AFIP SYSTEMIC PATHOLOGY

JPC SYSTEMIC PATHOLOGY

INTEGUMENTARY SYSTEM

October 2019

I-P11 (NP)

 

Signalment (JPC# 1685305): An age and breed unspecified chicken

 

HISTORY: Numerous yellowish nodules up to several millimeters in diameter were noted at slaughter.

 

HISTOPATHOLOGICAL DESCRIPTION: Feathered skin: Multifocally within the subcutis and dermis, separating dermal collagen bundles, are many variably sized, oval to elongate, cavitary spaces up to 500 um in diameter that contain multiple tangential and cross sections of arthropods. The arthropods are up to 400 um in diameter and are characterized by a fragmented chitinous exoskeleton with intact spines; partially intact, jointed appendages; a hemocoel; striated muscle; multiple cross sections of gastrointestinal organs; and male or female reproductive tracts. There is moderate to marked postmortem degeneration due to scalding and autolysis.

 

The other tissue sections on this slide are not related to Laminosioptes cysticola.

 

MORPHOLOGIC DIAGNOSIS: Feathered skin, subcutis and dermis: Cysts, multifocal, with multiple arthropod mites, chicken, avian.

 

ETIOLOGIC DIAGNOSIS: Subcutaneous acariasis

 

CAUSE: Laminosioptes cysticola

 

CONDITION: Laminosioptiasis

 

CONDITION SYNONYMS: Fowl cyst mite; subcutaneous mite

 

GENERAL DISCUSSION:

·      Heavy mite infestation can cause retarded growth, reduced egg production, lowered vitality, damaged plumage and even death (Hinkle, Diseases of Poultry 2013)

·      Lesions cause carcass condemnation

·      Infection is usually in older, emaciated birds kept in unsanitary conditions

 

PATHOGENESIS:

·      The life cycle is not known except:

·      Females lay embryonated eggs

·      All stages of offspring develop under the skin or in deep tissues of the host

·      Disease is rare and associated with heavy infestations

 

TYPICAL CLINICAL FINDINGS:

·      Typically no clinical disease

 

TYPICAL GROSS FINDINGS:

·      Round to oval, yellowish, caseous and calcareous nodules in subcutaneous tissues; especially thorax and abdomen

·      The initial infestation is on the skin with more frequent findings in the loose subcutaneous connective tissue, muscle, abdominal viscera, and lungs

·      Nodules are the host response to dead mites

 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

·      Mites are found in subcutis, peripheral nerves, heart, lungs, air sacs, abdominal viscera, muscle, and reproductive tracts

·      There is little or no inflammation associated with intact mites

·      Degenerate acarids and exoskeletal fragments elicit mild to moderate granulomatous reaction and mineralization

·      The female mite is about 0.25 X 0.11 mm (250um x 110um)

·      The gnathosoma is reduced and not visible from above

·      The body bears a few long setae

 

DIFFERENTIAL DIAGNOSIS:

·      Tuberculosis: Subcutaneous nodules can be mistaken for tuberculoid lesions (distinguished by the presence of acid‑fast bacilli)

·      Cytodites nudus (P-P19): Poultry air‑sac mite; it occurs in respiratory passages, air sacs, and other internal organs of domestic fowl and pheasants

 

COMPARATIVE PATHOLOGY:

·      Reported in chickens, turkeys, pheasants, geese, and pigeons

 

OTHER SPECIES OF MITES OF IMPORTANCE TO POULTRY:

·      Ornithonyssus sylviarum: Northern fowl mite; most significant poultry ectoparasite particularly in caged layer and breeder flocks; congregate around the vent; cause inflammation, irritation, scabbing and anemia (Hinkle, Diseases of Poultry 2013)

·      Knemidokoptes gallinae: Poultry depluming mite; found in the follicles and surrounding skin

·      Knemidokoptes mutans (I-P12): Scaly‑leg mite; found in the skin under the scales of the leg, and occasionally the comb, wattles, and neck of domestic fowl, turkeys, guinea fowl, pheasants, and pet birds

·      Dermanyssus gallinae: Poultry red mite; it infects poultry of all kinds and caged and wild birds

·      Trombicula sp.: Scrub itch mite or chiggers; only the larvae are parasitic

·      Syringophilus bipectanatus and S. columbae: Poultry‑quill mite

 

REFERENCES:

1.     Arends JJ. External parasites and poultry pests. In: Calnek BW, Barnes HJ, Beard, CW, et. al., eds. Diseases of Poultry. 10th ed. Ames, IA: Iowa State University Press; 1997:785, 800-807.

2.     Bowman DD, Lynn RC. Arthropods. In: Bowman DD, Lynn RC, eds. Georgis’ Parasitology For Veterinarians. 6th ed. Philadelphia, PA: W. B. Saunders Company; 1995:69-70.

3.     Hendrix CM, Kwapien RP, Porch JR. Visceral and subcutaneous acariasis caused by hypopi of Hypodectes propus bulbuci in the cattle egret. J Wildlife Dis. 1987;23(4):693-697.

4.     Hinkle NC, Corrigan RM. External parasites and poultry pests. In: Swayne DE, et al, eds. Diseases of poultry. 13th ed. Ames, IA: Iowa State University Press; 2013: 1099-1116.

5.     Keymer, IF. Parasitic diseases. In: Petrak ML, ed. Diseases of Cage and Aviary Birds. 2nd ed. Philadelphia, PA: Lea & Fabriger; 1982:535, 578-593.

6.     Smith KE, Quist CF, Crum JM. Clinical illness in a wild turkey with Laminosioptes cysticola infestation of the viscera and peripheral nerves. Avian Dis. 1997;41(2):484-489.


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