Avian Infectious Coryza (AIC)
Info-Bullets

• What is Avian Infectious Coryza?  It is an infectious disease of chickens affecting the nasal passages, trachea and lung. It is caused a bacterium (Haemophilus paragallinarum). Egg production in affected laying flocks may drop 10% to 80%. Affected birds have swollen faces, nasal discharge and may develop severe respiratory difficulties resulting in 2% to more than 10% mortality. Young birds grow poorly. The disease affects only chickens. It is not transmitted into eggs and is not infectious to pets or humans.

• Where does the disease occur? AIC has been seen worldwide. In the US it is most prevalent in California and the southeastern US. In New England AIC has occurred in Connecticut in the 80's, but has not been diagnosed in Maine during the last 20 years.

•  Can other birds or animals be infected? The chicken is the natural host. All ages of chickens can be infected, but the disease is usually more severe in older chickens. Turkeys, pigeons, sparrows, ducks, crows, mice, rabbit and guinea pigs cannot be infected.

•  How is the disease transmitted? Chickens that have recovered from the disease or chronically sick chickens are carriers of the bacterium and are the main source of the infection. On farms where multiple ages of chicken flocks are raised AIC occurs 1-6 weeks after contact between susceptible chickens and carrier birds. People handling sick birds or dead birds may transmit the disease to susceptible healthy birds. The disease may be spread by airborne route on high-density farms. Fomites contaminated with secretions from infected birds, such as people's clothing, crates and trucks, tools, egg flats may serve as vehicles of transmission to other locations for a short period of time (hours more likely than days). Wild birds are not infected but may possibly mechanically transmit AIC if they had contact with infected birds. Inside a chicken house or complex the disease is spread by contact between infected and non-infected birds, air-borne mucus droplets, contaminated feed augers or drinking water in trough systems. The disease is not transmitted into eggs or via the egg to baby chicks.

• How long does the bacterium survive outside the chicken? Fortunately the bacterium is very delicate and does not survive outside the chicken for long. The bacterium is killed in water within 4 hours at ambient temperature. It can survive in secretions from infected birds for several days at cool temperatures. Disinfectants for use in poultry facilities are fully effective at recommended recommendations.

• What are the signs of the disease? Watery or mucoid discharges from the nostrils, swollen face, often only on one side, occasionally swollen eyelid(s). The disease in Maine was characterized also by severe respiratory distress, gasping for air, respiratory rales and coughing up blood, resembling signs similar to Infectious Laryngotracheitis. Death may occur due to blockage of the air passage through the trachea or large bronchi by blood, mucus or fibrinous exudate. Flocks go off feed. The egg production drops over a course of 2-3 weeks. No shell or inner egg quality problems are reported but egg size decreases. Affected birds may go into a neck or partial molt. The disease spreads rapidly through a flock and to other houses in close proximity.

• How much time passes between infection and the first signs of disease? About  1 to 6 days. We placed two SPF hens in separate laying cages next to a naturally infected and sick hen. This hen showed a swollen face, respiratory rales and whitish diarrhea. The face swelling disappeared within three days and the bird recovered from respiratory signs within 4 days.  The diarrhea persisted for another 2 days. The hen started a partial molt within 9 days but started laying eggs 13 days after placement in isolation. One of the SPF birds had slightly watery eyes from day 3 after exposure, one swollen eyelid on day 6, severe respiratory distress on day 7 and died on day 8. The other bird showed respiratory distress on day 6, started molting on day 9, swelling of one side of the face on day  10. The swelling of the face disappeared within 2 days. The bird had clinically recovered 16 days after contact with a sick bird. 

• Do affected flocks recover? Birds without complicating secondary infections seem to recover within about 3-5 weeks and will return to the normal level of egg production. Secondary infections include Pasteurella hemolytica, Streptococcus and Staphylococcus and Mycoplasma gallisepticum. Elevated ammonia levels inside poultry barns may aggravate the disease signs. These complicating factors may also protract the disease and delay recovery.

• Can affected flocks be treated?  In a recent study in Mexico of 40 Haemophilus paragallinarum isolates all were sensitive to penicillin, ampicillin and erythromycin. 95% were sensitive to tetracycline, 80% to neomycin and 62.5% to streptomycin (Fernandez at al..Av. Path, 29:473-476,2000).  Medication via feed may not be effective unless given before the birds go off feed. Only erythromycin or chlortetracycline can be considered for egg laying flocks in the US. Experience with treatment attempts has provided very mixed results from being effective in reducing the impact of clinical disease to non-effective.

• Do more than one type of Haemophilus paragallinarum occur? Yes. The strains can differ in virulence (severity of disease induced), biochemically and most importantly antigenically. There are three serotypes recognized, serotype A, B, and C. Vaccines must be made against the specific serotype present on a farm or in an area. There are also non-pathogenic strains of Haemophilus (H. avium) that have to be differentiated by biochemical tests.

