will have facial swelling, swollen wattles, mucoid nasal discharge and respiratory rales. It has a short incubation cycle of one to three days and tends to run its course within two to three weeks, unless otherwise complicated by other bacteria or viruses.

Coryza Birds White Discharge

Infected birds initially have a clear mucus discharge, which then turns milky white and eventually becomes a caseous material. (Courtesy Sherrill Davison, DVM)

“Very high mortality, low feed consumption and a large drop in egg production are consistent with infectious coryza,” Gingerich said.

When birds are first infected, they have a clear mucus discharge, which then turns milky white and eventually it becomes a caseous material, Davison said. While performing necropsies of deceased birds, Davison found hemorrhages at the distal end of the trachea. She also saw things that looked like infectious laryngotracheitis.

The birds also displayed caseous pericarditis, perihepatitis, egg yolk peritonitis, regressing ovaries and empty gizzards. She said the first clinical signs of coryza is a decrease in feed and water consumption. Older birds seem to be more seriously impacted than younger birds.

Coryza Facial Swelling

Coryza causes birds to experience facial swelling, swollen wattles, mucoid nasal discharge and respiratory rales. (Courtesy Sherrill Davison, DVM)

Control and treatment

There are commercial bacterins available, however Davison said that it is her understanding that the supply of those vaccines is limited.

It has been debated whether antibiotic usage is beneficial. While Davison said she thought antibiotics were beneficial in reducing the duration of the disease, she explained that treatment options are troublesome in the cases where broilers for no-antibiotics-ever production and organic flocks have been affected.

The disease does not survive well outside of the bird, Davison said. She added that the disease does not do well in heat. In temperatures of 113 F or higher, it should be killed within two to three minutes.

“This was a question that came up about cleaning the egg supply and whether or not, those going through the washers, if it would get killed, and it should,” she said.

Exudate is infectious for at least 24 hours at 72 F and, at 40 F, it is infectious for several days.

“Disinfectants do work on this; it doesn’t like heat or drying,” she said. Even after treatment, birds remain carriers of the disease.

Davision added that it is important that consumers know coryza is not a food safety or public health issue.

 

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