JPC SYSTEMIC PATHOLOGY
HEMOLYMPHATIC SYSTEM
April 2018
H-V05

Signalment: (1834129):  Group of 40-60 pound pigs

HISTORY:  Tissues from one of a group of 40-60 pound pigs, which were inoculated with an infectious agent.  This pig was euthanized 7 days post-inoculation.

HISTOPATHOLOGIC DESCRIPTION:  Spleen:  Diffusely, there is lymphoid depletion within white pulp which is characterized by lymphocyte necrosis with loss of lymphocytes with replacement by moderate amounts of eosinophilic cellular and karyorrhectic debris (lymphocytolysis).  Multifocally red pulp contains mild to moderate amounts of necrotic debris, fibrin and increased numbers of neutrophils and erythrophagocytic macrophages.  Multifocally, arteriolar walls are disrupted, expanded and replaced by eosinophilic fibrillar to homogenous fibrin admixed with degenerate and non-degenerate inflammatory cells, and small amounts of necrotic cellular debris (necrotizing vasculitis).  Less effected vessels often have hypertrophied endothelium.  There is diffuse, moderate congestion.

MORPHOLOGIC DIAGNOSIS:  Spleen:  Lymphoid necrosis, diffuse, with necrotizing vasculitis, breed unspecified, porcine.

ETIOLOGIC DIAGNOSIS:  Asfarviral splenic necrosis

CAUSE:  African swine fever virus

CONDITION:  African pig disease, wart hog disease

GENERAL DISCUSSION: 

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ULTRASTRUCTURAL FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS: 

DIFFERENTIAL DIAGNOSIS:

 

ASF (acute)

ASF (subacute)

CSF

PRRS

Swine erysipelas

Septicemic salmonellosis

DNS

Skin

Erythema

Erythema

Erythema

Cyanosis

Diamond skin lesions

Cyanosis

Macules and papules

Lymph nodes

Marbled aspect

Hemorrhagic

Marbled aspect

Swelling or marbled

Marbled aspect

Swelling

Marbled aspect

Spleen

Hyperemic splenomegaly

Partial hyperemic splenomegaly or focal infarct

Multiple infarcts at the margin

Scattered infarcts or white spots on the surface

Hyperemic splenomegaly

Splenomegaly

-

Kidney

Petechial hemorrhages

Petechial hemorrhages, perirenal edema

Petechial hemorrhages

Petechial hemorrhages

Petechial hemorrhages

Petechial hemorrhages

Glomerulonephritis

Gall bladder

Petechial hemorrhages

Wall edema

Petechial hemorrhages

-

-

-

-

Tonsils

-

-

Necrotic areas

Swelling or with hemorrhages

-

-

-

Intestine

Petechial hemorrhages

Petechial hemorrhages

Button ulcers

-

-

Necrotic enterocolitis

-

Thrombocytopenia

Absence or slight (late)

Transient

Intense (early)

Absent

Absent

Absent

Absent

Other

-

-

Nervous signs; congenital malformation (congenital form)

Thymic atrophy; interstitial pneumonia

Arthritis and vegetative endocarditis (chronic form)

Nervous signs; congestion of gastric mucosa; necrotic foci in the liver; bronchopneumonia

-

Adapted from: Table 3 Differential diagnosis of African swine fever on the basis of gross lesions10

 

Classical swine fever       African swine fever virus
Splenic infarcts      Splenomegaly, NO infarcts 
No pulmonary edema   Pulmonary edema, especially septa Patchy interstitial pneumonia   
Button ulcers in colon  Massive hemorrhagic necrosis in colon
Rare frank lymphoid necrosis  (there is a lack of mature lymphoid tissue) Diffuse severe lymphoid necrosis
No particular liver lesions  Necrosis of periportal hepatocytes Lymphoid infiltrates  
Rare renal tubular degeneration    Common renal tubular degeneration 
Generally no brain lesions  Perivesicular cuffing with necrotic debris in brain Meningoencephalomyelitis 
Infects epithelium   No epithelial infection

 

COMPARATIVE PATHOLOGY:

REFERENCES: 

  1. Cappai S, Loi F, Coccollone A, et al. Evaluation of a commercial field test to detect African swine fever. Journal of Wildlife Diseases. 2017;53(3):602-606.
  2. Granja AG, Noga ML, Hurtado C, et al. The viral protein A238L inhibits TNF-alpha expression through a CBP/p300 transcriptional coactivators pathway. J Immunol. 2006;176(1):451-462.
  3. Guinat C, Gogin A, Blome S, et al. Transmission routes of African swine fever virus to domestic pigs: current knowledge and future research directions. Veterinary Record. 2016;178(11):262-267.
  4. Heimerman ME, Murgia MV, Wu P, Lowe AD, et al. Linear epitopes in African swine fever virus p72 recognized by monoclonal antibodies prepared against baculovirus-expressed antigen. J Vet Diagn Invest. 2018; [Epub ahead of print]: doi: 10.1177/1040638717753966.
  5. MacLachlan NJ, Dubovi EJ. In: Fenner’s Veterinary Virology. 5th ed. San Diego, CA: Academic Press; 2017:175-182.
  6. Miller LM, Gal A. Cardiovascular system and lymphatic vessels. In: Zachary JF, McGavin MD, eds. Pathologic Basis Of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2016: 608.
  7. Reperant LA, Brown IH, Haenen OL, et al. Companion animals as a source of viruses for human beings and food production animals. Journal of Comparative Pathology. 2016;155:S41-S53.
  8. Robinson WF, Robinson NA. The cardiovascular system. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 3. 6th ed. Philadelphia, PA: Elsevier Saunders; 2016:74-76.
  9. Salguero FJ, Gil S, Revilla Y, Gallardo C, Arias M, Martins C. Cytokine mRNA expression and pathological findings in pigs inoculated with African swine fever virus (E-70) deleted on A238L. Vet Immunol Immunopathol. 2008;124(1-2):107-119.
  10. Sanchez-Vincaino JM, Mur L, Gomez-Villamandos JC, Carrasco L. An update on the epidemiology and pathology of African swine fever. J Comp Pathol. 2015;152(1):9-21.
  11. Sastre P, Perez T, Costa S, et al. Development of a duplex lateral flow assay for simultaneous detection of antibodies against African and Classical swine fever JVDI. 2016;28(5):543-549.
  12. Vergne T, Chen-Fu C, Li S, et al. Pig empire under infectious threat: risk of African swine fever introduction into the People's Republic of China. Veterinary Record. 2017;181(5):117.


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