Infectious coryza in chickens

Infectious coryza is a serious bacterial disease of chickens which affects respiratory system and it is manifested by inflammation of the area below the eye, nasal discharge and sneezing.[1][2] The disease is found all over the world causing high economic losses. Economic loss is due to stumping off and reduction of egg production in case of laying chickens. The disease was discovered early 1930s by considering clinical signs.[1]

Signs and symptoms

Clinical appearance of the disease includes depression, a serous nasal discharge, and sporadically minor facial inflammation in mild form of the disease. In severe form, there is severe inflammation of one or both infraorbital sinuses with edema of the surrounding tissue. The swelling can cause closure of one eye or both of them. Intermandibular space and wattles of corks do swell as a course of the disease.[2][3]

Cause

The disease is caused by bacteria called Avibacterium paragallinarum, which is a gram-negative bacterium. The bacterium is microaerophilic rod-shaped and is nonmotile. Its growth requires presence of nicotinamide adenine dinucleotide. There are three serovars A, B and C of A. paragallinarum that relate by immunotype specificity.[1][2]

Transmission

The reservoirs of the disease are carrier chickens which could be healthy but harboring the disease or chronically sick chickens. The disease affects all ages of chickens. The disease can persist in the flock for 2-3 weeks and signs of the disease are seen between 1–3 days post infection. Transmission of the disease is through direct interaction, airborne droplets and drinking contaminated water. Chicken having infection and those carriers contribute highly to the disease transmission.[2][3]

Diagnosis

It is done through isolation of bacteria from chickens suspected to have history of coryza and clinical finds from infected chickens also is used in the disease diagnosis.[1][4] Polymerase chain reaction is a reliable means of diagnosis of the disease.[5][6][7][8]

Treatment

Prevention is through use of Stock coryza-free birds. In other areas culling of the whole flock is a good means of the disease control. Bacterin also is used at a dose of two to reduce brutality of the disease. Precise exposure has also has been used but it should be done with care. Vaccination of the chicks is done in areas with high disease occurrence. Treatment is done by using antibiotics such as erythromycin, dihydrostreptomycin, streptomycin, sulfonamides, tylosin, and fluoroquinolones.[2][3]

References
  1. Blackall P J, Matsumoto M., Yamamoto R. Infectious coryza. In: Calnek B W, Barnes H J, Beard C W, McDougald L R, Saif Y M, editors. Diseases of poultry. 10th ed. Ames: Iowa State University Press; 1997. pp. 179–190
  2. Merck Veterinary Manual, 2016
  3. "Poultry, Poultry Health, Welfare, Diseases, Poultry News, Articles, Photos of Chickens, Poultry Photo". The Poultry Site.
  4. Bragg R R, Greyling J M, Verschoor J A. Isolation and identification of NAD-independent bacteria from chickens with symptoms of infectious coryza. Avian Pathol. 1997;26:595–606
  5. Blackall P J, Yamamoto R. Infectious coryza. In: Swayne D E, editor. A laboratory manual for the isolation and identification of avian pathogens. 4th ed. Philadelphia, Pa: American Association of Avian Pathologists; 1998. pp. 29–34
  6. Chen X, Chen Q, Zhang P, Feng W, Blackall P J. Evaluation of a PCR test for the detection of Haemophilus paragallinarum in China. Avian Pathol. 1998;27:296–300.
  7. Chen X, Miflin J K, Zhang P, Blackall P J. Development and application of DNA probes and PCR tests for Haemophilus paragallinarum. Avian Dis. 1996;40:398–407
  8. Chen X, Song C, Gong Y, Blackall P J. Further studies on the use of a polymerase chain reaction test for the diagnosis of infectious coryza. Avian Pathol. 1998;27:618–624.
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