Identification diagnosis and prevention and control of infectious coryza Infectious coryza is an acute or subacute respiratory disease of chickens caused by Avibacterium paragallinarum. It is characterized by inflammation of the nasal cavity and sinuses, sneezing, nasal discharge, and facial swelling. This disease occurs in breeding chickens and laying hens, causing slow growth and development and poor evenness in breeding chickens, and increased culling rate and significant drop in egg production in laying hens(10%-30%).
Pathogen
Avibacterium paragallinarum is a Gram-negative pathogen. There are three serovars of A. paragallinarum(A, B, and C). These are not cross-protective so it is essential that any vaccines contain the appropriate serovar for that population of birds.
Epidemiology
Susceptible animals
Chickens over 4 weeks of age of all breeds are susceptible, and chicks under 1 week of age have a certain resistance. Other infected poultry(such as turkey, duck, goose, and pigeon) and study animals (such as rabbit, mouse, guinea pig), whether naturally or artificially, have strong resistance to the disease.
Route of transmission and source of infection
The disease is mainly transmitted by the excretion from the respiratory tract and digestive tract of infected chickens. Sick chickens, especially those with chronic diseases, are the main source of infection. The shed pathogens spread through the air, dust, drinking water, feed and so on.
Characteristics
This disease is not obviously seasonal, but due to poor ventilation, its incidence is relative high in cold season.
Clinical symptoms
Affected chickens initially have no obvious symptoms, only present with sneezing and thin watery nasal discharge. With the progression of the disease, there is sneezing, respiratory distress, serous or mucoid nasal discharge, which gradually thickens and becomes smelly. Infected chickens often shake head, and scratch nose and beak with claws from time to time. As the mucus dries, it progresses to a yellowish scab around the nostrils. Sick chickens show facial inflammation and swollen tissue around one or both eyes, leading in some severe cases to blindness. Late in the course of the disease, there are caseous casts in the oral cavity and cleft palate. In severe cases, the inflammation extends to the trachea, as well as bronchus and lungs, causing dyspnea and rales. Affected birds exhibit depression, inappetence, reduced weight, decreased egg production in hens, and enlarged wattle in roosters. The incubation period after natural infection is relative short, typically 1-3 days, and that after artificial infection is 18-36 hours. The course of the disease varies from 6 to 14 days caused by inoculated cultures to more than 50 days caused by infectious discharge from nasal sinus. The mortality rate is about 20% and increases if complications occur.
Pathological changes
The main lesions are acute, catarrhal inflammation of the nasal cavity, sinus, larynx and trachea mucosa, congestion, swelling, flushing, with surface covered with profuse mucus, exudate or caseous necrosis accumulated in the sinus, leading in severe cases to bronchopenitis and air sacculitis. There are edema of the subcutaneous tissues of the face and wattle, smelly secretions from the eyes and nose which process to scab, and occasionally adhesive eyelids. Visceral lesions are generally absent. Laying hens present with caseous yellow casts in the oviduct, and soft ovarian follicles with hematoma, swelling, necrosis or atrophy. In severe cases, peritonitis could occur.
Prevention and Control
Strengthen feeding management
Quality complete feed and multiple vitamins should be provided to ensure adequate supply of vitamins and trace elements, especially Vitamin A, Vitamin E and Vitamin C, so as to improve immunity of chickens. Keep drinking water clean and wash water line regularly. Decrease feeding density and ammonia concentration, and keep chicken houses warm and well-ventilated. Reduce stresses caused by climate change, temperature difference and improper feeding management.
Good biosafety, hygiene and disinfection
Regular disinfection and scientific management should be implemented to cut off the source of infection and stop the transmission of the disease. “All-in-all-out” management could be performed. It is forbidden to feed chickens at different days of age in a same premise, and the breeding density should be adjusted reasonably. Recovered chickens that are well tolerated often become carriers, acting as the main source of infection. Isolation, disinfection and culling of infected chickens and recovered carriers should be adopted in the affected premise(chicken house). Dead infected chickens are forbidden to throw around. They must be collected in time and sent to a designated place for burning or deep burial.
