Volume 30, Number 6—June 2024
Research
Outbreak of Highly Pathogenic Avian Influenza A(H5N1) Virus in Seals, St. Lawrence Estuary, Quebec, Canada1
Stéphane Lair
, Louise Quesnel, Anthony V. Signore, Pauline Delnatte, Carissa Embury-Hyatt, Marie-Soleil Nadeau, Oliver Lung, Shannon T. Ferrell, Robert Michaud, and Yohannes Berhane
, Louise Quesnel, Anthony V. Signore, Pauline Delnatte, Carissa Embury-Hyatt, Marie-Soleil Nadeau, Oliver Lung, Shannon T. Ferrell, Robert Michaud, and Yohannes Berhane
Table 3
Microscopic lesions documented in harbor (Phoca vitulina) and gray (Halichoerus grypus) seals infected by HPAI A(H5N1) during the 2022 outbreak in the St. Lawrence Estuary, Quebec, Canada
| Microscopic lesions | % Seals affected (no. with lesions/no. examined) |
|---|---|
| Brain | |
| Meningoencephalitis | 100 (15/15) |
| Predominantly neutrophilic | 80 (12/15) |
| Predominantly lymphoplasmacytic |
20 (3/15) |
| Lung | |
| Pulmonary inflammatory changes | 73 (11/15) |
| Acute multifocal fibrinosuppurative alveolitis | 60 (9/15) |
| Acute interstitial pneumonia | 53 (8/15) |
| Acute alveolar damage | 40 (6/15) |
| Alveolar emphysema |
27 (4/15) |
| Adrenal gland | |
| Adrenocortical necrosis |
60 (6/10) |
| Thymus | |
| Acute multifocal necrotizing thymitis |
50 (2/4) |
| Lymph nodes | |
| Reactional lymph nodes | 43 (6/14) |
| Acute multifocal necrotizing lymphadenitis |
36 (5/14) |
| Kidney | |
| Multifocal membranous glomerulonephritis |
40 (6/15) |
| Liver | |
| Necrotizing hepatitis |
29 (4/14) |
| Spleen | |
| Necrotizing splenitis |
21 (3/14) |
| Muscle | |
| Neutrophilic infiltration of the perimysium |
9 (1/11) |
| Heart | |
| Multifocal myocarditis | 7 (1/14) |
1Preliminary results from this study were presented at the International Association for Aquatic Animal Medicine Conference, May 24, 2023, Salt Lake City, Utah, USA.
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