Ilse H. Stalis

Hepatic Hemorrhage, Hemocoelom, and Sudden Death due to Haemoproteus Infection in Passerine Birds: Eleven Cases

Haemoproteus spp. are ancient apicomplexan hemoparasites that have undergone extensive coevolution with their natural hosts and are typically species specific, with inapparent or minimal pathogenicity. A promiscuous genotype of Haemoproteus capable of undergoing host switching on a familial level was identified. This protozoan caused severe disease with high mortality in 6 species of exotic passerine birds housed in California at the San Diego Zoos Wild Animal Park: Surinam crested oropendola (Psarocolius decumanus decumanus), Guianan turquoise tanager (Tangara mexicana mexicana), blue-necked tanager (Tangara cyanicollis caeruleocephala, Guianan red-capped cardinal (Paroaria gularis gularis), magnificent bird of paradise (Diphyllodes magnificus hunsteini), and superb bird of paradise (Lophorina superba). The birds had few or no clinical signs. Necropsy findings consisted of hemocoelom and irregularly scattered areas of hemorrhage and hepatocellular necrosis. Affected areas of liver contained solitary protozoal megaloschizonts in varied states of degeneration and peripheral nonsuppurative inflammation. No other parasite life stages were found in parenchymal organs or blood smears. Polymerase chain reaction using consensus primers for an avian malarial mitochondrial cytochrome B gene segment was positive in all cases. Sequencing and BLAST analysis identified the protozoan as a Haemoproteus sp. related to Haemoproteus spp. found in asymptomatic passerine birds native to North America. In situ hybridization was performed in 3 animals with a mitochondrial cytochrome B probe and was positive only in megaloschizonts. These findings suggest the recognition of a genotype of Haemoproteus that exhibits high levels of host infidelity and causes severe disease in captive birds exotic to North America.

Paramyxovirus infection in caiman lizards (Draecena guianensis)

Three separate epidemics occurred in caiman lizards (Dracaena guianensis) that were imported into the USA from Peru in late 1998 and early 1999. Histologic evaluation of tissues from necropsied lizards demonstrated a proliferative pneumonia. Electron microscopic examination of lung tissue revealed a virus that was consistent with members of the family Paramyxoviridae. Using a rabbit polyclonal antibody against an isolate of ophidian (snake) paramyxovirus, an immunoperoxidase staining technique demonstrated immunoreactivity within pulmonary epithelial cells of 1 lizard. Homogenates of lung, brain, liver, or kidney from affected lizards were placed in flasks containing monolayers of either terrapene heart cells or viper heart cells. Five to 10 days later, syncytial cells formed. When Vero cells were inoculated with supernatant of infected terrapene heart cells, similar syncytial cells developed. Electron microscopic evaluation of infected terrapene heart cells revealed intracyto-plasmic inclusions consisting of nucleocapsid strands. Using negative-staining electron microscopy, abundant filamentous nucleocapsid material with a herringbone structure typical of the Paramyxoviridae was observed in culture medium of infected viper heart cells. Seven months following the initial epizootic, blood samples were collected from surviving group 1 lizards, and a hemagglutination inhibition assay was performed to determine presence of specific antibody against the caiman lizard isolate. Of the 17 lizards sampled, 7 had titers of <1:20 and 10 had titers of >1:20 and <1:80. This report is only the second of a paramyxovirus identified in a lizard and is the first to snow the relationship between histologic and ultrastructural findings and virus isolation.

Malignant Catarrhal Fever-Like Disease in Barbary Red Deer (Cervus elaphus barbarus) Naturally Infected with a Virus Resembling Alcelaphine Herpesvirus 2

ABSTRACT Eight Barbary red deer (Cervus elaphus barbarus) developed clinical signs suggestive of malignant catarrhal fever (MCF) over a 28-day period. These animals were housed outdoors with four other species of ruminants. Affected red deer had lethargy, ocular signs, and nasal discharge and were euthanatized within 48 h. Lesions included ulcers of the muzzle, lips, and oral cavity associated with infiltrates of neutrophils and lymphocytes. Serologically, six of seven red deer tested during the outbreak were positive by competitive enzyme-linked immunosorbent assay for antibodies to a shared MCF virus antigen. PCR using oligonucleotide primers designed for a conserved protein of alcelaphine herpesviruses 1 (AlHV-1) and 2 (AlHV-2) and for conserved regions of a herpesvirus DNA polymerase gene was positive for tissues from all eight clinically affected animals and negative for eight out of eight red deer without clinical signs of MCF. DNA sequencing of PCR amplicons from the diseased red deer indicated that they were infected with a novel herpesvirus closely related to AlHV-2; immunohistochemistry using polyclonal anti-AlHV-2 serum and in situ hybridization demonstrated the presence of virus within salivary glands adjacent to oral lesions of affected animals. A survey of other ruminants near the outbreak subsequently showed that normal Jacksons hartebeest (Alcelaphus buselaphus jacksoni) that were cohoused with the diseased red deer were infected with the same virus and were shedding the virus in nasal excretions. These findings suggest that a herpesvirus closely related to AlHV-2 caused the MCF-like disease epizootic in Barbary red deer and that the virus may have originated from Jacksons hartebeest.

