Son susceptibles de padecerla aves de todas las edades. Grado 2. Grado 3. Grado 4. Epizootiology, prevention and control of infectious coryza.
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Infiltration of a large number of most cells into the lamina propria of the mucous membrane of the nasal cavity is also characteristic.
Numerous organisms are found on the cilia or on the surface of the epithelial cells of the nasal mucosa. Chickens with the lesions often have severe coryza. Adherence to and colonization of the encapsulated variant on the nasal mucosa seems to be a first step of infection Sawata et al. Colonization of the nasal mucosa by encapsulated A. Acute uncomplicated coryza is characterized by a short duration, with signs usually clinically visible for days, and subsequently results in birds being refractory to reinfection.
Chronic disease is usually found in complicated coryza and in this case clinical signs can persist for a month and longer. Chronic coryza can be produced experimentally, by creating a combined infection of Mycoplasma gallisepticum and A. IC may occur in growing chickens and layers. There is usually a rapid onset and morbidity is high in the flock, decreased feed and water consumption, retarded growth in young stock and reduced egg production in laying flocks.
The most common clinical signs are nasal discharge, facial swelling, lacrimation, anorexia, conjunctivitis with some adherence of eyelids, respiratory noise, swollen infraorbital sinuses and exudates in the conjunctival sac, occasionally diarrhoea Blackall et al.
There has been a recent emergence of disease in meat chickens in the USA and a swollen head-like syndrome associated with A. Additionally, arthritis and septicaemia, possibly complicated by the presence of other pathogens, have been reported in broiler and layer flocks in South America Sandoval et al.
A foul odour may be detected in flocks in which the disease has become chronic and complicated with other bacteria Blackall et al. Epidemiology Top of page The disease is observed primarily during the autumn and winter months in subtropical climates, or during the rainy season in a tropical climate. All age groups of chickens are susceptible, but the disease appears to be more severe in birds of 4 weeks old and upwards. The presence of disease in growing birds may result in poor growth, and reduced egg production.
Chronic or apparently healthy carrier birds have been recognized as the main reservoirs of infection. Spread within a flock is rapid via contact with infected birds, through ingestion of contaminated feed or water, and by the airborne route. Recovered birds are frequently carriers. No mechanical or biological carriers vectors have been demonstrated. The organism does not survive longer than hours in the environment outside its hosts Anon.
Susceptible birds exposed to infected birds may show signs of the disease within hours Rimler et al. Chickens inoculated with cultures of A. IC is often regarded as a disease that has its greatest impact in intensively raised chickens. In Indonesia, the disease was formerly not considered to be widespread in village chickens.
However the isolation of A. Disease Treatment Top of page Various sulfonamides and antibiotics have been used to treat IC, usually in feed or drinking water. Birds usually respond to treatment but relapses may occur when treatment is discontinued. Many drugs and antibiotics have been used, including streptomycin, erythromycin, sulfodimethoxine, tylosin tartrate and spectinomycin Charlton et al. It should be noted that sulfa drugs may cause a temporary drop in egg production and overdoses may be toxic.
Similarly, streptomycin causes severe stress in chickens, which can last for 24 hours Bains, Erythromycin and oxytetracycline are two commonly used antibiotics Blackall et al. Other antibiotics found effective in the treatment of IC include norfloxacin Lublin et al. Some strains of A. Strains of A. Prevention and Control Top of page Farm-level Control Recovered carrier birds are the main source of infection, so practices such as buying breeding males or started chicks from unknown sources should be discouraged.
Only day-old chicks should be secured for replacement purposes unless the source is known to be free of IC. Isolation rearing and the housing away from old stock are desirable practices. To eliminate the agents from a farm, it is necessary to depopulate the infected or recovered flock s , because birds in such flocks remain reservoirs of infection. After the cleaning and disinfecting of equipment and houses, the premises should be allowed to remain vacant for weeks before restocking with clean birds Blackall et al.
It is important to avoid the introduction of infected chickens to the farm and if this occurs then the early recognition of disease and institution of appropriate treatment is vital. Good husbandry and management procedures prevent spread of disease; isolation of age groups of chickens on an all-in, all-out basis Bain, It is necessary to depopulate flocks that have experienced the disease, because recovered birds remain reservoirs of infection.
The method of eradication depends upon circumstances on the farm, the size of the flock, facilities, and purpose of the flock. The infected birds may be marketed at once and the premises cleaned before new chicks are brought onto the farm. Another more popular method is to treat the affected flock and keep it isolated until new stock has been raised in isolation as replacements. After the infected or recovered birds are marketed, the house should be cleaned and disinfected before housing clean stock.
As the organism may survive in exudates for several days at low temperatures, it would be advisable to allow the cleaned house to remain vacant for about 1 week, particularly during the cooler periods of the year Yamamoto, Immunization and Vaccines Vaccination is normally effective for the control of disease, but some outbreaks have been caused by vaccine failure.
The mis-matching of challenge serovar with vaccine is the most likely explanation for these cases of vaccine failure. Other explanations such as improper vaccination technique may also have played a role. Where they occur there is a need for the active investigation of suspect infectious coryza vaccine failures, including the isolation and serotyping of suspect A. Commercial bacterins prepared from chicken embryos or broth may be autogenous or may combine strains of serotypes.
They may contain adjuvants Al OH 3 gel or mineral oil , stabilizers, or saline diluent Yamamoto, Bacterins are generally injected in birds between 10 and 20 week of age and yield optimal result when given weeks prior to an expected natural outbreak.
Two injections given approximately 4 weeks apart before 20 weeks of age results in better performance of layers than a single injection Feng et al.
Both subcutaneous and intramuscular injections have been found to be effective Blackall and Reid, Injection of the bacterin into the leg muscle has been found to give better protection than when it is injected into breast muscle. Inactivated IC bacterins provide protection only against the particular Page serovars included in the vaccine, so it is vital that vaccines contain all the serovars that may be present in infections in the target population Blackall et al.
Serovar B is widespread and must be included in inactivated bacterins in areas where it is present Tezalo et al. However, as different strains of serovar B provide only partial cross-protection among themselves it may be necessary to prepare an autogenous bacterin for use in areas where serovar B is endemic Mouchid et al.
Overview of Infectious Coryza in Chickens
Actualmente se est comprobado que los brotes prolongados de coriza estn complicados con otras bacterias: ORT, Gallibacterium sp, etc Sndrome respiratorio crnico. Fcilmente destruido por muchos de los desinfectantes comunes y por factores medio ambientales. Existen tres tipos antgenicos A, B, C de A. Paragallinarum, aunque todos los tipos comparten ciertos antgenos.
Avibacterium paragallinarum: protección, tipificación y filogenia de aislamientos de América