JPC SYSTEMIC PATHOLOGY
Signalment (JPC #1699088): A chimpanzee (Pan troglodytes)
HISTORY: This animal lived for many years in a large southwestern zoo and died from disseminated tuberculosis. This was an incidental finding.
HISTOPATHOLOGIC DESCRIPTION: Colon: Circumferentially, there is mucosal erosion and an overall decrease in the number of colonic crypts. The remaining crypts are surrounded and separated by variably sized, infiltrating aggregates of lymphocytes, plasma cells, and eosinophils that extend into and along with edema, expand the lamina propria. These inflammatory cells also multifocally surround submucosal vessels. Several submucosal arteries are lined by hypertrophied endothelial cells, with occasionally transmigrating eosinophils within the tunica media. Within the colonic lumen, there are few cross and tangential sections of a 90-150 um diameter nematode with a 5 um thin cuticle with lateral alae, platymyarian-meromyarian musculature, a pseudocoelom, and a muscular esophagus with a triradiate lumen.
Small intestine: Multifocally many eosinophils, lymphocytes and plasma cells expand the lamina propria and submucosa. Admixed with enterocytes are increased numbers of goblet cells (hyperplasia). Embedded at various depths within the mucosa and within the lumen are longitudinal and cross-sections of nematodes as described above.
MORPHOLOGIC DIAGNOSIS: Colon; small intestine: Colitis and enteritis, lymphoplasmacytic and eosinophilic, circumferential, moderate, with goblet cell hyperplasia and few Oxyurid nematodes, etiology consistent with Enterobius sp., chimpanzee (Pan troglodytes), nonhuman primate.
CAUSE: Enterobius sp.
ETIOLOGIC DIAGNOSIS: Intestinal enterobiasis
CONDITION: Pinworm infection
- Usually innocuous in the chimpanzee, although serious and even fatal infections have been reported
- Pathogenicity may be related to severity of infection and immunological status of host
- Family Oxyuridae (pinworms)
- Oxyurids are among the most host specific of nematodes
- Enterobius anthropopitheci: Chimpanzees, prosimian primates
- Enterobius vermicularis: Human pinworm; can infect chimpazees, Old World monkeys, and great apes
- Trypanoxyuris and Oxyuronema species: New World monkeys
- Inhabits colon and cecum of nonhuman primates
- Direct; fecal-oral infection
- Ingested embryonated eggs hatch in the small intestine and undergo two or more molts
- Adult Enterobius in the ileocecocolic region
- Gravid females migrate to the perianal skin and lay embryonated eggs; eggs become infectious within a few hours
- Pinworms have been found within all layers of the intestine and in lymph nodes of the chimpanzee
- There is controversy over whether mucosal attachment of larvae or adults is a normal part of the life cycle, and whether Enterobius is able to penetrate normal tissues:
- Heavy infestations may cause ulcerative colitis, allowing larva and adults to migrate into the mucosa
- Mechanical mucosal damage with secondary bacterial infection
- Parasites invade tissue damaged by some other process
- Inflammation and necrosis may occur when aberrantly migrating larvae die
TYPICAL CLINICAL FINDINGS:
- Anal pruritus and irritation; causes self mutilation, restlessness, and aggression
- Chimpanzees with severe enterobiasis develop depression, anorexia, weight loss/emaciation, dehydration, and mild to profuse watery diarrhea; death may occur within one week of the onset of diarrhea
TYPICAL GROSS FINDINGS:
- Fatal infections in the chimpanzee are characterized by extensive ulcerative enterocolitis, peritonitis, necrogranulomatous mesenteric lymphadenitis and possible ileocecal nodules
- Females (6-12mm x 0.3-0.6mm) often have long pointed tails, and are generally larger than males (2-5mm x 0.1-0.2mm)
TYPICAL LIGHT MICROSCOPIC FINDINGS:
- In severe infections there is mucosal and submucosal necrosis
- Neutrophilic and lymphoplasmacytic inflammation
- Oxyurids have a thin cuticle with cervical or lateral triangular alae (lateral in Enterobius), platymyarian-type musculature, cuboidal uninucleate intestinal cells, and a prominent rhabditiform esophagus (corpus, isthmus and bulb)
- Nematodes in all layers of the intestine
- Ellipsoid, asymmetrical eggs, 50-60um long; +/- embryonated when laid
ADDITIONAL DIAGNOSIC TESTS:
- Adult worms emerging from the anus
- Enterobius eggs rarely passed in the feces; not detected by fecal flotation or direct fecal examination
- Antemortem diagnosis is based on visualization of adults emerging from the anus, or from identification of eggs in perianal swabs or cellophane tape preparations.
- Prosthenorchis elegans: Causes pyogranulomatous enteritis with acanthocephalid parasites
- Oesophagostomum : Causes iIntramural nodules in the cecum, colon and adjacent mesentery of wild-caught monkeys
- Enterobius anthropopitheci: Nonhuman primates, chimpanzees, prosimian primates
- Enterobius vermicularis: Old World monkeys, great apes. Associated with appendicitis, intestinal abscesses, infections of the female reproductive tract, peritonitis, and nephritis in captive chimpanzees; public health concern.
- Oxyuris equi: Most common pinworm in domestic animals. Distal intestine, with rectal pruritus in horses
- Skrjabinema ovis: Sheep & goats
- Passalurus ambiguus: Ceca of rabbit. Heavy infectious cause impaired weight gains, poor breeding performance, and death
- Syphacia obvelata, Aspicularis tetraptera: Ceca and colon of rats
- Syphacia obvelata, Aspicularis tretraptera: Common in laboratory mouse. Heavy infectious associated with rectal prolapse, intussusception, fecal impaction and diarrhea.
- Pinworms do NOT infect the dog and cat
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