Synopsis on the pathology of viral-infected cases by Mohamed Hamed mohamed Elariny

Department of Pathology, Faculty of Veterinary Medicine, Zagazig University, Egypt.

Synopsis on The Pathology of Viral-Diseased Cases BY

Prof. Dr. Mohamed Hamed Mohamed mohamedelariny@yahoo.com +20124067373

2011

Diseases caused by viruses Mechanisms of virus induced disease:

1-Bind to the cell surface : Virus should be capable to attach the surface of target cells. The viruses have specific surface viral protein (legends) that binds with specific cellular protein on the surface of host cells.

2-Entering the cells and replication After entering the cell, the virus kill host cells and cause tissue damage through several ways i-Viruses inhibit host cell DNA or RNA and protein synthesis ii-Damage cell membrane or promote cell fusion iii-Replication of viruses inside cells results in host cell lysis iv-Killing the infected host cells by immune system this recognizes the viral protein on the cell surface.

Viral replication: i-Attachment to the cells: Binding of viral protein to specific cellular surface receptors ii-Penetration: immediately after attachment by endocytosis. iii-Eclipse phase: (multiplication of virus and cell damage). The RNA and protein synthesis take place in cytoplasm.

iv-Viral release: either by: A-Cytocidal viruses: They alter the cell metabolism of the host cells and leads to necrosis as Herpes, Picorna, Parvo, Adeno and Flavivirus. B-Non-Cytocidal viruses: The are replicated by budding i.e. the virus is extended through cell membranes without cytolysis after enveloped from Golgi apparatus and cellular membrane. They include: i-Persistent infection: as in case of Retrovirus. ii-Latent infection: the viruses reside the cells without replication e.g. Alfaherpes (IBR). iii-Chronic infection: recovery from acute destructive disease is occurred and the host becomes carrier and continues to be replicated the virus but with low levels as FMD. Remarks: Slow virus: It has long incubation period (5-10 years) which ends fatally e.g. Prions, Scrapie, and Visna.

Viruses donâ&#x20AC;&#x2122;t generate toxins. All non-envelope viruses are released by cell lysis (Cytocidal). Envelope viruses are released by budding without cell lysis. Poxviruses are released either with envelope (from Golgi or cellular membranes) without cell lysis or without envelope and induce cell lysis.

Positive-strand viruses: their RNA can serve directly as mRNA. Negative-strand viruses: (parent RNA strand for positive strand) it serves as a template for synthesis of positive strand RNA. Inclusion body: It is aggregation of viral particles (basophilic), viral proteins (eosinophilic) or both in the cells. Intranuclear Inclusion Bodies (IN/IB): all DNA viruses except poxvirus and iridovirus, and Bornavirus and Retrovirus (RNA). Intracytoplasmic Inclusion Bodies (IC/IB): All RNA viruses except Bornavirus and Retrovirus and poxvirus and iridovirus (DNA). Both IC and IN/IB: as Canine distemper, Measles, Cattle plague, Beta herpes (Cytomegalovirus).

All DNA-viruses: 1-They are replicated in the nucleus except poxvirus and iridovirus in the cytoplasm. 2-They are linear ds DNA except Circo and Parvo are ss DNA, and Hepadnavirus is partially ds DNA. 3-All viruses not need enzymes for replication but Poxvirus needs RNA polymerase and Hepadnavirus need DNA polymerases. 4-All DNA virus are icosahedral symmetry except Poxvirus is complex in structure (brick-shape).

5-All DNA viruses are non-enveloped except Poxvirus, Herpesvirus, Asfavirus, Iridovirus and Hepadnavirus are enveloped viruses.

All RNA-viruses: 1-They are replicated in the cytoplasm except Borna and Retro replicate in the nucleus. 2-All RNA viruses are enveloped except Reo, Birna, Picorna, Calci, Astro 3-All RNA viruses are ss RNA except Reo and Birna are ds RNA. ds RNA viruses need RNA-dependent RNA polymerase. 4-All â&#x20AC;&#x201C;ve ss RNA viruses need RNA-dependent RNA polymerase; but the +ve â&#x20AC;&#x201C; ss RNA viruses are not need such enzyme because they act as template for mRNA. Retroviridae need reverse transcriptase enzyme. 5-All RNA viruses are helical in shape except Picro, Reo, Birna, Retro, Flavi, Calci, Toga and Astro are icosahedral.

General Lesions of Viruses: 1-Vacuolar and hydropic degeneration as FMD and Pox. 2-Necrosis (coagulative) as in Cattle plague. 3--Hyperplasia as in Pox and Malignant catarrhal fever. 4-Damaged endothelium as Hog cholera. 5-Neoplasms and Cancer: as Polyomaviruses, Papillomaviruses, others. 6-Inclusion bodies. 7-Syncytial giant cells as in Paramyxo, Parvo and Herpes.

DNA Viruses Double Stranded DNA Virus (ds DNA)

Single Stranded Virus (ss DNA)

Partial Double Stranded Virus (pds DNA)

Poxviridae Herpesviridae Adenoviridae Asfaviridae Iridoviridae Papovaviridae

Circoviridae Parvoviridae

Hepadnaviridae

RNA Viruses Double stranded RNA Viruses (ds RNA)

Single Stranded RNA Viruses + Ve Sense - Ve Sense Non-segmented Segmented Reoviridae Birnaviridae Coronaviridae Bornaviridae Orthomyxoviridae Picornaviridae Paramyxoviridae Bunyaviridae Caliciviridae Rhabdoviridae Arenaviridae Flaviviridae Filoviridae Togaviridae Arteriviridae Astroviridae

Diseases caused by Poxviridae Causes: Poxviridae are ds DNA, brick-shaped epitheliotropic viruses. They have 7 genera as following:

1-Orthopoxviruses: (cowpox, vaccina, buffalopox, rabbitpox, monkeypox, camelpox and Variola â&#x20AC;&#x153;small poxâ&#x20AC;?). 2-capripoxviruses: (sheep pox, goat pox, lumpy skin disease). 3-Avipoxviruses: (fowlpox, canarypox, pigeonpox, turkeypox). 4- Suipoxviruses: (swinepox). 5-Parapoxviruses: (contagious ovine ecthyma, bovine papular stomatitis and pseudocowpox), 6-Leporipoxviruses: (infectious myxomatosis, shope fibroma). 7-unclassified poxviruses: (horsepox, molluscum contagiosum).

