Study of Gross and Microscopic Lesion of Viral Disease

• Cattle
• FMD, LSD, Rinderpest
• Sheep/Goat
• Bluetongue, PPR
• Dog
• Rabies, Canine Distemper, Infectious canine hepatitis
• Swine
• Swine fever

Swine fever

Numerous disseminated cortical petechiae ("turkey egg kidney").

Swine fever

The mucosa is reddened and contains multiple discrete ("button") ulcers surrounded by zones of hemorrhage.

Swine fever

There are multiple coalescing, swollen, dark red infarcts along the margins

Swine fever

G) Lymphocyte infiltration around the small blood vessels in brain. H&E stain, ×400. 

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I) Histological structure of spleen was disordered and characterized by necrotic lymphocytes and hemorrhage. H&E stain, ×100.

H) Proliferation of glial cells in brain. H&E stain, ×200. 

Swine fever

K) The glomerulus and mesenchyme were hemorrhagic. H&E stain, ×200.

Rabies

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1. Marked congestion of blood vessels in sulci of swollen cerebral hemispheres.
2. Massive perivascular infiltration with mononuclear cells (lymphocytes and macrophages) around dilated BV in WM of camel brain.
3. Dense eosinophilic and sharply outlined Negri bodies (arrow) of various sizes in the cytoplasm of intact neuron in camel brainstem
4. Brain section showing degenerated neurons, severe cuffing with mononuclear cells and edema. A Negri body is also visible in the degenerated neuron (arrow) having mild diffuse gliosis.

Canine Distemper

A. Lungs with "wet-like" appearance, which are not collapsed and display multifocal red to dark red mottling.

2. Lung section, H&E stain: Severe interstitial pneumonia.
3. Brain section, H&E stain: Intracytoplasmic, eosinophilic inclusions (arrows) in the ependymal epithelium.

Canine Distemper

Figure: The vacuolated appearance of the white matter (WM) which is due to demyelination.

PPR

PPR

Necropsy finding of trachea of a PPR virus infected goat

Figure: severe congestion in tracheal mucous membrane with frothy exudates in the lumen. 

FMD

Surface of Ox, tongue containing discrete vesicles within the mucosa

A large vesicle undermines approximately one-third of the mucosa. There is diffuse marked infiltration of the mucosa by innumerable neutrophils, largely concentrated at the edges of the vesicle as well as in the basal layers of the mucosa

The floor of the vesicle and basal layers of the mucosa are outlined by a heavy infiltrate of neutrophils and cellular debris.

D. Immunohistochemical staining demonstrating localization of FMDV within cardiomyocytes.

1. Gross image of porcine heart with confirmed FMDV-associated myocarditis. Multifocal pallor on the surface of both right and left ventricles (arrows).

B & C. Right ventricle of pig found dead at 5 days post infection with FMDV A₂₄ Cruzeiro. Interstitial edema and mixed mononuclear infiltrates consisting of lymphocytes, large macrophage-like cells, and scarce neutrophils. Myocyte necrosis and fragmentation (arrows). Hematoxylin and eosin (B) 4× magnification, (C) 20× magnification. 

(C) Mixed mononuclear infiltrate and interstitial edema separating myocardial fibers in histological specimen from heart. Hypereosinophilia and loss of striations indicates myofiber degeneration and necrosis. Hematoxylin and Eosin stain. 40x magnification.

Marked pulmonary edema with obliteration of alveoli with a homogenous pink fluid

Pulmonary congestion, edematous and consolidation in FMD fatal cases

Lumpy skin disease