Infectious Coryza in Chickens

Infectious Coryza in Chickens
Martin Ficken, DVM, PhD

Six 16-week-old male chickens from a flock of 500 birds were presented for necropsy at the Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) in Gonzales. History noted one-week of swollen sinuses with minimal abnormal respiratory sounds and negligible mortality.  The incidence was relatively low.

Upon necropsy examination, each of the six birds had one of the sinuses swollen while the other sinus appeared relatively normal (Figure 1).  A thick honey-like exudate was extracted from the sinuses of three birds. Two of the six birds also had a small abscess in the left wattle.  No other lesions of note were observed.

Bacterial cultures taken from the swollen sinus of each bird were plated on sheep blood agar and MacConkey plates. A Staphylococcus aureus nurse colony was provided on the blood agar plate for supplementation. Plates were aerobically incubated at 37^o C with 5% CO₂ for 24 hours.  From each bird, small bacterial colonies were isolated along the S. aureus nurse colony which were identified as Avibacterium paragallinarum.

Following testing, bacterial sinusitis (infectious coryza) caused by Avibacterium paragallinarum was determined as a diagnosis.

Infectious coryza is an acute respiratory disease of chickens caused by Avibacterium paragallinarum, once known as Haemophilus paragallinarum. It causes a catarrhal inflammation of mucus membranes of the nasal passages and sinuses. Infraorbital sinuses can be distended with thick mucus. Often, there is a mild conjunctivitis and edema of the face and wattles. Uncomplicated infections rarely cause mortality; however, co-infections with other bacteria, mycoplasmas, and viruses can result in significant mortality. Once recovered, birds are carriers and can periodically shed and be a source of infection for naïve chickens.

Differential diagnoses for an acute upper respiratory infection of chickens includes fowl cholera, mycoplasmosis, ornithobacteriosis, swollen head syndrome (infectious bronchitis virus and Escherichia coli co-infection), and avitaminosis A.

For more information about this case, contact Gonzales Resident Director Dr. Martin Ficken. To learn more about TVMDL’s test offerings, visit tvmdl.tamu.edu.

Reference:
Blackall, PJ and Soriano-Vargas, E.  Infectious Coryza and Related Bacterial Infections in Diseases of Poultry, 13^th edition, Wiley-Blackwell, ed. Swayne, DE et al.  pp. 859-873, 2013.