NB: Dogs and cats are rarely infected with poxviridae.

Pathogenesis: It summaries in 5 stages for poxviruses. 1-Macule (Roseola): After the pox viral invasion of epithelium small focal areas of erythema appeared (similar to flea bit). 2-Papules: At the red spots, the virus replicates causing epidermal hyperplasia and subepidermal edema. 3-Vesicles Formation: The proliferated epithelium undergoes hydropic and ballooning degeneration. Moreover, some cells ruptured and coalesced together and serous fluid accumulates in cystic spaces (vesicles). 4-Umbilicated pustules: The vesicles ruptured and invaded by pyogenic bacteria with accumulation of neutrophils forming pustules (epidermal abscesses) with depressed center. This is called pock (= pustule) lesions. 5-Crusts (scab or scar formation): It occurs due to dryness of pustules then followed by healing by scar formation and reepithelization.

Cowpox -It is a mild, localized and self limiting disease in cattle. Pathognomonic Lesions: 1-Stages of pox are seen in hairless parts A-In cow: They are seen on the udder, teat, under the tail, medial aspect of the thigh and abdominal wall. B-In bull: as cow + scrotum and prepuce. C-In calf: Muzzle, nostrils, buccal mucosa + as cow. 2-Microscopic appearance includes: i-Epidermal hyperplasia (acanthosis) and ballooning degeneration in the st. spinosum. ii-Eosinophilic IC/IB (Guarnieri bodies) composed of many minute spherical granules (Borrelâ&#x20AC;&#x2122;s or Bollingerâ&#x20AC;&#x2122;s bodies) which are the elementary particles of the virus. iii-Severe vasculitis with ischemic necrosis of the skin as a result of thrombosis. Perivascular lymphocytic aggregations are seen in the dermis. Intemal hyperplasia of blood-vessels forming interlacing network in the lumen.

NB: Swine, buffalo and camel pox are similar to cowpox.

Organ : Skin. Stain : H&E. Disease : Cowpox. Micro : Intemal hyperplasia of blood-vessels forming interlacing network in the lumen.

Lambs and kids under 1 month of age show fever, depression, conjunctivitis, lacrimation, and rhinitis. At necropsy, skin nodules are detected and extended into the lungs and kidneys with 80% mortalities.

Sheeppox It is a serious, systemic (generalized) infectious disease of sheep causing high mortality rate (100%) particularly in lamb.

Pathognomonic Lesions: Macroscopic Lesions: 1-Cutaneous lesions: Vesicular, and pock lesions with thin crusts. 2-Ulcerative and hemorrhagic lesions in GIT and respiratory tract. 3-S/C gelatinous edema. 4-Multifocal fleshy nodules in the renal cortex and lungs. 5-The regional Lns are congested, edematous and enlarged. 6-Healing of skin lesions by scar but remain for long time.

Microscopic lesions: 1-Acanthosis, hydropic and ballooning degeneration. 2-IC/IB (Guarnieri bodies). 3-Sheep pox cells (Cellules claveleuses) are seen in the dermis. 4-Severe vasculitis, thrombosis and ischemic necrosis in the skin. 5-Pneumonia with focal caseous necrosis and IC/IB in the septal cells

Organ : Skin. Disease : Sheeppox. Macro : Nodules over the whole body.

Organ : Skin. Disease : Sheeppox. Macro : Nodules over the ventral aspect of the tail.

Organ : Lung. Disease : Sheeppox. Macro : Multiple pulmonary consolidations due to proliferative alveolitis and bronchiolitis with focal caseous necrosis.

Organ : Kidneys. Disease : Sheeppox. Macro : Whitish nodules on the kidney.

Avipoxviruses They include Fowlpox, canarypox, pigeonpox and turkeypox. The elementary body in fowlpox, is called Borrel body, and the intracytoplasmic inclusion body is called Bollinger body.

The disease, in chickens has 2 forms: 1-Cutaneous or Dry Form: occurs on the skin of the head, particularly the comb and wattles 2-Diphthertic or Wet form: in the mucosa of the mouth or nasal passages

Pathognomonic Lesions: -yellowish nodules on the eyelids, peak and unfeathered areas. -On the feet, legs and body are less common (scaley legs) -Cheesy like material on the mm of buccal cavity, pharynx and respiratory passages.

Pigeon-suffered Pigeonpox show yellowish nodules on the eyelids and peak.

Pigeon-suffered Pigeonpox show yellowish nodules on the ventral aspect of the peak.

Pigeon-suffered Pigeonpox show yellowish nodules on the thigh.

On the summer of 1989, feedlot calves show umbilicated nodules generalized on the skin with enlargement of all peripheral lymph nodes. Some case lamed and others are died with similar nodules in the lungs, kidneys, abomasum and rumen.

Lumpy Skin Disease: Pathognomonic Lesions: Macroscopic Lesions: 1-Multiple nodules (0.5 to 5 cm in diameter) generalized on the skin 2-Similar nodules are seen in the lungs, pharynx, trachea, bronchi, rumen, abomasum and kidneys. 3-All peripheral Lns are enlarged and edematous. 4-Pododermatitis, synovitis, tendosynovitis and coronitis.

Microscopic Lesions: 1-Acanthosis, hyperkeratosis and hydropic degeneration besides vesicle formation in st. spinosum. 2-Vasculitis, thrombosis, ischemic necrosis and ulceration with round cells aggregations. 3-General serous lymphadenitis. 4-Eosinophilic IC/IB in the epidermal cells.

Calf-suffered Lumpy Skin Disease show umbilicated nodules on the whole body surface.

Cow-suffered Lumpy Skin Disease show umbilicated nodules on the whole body surface.

Organ : Skin. Stain : H&E. Disease : Lumpy Skin Disease. Micro : IC/IB, ballooning degeneration and ballooning degeneration

Lambs show vesicles and pustules at the oral mucosa, lips and commissures then they ruptured, forming scabs at these sites. Describe this case and lesions.

Contagious Ovine Ecthyma (orf) Pathognomonic Lesions: Macroscopic Lesions: 1-Presence of stages of pox (papules, vesicles and pustules). 2-These lesions are found at the commissures of lips, lip margins, muzzle, nostrils, oral mucosa, eyelids, genital organs and udder. 3-In complicated cases with bacteria (spheropherous necropherus) or parasites (screw worm or myiasis) deep ulcer may be seen on oral mucosa.

