Leslie W. Woods

West Nile Virus in California

The spread of WNV in California is tracked.

Neospora-Like Protozoal Infections Associated with Abortion in Goats

Neospora caninum was first identified and described in 1988 from a litter of puppies with encephalomyelitis. Since this first report, naturally occurring neonatal or fetal infections caused by Neospora-like protozoa have been described in cattle, sheep, and horses. Abortion or neonatal infection in cattle by this Neospora-like protozoa have been reported throughout the United States and in several other countries. Additionally, experimental infections have been produced in cats, rats, and mice. We report on 2 unrelated cases of abortion associated with a Neospora-like protozoan in pygmy goats. The first fetus and placenta (Fetus A), from a 2-year-old doe, were submitted in November 1989 from a small farm east of Sacramento, California. The doe had an uneventful pregnancy the previous year. The owner reported that abortions had occurred in 3 other does during the previous 2 years. These fetuses had been necropsied, but the etiology in each case was undetermined. No additional history on the flock was available. The fetus was 130 days gestational age and had a 24-cm crown-rump length. It was autolyzed, with blood staining of tissues and large amounts of deep red serous fluid in the body cavities. There were no significant gross pathologic findings. The placenta was very edematous. The second fetus and placenta (Fetus B) were submitted in March 1991 from a farm in the Sacramento Valley north of Sacramento, California. There was no history on this flock. The fetus had a 14-cm crown-rump length with no body hair. It was partially mummified with a small amount of fetal fluid in the thorax. There were no significant gross pathologic findings. Bacterial cultures of placenta, lung, liver, and abomasal fluid, darkfield examination of abomasal fluid, Chlamydial and viral cultures of pooled tissues, fluorescent antibody tests of kidney and placental impression smears for Leptospira spp. and Chlamydia psittaci, respectively, were performed as previously described and were all negative for both fetuses. Fluorescent antibody tests for border disease using frozen sections of liver and lung were negative in both fetuses. The total immunoglobulin G level in fluid from Fetus A was 2,720 mg/dl and in Fetus B was > 100 mg/dl. There was no antibody to Brucella ovis (enzyme-linked immunosorbent assay), bluetongue virus (agar-gel immunodiffusion), Leptospira spp. (microagglutination test), or Toxoplasma gondii (latex agglutination at a 1:16 dilution) in either fetus. Nitrate

Systemic Neosporosis in a California Black-Tailed Deer (Odocoileus Hemionus Columbianus)

to Neospora infection develop a parasite-specific antibody response that may provide valuable information on the exposure status of the cow. At this point, however, neither fetal nor maternal serology is a satisfactory substitute for histologic examination of brain for the diagnosis of Neosporainduced abortion. Eleven cows aborted during this abortion storm. Neospora was confirmed in all 7 of the fetuses in which brain was available and suitable for examination. This report illustrates the emerging importance of this disease in areas other than the West Coast and Southwest. Because Neospora has been reported from every region of the United States, it should be included on the list of agents capable of causing abortion storms in dairy cattle irrespective of the geographic location of the herd.

Circovirus-Like Infection in a Pigeon:

4,7,10-13 These viruses are similar in that they are small (15-17 nm), icosahedral, and nonenveloped and contain single-stranded circular DNA. Each virus, however, has distinct DNA sequences and antigenicity. Psittacine beak and feather disease virus has the largest host range and has been reported in over 35 species of Old World and New World psittaciforms but has never been reported in other avian families. 4 This is the first case report of circovirus-like infection in a pigeon (Columbiformes). A young female racing pigeon was submitted for necropsy to the Davis branch of the California Veterinary Diagnostic Laboratory System in the fall 1990. The owner had 50 birds (adult and young), and mortality in the squabs was 100%. Three to 5 birds had died per week. Squabs exhibited anorexia and lethargy and died 3-4 days after clinical signs appeared. On gross examination, the pigeon was emaciated, with pectoral muscle atrophy. The mucosal wall of the intestinal tract was slightly red, and luminal contents were foamy and yellow-green. The spleen was enlarged. Air sacs were edematous, and there were caseous cores within the primary bronchi of both lungs. The right lung was consolidated and red. A defined bursa of Fabricius was not evident on gross examination of the site dorsal to the cloaca. The lung and liver were cultured aerobically on blood agar. A Pasteurella sp. was isolated from the lung. Bacteria were not isolated from the liver. Air sacs cultured on selective media for Mycoplasma sp. exhibited no growth. Chlamydia was not identified in Gimenez-stained impression smears of the liver, air sac, and spleen nor in liver, air sac, and spleen impression smears stained with fluorescence-labeled monoclonal antibody specific for Chlamydia a and examined with ultraviolet light. However, Chlamydia psittaci was isolated in a McCoy cell culture system from an organ pool of liver, air sac, and spleen. Viruses were not isolated from pooled tissue homogenates of liver, spleen, lung, brain, and intestine

A retrospective study of circovirus infection in pigeons: nine cases (1986-1993)

Circovirus infections were diagnosed in 12 pigeons from the United States, 4 pigeons from Australia, and 1 pigeon from Canada (1986-1993). Circovirus was identified by electron microscopic examination of basophilic botryoid cytoplasmic inclusions that had a histologic appearance similar to that of psittacine beak and feather disease virus inclusions. Inclusions were seen in splenic, bursal, gut-associated, and bronchus-associated lymphoid tissue macrophages and in bursal epithelial cells. Inclusions were composed of paracrystalline arrays of tightly packed, nonenveloped icosahedral virions 14-17 nm in diameter. Histologic changes in the spleens ranged from lymphofollicular hyperplasia with mild discrete lymphocellular necrosis to lymphoid depletion and diffuse histiocytosis. Lesions in the bursa of Fabricius ranged from mild lymphocellular necrosis to severe cystic bursal atrophy. Remaining histologic findings coincided with concurrent bacterial, viral, fungal, and parasitic infections. Immunoperoxidase staining and DNA in situ hybridization demonstrated that pigeon circovirus is distinct from psittacine beak and feather disease virus; however, both viruses apparently share some homologous DNA sequences. Clinical and diagnostic findings indicate that pigeon circovirus may be similar to psittacine beak and feather disease virus with respect to acquired immunodeficiency and subsequent multiple secondary infections.

