Seroprevalence and genotyping of avian infectious bronchitis virus detected from Iranian unvaccinated backyard chickens
Background and Objectives: Different epidemiological studies have found that backyard chickens are a reservoir for poultry diseases. Most backyard chicken flocks have a poor level of biosecurity, which increases the risk of spread of diseases. In recent years, the number of backyard chickens has been on the rise in Iran. However, the health status of backyard flocks is still poorly documented. Thus, this study aimed at examining the seroprevalence of antibodies against infectious bronchitis virus (IBV) and molecular surveillance and genotyping of IBV among backyard chickens (without vaccination history) in Mazandaran province, North of Iran, 2014. Materials and Methods: A total of 460 blood samples of unvaccinated backyard chickens in the mentioned area were tested for antibodies against IBV using commercial ELISA. Also, cecal tonsils were collected from 75 chickens in the same area. Real time RT-PCR (for detection) and RT-PCR and sequencing spike gene were performed. Results: The seropositivity rate was 54.5%. In addition, we detected 793/B, Variant 2, and QX in the backyard flocks and performed phylogenetic studies on them. The phylogenetic study revealed that the detected genotypes had high homology with IBV strains that were infected broilers, pullets, and layers in Iran. Conclusion: There is a need for continuous monitoring of IBV among avian species to complete the epidemiological map and work on the pathogenesis of Iranian IBV strains in Iranian backyard chickens.
Seroprevalence of major avian respiratory diseases in broiler and sonali chicken in selected areas of Bangladesh
Objective: This study was conducted to investigate different respiratory diseases in broiler and sonali birds in some selected districts of Bangladesh. Materials and Methods: We were collected a total of 460 blood samples from 46 farms with 36 broiler farms and 10 sonali farms (cross-breed) from 2015 to 2017. All the collected serum samples were tested for determining specific antibodies of avian rhinotracheitis (ART) virus, infectious laryngotracheitis (ILT) virus, infectious bronchitis (IBV) virus, and Ornithobacterium rhinotracheale (ORT) infection using commercially available enzyme-linked immunosorbent assay kits. Results: The overall seropositivity was highest in ORT (45.9%), followed by IBV (37.6%), ART (2.6%), and ILT (0.4%). Out of 360 broiler samples, highest seropositivity was recorded in ORT (43.3%) and lowest in IBV (31.4%). Surprisingly, no broiler samples were found positive for ART and ILT. In case of sonali, the seropositivity was highest in IBV (60%) and lowest in ILT (2%). With respect to types of birds and age groups, the seropositive percentage of all four pathogens was found higher in sonali than broiler. Between two age groups of sonali, the seropositive percentage of ART (12%), ORT (55%), ILT (2%), and IBV (60%) was highest at 21–60 weeks of age compared to 5–20 weeks of age. However, based on location, the seropositive of ORT and IBV was highest in Jamalpur (63.3%) and Fulbariya and Trishal (50%) and lowest in Sreepur (16.7%) and Jamalpur (3.3%). Conclusion: The four pathogens are ubiquitous in nature for the sonali chickens, and the prevalence of ORT and IBV was the most prevalent viruses in the study areas. This study indicates a need for improved surveillance and characterization of ORT and ART circulating in all types of poultry in Bangladesh.
Velocity moments in alongshore bottom stress parameterizations
The time-averaged alongshore bottom stress is an important component of nearshore circulation models. In a widely accepted formulation the bottom stress is proportional to , the time average of the product of the instantaneous velocity magnitude |u→| and the instantaneous alongshore velocity component υ. Both mean and fluctuating (owing to random, directionally spread waves) velocities contribute to . Direct estimation of requires a more detailed specification of the velocity field than is usually available, so the term is parameterized. Here direct estimates of based on time series of near-bottom currents observed between the shoreline and 8-m water depth are used to test the accuracy of parameterizations. Common parameterizations that are linear in the mean alongshore current significantly underestimate for moderately strong alongshore currents, resulting in overestimation of a drag coefficient determined by fitting modeled (with a linearized bottom stress) to observed alongshore currents. A parameterization based on a joint-Gaussian velocity field with the observed velocity statistics gives excellent overall agreement with the directly estimated and allows analytic investigation of the statistical properties of the velocity field that govern . Except for the weakest flows, depends strongly on the mean alongshore current and the total velocity variance but depends only weakly on the mean wave angle, wave directional spread, and mean cross-shore current. Several other nonlinear parameterizations of are shown to be more accurate than the linear parameterizations and are adequate for many modeling purposes.