Chris H. Gardiner

FATAL TOXOPLASMOSIS IN FREE-RANGING ENDANGERED 'ALALA FROM HAWAII

The ‘Alala (Corvus hawaiiensis) is the most endangered corvid in the world, and intensive efforts are being made to reintroduce it to its former native range in Hawaii. We diagnosed Toxoplasma gondii infection in five free-ranging ‘Alala. One ‘Alala, recaptured from the wild because it was underweight and depressed, was treated with diclazuril (10 mg/kg) orally for 10 days. Antibodies were measured before and after treatment by the modified agglutination test (MAT) using whole T. gondii tachyzoites fixed in formalin and mercaptoethanol. The MAT titer decreased four-fold from an initial titer of 1:1,600 with remarkable improvement in physical condition. Lesions of toxoplasmosis also were seen in two partially scavenged carcasses and in a third fresh intact carcass. Toxoplasma gondii was confirmed immunohistochemically by using anti-T. gondii specific serum. The organism was also cultured by bioassay in mice from tissues of one of these birds and the brain of a fifth ‘Alala that did not exhibit lesions. The life cycle of the parasite was experimentally completed in cats. This is the first record of toxoplasmosis in ‘Alala, and the parasite appears to pose a significant threat and management challenge to reintroduction programs for ‘Alala in Hawaii.

Myxozoan parasitism in waterfowl

Myxozoans are spore-forming, metazoan parasites common in cold-blooded aquatic vertebrates, especially fishes, with alternate life cycle stages developing in invertebrates. We report nine cases of infection in free-flying native and captive exotic ducks (Anseriformes: Anatidae) from locations across the United States and describe the first myxozoan in birds, Myxidium anatidum n. sp. We found developmental stages and mature spores in the bile ducts of a Pekin duck (domesticated Anas platyrhynchos). Spores are lens-shaped in sutural view, slightly sigmoidal in valvular view, with two polar capsules, and each valve cell has 14-16 longitudinal surface ridges. Spore dimensions are 23.1 microm x 10.8 microm x 11.2 microm. Phylogenetic analysis of the ssrRNA gene revealed closest affinity with Myxidium species described from chelonids (tortoises). Our novel finding broadens the definition of the Myxozoa to include birds as hosts and has implications for understanding myxozoan evolution, and mechanisms of geographical and host range extension. The number of infection records indicates this is not an incidental occurrence, and the detection of such widely dispersed cases suggests more myxozoans in birds will be encountered with increased surveillance of these hosts for pathogens.

Cerebrospinal Nematodiasis and Vertebral Chondrodysplasia in a Calf

from vasculitis and tissue infiltration of leukocytes to necrosis with granulation tissue. The age of these primary lesions was estimated to be less than 1 day and up to a week or more.9 The inflammatory process had started before slaughter, and the affected valves were less elastic and somewhat fragile. The fact that erythrocyte destruction, erythrophagocytosis, and hemosiderosis were not observed indicates that the hemorrhages were fresh and had developed shortly before or during the slaughter procedure. The great fluctuations in blood pressure as a consequence of stress, stunning, and sudden massive bleeding (hypovolemic shock4,14) probably caused greater vascular strain than these altered valves could bear. Demonstration of an Erysipelothrix sp. and a Streptococcus sp. in 4 out of the 6 valves investigated is in accordance with the earlier reports that these bacteria are the most common cause of valvular endocarditis in the pig.11,15 The findings presented indicate that hemorrhages in the left atrioventricular valves of conventionally slaughtered pigs reveal an apparent early phase of valvular endocarditis and thus provide material suitable for morphological studies. Even if the material presented here is limited, the findings indicate that inflammation in a previously undamaged valve may start as vasculitis within the spongiosa of the valve. Acknowledgement. The assistance of Mr. Christer Rundberg is gratefully acknowledged.