Coccidioidomycosis in Przewalski's horses (Equus przewalskii)

Abstract Coccidioidomycosis is a rare, often subclinical infection in domestic animals caused by the fungus Coccidioides immitis. Because of an apparent high incidence of coccidioidomycosis in Przewalskis horses (Equus przewalskii) housed at a single facility, necropsy records and biomaterials from animals that died between 1984 and 2000 were reviewed (n = 30, 15 males, 15 females). Coccidioidomycosis was the leading cause of death (33%) in this population with lesions in the lungs and tracheobronchial lymph nodes of all animals and variable involvement of the skeletal muscle, heart, kidney, liver, skin, brain, spinal cord, spleen, as well as other regional lymph nodes. At the time of death, affected horses tended to be younger than unaffected animals, were from multiple lineages, and males were over represented. During the same time period, no other exotic equids (n = 76) housed at the same facility were diagnosed with coccidioidomycosis, suggesting that environmental factors are not the sole cause of the high incidence in E. przewalskii. Numbers of the lymphocyte subsets (CD3, CD4, CD5, CD8, CD21+ cells) quantified by flow cytometry were similar between Przewalskis horses and domestic horses (Equus caballus). Although responses of lymphocyte blastogenesis assays were similar between Przewalskis (n = 5) and domestic horses (n = 5) in response to the T cell mitogen concanavalin A, lymphocytes from two of the Przewalskis horses failed to proliferate in response to Coccidioides. One of these horses had systemic disease and the second developed coccidioidomycosis 2 yr later. These results suggest that the immune system of some Przewalskis horses fails to respond appropriately to Coccidioides.

Investigation of factors predicting disease among zoo birds exposed to avian mycobacteriosis.

OBJECTIVE To characterize infection patterns and identify factors associated with avian mycobacteriosis among zoo birds that were housed with infected enclosure mates. DESIGN Matched case-control study. ANIMALS 79 birds with avian mycobacteriosis (cases) and 316 nondiseased birds (controls) of similar age and taxonomic group that were present in the bird collection of the Zoological Society of San Diego from 1991 through 2005. PROCEDURES Inventory and necropsy records from all eligible, exposed birds (n = 2,413) were examined to determine disease incidence and prevalence in the exposed cohort. Cases were matched in a 1:4 ratio to randomly selected controls of similar age and taxonomic grouping. Risk factors for mycobacteriosis (demographic, temporal, enclosure, and exposure characteristics as well as translocation history) were evaluated with univariate and multivariable conditional logistic regression analyses. RESULTS Disease prevalence and incidence were estimated at 3.5% and 8 cases/1,000 bird-years at risk, respectively. In the multivariable model, cases were more likely to have been imported into the collection, exposed to mycobacteriosis at a young age, exposed to the same bird species, and exposed in small enclosures than were controls. Odds for disease increased with an increasing amount of time spent with other disease-positive birds. CONCLUSIONS AND CLINICAL RELEVANCE The low incidence of mycobacteriosis and the risk factors identified suggested that mycobacteria may not be easily transmitted through direct contact with infected enclosure mates. Identification of risk factors for avian mycobacteriosis will help guide future management of this disease in zoo bird populations.

Investigation of characteristics and factors associated with avian mycobacteriosis in zoo birds.

