The clinical features, pathobiology, and epidemiology of influenza infections in pigs

Detmer, Susan E.

doi:10.1002/9781118924341.ch16

Cited by 1 publication

(3 citation statements)

References 74 publications

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“…The clinical outcome of infections of swine with IAVs is not only affected by the immune status but also different factors such as age, infection pressure, climatic conditions, homing, and secondary infections with bacteria or other viruses [ 4 ]. Outbreaks of IAV infections in swine are usually of low mortality [ 4 , 8 , 9 ]. There are only a few reports about spontaneous outbreaks of fatal IAV infections with severe lung lesions in pigs in the field [ 10 , 40 ].…”

Section: Discussionmentioning

confidence: 99%

“…Clinical signs in typical outbreaks of influenza in pigs include fever, lethargy, dyspnea, nasal discharge, cough, and inappetence [ 4 ]. Outbreaks of IAV infections of swine in the field usually are subclinical or mild and can reach a high morbidity rate, but are in general, except from rare reports, of less than 1% mortality [ 4 , 8 , 9 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

“…The virulence and pathogenicity of IAV in pigs, however, can be quite variable [ 4 , 8 , 9 ]. Several reports describe that the inoculation of non-vaccinated pigs with different influenza viruses of porcine, avian, or human origin resulted in non-fatal respiratory disease and lung lesions of varying degrees from only mild to moderate or even severe [ 11 , 12 , 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

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Spontaneous Lethal Outbreak of Influenza A Virus Infection in Vaccinated Sows on Two Farms Suggesting the Occurrence of Vaccine-Associated Enhanced Respiratory Disease with Eosinophilic Lung Pathology

Reineking,

Hennig-Pauka,

Schröder

et al. 2024

Viruses

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Influenza A virus (IAV) infections in swine are usually subclinical, but they can reach high morbidity rates. The mortality rate is normally low. In this study, six vaccinated, spontaneously deceased sows revealed IAV infection and enhanced neutrophilic bronchopneumonia with unexpectedly large numbers of infiltrating eosinophils. The purpose of this study was to characterize these lung lesions with special emphasis on the phenotypes of inflammatory cells, the presence of eosinophilic peroxidase (EPO), and neutrophil extracellular traps (NETs). The number of Sirius red-stained eosinophils was significantly higher in the lungs of IAV-infected sows compared to healthy pigs, indicating a migration of eosinophils from blood vessels into the lung tissue stimulated by IAV infection. The detection of intra- and extracellular EPO in the lungs suggests its contribution to pulmonary damage. The presence of CD3+ T lymphocytes, CD20+ B lymphocytes, and Iba-1+ macrophages indicates the involvement of cell-mediated immune responses in disease progression. Furthermore, high numbers of myeloperoxidase-positive cells were detected. However, DNA-histone-1 complexes were reduced in IAV-infected sows, leading to the hypothesis that NETs are not formed in the IAV-infected sows. In conclusion, our findings in the lungs of IAV-infected vaccinated sows suggest the presence of so far unreported field cases of vaccine-associated enhanced respiratory disease.

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