Microscopic picture: 1-Acanthosis, vacuolations, ballooning and vesiculation are seen 2-Epidermal pustules. 3-Eosinophilic IC/IB in the epidermal cells.

Lamb-suffered Orf show Scabs at lips and commissars

Ewe-suffered Orf show Scabs at lips and commissars

Ewe-suffered Orf show Scabs at lips and stages of pox

Horsepox Contagious Pustular Stomatitis (CPS) Coital Vesicular Exanthema Pathognomonic Lesions: *Presence of pox lesions (papules, vesicles and pustules): A-Oral lesions: on lips and oral mucosa (CPS). B-Fetlock lesions: (Grease-heel) on fetlock. C-Genital lesions: (Coital vesicular exanthema) on external genitalia.

Lumpy Skin Disease

Pseudolumpy

Poxvirus (DNA) IC/IB Cutaneous Nodules Affect on L ns

Allertonâ&#x20AC;&#x2122;s disease (DNA) IN/IB Cutaneous Nodules Not affect on L ns

Herpesviridae They are double strand DNA viruses included Alpha Beta and Gamma. A heifer with a history of nervous signs and chewing its skin was submitted to the necropsy. Lacerated or ulcerated skin, edematous congested lungs, subendocardial hemorrhages and hydropericardium besides IN/IB in the hepatocytes and neurons. Describe the case and its pathognomonic lesions.

Alphaherpes viruses 1-Pseudorabies - Aujeszky's disease Alphaherpes Pathognomonic Lesions: Macroscopic Lesions: 1-No detectable lesions in the brain. 2- The skin is severely lacerated and ulcerated. 3-The lungs are congested, edematous and hemorrhagic. 4-Subendocardial hemorrhages and hydropericardium.

Microscopic Lesions: 1-Non-suppurative encephalomyelitis 2-IN/IB in neuron and glial cells. 3-Focal necroses with IN/IB in pharyngeal mucosa, lymph nodes, liver, lungs and adrenal cortex.

Swine-suffered Pseudorabies show congested, edematous and hemorrhagic lungs.

Organ : Brain. Stain : H&E. Disease : Pseudorabies. Micro : Non-suppurative encephalitis

Organ : Liver. Stain : H&E. Disease : Pseudorabies. Micro : INIB in the liver cells

Organ : Lung. Stain : H&E. Disease : Pseudorabies. Micro : INIB in the septal cells

Organ : Kidney. Stain : H&E. Disease : Pseudorabies. Micro : INIB in the endothelial cells of capillaries.

A cow with a history of respiratory and genital lesions, and abortion 6 months of gestation. The genital lesions were pustular type. Mention the disease, forms and lesions.

2-Infectious Bovine Rhinotracheitis or IBR Forms and Pathognomonic Lesions: I-Respiratory Form: 1-Hemorrhagic or necrotic rhinitis, sinusitis, tracheitis and bronchopneumonia (cause of death). 2-Necrosis in epiglottis, oral mucosa and gum. 3-Eosinophilic IN/IB in the lining epithelium of nasal passage and trachea. II-Genital Form: (Infectious pustular vulvovaginitis) 1-Pustular vulvovaginitis and the pustules are covered with yellowish membrane on the vulval and vaginal mucosa. 2-Pustular balanoposthitis. 3-Eosinophilic IN/IB in the lining epithelium of genitalia.

III-Neonatal Form: 1-Necrosis in respiratory epithelium, oral mucosa, esophagus, forestomach, liver, kidneys, spleen and Lns. 2-Eosinophilic IN/IB in the affected tissues.

Iv-Abortion Form: 1-Abortion occurs after 2 weeks to 2 months after the respiratory form. 2- The aborted fetus shows advance autolysis because it dies 24 to 36 hours before abortion. 3-Diffuse hemorrhages and coagulative necrosis are seen in the fetal liver, spleen, kidneys and lymph nodes. 4- Eosinophilic IN/IB in the hepatic cells.

Calves-suffered IBR show dyspnea.

Organ : Trachea. Disease : IBR. Macro : Dirty fibrinous exudate in the tracheal lumen.

Organ : Testis. Disease : IBR. Macro : Periorchitis.

Aborted fetus. Disease : IBR. Macro : Diffuse hemorrhages.

Organ : Lung (trachea). Stain : H&E. Disease : IBR. Micro : Fibrinous tracheitis.

Organ : Lung (trachea). Stain : H&E. Disease : IBR. Micro : INIB in the lining epithelium.

Organ : Placenta. Stain : H&E. Disease : IBR. Micro : INIB in the trophoblasts.

3-Equine Viral Rhinopneumonitis Equine Viral Abortion Pathognomonic Lesions:

In Adult: 1-Rhinitis, laryngitis, tracheitis, â&#x20AC;Ś..pneumonia. 2-Purpura hemorrhagica due to complication with

Strept. hemolyticum. 3-Enterocolitis (inflammation of intestine and colon). 4-Cause storm abortion (90%) at late stage 8-11 months of gestation.

In Aborted Fetus: 1-The liver is congested and show coagulative necrosis. 2-Bronchopneumonia and hydrothorax. 3-IN/IB in the liver cells.

Betaherpes Cytomegalic inclusion diseases It characterized by 1-The affected cells are enlarged. 2-Large basophilic IN/IB.

Gammaherpes A cow with a history of respiratory signs, erosions of oral mucosa and corneal opacity was submitted to Veterinary pathology Department, Mansoura university. Mention the disease and its lesions.

Malignant Catarrhal Fever They are lymphotropic viruses for B or T lymphocytes. Pathognomonic Lesions: Macroscopic Lesions: 1-Erosions of oral mucosa (covered by mucopurulent exudate). 2-Erosions, ulcerations and hemorrhages in abomasum and small intestine 3-Corneal opacity due to degeneration and vesiculation of corneal epithelium and deposition of fibrinous exudate and lymphocytes in the anterior and posterior chambers leading to synechia anterior or posterior.