The objective of the current study was to identify factors associated with avian mycobacteriosis in zoo birds. Inventory data, population health records, and necropsy data from eligible birds in the Zoological Society of San Diegos (ZSSD) collection from 1991–2005 (n = 13,976) were used to describe disease incidence, prevalence, and postmortem findings. A matched case-control study was then conducted to identify factors describing demographic, temporal, and enclosure characteristics, along with move and exposure histories. Cases (disease-positive birds; n = 167) were matched in a 1:7 ratio with controls (disease-negative birds; n = 1169) of similar age and taxonomic grouping. Potential risk factors were evaluated using univariate and multivariable conditional logistic regression. Disease prevalence and incidence were estimated for the study period at 1.2% and 3 cases/(1,000 bird-years at risk), respectively. Lesion characteristics and order prevalence are described. In the multivariable model, case birds were more likely to have been previously housed with a bird with mycobacterial disease involving the intestinal tract (odds ratio [OR] = 5.6, P < 0.01) or involving only nonintestinal sites (OR = 2.0, P < 0.01). Cases were more likely to have been imported into the collection than hatched at the ZSSD (OR = 4.2, P < 0.01). Cases were moved among ZSSD enclosures more than controls (OR = 1.1 for each additional move, P < 0.01). Findings will help guide future management of this disease for zoo bird populations.

SERUM GAMMA-GLUTAMYLTRANSFERASE AS A PROGNOSTIC INDICATOR OF NEONATAL VIABILITY IN NONDOMESTIC RUMINANTS

Abstract Rapid assessment of immune status in neonatal ruminants of endangered species facilitates early intervention in cases of inadequate passive transfer of maternal immunoglobulins. Serum gamma-glutamyltransferase (GGT) was used to evaluate suspected passive transfer status in 25 North Indian muntjac (Muntiacus muntjak vaginalis), 45 Cretan goats (Capra algagrus cretica), 20 white-lipped deer (Cervus albirostris), 25 Mhorr gazelles (Gazella dama mhorr), and 31 Soemmerrings gazelles (Gazella soemmerringi soemmerringi). Serum GGT, measured within 48 hr of birth, was compared with clinical condition at 5 days of age. Neonatal Soemmerrings and Mhorr gazelles with GGT >600 U/L were likely to survive without medical intervention, whereas GGT <400 U/L was a good indicator that the gazelle neonate would need medical intervention. Neonatal muntjac with GGT >200 U/L were also likely to survive without medical intervention. Because there is no gold standard for evaluating passive transfer status in neonatal nondomestic ruminants, it is recommended to evaluate the results of more than one diagnostic test, as well as clinical condition, in considering health status and disposition of neonatal ruminants of endangered species.

Disseminated Coccidoidomycosis in a Koala (Phascolarctos cinereus)

Abstract:  A16-yr-old male koala (Phascolarctos cinereus) presented for nonspecific signs of illness and weight loss. Despite 2 mo of diagnostics and supportive care, the koalas health declined and euthanasia was elected. On histopathologic examination, lesions containing fungal organisms morphologically consistent with coccidioidomycosis were found in the lung, liver, spleen, kidney, lymph node, heart, eye, and bone marrow. Although disseminated infection was present, the koala was IgM and IgG seronegative for Coccidioides spp. 1 mo prior to euthanasia.

DETECTION OF VIRUS-LIKE PARTICLES IN THE LIVER OF BLACK AND WHITE RUFFED LEMURS WITH HEPATITIS

Two young black and white ruffed lemurs (Varecia variegata variegata) died at the San Diego Zoo (San Diego, California, USA) with extensive liver lesions suggestive of acute viral infection. Immunoassays performed to detect hepatitis B virus (HBV) markers were negative. Polymerase chain reaction (PCR) primers overlapping the HBV core gene produced an amplicon of approximately 411 base pairs (bp) from serum DNA of a HBV-positive western lowland gorilla (Gorilla gorilla gorilla) but not from serum DNA of either lemur. Cesium chloride gradient fractions of liver homogenates from both lemurs contained a peak protein fraction with a density of 1.18 g/cm3. Electron microscopic analysis of fraction contents, concentrated by ultracentrifugation, revealed numerous pleomorphic, spherical particles varying in diameter from 16–25 nm. In one of the lemurs, this peak fraction also contained a double-shelled virus-like particle 47–50 nm in diameter. The size, morphology, and density of these particles suggest they are members of the Hepadnaviridae, a group of hepatotropic DNA-genome viruses for which HBV is the prototype.

Elaeophora in the meninges of a Malayan sambar (Rusa unicolor equina)

An adult nematode was grossly identified in the meninges of a Malayan sambar (Rusa unicolor equina), with numerous microfilariae associated with encephalitis and vasculitis on histopathology. The nematode was confirmed to be Elaeophora schneideri by sequencing a portion of the 18S rRNA gene. Our report highlights the potential for aberrant migration of E. schneideri in exotic deer species and the use of advanced testing to specifically identify this metazoan parasite, avoiding misidentification of Parelaphostrongylus tenuis.