The principles of rational chemotherapy of bacterial infections in poultry

Growing levels of microbial resistance to chemotherapeutic agents pose a threat to public health and constitute a global problem. The above can be often attributed to improper and excessive use of antibacterial drugs in veterinary and human medicine, animal breeding, agriculture and industry. To address this problem, veterinary and human health practitioners, animal breeders and the public have to be made aware of the consequences and threats associated with the uncontrolled use of antibacterial preparations. In recent years, many countries have implemented programs for monitoring antibiotic resistance which provide valuable information about the applied antibiotics and the resistance of various bacterial species colonizing livestock, poultry and the environment. Special attention should be paid to the sources and transmission routes of antibiotic resistance. There are no easy solutions to this highly complex problem. The relevant measures should address multiple factors, beginning from rational and controlled use of chemotherapeutic agents in veterinary practice, to biosecurity in animal farms, food production hygiene, and sanitary and veterinary inspections in the food chain. The tissues of treated birds should not contain antibiotic residues upon slaughter. Rational use of antibiotics should minimize the risk of drug resistance and decrease treatment costs without compromising the efficacy of treatment. Therefore, the key principles of antibiotic therapy of bacterial infections in poultry should be the adequate selection and dosage of the administered drug, a sound knowledge of the drug’s pharmacokinetic and pharmacodynamic properties, as well as a knowledge of the differences between bacteriostatic and bactericidal drugs and between time-dependent and concentration-dependent drugs. There is an urgent need to revise the existing approach to the use of chemotherapeutic agents in the treatment of poultry diseases, and to increase the awareness that antibiotics cannot compensate for the failure to observe the fundamental principles of biosecurity in all stages of poultry farming

Evaluation of the efficacy of an autogenous Escherichia coli

In poultry production Escherichia coli autogenous vaccines are often used. However, the efficacy of autogenous E. coli vaccinations has not been evaluated experimentally in chickens after start of lay. The aim of the present study was to evaluate the protective effect of an autogenous E. coli vaccine in broiler breeders. Three groups of 28 weeks old broiler breeders (unvaccinated, vaccinated once and twice, respectively) were challenged with a homologous E. coli strain (same strain as included in the vaccine) or a heterologous challenge strain in an experimental ascending model. The clinical outcome was most pronounced in the unvaccinated group; however, the vast majority of chickens in the vaccinated groups had severe pathological manifestations similar to findings in the unvaccinated group after challenge with a homologous as well as a heterologous E. coli strain. Although significant titer rises in IgY antibodies were observed in the twice vaccinated group, antibodies did not confer significant protection in terms of pathological impact. Neither could transfer of maternal derived antibodies to offspring be demonstrated. In conclusion, with the use of the present model for ascending infection, significant protection of an autogenous E. coli vaccine against neither a homologous nor a heterologous E. coli challenge could not be documented

Neurologic Involvement in Children and Adolescents Hospitalized in the United States for COVID-19 or Multisystem Inflammatory Syndrome

This article is made available for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.Importance Coronavirus disease 2019 (COVID-19) affects the nervous system in adult patients. The spectrum of neurologic involvement in children and adolescents is unclear. Objective To understand the range and severity of neurologic involvement among children and adolescents associated with COVID-19. Setting, Design, and Participants Case series of patients (age <21 years) hospitalized between March 15, 2020, and December 15, 2020, with positive severe acute respiratory syndrome coronavirus 2 test result (reverse transcriptase-polymerase chain reaction and/or antibody) at 61 US hospitals in the Overcoming COVID-19 public health registry, including 616 (36%) meeting criteria for multisystem inflammatory syndrome in children. Patients with neurologic involvement had acute neurologic signs, symptoms, or diseases on presentation or during hospitalization. Life-threatening involvement was adjudicated by experts based on clinical and/or neuroradiologic features. Exposures Severe acute respiratory syndrome coronavirus 2. Main Outcomes and Measures Type and severity of neurologic involvement, laboratory and imaging data, and outcomes (death or survival with new neurologic deficits) at hospital discharge. Results Of 1695 patients (909 [54%] male; median [interquartile range] age, 9.1 [2.4-15.3] years), 365 (22%) from 52 sites had documented neurologic involvement. Patients with neurologic involvement were more likely to have underlying neurologic disorders (81 of 365 [22%]) compared with those without (113 of 1330 [8%]), but a similar number were previously healthy (195 [53%] vs 723 [54%]) and met criteria for multisystem inflammatory syndrome in children (126 [35%] vs 490 [37%]). Among those with neurologic involvement, 322 (88%) had transient symptoms and survived, and 43 (12%) developed life-threatening conditions clinically adjudicated to be associated with COVID-19, including severe encephalopathy (n = 15; 5 with splenial lesions), stroke (n = 12), central nervous system infection/demyelination (n = 8), Guillain-Barré syndrome/variants (n = 4), and acute fulminant cerebral edema (n = 4). Compared with those without life-threatening conditions (n = 322), those with life-threatening neurologic conditions had higher neutrophil-to-lymphocyte ratios (median, 12.2 vs 4.4) and higher reported frequency of D-dimer greater than 3 μg/mL fibrinogen equivalent units (21 [49%] vs 72 [22%]). Of 43 patients who developed COVID-19–related life-threatening neurologic involvement, 17 survivors (40%) had new neurologic deficits at hospital discharge, and 11 patients (26%) died. Conclusions and Relevance In this study, many children and adolescents hospitalized for COVID-19 or multisystem inflammatory syndrome in children had neurologic involvement, mostly transient symptoms. A range of life-threatening and fatal neurologic conditions associated with COVID-19 infrequently occurred. Effects on long-term neurodevelopmental outcomes are unknown