4-The Lns are enlarged and edematous due to hyperplasia of lymphocytes (immature) and REC. 5-The brain has cooked appearance with broth odor. Macroscopic Lesions: 1-Lymphocytic vasculitis (arteritis) in all organs with fibrinoid necrosis of media, endothelial swelling of the intema and infiltration of the adventitia with lymphocytes and plasma cells. 2-Non suppurative meningoencephalitis. 3-Neither inclusion bodies nor syncytial giant cells are seen.

1-Uveitis: inflammation of iris, ciliary body and choroid. 2-Iridocyclitis: inflammation of iris and ciliary body. 3-Synechia anterior: adhesion between anterior surface of iris and posterior surface of the cornea. 4-Synechia posterior: adhesion between posterior surface of iris and anterior surface of the lens capsule. NB: To differentiate between Lns from cattle plague (necrosis) and MCF (immature hyperplasia of lymphocytes).

Buffalo-suffered MCF show Corneal opacity

Organ : Blood vessels of eye. Stain : H&E. Disease : MCF. Micro : Vasculitis with severe conjunctivitis and keratitis.

Organ : Hard palate. Disease : Malignant Catarrhal Fever. Macro : Erosions on the hard palate.

Organ : Gum. Disease : Malignant Catarrhal Fever. Macro : Erosions on the gum.

Organ : Gum. Disease : Malignant Catarrhal Fever. Macro : Acute catarrhal gingivitis.

Organ : Tongue. Disease : Malignant Catarrhal Fever. Macro : Erosions on the tongue.

Organ : Nostril. Disease : Malignant Catarrhal Fever. Macro : Acute rhinitis.

Organ : Buccal cavity. Disease : Malignant Catarrhal Fever. Macro : Acute stomatitis.

Organ : Blood vessels (skin). Stain : H&E. Disease : MCF. Micro : Vasculitis with fibrinoid necrosis in media.

Adenoviridae Two cases of very young puppies (6-week old mixed breed) are suddenly died after very short course of fever with large congested liver and edematous wall of gallbladder. Describe the disease and its lesions.

Canine Infectious Hepatitis Pathognomonic Lesions: Macroscopic Lesions: 1-The liver is enlarged, congested and mottled. 2-Spleen and Lns are enlarged, congested and hemorrhagic. 3-The wall of gallbladder is thickened and hemorrhagic. 4-Juandice (toxic or intrahepatic type). 5-Tonsilitis (serous to hemorrhagic). 6-Paint brush-like hemorrhages on the serosa of the stomach. Microscopic Lesions: 1-Coagulative necrosis in the liver. 2-Large basophilic IN/IB in hepatic and kupffer cells adjacent to necrosis. 3-These inclusion bodies are also found in REC and endothelium of spleen and Lns. 4-Nonsuppurative interstitial nephritis. 5-Encephalomalacia, hemorrhages, demyelination and gliosis.

Dog-suffered Canine Infectious Hepatitis show blue eye (corneal edema)

Organ : Liver. Disease : Canine Infectious hepatitis. Macro : Edema in gallbladder.

Organ : Liver. Stain : H&E. Disease : Canine Infectious Hepatitis. Micro : Basophilic INIB in the liver cells.

Organ : Kidney. Stain : H&E. Disease : Canine Infectious Hepatitis. Micro : Basophilic INIB in the glomerular endothelium.

Organ : Brain. Disease : Canine Infectious hepatitis. Macro : Hemorrhages and malacia.

Iridoviridae African Swine Fever (Wart Hog Disease) It is similar to â&#x20AC;&#x153;Hog Choleraâ&#x20AC;?. Pathogenesis: The virus induces only thrombocytopenia (destruction of platelets) in the affected pigs with extensive hemorrhages without thrombosis. This virus not affects the endothelial cells as Hog cholera.

Diseases caused by Papovaviridae The Papovaviridae is the acronym derived from grouping of papilloma virus, polyoma virus and vacuolating agent. The papilloma viruses cause papilloma in different animals. The polyoma viruses are apparent only in immune suppressed animals.

Parvoviridae A four-month-old kitten has a history of vomiting and diarrhea. She has a fever and leukopenia. Suspect the disease and its lesions.

Feline Panleukopenia Pathognomonic Lesions: A-In GIT: 1-Severe desquamation and necrosis of enterocytes (erosions in ileum). 2-The crypts are dilated with mucus. 3-The lymphoid tissues and Payer's patches show necrosis of lymphocytes and hyperplasia of histiocytes. 4-Eosinophilic IN/IB are found in the enterocytes.

B-Bone Marrow: 1-The bone marrow appears greasy and semifluid with necrosis of stem cells resulting in Agranulocytosis (panleukopenia) and anemia. 2-Extramedullary hematopoiesis (in the liver).

C-Fetus of infected dam: 1-Hypoplastic cerebellum due to necrosis and IN/IB with loss of balance. 2-The spleen shows depletion of lymphocytes and hyperplasia of histiocytes.

Cat-suffered Panleukopenia show congested viscera and hemorrhagic enteritis.

Organ : Colon. Disease : Panleukopenia. Macro : Hemorrhagic colitis.

Organ Stain Disease Micro

: Intestine. : H&E. : Panleukopenia. : necrosis of mucosa and dilated crypts are with mucus.

Organ : Brain. Disease : Panleukopenia. Macro : Hypoplastic cerebellum.

Picornaviridae (RNA) On July 20, 2008, a suspected vesicular disease outbreak in cattle was reported in Dakhalia province, Egypt with lameness and high mortalities among calves. What is the suspected disease and lesions.

Foot and Mouth Disease (FMD) Pathognomonic Lesions: A-In Adult Animals: 1-Vesicles (aphthae) on lips, anterior 2/3 dorsum and lateral of the tongue, palates and gums lead to excessive salivation (ptylism). 2-The vesicles fuse together to form bullae (large up to 25 Âľ) then ruptured leaving erosions on the oral mucosa. 3-Vesicles are found in the interdigital space and around the coronets, teats, udder and vulva. 4-Hydropic and ballooning degenerations, vesicles with loss of cellular bridges. 5-Intense lymphocytes infiltration and edema in the dermis.

B-In Young Animals (calf and lamb): Similar to adult animals except. 1-Hyaline degeneration and coagulative necrosis in the heart (wall and septum of left ventricle). The necrosis appeared as grayish foci or striations give the heart the appearance of the tiger (Tiger heart). It is the cause of death in young. 2-Lymphocytes infiltrations between the cardiac muscle fibers (non-suppurative myocarditis). NB: Define: Aphtha: Small vesicle Bulla: Large vesicle Ptylism: Excessive salivation Tiger heart: It is the pathognomonic lesion for FMD in the heart of young animals and represented by coagulative necrosis in the wall and septum of left ventricle.