Detection of Persistent West Nile Virus RNA in Experimentally and Naturally Infected Avian Hosts

To determine whether West Nile virus (WNV) persistent infection in avian hosts may potentially serve as an overwintering mechanism, House Sparrows and House Finches, experimentally and naturally infected with several strains of WNV, and two naturally infected Western Scrub-Jays were held in mosquito-proof outdoor aviaries from 2007-March 2008. Overall, 94% (n = 36) of House Sparrows, 100% (n = 14) of House Finches and 2 Western Scrub-Jays remained WNV antibody positive. When combined by species, 37% of the House Sparrows, 50% of the House Finches, and 2 Western Scrub-Jays were WNV RNA positive at necropsy, up to 36 weeks post-infection. Infectious WNV was not detected. Our study supports the hypothesis that some avian hosts support the long-term persistence of WNV RNA, but it remains unresolved whether these infections relapse to restart an avian-arthropod transmission cycle and thereby serve as an overwintering mechanism for WNV.

A model of avian mycobacteriosis: Clinical and histopathologic findings in japanese quail (Coturnix coturnix japonica) intravenously inoculated with Mycobacterium avium

Abstract Mycobacterial infections are an important cause of morbidity and mortality in birds and a considerable diagnostic challenge until the disease is advanced. In order to develop more clinically useful antemortem tests, a biological model was created that replicated naturally occurring disease. Japanese quail (Coturnix coturnix japonica; n = 8) were inoculated intravenously with Mycobacterium avium. Two additional birds served as uninoculated controls. Mean survival time of the inoculated birds was 68 ± 13 days postinoculation (PI). Seven of the eight inoculated birds died naturally. Clinical and postmortem abnormalities in inoculated birds were characteristic of naturally occurring mycobacteriosis. Abnormal clinical findings included decreased activity, feather erection, and sudden death. Mean body weight and packed cell volume declined and mean total white blood cells (primarily heterophils, bands, and monocytes) increased from 28 days PI onward. Similar to birds that are naturally infected with mycobacteriosis, the inoculated birds were thin and had severe hepatosplenomegaly on postmortem examination. All eight birds had lesions in the liver, spleen, intestine, lung, gonads, and serosa. Less commonly affected tissues included bone marrow, thymus, gizzard, heart, pancreas, and brain. Lesions were invariably severe in the liver and spleen. These gross postmortem findings were consistent with natural infections of avian mycobacteriosis. Mycobacterium avium was isolated from the liver, spleen, and intestine of all inoculated birds. Both control birds remained disease free and culture negative. This inoculation protocol is a reliable and practical means of inducing avian mycobacteriosis for further study.

Systemic granulomatous disease in a horse grazing pasture containing vetch (Vicia sp.)

A lo-year-old quarterhorse gelding was presented to theCalifornia Veterinary Diagnostic Laboratory in early Mayfor euthanasia and necropsy. Presenting clinical signs in-cluded weight loss; severe generalized dermatitis; dependentedema in the limbs, preputial sheath, and ventral abdomen;lymphadenomegaly of superficial and palpable lymph nodes;

Dynamics of West Nile Virus Persistence in House Sparrows (Passer domesticus)

West Nile Virus (WNV) is now endemic throughout North America, with annual recurrence dependent upon successful overwintering when cold temperatures drive mosquito vectors into inactivity and halt transmission. To investigate whether avian hosts may serve as an overwintering mechanism, groups of eight to ten House Sparrows were experimentally infected with a WN02 genotype of WNV and then held until necropsy at 3, 5, 7, 9, 12, 15, or 18 weeks post-infection (pi) when they were assessed for the presence of persistent infection. Blood was collected from all remaining birds every two weeks pi, and sera tested for WNV RNA and WNV neutralizing antibodies. West Nile virus RNA was present in the sera of some birds up to 7 weeks pi and all birds retained neutralizing antibodies throughout the experiment. The detection of persistently infected birds decreased with time, from 100% (n = 13) positive at 3 weeks post-infection (pi) to 12.5% (n = 8) at 18 weeks pi. Infectious virus was isolated from the spleens of birds necropsied at 3, 5, 7 and 12 weeks pi. The current study confirmed previous reports of infectious WNV persistence in avian hosts, and further characterized the temporal nature of these infections. Although these persistent infections supported the hypothesis that infected birds may serve as an overwintering mechanism, mosquito-infectious recrudescent viremias have yet to be demonstrated thereby providing proof of principle.

Novel Polyomavirus associated with Brain Tumors in Free-Ranging Raccoons, Western United States

Tumors of any type are exceedingly rare in raccoons. High-grade brain tumors, consistently located in the frontal lobes and olfactory tracts, were detected in 10 raccoons during March 2010–May 2012 in California and Oregon, suggesting an emerging, infectious origin. We have identified a candidate etiologic agent, dubbed raccoon polyomavirus, that was present in the tumor tissue of all affected animals but not in tissues from 20 unaffected animals. Southern blot hybridization and rolling circle amplification showed the episomal viral genome in the tumors. The multifunctional nuclear protein large T-antigen was detectable by immunohistochemical analyses in a subset of neoplastic cells. Raccoon polyomavirus may contribute to the development of malignant brain tumors of raccoons.