• How can Avian Infectious Coryza be prevented? Coryza has not been known to occur in Maine and the source of the infection of the current outbreaks is not known at this time.

  Biosecurity:

  • Pullets: Pullets should come from a reliable source. The major risk factors are infected birds. Started pullets originating from infected pullet flocks or areas where the infection is present are the greatest risk for egg laying farms.

  • Dead birds: Dead birds should be disposed of properly.

  • Spent fowl: Spent fowl should not be moved during the acute stage of the disease.

  • Depopulation: Where practical, depopulation of infected flocks is the most effective method of eliminating the infection. Depopulated premises should be cleaned and disinfected and left vacant for 2- 3 weeks.

  • Backyard flocks: Small backyard flocks are believed to be a reservoir for the infection. Therefore, personnel working on poultry farms should not keep any poultry at home.

  • People: Personnel traffic between infected flocks/premises and clean premises should be restricted. People can transmit the infection after handling sick or dead birds. People picking up spent fowl should be allowed into poultry houses only with appropriate biosecurity precautions. Unauthorized person should be kept out. Maintenance personnel should be trained in and equipped for biosecurity.

  • Crates and Trucks: Pullets should be transported in cleaned and disinfected crates and trucks.

  • Air-borne transmission: To slow the spread of infection on multiple-house laying complexes, fans should preferably face each other. Barn doors and hallway fire doors should be kept closed.

  • Wild birds and pets:  These animals should be kept out.

  Vaccinations: 

  While depopulation, C&D and fallowing is the most effective method of controlling the disease in areas where the disease is not endemic. It is not practical for multiple age farms or areas where the disease is endemic.

  In these situations vaccinations are essential for the control of Coryza:

• Types of vaccines:  Inactivated vaccines are the most effective vaccines currently used in the US. There two types of inactivated vaccines:

  • Oil emulsion vaccines. These vaccines elicit a strong long lasting immune response. These vaccines also are initially more stressful to the birds, cause a strong local reaction and may affect egg production adversely if flocks in production are vaccinated. A single vaccination may provide about 80% protection (G. Cutler, personal communication).

  • Aluminum hydroxide vaccines: These vaccines are slightly less stressful and reactive and may stimulate an earlier and but weaker immune response. Protection is of shorter duration than with oil emulsion vaccines.

  • Live attenuated vaccines or controlled exposure with milder strains of coryza have been used in some places in the past.

• Serotypes: Vaccines are only effective against the serotype that is used to produce the vaccine. There are three serotypes, A, B,  and C. All serotypes are known to occur in the US. It is best to serotype isolates from the affected farm. Serotype A  vaccine should be used if this serotype is present on the farm. Vaccines that contain all three serotypes should be used if the serotype causing the disease is unknown.

• Autogenous vaccines: These vaccines are made with the Haemophilus isolate from the farm location. These vaccines may be used in 3 possible scenarios:

  • The isolate from the farm is not known,

  • The isolate from the farm cannot be serotyped because it is different from serotype A, B and C,

  • The serotype of the  isolate is known, but the vaccine does not protect the homologous isolate, because of antigenic variation within a serotype.

• When to vaccinate: Replacement flocks should be vaccinated at least three weeks before placement in a laying house. Egg-type flocks may be vaccinated twice at 9 - 12 weeks and again at 14 - 16 weeks of age (2-3 weeks before onset of egg production). Oil emulsion vaccines are preferred in endemic areas. Laying flocks may be vaccinated in the face of an outbreak. Oil emulsion vaccine may effect the egg production more than aluminum hydroxide vaccines.

• Site of inoculation: Inactivated vaccines must be injected subcutaneously. The inguinale web (leg web) is presently the preferred site. An alternative site is under the skin of the lower neck. 

• Combination with other vaccines: Since inactivated haemophilus vaccines are reactive,  vaccine manufacturers should be consulted before using them in combination with other vaccines. Haemophilus vaccines have been given simultaneously with killed Newcastle Disease and Infectious Bronchitis vaccines. Limited information is available of combining Haemophilus with other inactivated bacterial vaccines, especially Cholera and Salmonella vaccines. Caution is advised before embarking on large-scale use of such combinations.

• Other Control Measures:  
  Experience with the control of coryza in multiple age in-line layer complexes is limited. The following approach can be considered  

• Depopulate laying houses completely at the end of the laying cycle. This must include every escaped chicken.

• Remove manure and dry-clean house, control rodents, flies, beetles.

• Preferably clean and disinfect the house.

• Keep house empty for at least 10 days, preferably 3 weeks.

• Vaccinate all replacement flocks at least 3 weeks prior to housing. Two vaccinations are recommended for better protection 6-7 and 2-3 weeks before housing.

• Implementation of good management and biosecurity practices