Cattle-suffered FMD show Ptylism

Cattle-suffered FMD show vesicles and erosion on gum.

Organ : Tongue (cattle). Stain : H&E. Disease : FMD. Micro : Large vesicle replacing the lingual epithelium.

Organ : Tongue (cattle). Stain : H&E. Disease : FMD. Micro : Vesicopastule with secondary infection.

Cattle-suffered FMD show vesicles in the interdigital space.

Organ : Skin (cattle). Stain : H&E. Disease : FMD. Micro : Vesicles, hydropic and ballooning degeneration.

Calf-suffered FMD was died.

Heart of calf-suffered FMD show tiger heart Organ : Heart. Disease : FMD. Macro : Grayish-white streaks (Tiger heart).

Diseases

Causes

Swine Ruminant

Horse Human

FMD

Picornaviridae Aphthoviruses

Bovine ulcerative mamillitis

Herpesviridae

Swine vesicular exanthema Swine vesicular disease

Caliciviridae Picornaviridae enteroviruses Rhabdoviridae

+ +

Infectious vesicular stomatitis

Reoviridae (Orbivirus) A two-month old lamb show sign of severe neurological disease characterized by muscular tremors and motor incoordination. At necropsy, the major findings were a marked reduction of the size of the cerebellum and bilateral dilation of the lateral ventricles. Mention the case and lesions in infected ewe.

Bluetongue Pathognomonic Lesions: Macroscopic Lesions: 1-The mucosa of buccal cavity and tongue are congested cyanotic (blue color). 2-S/C edema are seen in the head and neck. 3-Coronitis (inf. of coronet) and pododermatitis (horny wall of hoof) resulting in sloughing of hoof and lameness. 4-The spleen is severely congested and enlarged. 5-Subendocardial hemorrhages in the left ventricle of the heart.

Microscopic Lesions: 1-Coagulative (Zenkerâ&#x20AC;&#x2122;s) necrosis and hemorrhages in the lingual muscles. 2-Fatty change in the liver. 3-Eosinophilic IC/IB (not diagnostic) 4-Pulmonary edema. 5-Necrotic meningoencephalitis is seen in lambs their dams are vaccinated with live vaccine of blue tongue disease (at 1 â&#x20AC;&#x201C; 2 months of gestation). These lambs have hemorrhages on the mucosa of duodenum and abomasum besides enlargement of body Lns.

Ewe-suffered bluetongue show cyanosis of buccal mucosa.

Ewe-suffered bluetongue show coronitis and pododermatitis with hemorrhage on the coronary band.

Ewe-suffered Blue tongue show destruction of brain

On rainy seasons, outbreak of highly infectious disease was seen among South African horses with anasarca and thick head. At necropsy edema in lungs with frothy fluid, hydrothorax and hydropericardium were recorded. Describe the disease and its pathognomonic lesions.

African Horse Sickness â&#x20AC;&#x153;Orbivirusâ&#x20AC;? Pathognomonic Lesions: A-Acute Form: the virus affect on the b.vs. of lungs and increase the permeability and inducing edema. 1-Edema in the lungs (heavy and fail to collapse). 2-The respiratory passages (trachea, bronchioles,..) contain frothy exudates. 3-Hydrothorax and hydropericardium. 4-The bronchial and mediastinal Lns are enlarged and edematous. 5-Hemorrhages on epicardium and endocardium. 6-General venous congestion due to pressure on the heart by fluid.

B-Subacute Form: 1-Edema in S/C tissue of the head and neck with obliteration of

i-Supraorbital fossa ii-Jugular furrow iii-Intermandibular space 2-The eyelids are thickened and edematous.

NB: The cause of death in AHS is i-In acute form from dyspnea ii-In subacute form from cardiac failure

Horse-suffered African Horse Sickness show edematous fluid from nostrils.

Horse-suffered African Horse Sickness show edema in the trachea with frothy exudate.

Horse-suffered African Horse Sickness show edema in the lung with frothy exudate.

Horse-suffered African Horse Sickness show hydropericardium.

Horse-suffered African Horse Sickness show edema in the S/C tissue with obliteration of supraorbital fossa.

Togaviridae (Alphavirus) Equine Encephalomyelitis Three virus strains were isolated from horse: Eastern strain: less virulence up to 50% mortalities (east). Western strain: more virulence 90% mortalities (west). Venezuelan strain: observed in Venezuela induce 80% mortality. NB: The virus is transmitted by mosquitoes and may infect other animals. The primary target cells is the neuron with vascular injury and thrombosis.

Pathognomonic Lesions: 1- No characteristic gross lesions are seen. 2-Non-suppurative polioencephalomyelitis characterized by i-Degeneration and necrosis of neurons (in cerebral cortex, thalamus and hypothalamus). ii- Satellitosis, neuronophagia and gliosis. iii-Perivascular lymphocytic cuffing. 3-Endothelial proliferation, hemorrhages and thrombosis in the b. v 4-Degenerative changes in the liver, heart and pancreas.

Flaviviridae (Flavivirus) Ovine encephalomyelitis (Louping ill) It is a tickborne disease of sheep (tickborne encephalitis) Pathognomonic Lesions: 1-Polioencephalomyelitis (in cerebral cortex and cerebellum) and characterized by : -Diffuse neuronal degeneration (Purkinje cells). -Perivascular lymphocytic cuffing. -Focal glial or inflammatory nodules.

2-Louping gait.

Flaviviridae (Pestivirus) Hog Cholera A juvenile Yorkshire cross pig with rapidly progressive acute renal failure was submitted for necropsy. Marked splenic infarction and disseminated petechiation of both kidneys give the "turkey-egg" appearance. Describe the disease and its lesions.

Pathognomonic Lesions: A-Acute Form: 1-Petechial hemorrhages and edema on all internal organs and skin. 2- Petechial hemorrhages on the kidneys give the appearance of â&#x20AC;&#x153;turkey egg appearanceâ&#x20AC;?. 3-Infarction in the spleen due to thrombosis (red type) with depletion of lymphocytes. 4-Non-suppurative meningoencephalitis. 5-Secondary invaded of Pasteurella multocida which cause pneumonia.

