Blackall PJ, Matsumoto M. Infectious Coryza. Terzolo HR. Rev Med Vet ; Blackall PJ. Infectious coryza: overview of the disease and new diagnostic options.

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Servicios Personalizados Revista. Citado por SciELO. Similares en SciELO. The results corroborated the presence of M. The serological kinetics of the bird population vaccinated against avian infectious bronchitis evidenced a second seroconversion event, probably due to the circulation of this infectious agent.

No serological responses against Newcastle Disease Virus were detected. Further studies for the isolation and characterization of different O. Desde las 12 hasta las 50 semanas de edad, mensualmente se muestrearon estas aves. Several bacterial species, such as Avibacterium paragallinarum , Pasteurella multocida , Mannheimia haemolytica , Ornithobacterium rhinotracheale , Staphylococcus spp.

However, recent reports have also demonstrated the participation of highly pathogenic strains of Mycoplasma synoviae that cause typical CRS lesions 8. The incidence of pneumotropic viruses is often controlled through the implementation of biosafety management practices and the application of live or inactivated vaccines that elicit a specific immune response Cuba has implemented immunization programs against IBV and NDV, administering live or inactivated vaccines to the breeding or laying hen stocks, respectively Also, there are commercially available inactivated vaccines for the control of pathogenic mycoplasma species that have been tested under natural and experimental conditions 18, 19 , and the poultry farming industry has procured vaccine preparations for the control of the main bacterial serovars associated to CRS, such as P.

However, the control of CRS-associated bacterial agents is currently implemented in Cuba through the application of biosafety management practices, which have the added advantage of being applicable not only to endemic, but to exotic infectious diseases as well A number of diverse methodologies are currently employed for the diagnosis of the main viral and bacterial agents associated to CRS, ranging from the conceptually simple methods such as the isolation of the microorganism itself, to the technically complex methods such as molecular assays.

Cuba, where the poultry stock undergo extensive immunization following the established mass-scale vaccination programs and where biosafety procedures and practices are enforced, still experiences outbreaks of respiratory disease with high morbidity and low mortality in laying hens.

These outbreaks not only affect their genetic, productive and breeding potential, but result in significant economic losses due to decreases in egg and meat production and increases in medication expenses. This paper is therefore aimed at the evaluation of serological response to microbiological agents commonly associated with chronic respiratory syndrome in laying hens.

They were obtained from a Poultry Production Unit of the province of Havana, and identified by wing bands. After reaching 16 weeks, they were transferred to a Commercial Layers Unit, under a productive system of mixed ages, with a history of outbreaks of respiratory processes.

They received a well balanced diet, as indicated by trained technicians or following technical regulations for rearing used in Cuba. Immunization schedule The birds were vaccinated according to the Cuban immunization program Technical Instruction, Table. In addition, a fourth dose of the NDV vaccine was applied, due to the low proportion of responding individuals according to the HIA titers after the third dose. Sampling Blood samples were taken monthly from week 12 and up to week 50, by puncturing the marginal vein of the wing.

Serology The serological study for the indirect demonstration of the presence of birds reactive to M. Twohundred microliters of the testing serum were mixed with an identical volume of the specific antigen on a glass plate, which was rotated for minutes.

The reaction was scored as positive if it yielded visible, defined clumps within that time The sera underwent serial two-fold dilutions in PBS at pH 7. All plates contained control wells of 4 HAU and erythrocytes.

This step was followed by the inclusion of an anti-chicken IgG peroxidase conjugate, and the entire reaction was developed for 15 minutes at RT with tetramethylbenzidine as the substrate; the results were read after the addition of a stopping solution on a SUMA PR plate reader at nm.

The results were interpreted as instructed by the manufacturer, considering a sample as positive for antibodies against aIBV if the serum titer was higher than , and positive to O. An analysis of variance Anova was performed for the geometric means of the titer of anti-aIBV antibodies, using the statistical software packages Comprop-1 and Statgraphics Plus 5.

Serological studies by different researchers have revealed the presence of M. The present study has detected birds reactive to M. When studying the proportion of birds reactive to M. However, for an infection with M. Additionally, Valencia in 38 highlighted other factors that could have played a role in the increase in the proportion of M. Its isolation and identification as a pathogenic agent in commercial poultry farming occurred at the beginning of the nineteen nineties by Vandamme et al.

However, no studies have evidenced the presence of this microorganism in Cuban poultry farms. This study evaluated the positivity for O. No positive results for this microorganism were detected during the two first sampling rounds at weeks 12 and However, a significant, persistent increase in positivity for O.

