Characteristics of H7N2 (Nonpathogenic) Avian Influenza Virus Infections in Commercial Layers, in Pennsylvania, 1997-98

• Published in: Avian diseases 1999-01, Vol.43 (1), p.142-149
• Main Authors: Ziegler, Andre F., Davison, Sherrill, Acland, Helen, Eckroade, Robert J.
• Format: Article
• Language: English
• Subjects: Animals; Case Reports; Chickens; Disease outbreaks; Eggs - microbiology; Eggs - virology; H7N2 subtype influenza A virus; Infections; Influenza A virus; Influenza in Birds - epidemiology; Influenza in Birds - virology; Lesions; Mortality; Oviducts; Pennsylvania - epidemiology; Poultry Diseases - epidemiology; Poultry Diseases - virology; Tissue samples; Viruses
• ISSN: 0005-2086; 1938-4351
• DOI: 10.2307/1592774

Between January 1997 and March 1998, 11 cases of H7N2 avian influenza (nonpathogenic) were diagnosed at the Laboratory of Avian Medicine and Pathology, Kenneth Square, PA. These cases involved either commercial leghorn laying hens or leghorn pullets raised in Pennsylvania. Grossly and histologically, the most striking lesion associated with disease was salpingitis, usually with edema and occasionally with oviduct necrosis. Fluid, fibrinous, and egg yolk material in the peritoneum (egg yolk peritonitis) as well as pulmonary congestion and pulmonary edema were also frequently seen. Oviduct lesions have rarely been described in association with avian influenza infections in previous outbreaks. Mortality in affected houses was mild to moderate (less than 4% total mortality during the outbreak), with concurrent mild to moderate egg production declines (2%-4% at the time of disease onset). /// Entre enero de 1997 y marzo de 1998, en el Laboratorio de Medicina y Patología Aviar en Kenneth Square, Pensilvania, se diagnosticaron once casos de influenza aviar producidos por la cepa apatógena H7N2. Estos casos involucraron gallinas ponedoras Leghorn o pollonas criadas en Pensilvania. La lesión macroscópica e histológica más significante asociada con la enfermedad fue salpingitis, usualmente con edema y ocasionalmente con necrosis del oviducto. Se observó con frecuencia líquido, fibrina y yema de huevo en el peritoneo (peritonitis por ruptura de la yema de huevo), como también congestión y edema pulmonar. Las lesiones del oviducto asociadas con influenza aviar han sido muy rara vez descritas en brotes anteriores. La mortalidad en las granjas afectadas fue de suave a moderada (menor del 4% durante todo el brote), con una disminución concurrente en la producción de huevo de suave a moderada (2%-4% en el momento del inicio de la enfermedad).