For infectious coryza, prevention betters than treatment
Therefore, the strategy of prevention in the first place and integrating prevention with treatment should be taken. Once an outbreak occurs, timely cull infected chickens and conduct a thorough disinfection. Sulfonamides, enrofloxacin, florfenicol, doxycycline, or gentamicin can be used, and the early treatment will produce a good effect. Emergency immunization with inactivated vaccines against infectious coryza when the disease outbreaks will also contribute to a good effect. Animals tend to develop resistance when treated with antibiotics. It is advisable to perform antimicrobial susceptibility test after isolating bacteria, and to combine 2-3 drugs according to the results. There are three serovars of A. paragallinarum(A, B, and C) worldwide. These are not cross-protective so there is a high demand for infectious coryza vaccines. How to treat infectious coryza in chickens?
Vaccination programs and vaccines
Infectious Coryza(Serotype A+Serotype B+Serotype C) Vaccine, Inactivated from WIXBIO can be used for the prevention and control of infectious coryza. With three serovars of A. paragallinarum(A, B, and C), it can provide comprehensive protection for chickens, with a proven protection rate of higher than 90%. In addition, it has a high safety profile and causes small side effects.
Vaccination against infectious coryza in chickens
Bacterial vaccines usually have lower immunogenicity and induce antibodies slower than viral vaccines. Therefore, vaccination against infectious coryza should be not fewer than two times.
According to statistics, a single vaccination brings poor immune effect and a relative high incidence of infectious coryza in layers. Two vaccinations have to be performed in laying hen farms. The first vaccination induces a small amount of antibodies, and mainly the memory cells. After the second vaccination, the antibodies surges and provides a long-lasting protection. For breeding chicken farms, young chickens must be vaccinated with inactivated vaccine against infectious coryza before sold, and their immune status should be informed to customers.
And a second vaccination is recommended. It is necessary to know the vaccination status of breeders against infectious coryza, so as to determine the timing of the first immunization. Three vaccinations should be performed by breeder farms to ensure that breeders have enough high antibody level and sufficient maternal antibodies to protect their offspring. The recommended vaccination programs are as follows(Tables 1, 2, and 3)
| Recommended routine vaccination programs | ||||
| Age | Vaccine | Strain | Injection Site | Dosage |
| 5-7 weeks of age | Infectious Coryza (Serotype A +Serotype B+ Serotype C)Vaccine,Inactivated | Serotype A +Serotype B + | Superficial breast muscle(Recommended)Intramuscularinjection in the leg region is forbidden. | 0.5mL/dose |
| 12 weeks of age | Infectious Coryza (Serotype A +Serotype B+ Serotype C)Vaccine,Inactivated | Serotype A +Serotype B + | Superficial breast muscle(Recommended)Intramuscularinjection in the leg region is forbidden. | 0.5mL/dose |
| Recommended vaccination programs for purchased young chickens (never vaccinated with vaccinesagainst infectious coryza) | ||||
| Days ofage/day | Vaccine | Strain | Injection Site | Dosage |
| 65-70 | Infectious Coryza (Serotype A+Serotype B+Serotype C) Vaccine, Inactivated | Serotype A +Serotype B +Serotype C | Superficial breast muscle(Recommended)Intramuscular injection in the leg region is forbidden. | 0.5mL/dose |
| 100-110 | Infectious Coryza (Serotype A+Serotype B+Serotype C) Vaccine, Inactivated | Serotype A +Serotype B +Serotype C | Superficial breast muscle(Recommended)Intramuscular injection in the leg region is forbidden. | 0.5mL/dose |
| Recommended vaccination programs for farms attacked by serious infectious coryza | ||||
| Days ofage/day | Vaccine | Strain | Injection Site | Dosage |
| 300 | Infectious Coryza (Serotype A+Serotype B+Serotype C) Vaccine, inactivated | Serotype A +Serotype B +Serotype C | Superficial breast muscle(Recommended)Intramuscular injection in the leg region is forbidden. | 0.5mL/dose |
Related products recommendation
