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Infectious Coryza

Other Names: Roup, Catarrh, Cold, Hemophilus Infection, Infectious Catarrh

Infectious coryza (IC) is an acute upper respiratory disease of chickens caused by Avibacterium paragallinarum (formerly Haemophilus paragallinarum). The disease occurs worldwide and, within the United States, is most prevalent in California and the southeastern regions.

Following infection, disease progression is rapid. Susceptible birds typically develop clinical signs within 24 to 72 hours. Early signs include depression and reduced appetite. As the disease advances, affected chickens commonly exhibit facial swelling, nasal discharge, and lacrimation (watery eyes). Co-infection with other pathogens is common and may increase disease severity, contribute additional clinical signs, and complicate diagnosis.

Diagnosis of Infectious Coryza

Diagnosis is based on flock history, clinical presentation, and bacteriological testing to isolate and identify the causative organism. Available diagnostic methods include:

Direct isolation: The organism can be cultured from sterile swabs collected from the infraorbital sinus, trachea, or air sacs. Successful isolation is most likely during the acute stage of infection (typically within 1 to 7 days).
Hemagglutination inhibition (HI) testing: Widely used to detect changes in antibody titers following infection or vaccination and to assess flock-level exposure.
Polymerase chain reaction (PCR): Provides rapid and sensitive detection, often yielding results within hours.

Diagnosis may be more challenging in cases involving concurrent infections.

Transmission

The primary reservoirs of A. paragallinarum are chronically infected or asymptomatic carrier birds. Once introduced into a flock, the pathogen spreads rapidly through direct and indirect contact, ingestion of contaminated feed or water, and aerosol transmission. Exposed birds may develop clinical signs within 24 to 72 hours. Recovered birds can remain carriers and may intermittently shed the bacteria, particularly during periods of stress..

Clinical Signs

Facial swelling

Nasal discharge

Conjunctivitis and ocular discharge

Depression/lethargy

Reduced appetite

Diarrhea

Weight loss

Decreased egg production

Ruffled feathers

Diagnosis

History
Clinical signs
Physical exam
Necropsy
Lab tests

Reported Cases

Case 1: Infectious coryza in a Chickens 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. 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 37o 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 A. paragallinarum was determined as a diagnosis. Ref

Case 2: Otitis and meningoencephalitis in a Chickens In March 2017, the Turlock branch of the California Animal Health and Food Safety laboratory system encountered an unusual clinical and pathologic presentation of infectious coryza in 6 live, 29-d-old, commercial broiler chickens that were submitted for diagnostic investigation. Antemortem evaluation revealed severe neurologic signs, including disorientation, torticollis, and opisthotonos. Swollen head–like syndrome and sinusitis were also present. Histologically, severe sinusitis, cranial osteomyelitis, otitis media and interna, and meningoencephalitis were noted, explaining the clinical signs described. A. paragallinarum was readily isolated from the upper and lower respiratory tract, brain, and cranial bones. Infectious bronchitis virus (IBV) was also detected by PCR, and IBV was isolated in embryonated chicken eggs. Based on sequencing analysis, the IBV appeared 99% homologous to strain CA1737. A synergistic effect between A. paragallinarum and IBV, resulting in exacerbation of clinical signs and increased mortality, may have occurred in this case. A. paragallinarum should be considered among the possible causes of neurologic signs in chickens. Ref

Case 3: Infectious coryza and fowl adenovirus in a Commercial laying hens The diagnosis of a concurrent infection of Avibacterium paragallinarum and fowl adenovirus (FAdV) in an infectious coryza–like outbreak in the outskirt of Beijing was reported. The primary signs of the infection were acute respiratory signs, a drop in egg production, and the presence of hydropericardium–hepatitis syndrome–like gross lesions. Laboratory examination confirmed the presence of A. paragallinarum by bacterial isolation and a species-specific PCR test. In addition, conventional serotyping identified the isolates as Page serovar A. Fowl adenovirus was isolated from chicken liver specimen and identified by hexon gene amplification. In addition, histopathologic analysis and transmission electron microscopy examination further confirmed the presence of the virus. Both hexon gene sequencing and phylogenetic analysis defined the viral isolate as FAdV-4. The pathogenic role of A. paragallinarum and FAdV was evaluated by experimental infection of specific-pathogen-free chickens. The challenge trial showed that combined A. paragallinarum and FAdV infection resulted in more severe clinical signs than that by FAdV infection alone. The concurrent infection caused 50% mortality compared with 40% mortality by FAdV infection alone and zero mortality by A. paragallinarum infection alone. Ref

Case 4: Infectious coryza complicated by Ornithobacterium rhinotracheale in a Chickens The coinfection of Avibacterium paragallinarum and Ornithobacterium rhinotracheale in two outbreaks of infectious coryza from Peru was reported. The diagnosis was confirmed by bacteriologic isolation, PCR testing, and sequencing of the 16S rRNA gene. The susceptibility of the isolates to 12 antimicrobial agents was tested by a disk diffusion method. The isolates were susceptible to amoxicillin/clavulanic acid and florfenicol and were resistant to oxacillin and sulfamethoxazole/trimethoprim. The coinfection of Av. paragallinarum and O. rhinotracheale and the severity of clinical signs were evaluated by experimental infection of specific-pathogen-free chickens. The group inoculated with O. rhinotracheale alone presented minimal clinical signs in 3 of 10 chickens. However, the groups inoculated with both Av. paragallinarum and O. rhinotracheale induced the most-severe clinical signs compared with the group inoculated with Av. paragallinarum alone. Ref

Treatment

Name	Summary
Supportive care	Isolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Antibiotic therapy	Antimicrobials should be selected based on culture and sensitivity testing, as resistance is common and co-infections may require targeted treatment.

Support

Prevention

Vaccination : Typically administered via intramuscular injection, often on a biannual schedule depending on risk.
Provide warm, draft-free housing in the winter
Biosecurity: Quarantine new birds before introducing them to the flock.
Exposure control: Avoid participation in poultry shows, auctions, or other events where birds may be exposed to outside flocks.