One-hundred six birds of 14 species were inoculated with approximately 10²⁷ plaqueforming units of Ockelbo virus and bled daily for 5 days to determine viremia levels. Virus was detected in birds of all 14 species tested (four Anseriformes, one Galliformes and nine Passeriformes). The onset of viremia occurred earlier and viral titers were higher in very young anseriforms and galliforms than in older birds. Adult passeriforms had Ockelbo viremias of higher titer and longer duration than did adult anseriforms. Viremia titers in adult birds of all three orders tested were sufficient to induce high transmission rates in enzootic mosquito vectors, and viremias in passeriforms could induce high transmission rates in bridging vectors as well. Passeriforms of the genera Turdus and Fringilla could serve as amplification hosts for Ockelbo virus based on the presently demonstrated viremia of high titer and long duration in these birds, and the previously demonstrated high prevalence of Ockelbo virus neutralizing antibodies in free-ranging individuals and great population size compared to birds of other taxa. Bird species of all three orders tested, however, could function as incidental hosts of the virus.

Field isolates of herpesviruses recovered from falcon, pigeon, and psittacine birds were compared by restriction endonuclease (RE) analysis using four separate enzymes. Pigeon and falcon herpesviruses had strikingly similar DNA cleavage patterns, while DNA cleavage pattern of virus isolates from a double-yellow headed Amazon and an African grey parrot had different genomic patterns to both the pigeon and falcon herpesviruses. These findings support the field observations that pigeon herpesvirus causes a fatal herpesviral infection in the livers of pigeon-eating falcons.

Signs and pathologic changes of European brown hare syndrome (EBHS) were reproduced in four hares (Lepus europaeus) after experimental inoculation of a liver suspension from hares from Belgium, which naturally died of EBHS. Virus particles were demonstrated by electron microscopy in the liver of an experimentally infected hare. They were spherical with a diameter of 28 to 30 nm. After density gradient centrifugation, virus particles were detected in the density zone of 1.34 g/ml. Based on immunoelectron microscopy with a convalescent serum, we identified the virus as the cause of EBHS. Clinical signs were not produced in three seronegative domestic rabbits after subcutaneous inoculation of the EBHS virus. Although low levels of antibodies against EBHS virus were found in the serum of these three rabbits 4 weeks after the inoculation of EBHS virus, the rabbits were not protected when challenged with viral hemorrhagic disease (VHD) virus. The different pathogenicity of the Belgian EBHS and VHD virus isolates in rabbits and the lack of protection in rabbits with circulating EBHS virus antibodies against a challenge with VHD virus indicates that both Belgian virus isolates form two different virus populations.

We compared 24 rabies samples collected in Estonia in 1989 to 1992, to identify the kinds of rabies strains circulating in this country. Eleven of the strains came from the islands of Saaremaa, Hiiumaa and Muhu, off the Baltic coast; 13 came from the mainland. The mainland strains, like those from the 1988 to 1989 epizootic in Finland, were antigenically different from the 11 island isolates. The island isolates reacted negatively with monoclonal antibody W-187.5 as does the SAD B19 rabies vaccine strain, currently spread as baits to wildlife in Finland and other parts of Europe. In order to unambiguously distinguish the island isolates from the SAD B19 vaccine, we developed a polymerase chain reaction (PCR) protocol for rabies, followed by a single restriction enzyme digestion. This method enabled the island isolates to be differentiated with ease from the vaccine strain SAD B19 at the level of the nucleoprotein-coding region. Additionally, this method had the ability to distinguish other polar field isolates examined, as well as the laboratory challenge virus strain CVS, from SAD B19 vaccine. Modifications of the above PCR method may be used for epidemiological investigations of new outbreaks or of outbreaks involving different species.