Practical aspects of estimation of optimal time for vaccination of chicken against IBD with use of „Deventer formula”

One of the most commonly applied vaccination strategies against chicken infectious bursal disease (IBD) is the use of live vaccines at the optimal time estimated with the use of Deventer formula. The present study investigated the impact of different factors on maternally derived antibodies decline and therefore on the vaccination schedule against IBD. Our results suggest that blood collection from birds older than 3 days is more reliable in order to estimate the optimal date for IBD vaccination, due to disturbances in yolk sac resorption early after hatch

Biochemical and immunological responses of young turkeys to vaccination against Ornithobacterium rhinotraheale and different levels of dietary methionine

The objective of this study was to verify the hypothesis that increasing levels of dietary methionine can stimulate the mechanisms of cell-mediated and humoral immunity in young turkeys. The blood and organs involved in cell-mediated and humoral immune responses were analyzed in 8-week-old turkeys that had been vaccinated against Ornithobacterium rhinotraheale (ORT) infection (on days 17 and 48). The birds were fed diets with a low (LM), medium (MM) and high (HM) methionine content (0.45 and 0.40%, 0.60 and 0.51%, 0.71 and 0.57% in weeks 1 – 4 and 5 – 8, respectively). Dietary methionine supplementation led to a significant increase in body weights of turkeys at 56 days of age, from 3532 g in group LM to 3720 g in group MM and 3760 g in group HM (p=0.001). A significant increase in vaccine-induced antibody titers against ORT was noted in group HM relative to group LM (p=0.006). Increasing levels of methionine had no significant effect on total serum IgG nor IgM levels and most serum biochemical parameters, TP, ALB, GLOB, GLU, AST, ALP, P and Ca. In comparison with group LM, group HM turkeys were characterized by a lower percentage of IgM⁺ B cell subpopulation in the blood and bursa of Fabricius. The percentages of CD4⁺ and CD8⁺ T cell subpopulations in the bursa of Fabricius in group HM were significantly different from those found in groups LM and MM. The highest percentages of CD4⁺ T cells and CD8⁺ T cells in the spleen were observed in groups LM (p<0.001) and HM (p=0.04), respectively. The differences were statistically significant relative to the remaining groups. Turkeys of group LM were characterized by a lower CD4⁺ T cell percentage in the thymus (p<0.001) and a lower CD8⁺ T cell percentage in the cecal tonsils (Cts) (p<0.01). Vaccination against ORT resulted in a significant increase in the percentage of CD4⁺/CD8⁺ T cell subpopulation and a decrease in the percentage of CD8⁺ T cell subset in the spleen

Identification of Transmissible Viral Proventriculitis (TVP) in broiler chickens in Poland

The aim of the study was to investigate the possibility of Transmissible Viral Proventriculitis (TVP) occurrence in broiler chickens in Poland. In march 2016 proventriculi samples were collected from broiler chickens showing poor uniformity and decreased body weight, accompanied by enlarged proventriculi. Histopathological examination of affected proventriculi revealed typical lesions associated with TVP (vacuolar degeneration and necrosis of glandular epithelium, replacement of glandular epithelium by hyperplastic ductal epithelium and moderate to severe lymphocytic infiltration). To our best knowledge, up to date there is no report indicating the presence of TVP in Poland nor in Central and Eastern Europe

Occurrence, characteristics and control of pigeon paramyxovirus type 1 in pigeons