Cerebral Angiostrongylus cantonensis infection in a captive African pygmy falcon (Polihierax semitorquatus) in southern California

A 10-month-old, female African pygmy falcon (Polihierax semitorquatus) hatched and housed at the San Diego Zoo developed neurologic signs and died from a cerebral infection with the rat lungworm Angiostrongylus cantonensis. There was an associated mild nonsuppurative meningoencephalitis. This infection was diagnosed on histology and confirmed by detection of species-specific A. cantonensis DNA in formalin-fixed and frozen brain tissue by a polymerase chain reaction assay. To the authors’ knowledge, this infection has not previously been reported in a bird in the United States and has not been known to be naturally acquired in any species in this region of the world. The source of the infection was not definitively determined but was possibly feeder geckos (Hemidactylus frenatus) imported from Southeast Asia where the parasite is endemic.

Proventricular Nematodiasis in Wrinkled Hornbills (Aceros corrugatus)

Abstract Three immature Sunda wrinkled hornbills (Aceros corrugatus) were diagnosed postmortem with proventricular spirurid nematodiasis. Concurrent severe disseminated larval granulomatosis in other visceral organs was considered contributory to mortality in each case. Clinical signs of nematodiasis were vague but generally consisted of weight loss, anorexia, and lethargy. Frequent antemortem fecal examinations were negative for spirurid eggs. In these present cases, based on routine histopathology, both prophylactic and empirically based therapeutic anthelmintic treatments had no evident benefit in the elimination of the proventricular nematodes. Spirurid nematodiasis may be an important cause of mortality in young hornbills.

Use of laser rhinoscopy to treat a nasal obstruction in a captive California sea lion (Zalophus californianus).

Abstract Laser rhinoscopy was used to treat a nasal obstruction in a captive California sea lion (Zalophus californianus). The rehabilitated, adult, female sea lion developed mucopurulent, intermittent, bilateral nasal discharge and functional nasal obstruction 20 mo after acquisition by the Aquarium of the Pacific in Long Beach, California. A 3-mm-thick soft tissue structure spanning the region between the soft and hard palates, a deviated nasal septum, and several nasopharyngeal polyps were identified. Biopsies and cultures of the obstructive web showed ulcerative granulation tissue with suppurative inflammation, bacterial infection, and a partial section of an arthropod larva (not speciated). Laser rhinoscopy was performed to relieve the caudal nasopharyngeal obstruction and ablate the polyps. The sea lion appeared to breathe through the nares with lessened nasal discharge for a period of 6 wk after laser therapy, but within 8 wk the mucopurulent nasal discharge returned, the obstruction had reformed, and the sea lion was euthanized. Postmortem examination confirmed antemortem diagnoses of caudal nasopharyngeal obstruction secondary to inflammatory tissue; however, no additional sections of arthropod parasites were located microscopically.

