12-year-old male ring-tailed lemur (Lemur catta)This captive ring-tailed lemur was housed in a Midwestern American zoo and first presented with labored
breathing and was immobilized for a physical examination. It had significant respiratory effort under anesthesia. A
large mass was observed on a thoracic radiograph, obscuring the heart shadow. The lemur recovered from anesthesia
but continued to have labored breathing and lethargy. It was humanely euthanized.
A 9 x 7 x 9 cm gelatinous mass was present in the pleural cavity, replacing and displacing most
normal lung parenchyma.
The lung tissue is largely replaced in many sections by large thickwalled
fibrous cavities with adjacent and intramural abundant lymphoplasmacytic nodular aggregates of
macrophages, neutrophils, and eosinophils.Â The cavities are often lined by activated macrophages.Â Within many
cavities are large, often multiple, viable and degenerate larval cestodes characterized by their segmented integument,
calcareous corpuscles, a scolex with a rostellum bearing hooklets, and spinous tegument.Â Exogenous budding from
the end opposite the scolex is present in some slides.Â In the remaining lung, there were multifocal areas of
parenchymal collapse of airways, peripheral emphysema, and pools of neutrophils, fibrin, and hemosiderin-laden
macrophages in alveolar spaces and within capillaries.Â Many megakaryocytes were also circulating in the capillaries.
Small nodular areas of lymphoplasmacytic inflammation are noted on the serosa of the intestine and on the diaphragm.
Lung: Severe granulomatous and fibrous pleuropneumonia with intralesional larval cestodes (presumptive Cysticercus longicollis, the larval form of Taenia crassiceps)
Larval cestodes often present as cysts, of which there are several forms: cysticercoids,
cysticercus, coenurus, and hydatid cyst.(3) Of these, the presented case is a cysticercus based on the presence of only
one scolex in each bladder (though bladder walls have degenerated in many of the fibrous cavities).Â Other key
features to note are the thick tegument and the deeply basophilic calcareous corpuscles which are most numerous on
the neck and scolex, but not in the bladder wall.(3)
Pulmonary, pleural, or peritoneal infection of lemurs by cysticerci has been well documented anecdotally and in the literature.(2,4) Based on these reports, one of which included molecular confirmation, and the similar morphology including rare budding seen in this case, the most likely etiology is Cysticercus longicollis, the larval form of Taenia crassiceps, though other Taenia sp.Â are possible.
Exposure to feces of the definitive host (typically wild canids, but also domestic cats and dogs) or consumption of infected secondary rodent hosts are possible modes of transmission to the lemur in this case.Â After ingestion by an aberrant host, it is not well-documented as to how the cysticerci migrate to the peritoneal or pleural cavities, but once there, these cases can be remarkably fulminating since the organism can proliferate by budding both endogenously and exogenously.Â Infection and rapid proliferation is associated particularly with immunosuppression. This disease is zoonotic, most recently associated with AIDS patients.Â There was no history or clinical pathology data to suggest this lemur is immunocompromised, but the perceived high frequency of cysticercosis in lemurs might indicate a predisposition in this exotic species which has presumably never been exposed to canid or felid parasites in their evolutionary history until very recently.
Lung: Cysticerci, multiple, with fibrosis and mild histiocytic and eosinophilic pneumonia.
There is some variation among slides, and some participants may have received two
sections of lung in which the histiocytic and eosinophilic pneumonia and bronchitis are a more prominent feature
due to the presence of larval cysticerci in airways.
Other important cysticerci in veterinary species are as follows(1):
|ADULT TAPEWORM||DEFINITIVE HOST||LARVAL FORM||INTERMEDIATE HOST||SITE|
|Taenia saginata||man||Cysticercus bovis||cattle||muscle|
|Taenia solium||man||Cysticercus cellulosae||pig, man||muscle|
|Taenia(Multiceps) multiceps||dog||Coenurus cerebralis||sheep, cattle||CNS|
|Taenia hydatigena||dog||Cysticercus tenuicollis||sheep, cattle, pig||peritoneum|
|Taenia ovis||dog||Cysticercus ovis||sheep||muscle|
|Taenia pisiformis||dog||Cysticercus pisiformis||rabbit||peritoneum, liver|
|Taenia serialis||dog||Coenurus serialis||rabbit||connective tissue|
|Taenia taeniaeformis||cat||Cysticercus fasciolaris (strobilocercus)||mouse, rat||liver|
|Taenia krabbei||dog||Cysticercus tarandi||reindeer||muscle|
|Taenia mustelae||wild felids||rodents||liver|
|Diphyllobothrium latum||bear, man||fish||muscle|
|Diphyllobothrium pacificum||seal, sea lion||marine birds||muscle|
1.Â Bowman DD, Lynn RC, Eberhard ML.Â Georgi's Parasitology for Veterinarian.Â 8th ed.Â St.Â Louis, MO: Saunders; 2003:130-153, 269, 275, 375-7
2.Â Dyer NW, Greve JH: Severe Cysticercus longicollis cysticercosis in a black lemur (Eulemur macaco macaco).Â J Vet Diagn Invest 10: 362-364, 1998
3.Â Gardiner CH, Poynton SL: An atlas of metazoan parasites in animal tissues Armed Forces Institute of Pathology, Washington, D.C., 2006
4.Â Luzon M, de la Fuente-Lopez C, Martinez-Nevado E, Fernandez-Moran J, Ponce-Gordo F: Taenia crassiceps cysticercosis in a ring-tailed lemur (Lemur cata).Â J Zoo Wildl Med 41: 327-330, 2010