Unraveling frontiers in poultry health (part 1) - Mitigating economically important viral and bacterial diseases in commercial Chicken and Turkey production

This symposium offered up-to-date perspectives on field experiences and the latest research on significant viral and bacterial diseases affecting poultry. A highlight was the discussion on the use of enteroids as advanced in vitro models for exploring disease pathogenesis. Outcomes of this symposium included identifying the urgent need to improve the prevention and control of avian influenza by focusing research on vaccine effectiveness. In this regard, efforts should focus on enhancing the relatedness of vaccine antigen to the field (challenge) virus strain and improving immunogenicity. It was also revealed that gangrenous dermatitis could be controlled through withholding or restricting the administration of ionophores during broiler life cycle, and that administration of microscopic polymer beads (gel) based-live coccidia vaccines to chicks could be used to reduce necrotic enteritis-induced mortality. It was emphasized that effective diagnosis of re-emerging Turkey diseases (such as blackhead, fowl cholera, and coccidiosis) and emerging Turkey diseases such as reoviral hepatitis, reoviral arthritis, Ornithobacterium rhinotracheale infection, and strepticemia require complementarity between investigative research approaches and production Veterinarian field approaches. Lastly, it was determined that the development of a variety of functionally-specific enteroids would expedite the delineation of enteric pathogen mechanisms and the identification of novel vaccine adjuvants.

Antimicrobial usage in broiler chicken production in the United States, 2013-2021

Although efforts to improve antimicrobial stewardship should include the collection of antimicrobial use data, most antimicrobial datasets collected at the national level consist of antimicrobial sales data which cannot inform stewardship. These data lack context, such as information regarding target species, disease indication, and regimen specifics like dose, route and duration. Therefore, the goal of this study was to develop a system for collecting data on the use of antimicrobials in the U.S. broiler chicken industry. This study utilized a public-private partnership to enable collection and protection of sensitive data from an extremely large industry while releasing deidentified and aggregated information regarding the details of antimicrobial use on U.S. broiler chicken farms over time. Participation was voluntary. Data were collected for the period 2013 through 2021 and are reported on a calendar year basis. Using production statistics from USDA:NASS as a denominator, the data supplied by participating companies represented approximately 82.1% of broiler chicken production in the U.S. in 2013, approximately 88.6% in 2017, and approximately 85.0% in 2021. The data that were submitted for 2021 are based on approximately 7,826,121,178 chickens slaughtered and 50,550,817,859 pounds liveweight produced. Granular flock-level treatment records were available for 75-90% of the birds represented in the 2018-2021 dataset. There was no use of antimicrobials in the hatchery for the years 2020 and 2021. Medically important in-feed antimicrobial use decreased substantially, with all in-feed tetracycline use being eliminated by 2020, and the use of virginiamycin being reduced by more than 97% since 2013. Medically important water-soluble antimicrobials are used for the treatment of disease in broiler production. Use decreased substantially for most water-soluble antimicrobials. The most important diseases necessitating treatment were necrotic enteritis and gangrenous dermatitis as well as E. coli-related disease. A focus on reducing the incidence of these diseases would reduce the need for antimicrobial therapy but will require an investment in research to find efficacious and cost-effective interventions for these diseases.

The diseases suspected of the involvement of chicken anemia virus infection in 11 to 14-weeks old replacement pullets from eastern Japan: a case report

Three strains of chicken anemia virus (CAV) were detected in 11 to 14-weeks old chickens, showing depression, wasting, and increased mortality, from three farms in eastern Japan. Another strain was detected in 12-weeks old chickens from one farm without clinical signs. Bacterial infections were suggested in three farms with clinical signs and its involvement in the occurrence of the diseases might be suspected. Sequence analysis of the VP1, VP2, and VP3 genes of four CAV strains revealed that the three from farms with clinical signs belonged to genotype A2, whereas that from the apparently-normal farm belonged to A3. This may be a rare case report about the diseases suspected of the involvement of the CAV infection in older birds.

Gangrenous dermatitis in chickens and turkeys

Gangrenous dermatitis (GD) is a disease of chickens and turkeys that causes severe economic losses in the poultry industry worldwide. Clostridium septicum, Clostridium perfringens type A, and occasionally Clostridium sordellii are considered the main causes of GD, although Staphylococcus aureus and other aerobic bacteria may also be involved in some cases of the disease. GD has become one of the most significant diseases of commercial turkeys in the United States. Several infectious and/or environmental immunosuppressive factors can predispose to GD. Skin lesions are considered to be the main portal of entry of the microorganism(s) involved. GD is characterized by acute onset of mortality associated with gross skin and subcutaneous tissue lesions consisting of variable amounts of serosanguineous exudate together with emphysema and hemorrhages. The underlying skeletal muscle can also be involved. Ulceration of the epidermis may be also noticed in cases complicated with S. aureus. Microscopically, necrosis of the epidermis and dermis, and subcutaneous edema and emphysema are commonly observed. Gram-positive rods can be identified within the subcutis and skeletal muscles, usually associated with minimal inflammatory infiltrate. A presumptive diagnosis of GD can be made based on history, clinical signs, and gross anatomic and microscopic lesions. However, confirmation should be based on demonstration of the causative agents by culture, PCR, immunohistochemistry, and/or fluorescent antibody tests.