Amebiasis in a Dog with Gastric Ulcers and Adenocarcinoma

Reports of disease caused by free-living amoebas are infrequent. These organisms occur worldwide and have been isolated from a variety of soil and water habitats. Pathogenic free-living amebae include the genera Naegleria, Acanthamoeba, and Balamuthia. A 4-year-old male Great Pyrenees dog presented with a history of vomiting the previous day and hind limb weakness for the previous 10-14 days. Results of a complete blood count and serum chemistry panel were within reference ranges and a myelogram failed to demonstrate abnormalities. Serum antibody titers for Ehrlichia canis and Coccidioides immitis were negative. The dog was treated with chlorpromazine, dexamethasone, and high doses of oral prednisone over the next 4 days. Twelve days after initial presentation, the dog developed melena and collapsed. At the request of the owner, euthanasia was performed by the attending veterinarian. Necropsy revealed that the stomach was filled with clotted blood and contained 3 discrete ulcers in the pyloric region. The largest ulcer was 2 x 3 cm and had a central perforation measuring 1.5 cm in diameter. All ulcers had raised margins with dark red bases. The surrounding submucosa was thickened and firm. The serosa surrounding the perforation was covered by a focally extensive omental adhesion that contained multiple pockets of greenish yellow fluid. The small intestine and colon were filled with liquid to tarry black material interpreted to be partially digested blood. surface was also covered by a layer of fibrin and neutrophils, and this exudate extended into attached mesentery. The submucosa and tunica muscularis were edematous, and scattered submucosal blood vessels contained fibrin thrombi. Numerous amoebas were present within the superficial areas of the margins of the perforated ulcer (Fig. 1) and within the serosal exudate. Fewer amoebas were seen in the granulation tissue. Amoebas were also present within the surface debris that covered the smallest ulcer and within the margins of the third ulcer. The amoebas were spherical to ovoid and 10-25 μm in diameter and contained abundant granular to vacuolated cytoplasm (Fig. 2). Each contained a single eosinophilic nucleus that measured up to 5 μm in diameter, with a distinct, darker 2-4-μm nucleolus (karyosome). Occasional binucleate forms with central dividing membranes demonstrated protozoal replication. Cytoplasmic granules stained dark brown to black with GMS and bright red by the PAS reaction. All amoebas identified were trophozoites. We were unable to demonstrate, by HE or special stains, the typical bilayered cyst wall that is characteristic of most freeliving forms and is also seen in the tissue forms of some pathogenic amoebas. The amoebas in histologic sections reacted with the antiWillaertia serum (Fig. 3), exhibiting bright apple-green flu-

LETHAL PROCYRNEA INFECTION IN A BLACK-BACKED WOODPECKER (PICOIDES ARCTICUS) FROM CALIFORNIA

Abstract:  The black-backed woodpecker (Picoides arcticus) is a species of management concern in California. As part of a study of black-backed woodpecker home range size and foraging ecology, nine birds in Lassen National Forest (Shasta and Lassen Counties, California) were radio-tracked during the 2011 breeding season. One of the marked birds was found dead after being tracked for a 10-wk period in which it successfully nested. A postmortem examination of the dead bird revealed that it was emaciated and autolyzed, with the presumptive cause being numerous spiruroid nematodes of the genus Procyrnea in the gizzard. This first observation of Procyrnea nematodes in a black-backed woodpecker is notable because the Procyrnea infection was considered lethal and because Procyrnea has been implicated in substantial die-offs in other bird species, including woodpeckers.

Spirocerca lupi granulomatous pneumonia in two free-ranging maned wolves (Chrysocyon brachyurus) from central Brazil

The current report describes granulomatous pneumonia due to Spirocerca lupi in 2 free-ranging maned wolves (Chrysocyon brachyurus). Both wolves had multiple, white, 1–1.5 cm in diameter, soft, encapsulated granulomas in the caudal lung lobes, which contained centrally placed parasites on cut sections. Microscopically, there was granulomatous inflammation with numerous intralesional sections of spirurid nematodes. Representative complete adult specimens of nematodes derived from these lesions were submitted for parasitological exam and identified as the spirurid S. lupi. To the authors’ knowledge, there have been no published reports of S. lupi in maned wolves.

PELODERA STRONGYLOIDES INFECTION IN PACIFIC HARBOR SEALS (PHOCA VITULINA RICHARDII) FROM CALIFORNIA

Skin biopsies were collected from free-ranging harbor seals (Phoca vitulina richardii) from central California (n = 53). Microscopic examination of hematoxylin and eosin-stained tissue sections revealed the presence of tightly coiled nematode larvae within the ostia of numerous hair follicles of four seals. Parasites were characterized by paired lateral alae, platymyarian musculature, and an indistinct, uninucleate digestive tract. Mild chronic superficial dermatitis and perifolliculitis were evident microscopically in association with the intrafollicular parasites. Histomorphologic features of the larvae and their presence within hair follicles are consistent with previous reports of the facultative nematode parasite Pelodera strongyloides. This is the first published report of P. strongyloides infection in any marine mammal. This parasite may be acquired by marine mammals through close contact with soil or decaying organic material and should be considered as a potential differential diagnosis for dermatitis in marine mammals that use terrestrial resting sites.