Three methods were tested for recovering Borrelia burgdorferi from live mice onto BSK II culture medium. Four laboratory-reared Peromyscus leucopus were inoculated intraperitoneally with the JD-1 isolate of Borrelia burgdorferi. Borrelia burgdorferi spirochetes were recovered from 13 of 20 (65%) samples taken by needle aspiration between days 7 and 40 post-inoculation (PI) and from 1 of 16 samples of skin obtained by ear punch biopsy during the same sampling period. Spirochetes were not recovered from culture media inoculated with mouse blood. The use of needle aspirates for recovering spirochetes was compared among three species of mice: P. leucopus, P. maniculatus, and Reithrodontomys fulvescens. Spirochetes were isolated from 14 of 15 aspiration samples from four P. maniculatus, 12 of 20 from three P. leucopus, and 15 of 20 from four R. fulvescens taken between days 7 and 48 PI. Spirochetes were isolated from only one aspiration sample between days 80 and 95 PI from any of the mice tested. Needle aspiration was an efficient method for repeated recovery of B. burgdorferi from live, experimentally infected mice. We also document R. fulvescens as an experimental host for B. burgdorferi. Based on their susceptibility to infection, all species of mice tested herein may play a role in the epidemiology of Lyme disease where their distribution is compatable with endemic transmission.

Plasma samples from 267 wild house mice (Mus domesticus) trapped at 14 sites in southeastern Australia were screened for antibody to 14 viruses normally associated with laboratory-reared rodents and to Mycoplasma pulmonis. Serologic prevalence was high for murine cytomegalovirus (99%, n = 94), murine coronavirus (95%), and murine rotavirus (74%). Samples from mice collected at all sites contained antibody to these viruses. The serologic prevalence was lower for mouse adenovirus, strain K87 (37%), parvovirus (33%), and reovirus type 3 (28%), with substantial site-to-site variation. Plasma from mice collected at 12 sites contained mouse adenovirus or reovirus antibody, and samples from mice at eight sites contained parvovirus antibody. Parvovirus-antibody positive mice were typically from high density populations or from low density populations that had recently declined from high density. Antibody to lymphocytic choriomeningitis virus (LCMV) and Sendai virus occurred at only three sites, and the serologic prevalence was very low (9.6% and 1.8%, respectively). All of the LCMV-positive mice were from northeastern New South Wales. The presence of this zoonotic virus in a mouse plague-prone region raises questions about human health risks resulting from cohabitation with large numbers of mice. It appeared that mouse populations at high density or declining from high density had higher prevalence of viral antibody than populations that had been at low or moderate density for some time. Thus, viral epizootics may occur among high-density populations and may be responsible for or precipitate declines in mouse density. These data raise the possibility of rodent viruses having potential as biological control agents.

A serologic survey for antibodies to Borrelia burgdorferi utilizing an enzyme-linked immunosorbent assay (ELISA) was conducted on white-tailed deer (Odocoileus virginianus) serum samples collected in Georgia (USA) from 1979 to 1990. Serologic results from four regions (Barrier Islands, Coastal Plain, Piedmont, and Mountain) and three age classes (0.5, 1.5, and ≥2.5 yr) were compared. Antibody prevalence, as determined by positive results at a 1:64 dilution or higher, was 36% in the Barrier Islands, 14% in the Coastal Plain, 8% in the Piedmont, and 4% in the Mountain regions. Statewide antibody prevalence was 19%. Antibody titers generally were low, and if a more conservative cutoff titer of 1:128 were used, the statewide prevalence estimate would have been reduced to 5%. Antibody prevalence as determined at this higher cutoff value, however, still remained highest in the Barrier Islands and lowest in the Mountains. Prevalence estimates were lower in the 0.5-yr age class than in the 1.5-yr or ≥2.5-yr age class (P < 0.05). A more in-depth retrospective study of the Barrier Islands region from 1971 to 1985 revealed a 50% overall antibody prevalence; positive results were found in every year represented except 1990. Based on these results, we propose that B. burgdorferi has been present in Georgia since at least 1971.

