JPC SYSTEMIC PATHOLOGY

SPECIAL SENSES SYSTEM

April 2024

S-B01

 

Signalment (JPC #1379468): Young turkey

 

HISTORY: Young turkey from a flock of over 13,000. Total mortality in the flock was three times normal over a 3-month period.

 

HISTOPATHOLOGIC DESCRIPTION:  

Slide A: Eye: Expanding the anterior and posterior chambers and posterior compartment are abundant viable and necrotic heterophils and fewer lymphocytes, plasma cells, and macrophages admixed with hemorrhage, fibrin, and large colonies of 1 x 3 µm bacilli. Multifocally, the retinal inner limiting membrane is lined by large colonies of bacilli and the nerve fiber layer is infiltrated by variable numbers of heterophils with concomitant expansion by fibrin and edema. The iris is diffusely thickened by increased clear space and ectatic lymphatics (edema), low numbers of heterophils, lymphocytes, and plasma cells, and multiple foci of hemorrhage and fibrin. The conjunctiva is expanded by abundant hemorrhage and few hemosiderin-laden macrophages.

 

Slide B: B & H: Lining the retinal inner limiting membrane and scattered throughout the fibrinocellular exudate within the posterior compartment are multifocal large colonies of 1 x 3 µm gram-negative bacilli.

 

MORPHOLOGIC DIAGNOSIS: Eye: Endophthalmitis, heterophilic, subacute, diffuse, moderate, with hemorrhage, edema, fibrin, and numerous gram-negative bacilli, turkey, avian.

 

ETIOLOGIC DIAGNOSIS: Ocular salmonellosis

 

ETIOLOGY: Salmonella enterica subsp. arizonae (Arizona arizonae, Arizona hinshawii)

 

CONDITION: Avian arizonosis (AA)

 

GENERAL DISCUSSION:

• Gram-negative, non-spore forming, motile bacillus (family Enterobacteriaceae)
• Arizonosis is an egg-transmitted disease primarily of young turkey poults that causes significant morbidity and mortality 
  • Occasionally seen in chicks, ducklings, canaries, psittacines
• Arizonosis is characterized either by acute septicemia or localization of infection to intestine, peritoneal cavity, eye(s), brain, or other sites
• Public health implication: Human arizonosis is associated infection from reptiles

 

PATHOGENESIS:

• The organism often localizes to the ovary of carrier birds (infected adults) à organism included within egg à infects developing embryo à infected progeny
• Infected adults (often asymptomatic) are often intestinal carriers with intermittent shedding à infected fecal contamination of egg surface à eggshell penetration à infected progeny
• Infected progeny transmit infection horizontally to uninfected birds in the hatch, may become carriers/shedders
• Other sources of infection include: reptiles, rats, mice, many mammals, contaminated hatchers, fomites

 

TYPICAL CLINICAL FINDINGS:  

• Not specific; hallmarks are septicemia, neurological signs, blindness, increased mortality
• Adults: Usually subclinical, may be intestinal carriers and shed intermittently; in older birds there is a reduction in egg production and hatchability with little to no morbidity or mortality (age-dependent resistance).
• Poults/chicks under 3 weeks of age are most affected clinically:
  • Similar to salmonellosis, but ocular lesions are suggestive, with blindness due to corneal opacity and/or intraocular caseous material
  • Listlessness, weakness, sitting on hocks, huddled together near heat sources
  • Anorexia, diarrhea with pasty feces around vent feathers
  • Paralysis, ataxia, twisted necks, torticollis, opisthotonos, convulsions, trembling
  • Variable mortality (3-5% most common, up to 50%)

  

TYPICAL GROSS FINDINGS:  