Newcastle disease (ND) is a highly contagious and devastating viral disease of poultry and other birds that has a worldwide distribution. ND in pigeons is called paramyxovirosis and is caused by antigenic “pigeon variant” of the virus (pigeon paramyxovirus type 1, PPMV-1). During PPMV-1 infections, central nervous system symptoms and sometimes high mortality are observed. In the case of infection with viscerotropic strains which exhibit specific affinity for the kidneys, the first observed sign is polyuria, and neural symptoms appear only in individual birds in the flock. Due to the similarity of symptoms of paramyxovirosis to the pigeon herpes virus infection (PHV), sodium chloride poisoning, overdose of ronidazole or vitamin B1 deficiency, it is necessary to perform laboratory tests to make a correct diagnosis. After virus isolation PPMV-1 can be detected initially by haemagglutination assay (HA). PPMV-1 can be confirmed by conventional serological tests such a haemagglutination inhibition test (HI) or molecular-based techniques. In the prophylaxis of paramyxovirosis in pigeons, inactivated vaccines are used, administered by subcutaneous injection in various prevention programs. However, vaccination should be only one component of a strategy of PPMV-1 control, on a par with effective biosecurity and proper, effective methods of prevention and diagnostics of paramyxovirosis

The perspective of immunoprophylaxis and selected immunological issues in the course of the turkey rhinotracheitis

This review article presents immunological issues in the course of the turkey rhinotracheitis (TRT) emphasizing local immunity mechanisms, both humoral and cell-mediated, in the upper respiratory system. Studies on the influence of the humoral immunity in the course of infection and vaccinations against TRT have revealed many times the absence of correlation between the titre of specific IgY anti-aMPV (avian Metapneumovirus) antibodies in the serum and in the upper respiratory washings and the immunity against the occurrence of the clinical form of the TRT. Considering the above, T cells are increasingly often regarded as the main factor involved in the upper respiratory immunity against the TRT. However, there have been just a few reports on the role of the T cells in the local immunity processes in the infection with aMPV in turkeys. Additionally, studies of the T-cell-associated immunity against the TRT have given ambiguous results. Immunoprophylaxis issues against the aMPV infections are a significant part of the work where the authors confront current vaccination programmes against the perspectives of use of the future vaccines against the TRT. Future vaccines should face the following criteria: absence of the risk of immunosuppressive effect and reversion of vaccine strains virulence, ease-of-use combined with the possibility of administration of the vaccine to the large numbers of turkeys. The leading role in future vaccination programs for birds against the TRT is likely to be played by the in ovo technique and the recombinant vaccines. Great hopes are also linked with the development of subunit vaccines against the aMPV

Local immunity of the respiratory mucosal system in chickens and turkeys

This review article presents fundamental mechanisms of the local mucosal immunity in selected regions of the respiratory tract in healthy birds and in some pathological conditions. The respiratory system, whose mucosa come into direct contact with microorganisms contaminating inhaled air, has some associated structures, such as Harderian gland (HG), conjunctive-associated lymphoid tissue (CALT) and paranasal glands (PG), whose participation in local mechanisms of the mucosal immunity has been corroborated by numerous scientific studies. The nasal mucosa, with structured clusters of lymphoid tissue (NALT – nasal-associated lymphoid tissue) is the first to come into contact with microorganisms which contaminate inhaled air. Lymphoid nodules, made up of B cells with frequently developed germinal centres (GC), surrounded by a coat of CD4+ cells, are the major NALT structures in chickens, whereas CD8+ cells are situated in the epithelium and in the lamina propria of the nasal cavity mucosa. Studies into respiratory system infections (e.g. Mycoplasma gallisepticum) have shown the reactivity of the tracheal mucosa to infection, despite a lack of essential lymphoid tissue. Bronchus-associated lymphoid tissue (BALT) takes part in bronchial immune processes and its structure, topography and ability to perform defensive function in birds is largely age-dependent. Mature BALT is covered by a delicate layer of epithelial cells, called follicle-associated epithelium (FAE). Germinal centres (GC), surrounded by CD4+ cells are developed in most mature BALT nodules, while CD8+ lymphocytes are dispersed among lymphoid nodules and in the epithelium, and they are rarely present in GC. Macrophages make up the first line of defence mechanisms through which the host rapidly responds to microorganisms and their products in the respiratory mucosal system. Another very important element are polymorphonuclear cells, with heterophils being the most important of them. Phagocytic cells obtained from lung lavages in birds are referred to as FARM (free avian respiratory macrophages). Their number in chickens and turkeys is estimated to be 20 times lower than that in mice and rats, which indicates a deficit in the first-line of defence in the birds’ respiratory system. There are numerous B cells and antibody secreting cells (ASC) present throughout the respiratory system in birds. Their role comes down to perform antigen-specific protection by producing antibodies (IgM, IgY or IgA class) as a result of contact with pathogenic factors