A total of 2,167 individuals representing 15 species of wading birds was examined for infection with the nematode Eustrongylides ignotus in Florida (USA). Ten of the species were infected with the greatest prevalences occurring in great blue herons (Ardea herodius) (33%), great egrets (Casmerodius albus) (22%), and snowy egrets (Egretta thula) (19%). Among nestlings, prevalences increased with age. This parasite was estimated to cause at least 80% mortality among nestling ciconiiforms at one colony in Everglades National Park, and was found in 15% of nestling ardeids throughout the state. Despite wide sampling efforts, infected fish (second intermediate hosts) were only found at six sites in Florida, all of which had been physically altered, such as with canals and ditches, and had an anthropogenic (human-caused) source of nutrient pollution. Colonies near sources of infected fish experienced significantly higher prevalences of eustrongy-lidosis than did colonies for which no source of infected fish could be found within 20 km. Higher prevalences were found at freshwater and estuarine mainland colonies than at marine colonies. Densities of aquatic oligochaetes, which may act as first intermediate hosts, were highest at sites containing infected fish and at sites with a source of nutrient pollution. Conservation and management of wading bird species should include consideration of this disease, epizootics of which seem to be linked to nutrient pollution.

Natural (n = 157) and experimental (n = 5) infections with the nematode Eustrongylides ignotus are described for ciconiforms collected in Florida (USA). Larvae perforated the ventriculus in 3 to 5 hr and caused hemorrhage and bacterial peritonitis that sometimes progressed to a fibrous peritonitis with extensive adhesions. Severity of the disease was related inversely to the age of the bird and directly to the number of parasites involved. Some infections in adult birds were resolved. As a consequence of eustrongylidosis, anorexia and behavioral abnormalities resulted in emaciation and may have predisposed birds to traumatic death. Host–parasite adaptations apparently were not adequate for nestling ciconiforms as death of nestlings usually occurred before infections become patent (longer than 14 days, less than 23 days). Patent infections were found in both color morphs of the great blue heron (Ardea herodius), and in great egrets (Casmerodius albus) and snowy egrets (Egretta thula). We propose that birds of the family Ardeidae are the primary definitive hosts.

White-tailed deer (Odocoileus virginianus) obtained from Noxubee National Wildlife Refuge, Noxubee County, Mississippi (USA) during April (n = 3), June (n = 5), September (n = 5), and November (n = 5) 1989, were necropsied for counting and identification of adult and larval stages of abomasal nematodes. Fourth-stage larvae (L4) (n ≤ 25) from each deer were randomly selected for measurement of total worm length and width. Adults of four worm species were found: Mazamastrongylus odocoilei, M. pursglovei, Ostertagia mossi, and O. dikmansi. There were no differences between months in adult male worm burdens for all species except O. dikmansi for which the April worm burden was greatest (P ≤ 0.05). Overall, the length of L4 ranged from 929 to 4,361 μm. There were no significant differences (P > 0.05) between months in the mean length (1,334 to 1,532 μm) of L4. Except for low numbers of developing fourth-stage larvae (length > 1,650 μm) in April (2.6%), June (7.4%), September (11.3%), and November (3.7%), worms were early fourth-stage larvae (EL4) or fully developed adults. Overall, the proportion of EL4 in individual deer ranged from 19 to 97%; in male (n = 3) and female (n = 15) deer the proportions of EL4 were 22.5% and 67%, respectively. The mean proportions of EL4 in female deer were 51.4% (April), 63.2% (June), 78.1% (September), and 74.7% (November), but there was no difference (P > 0.05) among the 4 months. In spite of the absence of a significant difference between months in proportions of EL4, we propose that the larger absolute numbers of EL4 in June and September was due to a seasonal arrested development that occurred among stomach worms of white-tailed deer. Further, based on the presence of higher numbers of EL4 and adults compared to developing fourth-stage larvae at all collections, we believe that arrested development is an integral part of the life cycle of these nematodes.

White-tailed deer (Odocoileus virginianus) collected in Maine (USA) from November 1988 to December 1989 were examined for Parelaphostrongylus tenuis. Relationships of deer age class, sex, collection year, and deer density to prevalence and intensity of P. tenuis infections were analyzed. Prevalence increased with deer age (P < 0.001) and interaction of deer age class and collection year (P < 0.001). Prevalence did not vary by year in deer ≥1 yr old (85%, n = 519), but was higher in fawns in 1988 (66%, n = 87) than 1989 (23%, n = 73, P < 0.001). Based on such yearly variations, prevalence in fawns during late autumn could provide an index of annual transmission of P. tenuis. Intensity of P. tenuis averaged 2.5 worms per infected fawn (SD = 2.8, n = 72) versus 3.9 (SD = 3.1, n = 375) in deer ≥1 yr old (P = 0.032). Neither prevalence (P > 0.50) nor intensity (P > 0.50) of infection was associated with deer density over a range of 1.4 to 5.8 deer per km². Heads and fecal samples from the same individuals (n = 42) provided prevalence estimates of 73% and 44%, respectively. No differences in prevalence, intensity, or geographic distribution of P. tenuis in adult deer collected in Maine during fall were evident between the late 1980’s (this study) and the late 1960’s (Gilbert, 1973). Moose (Alces alces) populations increased from the 1960’s through 1980’s in areas of Maine where >80% of adult deer carried P. tenuis, despite the risk of a lethal neurologic disease that occurs when moose become infected with the parasite.