• Generalized gram-negative septicemia: may have no gross lesions
  • Retained yolk sacs with watery or caseous contents
  • Prominent yolk stalks
  • Enlarged, mottled, yellow liver
  • Splenomegaly
  • Peritonitis, swollen joints, pericarditis, air sacculitis, discolored heart
  • Cloudy meninges
  • Corneal opacity
• Caseous cecal cores
• Oophoritis, salpingitis
• Eyes: A small but significant number of poults have opacity or turbidity of the eyes (ophthalmitis) with white or yellow exudate in the anterior chamber and/or vitreous chamber, followed by post-infection ocular atrophy (useful in identifying previously infected flocks)
• CNS: Purulent exudate in the meninges, lateral ventricles, or middle and inner ear

 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

• Yolk sac and stalk: Fibrinosuppurative inflammation
• Brain: Heterophilic and fibrinous meningitis; exudate in ventricles; cerebral malacia, inflammation, and thrombi
• Liver: Hepatocyte necrosis; mononuclear cell infiltrate
• Spleen: Increased numbers of mononuclear inflammatory cells
• +/- heterophilic inflammation in pericardium, air sacs, synovium, ceca, eye(s)

 

ADDITIONAL DIAGNOSTIC TESTS:  

• Isolation with identification is required for definitive diagnosis

• Recover from unabsorbed yolk, intestine, liver, spleen, heart, eyes, ear, brain
• S. arizonae slowly ferments lactose – must hold fermentation tubes for a few days to accurately differentiate from other Salmonella spp.

 

DIFFERENTIAL DIAGNOSIS:

• Septicemia: Salmonellosis (e.g., S. typhimurium, S. heidelberg), paratyphoid (Salmonella Enteriditis)
• Ocular lesions: Although more typical of arizonosis, similar lesions can occur with paratyphoid (Salmonella Enteriditis), aspergillosis, or colibacillosis; blindness due to cataracts
• Caseous cecal cores: Pullorum disease (Salmonella Pullorum-Gallinarum), coccidiosis (Eimeria adenoeides), Histomonas meleagridis
• Neurologic signs: Newcastle disease (avian paramyxovirus 1), aspergillosis, vitamin E deficiency-induced encephalomalacia

 

COMPARATIVE PATHOLOGY:  

• Avian: Chickens, ducks, wild birds, canaries, parrots can also be affected
• Reptiles: S. enterica subsp. arizonae is part of the normal flora in reptiles
  • Ridgenose rattlesnakes: Specific serotype with flagellar antigens z4 and z23 is osteotropic – Heterophilic and granulomatous osteomyelitis, osteonecrosis, sequestra, and pathologic fractures
• Rodents:  Rats and mice are frequent carriers of the organism
• Rhinoceros and tapir: salmonellosis is a common cause of septicemia and enteritis
  • S. enterica subsp. arizonae cultured from captive black rhinos with septicemia and gastroenteritis
• Sheep and lambs: S. enterica subsp. arizonae can cause acute enterocolitis and septicemia

 

REFERENCES:

1. Crespo R, França MS, Fenton H, Shivaprasad HL. Galliformes and Columbiformes. In: Terio KA, McAloose D, St. Leger, eds. Pathology of Wildlife and Zoo Animals. San Diego, CA:Elsevier. 2018:760.
2. Duncan M. Perissodactyls. In: Terio KA, McAloose D, St. Leger, eds. Pathology of Wildlife and Zoo Animals. San Diego, CA:Elsevier. 2018: 448.
3. Fulton RM.  Bacterial diseases.  In: Boulianne M., ed. Avian Disease Manual. 8^th ed. Jacksonville, FL: American Association of Avian Pathologists; 2019:105-106.
4. Ossiboff RJ. Serpentes. In: Terio KA, McAloose D, St. Leger, eds. Pathology of Wildlife and Zoo Animals. San Diego, CA:Elsevier. 2018:904, 911.
5. Swayne DE, Barnes HJ, Abdul-Aziz T, Fletcher OJ. Chapter 10: Nervous System. In: Abdul-Aziz T, Fletcher OJ, Barns HJ, eds. Avian Histopathology. 4th ed. Madison, WI: Omnipress; 2016: 477; 523.
6. Uzal FA, Plattner BL, Hostetter JM. Alimentary system. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol. 2. 6^th ed. St. Louis, MO: Elsevier; 2016: 115.

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