Asymptomatic positive birds kept in a laying hen flock may, however, suffer from a slightly increased mortality rate, a decrease in egg-laying productivity and the deterioration of shell quality 6, This is also suggested by our data, which revealed a high proportion of asymptomatic laying hens after the 25 th w eek of age. Several authors have reported that the association of M. The large number of individuals reactive to these microorganisms could be related to the eventual appearance, at the 21 st w eek of age, of clinical signs and lesions typical of an acute respiratory process affecting the upper airways, characterized by sero-catarrhal rhinitis, blepharitis, conjunctivitis, facial edema and genital hypoplasia.

This process followed a chronic course, affecting the lower airways and resulting in facial tumefaction with a hard consistency leading to loss of vision, muco-fibrinous rhinitis, cachexia, serosal atrophy of subcutaneous fat and the coronary ridge, focal pneumonia of the anteroventral unilateral lobule and diarrhea.

These results match those of other authors 42, 43 describing a similar clinical-pathological picture in birds with CRS. Another important microorganism associated to CRS is the causative coronavirus of infectious bronchitis IB , which has a special tropism for the respiratory, reproductive and renal tracts.

It affects poultry at any age, but its expressions are more severe in young individuals under intensive production systems, causing problems for the adequate application of biosafety management procedures The control of BI in Cuban flocks in intensive production systems is implemented through the immunization of replacement layer pullets and the evaluation of the serological response of layers, which enables the examination of the level of protection or the detection of viral infections if antibody levels are monitored at different time points after vaccination 33, The analysis of the geometric means of the titers of antibodies against aIBV Figure 3 revealed an increase in this parameter starting at week 16 and peaking at week This result coincides with that of Cavanagh in 44 , which suggest that several doses of the aIBV vaccine provide greater protection; and those of Acevedo in 45 , showing that antibody titers can be maintained for a longer period, but start to decline 3 months after vaccination.

However, another significant increase in Ab titers against aIBV is detected at week 33 among otherwise asymptomatic individuals. This may start through an infection with another viral strain rather than from the persistence of the vaccine strain since, coincidentally, a similar complicated respiratory process appeared one week earlier among a different hen batch that had been laying for 9 to 10 months. Using clinical samples from these birds, which had high antibody titers against aIBV, Acevedo et al.

Valencia, in 38 , pointed out that different variants of aIBV continue to appear, and many of them are found circulating among otherwise healthy chickens. Shane 46 , on the other hand, suggests viral persistence as one of the factors contributing to the appearance of variant aIBV strains, since some recent studies prove that the dissemination of the virus from the trachea and cloaca continues for up to 70 days post-immunization.

In addition, it is possible to isolate viable IB virus from lungs and kidneys of previously vaccinated birds for a period of up to days, regardless of their isolation status.

This confirms the efficacy of the vaccine, as underscored by Viamontes et al. In the light of this result, we concluded that no association of NDV with CRS could be detected in the population analyzed. The present study confirmed the presence of M. The serological study performed in birds vaccinated against aIBV revealed a pattern of seroconversion that suggests that this infectious agent is circulating among the sample population, a finding with potentially detrimental implications if not addressed promptly.

The HIA titers measured when evaluating the birds for NDV do not suggest an ongoing infection, but rather demonstrate the efficacy of the vaccine. As a whole, these results help to better characterize the Cuban epidemiological situation and can be used to defi ne the sanitary procedures required for the control of these diseases.

We consider that further studies on the different serovars of O. Similarly, we would like to extend our appreciation to Drs. Sandra Cuello and Julia Noda, from the National Center for Agricultural Health, for their cooperation in the interpretation of the serological results. Rev Cubana Cienc Vet ; 28 1 Burch D. Guadalupe A. Kleven SH. Merial-Cerval, Georgia, Estados Unidos; Ricci, M. Avicultura Profesional ;25 2 Icochea E.

Dave C. Severe acute respiratory syndrome vaccine development: experiences of vaccination against avian infectious bronchitis coronavirus. Avian Pathol ; 32 6 : Osman E. Evaluation of three different vaccination regimes against Newcastle disease in central Anatolia Turk. J Vet Anim Sci ; Hidalgo H. Avicult Profes ;24 1 Avicult Profes ;24 3 Kannan G. Avian Metpneumovirus: Diagnosis and Prevention. World Poult ;23 5 Alzamora L, Andina I.

Avicult Profes ;26 5 : Aziz T. Laringotraqueitis infecciosa. World Poultry ;25 6 Viamontes O. Memorias del V Congreso de avicultura; Whithear KG. Rev Sci Tech Off Int. Epiz ; 15 4 Consultado: 16 de octubre de

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