B-Chronic Form: 1-Button-like ulcers in large intestine, particularly at the ileocecal junction due to Salmonella cholera suis. 2-Infarcts of the mucosa and submucosa of small intestine. 3-The ulcers may be seen in epiglottis, tongue, pharynx, stomach and skin of ear and legs. 4-The necrotic center of the ulcers slough and healed by scar. 5-The Peyerâ&#x20AC;&#x2122;s patches are necrotic.

Criterion African Swine Fever Hog Cholera Iridoviridae (DNA) Flaviviridae (RNA) Cause Induce endothelial damage Pathogenesis Induce thrombocytopenia

Lesions

Hemorrhages (without thrombosis) on all organ

Thrombosis, infarction and hemorrhages

Piglet-suffered Hog Cholera show petechial hemorrhages on the kidney (turkey-egg appearance).

Piglet-suffered Hog Cholera show petechial hemorrhages on the serosal surface of the colon.

Piglet-suffered Hog Cholera show splenic infarctions.

Piglet-suffered Hog Cholera show button-like ulcers in large intestine.

Cattle Plague (Paramyxoviridae, morbillivirus) Calves with a history of high fever, erosions of the mouth and GIT along with severe diarrhea were imported from the Ethiopia. Almost all these calves were died. Describe the disease, lesions and differential diagnosis.

Cattle Plague Pathognomonic Lesions: Macroscopic Lesions: 1-Erosions (not ulcers) on the buccal mucosa, lower lips, ventral and lateral borders of the tongue, cheek and gum. 2-The mucosa of the abomasum is severely congested and hemorrhagic 3-The rectum has hemorrhages in the form of lines (zebra marks or zebra striations). 4-The esophagus and pharynx not affected or only the anterior portion. 5-The Peyerâ&#x20AC;&#x2122;s patches are necrotic, and then sloughed leaving ulcerated mucosa of the small intestine. 6-The Lns are edematous and hemorrhagic. 7-The liver is severely congested and show petechial hemorrhages in gallbladder mucosa. 8-The heart show subendocardial hemorrhages.

Microscopic Lesions: 1-Necrosis in the epithelial lining of GIT. 2-Depletion and necrosis of the lymphocytes in the lymphoid tissue (Peyerâ&#x20AC;&#x2122;s patches, spleen and Lns) 3-Presence of syncytial giant cells in abomasum. 4-These giant cells contain eosinophilic IC/IB. Differences between cattle plague, mucosal disease and BVD Criteria

Cattle plague

Mucosal disease

BVD

Cause

Paramyxoviridae (Paramyxovirus)

flaviviridae, (Pestivirus)

flaviviridae, (pestivirus)

All ages

6 â&#x20AC;&#x201C; 24 months

All ages

Morbidity

High

Low

High

Mortality

High

Low

Esophagus

- ve

+ ve

+ve

Age

Dairy farm-suffered Cattle plague show watery bloody diarrhea with high mortalities.

Cow-suffered Cattle plague show mucopurulent eye discharge

Cow-suffered Cattle plague show oral erosions

Cattle plague: Oral erosions

Organ : Abomasum. Disease : Cattle plague. Macro : Congestion and hemorrhages.

Organ : Ileum. Disease : Cattle plague. Macro : Necrosis and ulceration of Peyerâ&#x20AC;&#x2122;s patches with hemorrhages.

Organ : Rectum. Disease : Cattle plague. Macro : Zebra marks due to linear hemorrhages.

Flaviviridae(pestivirus) A 18-month old calf with profuse diarrhea was submitted to necropsy. Erosions and ulcerations in the buccal cavity, esophagus and intestine with hemorrhages. Describe the pathognomonic lesions of this case.

Mucosal Disease i-Both of bovine viral diarrhea and mucosal diseases are caused by antigenically related viruses with variable signs, morbidity and mortality. ii-M (microfold) cells serve as portal of entry by tacking the viruses from the gut and transport it to the gut associated lymphoid tissues. iii-The BVD virus is present in two forms according to its effect on tissue culture: i-Cytopathogenic BVDV: causes bovine viral diarrhea.

ii-Non-cytopathogenic BVDV: causes mucosal disease. The mucosal disease infected the cattle during embryogenesis and penetrates the uterus to fetus and become immunotolerant. At 6-month old and under several factors (presence of 80-kDa protein) affecting the virus and transforming it from non to cytopathogenic inducing its lesions.

Pathognomonic Lesions: 1-Erosions and ulcers on the buccal mucosa, lower lips, ventral, dorsal and lateral borders of the tongue, cheek and gum. 2-The erosions and ulcers extended to pharynx, larynx and esophagus. 3-The rumen and omasum have erosions and ulcers. 4-The abomasal mucosa is congested, hemorrhagic (red) and ulcerated. 5-The mucosa of small intestine is ulcerated and hemorrhagic. 6-The large intestine (cecum, colon) show erosions and hemorrhages. 7-The Peyerâ&#x20AC;&#x2122;s patches are necrotic and sloughed leaving ulcerated mucosa. 8-The Lns are edematous, hemorrhagic and show necrosis of lymphocyte.

N.B: A skeletal disorder in cattle called hyena disease due to short longitudinal growth rate of femur and tibia is seen.

Organ : Intestine. Disease : Bovine Viral Diarrhea (BVD). Macro : Intestinal ulcerations.

Organ : Esophagus. Disease : Bovine Viral Diarrhea (BVD). Macro : Linear esophageal erosions.

Organ : Esophagus. Disease : Bovine Viral Diarrhea (BVD). Macro : Esophageal erosions.

Organ : Intestine. Stain : H&E. Disease : Bovine Viral Diarrhea. Micro : Necrosis and hemorrhages.

Flaviviridae(pestivirus) 3-Equine Viral Arteritis Pink Eye This virus affects on arteries inducing necrosis and inflammation with increase the permeability (edema, petechial hemorrhages and thrombosis).

Pathognomonic Lesions: 1-Edema and hemorrhages in all parts of the body especially the eye. 2-The eyelids are thickened, edematous (palpebral edema). 3-The conjunctiva become red (pink eye) due to the hemorrhages. 4-Hydrothorax, hydropericardium and hydroperitoneum. 5-The wall of the arteries show hyalinization, necrosis and lymphocytes infiltrations.

(Paramyxoviridae, morbillivirus) Canine Distemper Hardpad Disease A stray dog with respiratory signs, scaly foot pad and paraplegia. Mention the case and its macroscopic and microscopic lesions.

Pathognomonic Lesions: Macroscopic Lesions: 1-Catarrhal to fibrinous (if complicated with Bordetella bronchoseptica) bronchopneumonia with fibrinous pleurisy. 2-Ulcerative Keratitis (inf. of cornea) and conjunctivitis. 3-Hydrothorax and hydropericardium. 4-Catarrhal to hemorrhagic gastroenteritis. 5-The Lns are enlarged, congested and edematous. 6-Cutaneous lesions â&#x20AC;&#x153;hard pad diseaseâ&#x20AC;?: the skin of the foot pad and nose is thickened and scaly due to hyper and parakeratosis. 7-Paraplagia (bilateral posterior paralysis).

Microscopic Lesions: 1-Eosinophilic IC and IN/IB are seen in the lining epithelium of bronchi, alveoli, gallbladder, urinary bladder, stomach and astrocytes. 2-These inclusions appear from 10-15 days and disappear at 5th-7th weeks. 3-Syncytial multinucleated giant cells are seen in the lungs. 4-Depletion of the lymphocytes from the spleen and Lns and with hyperplasia of REC. 5-Hyperkeratosis and parakeratosis of the skin of foot pad and nose. 6-Non-suppurative encephalomyelitis characterized by i-Focal encephalomalacia. ii-Astrogliosis. iii-Demyelination (loss of myelin with intact axon). iv-Perivascular lymphocytic cuffing. v-Deg. neurons, satellitosis, neuronophagia. NB: Gemistocytes: It is multinucleated astrocytes which contain eosinophilic IN/IB and ICLIB in case of â&#x20AC;&#x153;canine distemperâ&#x20AC;?

Organ : Bronchus. Stain : H&E. Disease : Canine Distemper. Micro : ICIB in the bronchial epithelium.

Organ : Brain. Stain : H&E. Disease : Canine Distemper. Micro : INIB in astrocytes (Gemistocytes) and neurons.

Organ : Brain. Stain : H&E. Disease : Canine Distemper. Micro : Gemistocytes with INIB (astrocytes).

Organ : Brain. Stain : H&E. Disease : Canine Distemper. Micro : Chronic non-suppurative encephalitis.

Organ : Brain. Stain : H&E. Disease : Canine Distemper. Micro : Focal demyelination of nerve fibers.

Organ : Brain. Stain : H&E. Disease : Canine Distemper. Micro : Focal demyelination of nerve fibers and INIB.

Organ : Bile duct. Stain : H&E. Disease : Canine Distemper. Micro : ICIB in the epithelium of bile duct.

Organ : Stomach. Stain : H&E. Disease : Canine Distemper. Micro : ICIB in the epithelium of stomach.

Organ : Urinary bladder. Stain : H&E. Disease : Canine Distemper. Micro : ICIB in the epithelium of urinary bladder.

Dog-suffered Hardpad disease (Canine distemper) show hyperkeratosis on the nose and foot pad.

Organ : Skin. Stain : H&E. Disease : Canine Distemper (Hardpad Disease). Micro : Hyper and Parakeratosis.

Rhabdoviridae (Lyssavirus) Rabies Hydrophobia or Rage An old dog with history of attacks and bits other animals and peoples as well as a foreign material. At the necropsy, no specific lesions are seen except for damaged foot pad, broken tooth and stones in the stomach.

It has 2 forms: A-Dumb form B-Furious Form Pathognomonic Lesions: Macroscopic Lesions: (non-specific). 1-The brain congested meninges and petechial hemorrhage 2-Hyperemia, hemorrhages and edema in the stomach. 3-The stomach contains foreign materials (stones, wood). 4-The foot pad is damaged (show wounds). 5-Broken teeth.

Microscopic Lesions: 1-Non-suppurative meningoencephalomyelitis, ganglioneuritis and parotid adenitis. 2-The meningoencephalomyelitis is represented by -Degenerated neurons, satellitosis and neuronophagia. -Perivascular lymphocytic cuffing -Hemorrhages 3-As a result of degenerated neurons, aggregations of microglia are seen (called Babes nodules that consist of 6-100 microglias). 4-Eosinophilic IC/IB (Negri’s bodies) are seen in neurons (Purkinje cells), and paravertebral and Gasserian ganglia. 5-These inclusions are detected in Hippocampus in carnivore (canine). Cerebellum Herbivore (ruminant). 6-Special stains of Negri’s bodies: i-Seller’s stain stained red surrounded by clear thin halo. ii-Mann’s and Giemsa bright red against blue cytoplasm.

Dog-suffered Rabies show wild look with broken teeth

Dog-suffered Rabies show abnormal appetite or pica with stones in the stomach.

Organ : Brain. Stain : H&E. Disease : Rabies. Micro : Eosinophilic ICIB in Purkinje cells.

Bunyaviridae Rift Valley Fever On summer of 2006, Storm abortion was noticed among pregnant ewes with mottled liver and thickened hemorrhagic gallbladder on necropsy. Describe the case and its associated lesions.

Pathognomonic Lesions: Macroscopic Lesions: 1-Erosions of buccal mucosa. 2-Necrosis of the skin of udder and scrotum. 3-Laminitis tendinitis, synovitis and coronitis . 4-The liver is enlarged and show grayish necrotic foci. 5-The gallbladder shows thickened, edematous and hemorrhagic wall

Microscopic Lesions: 1-Coagulative necrosis of the hepatic cells (paracentral zone). 2-IN/IB and Councilman bodies are seen in the liver cells. 3-Depletion and necrosis of the lymphocytes in the spleen. 4-The kidneys show hemorrhages, hemosiderosis and nephrosis.

Ewe-suffered Rift Valley Fever show hydroamnion

Organ : Liver. Disease : Rift Valley Fever. Macro : Congestion and hemorrhages besides hemorrhagic necrotic foci.

Organ : Liver. Disease : Rift Valley Fever. Macro : Hemorrhagic and yellow necrotic streaks on the cut surface.

Organ : Intestine. Disease : Rift Valley Fever. Macro : Hemorrhagic enteritis.

Organ : Intestine. Disease : Rift Valley Fever. Macro : Hemorrhagic content in the intestine.

Organ : Liver (lamb). Stain : H&E. Disease : Rift Valley Fever. Micro : Multifocal necrotic and degenerative areas.

Organ : Liver (lamb). Stain : H&E. Disease : Rift Valley Fever. Micro : Multifocal necrosis and aggregations of lymphocytes.

Organ : Liver (lamb). Stain : H&E. Disease : Rift Valley Fever. Micro : Eosinophilic IN and IC IB in the hepatocytes.

Organ : Liver (lamb). Stain : H&E. Disease : Rift Valley Fever. Micro : Necrosis and mineralization in the liver.

Organ : Kidney (lamb). Stain : H&E. Disease : Rift Valley Fever. Micro : Multifocal area of nephrosis.

Organ : Kidney (lamb). Stain : H&E. Disease : Rift Valley Fever. Micro : Glomerular hemorrhage.

Organ : Kidney (lamb). Stain : H&E. Disease : Rift Valley Fever. Micro : Glomerular thrombosis.

Organ : Spleen (lamb). Stain : H&E. Disease : Rift Valley Fever. Micro : Splenic necrosis with depletion of the lymphocytes.

Rift Valley Fever tendinitis and synovitis

Rift Valley Fever-infected ewe show aborted fetus

Retroviridae (lentivirus) Visna/Maedi Visna means wasting or shrinkage. Maedi means dyspnea or short breathing. Pathognomonic Lesions: A-Visna: 1-Demyelination of nerve fibers of white matter of spinal cord and brain 2-Submeningeal and perivascular lymphocytic infiltrations. 3-Proliferation of glial cells (gliosis). 4-Pleocytosis (increase the number of cells in the CSF).

B-Maedi: 1-The lungs are rubbery, grayish yellow or grayish blue in color with dry cut surface and not collapsed. 2-Thickening of the alveolar septa by REC and fibrous tissue. 3-Alveolar fetalization near the terminal bronchioles with hypertrophy of the bronchial smooth muscles. 4-The spleen and lymph nodes show follicular hyperplasia. 5-Polyarthritis with villous hyperplasia of synovial membrane which infiltrated with lymphocytes and plasma cells. 6-Intracytoplasmic inclusion bodies are seen in large mononuclear cells.

Organ : Lung of sheep. Disease : Visna-Maedi. Macro : Rubbery, grayish yellow lungs.

Organ : Lung of sheep. Disease : Visna-Maedi. Macro : Grayish-blue lungs.

Organ : Lung of sheep. Stain : H&E. Disease : Visna-Maedi. Micro : Interstitial pneumonia with lymphocytes aggregations

Organ : Lung of sheep. Stain : H&E. Disease : Visna-Maedi. Micro : Interstitial pneumonia with lymphocytes aggregations.

Retroviridae (lentivirus) Equine Infectious Anemia Swamp Fever Pathognomonic Lesions: 1-Emaciatibn and edema in the lower abdomen. 2-Petechial hemorrhages on â&#x20AC;&#x153;Franulum linguaeâ&#x20AC;?. 3-The bone marrow (shaft of long bones) changes from yellow (inactive) to red (active). 4-Hemosiderosis in all body organs and blood (indicated by Prussian blue stain). 5-Juandice (yellow mucous membranes).

Horse-suffered equine infectious anemia show emaciation and S/C edema.

Organ : Spleen (horse). Disease : Equine Infectious Anemia. Macro : Splenomegaly.

Organ : Liver (horse). Stain : H&E. Disease : Equine Infectious anemia. Micro : Round cell aggregations and hemosiderosis.

Prion Disease Scrapie Ovine Spongiform Encephalopathy (OSE) An ewe rub against rocks or other hard surfaces, scraping their fleeces and severely emaciated. At necropsy, no detectable lesions are noticed.

Pathognomonic Lesions:

Macroscopic Lesions: Emaciation, lacerated skin and loss of wool or hair.

Macroscopic Lesions: 1-Presence of large vacuoles in the cytoplasm of the medulla oblongata, pons, midbrain and spinal cord. 2-Diffuse Astrogliosis (proliferation of astrocytes). 3-Perivascular lymphocytic cuffing. 4-Amyloid plaques (prion protein) are found in the molecular and granular layers of the cerebellum.

Ewe-suffered Scrapie show loss of wool and lacerated skin.

Organ : Brain (sheep). Stain : H&E. Disease : Scrapie. Micro : Neuronal vacuolations and degeneration.

Organ : Brain (sheep). Stain : H&E. Disease : Scrapie. Micro : Neuronal vacuolation and degeneration.

Prion Disease Bovine Spongiform Encephalopathy (BSE) Mad Cow Disease In England, several sporadic cases of Frisian cows show nervous signs (paralysis) and wild look particularly those fed on meat feed additive. No gross lesions are seen. Microscopically, spongy appearance of mid brain is the most predominant lesion. Suspect the disease and its lesions.

Pathognomonic Lesions: Macroscopic Lesions: No detectable lesions. Microscopic Lesions: 1-Bilateral spongiform appearance in brain stem with cerebellar atrophy. 2-This appearance represented by membrane-bounded vacuoles. 3-There is single or multiple vacuoles in neurons (perikaryon) with pouching the nucleus to one side and neuropil (axons and dendrites). 4-These vacuoles are also seen in the dorsal ganglion of vagus 5-Scrapie-associated fibrils (amyloid plaque) are present.

Brain stem

Mad Cow Disease (BSE)

Bull-suffered Mad Cow Disease (BSE) show wild look.

Organ : Brain Disease : BSE. Macro : Severe brain atrophy.

Organ : Brain. Stain : H&E. Disease : BSE. Micro : Cerebral degeneration.

Organ : Brain. Stain : H&E. Disease : BSE. Micro : Vacuoles in the brain (perikaryon and neuropils)

Organ : Brain. Stain : H&E. Disease : BSE. Micro : Amyloid plaques (Scrapie associated fibrils).

Single stranded RNA unclassified virus Borna Disease

Pathognomonic Lesions: 1-Non-suppurative polioencephalomyelitis characterized by: -Degenerated neurons. -satellitosis and neuronophagia. -Perivascular lymphocytic cuffing 2-Eosinophilic IN/IB (Joestâ&#x20AC;&#x2122;s bodies) in hippocampus.