The prevalence of Pneumocystis carinii was compared in two species of shrews, Sorex araneus and Sorex caecutiens in Finnish Lapland. The overall prevalence of P. carinii in S. araneus was 70% and in S. caecutiens was 17%. The prevalence for S. araneus is the highest reported for wild animals. The interspecific differences in prevalence were significant for all sex and age groups except for adult males. Based on multiway contingency tables (log-linear models), there was no dependence between sex or age of S. araneus and occurrence of P. carinii. In individual S. araneus the intensity of P. carinii was not related to the total number of helminths or the number of helminth species, and no dependence was observed between the presence of P. carinii and various helminth species.

Hippoboscid flies were found on 62 (17%) of 382 northern spotted owls (Strix occidentalis caurina) captured between April and September, 1986 through 1990. Two species of hippoboscids were identified: Icosta americana and Ornithomya anchineuria. Male and female adult spotted owls had similar prevalences and relative densities of hippoboscid flies. Juvenile owls had lower prevalence and relative densities than adults. There were no significant differences in mean intensity of hippoboscids on adult male, adult female and juvenile spotted owls. Relative densities of flies infesting adult owls were significantly greater during years of increased fall temperatures, decreased winter precipitation, and decreased summer temperatures.

We studied three methods (line transect, circular quadrat, complete count) for estimating density of dead birds, using models of sparrows and meadowlarks placed at a density of 50 birds of each type/ha. Line transects with a 500-m search line were used in cultivated pasture and native prairie habitats. The number of birds found by individual searchers in line transects varied markedly, particularly, in pasture habitat. More birds were found, and birds were detected at a greater distance, in prairie than in pasture. More meadowlarks than sparrows were found in both habitats but the mean estimated density of meadowlarks was greater than that of sparrows only in prairie. The number of birds found during most searches was less than that suggested for estimating density accurately and longer search lines were required. Density estimates obtained using circular plots to sample 10% of the prairie area ranged from 20 to 80 birds/ha for meadowlarks and from 10 to 60 birds/ha for sparrows in prairie habitat. A complete search by 25 volunteers spaced at 4 m intervals detected 90% of meadowlarks but only 62% of sparrows in pasture habitat. Mean (SD) time for a single search, including searchers and recorders, was 3.0 (0.8), 1.5 (0.3), and 7.5 person-hours, for line transect, circular plot and complete search, respectively.

A field study was conducted on the island of Antigua, West Indies, to evaluate baits for delivering an oral rabies vaccine to the small Indian mongoose (Herpestes auropunctatus). Tracking tiles were used to determine that mongooses were nonselective and took both egg-flavored polyurethane baits and fish-flavored polymer baits containing several different food materials. A high proportion of baits were taken the day of placement with minimal disturbance by nontarget species. DuPont Oil Blue A™ dye was an effective short-term biomarker for use in baits; based on its subsequent detection in mongooses, some of the population had consumed and not cached or discarded baits. Central point baiting stations showed promise as an alternative delivery technique.

During the 1989 caribou (Rangifer tarandus) calving season on the Arctic National Wildlife Refuge, Alaska (USA), 61 calf carcasses were examined for cause of death and associated pathology. Dead calves were located by low-level aerial searches with two fixed-wing aircraft and a helicopter over high density calving areas between the Hulahula and Aichilik rivers. Primary diagnoses included emaciation (39%), malnutrition (8%), stillbirth (21%), trauma (16%), other primary causes (7%), and undetermined causes (8%). Twenty calves had contributory renal tubular degeneration. The findings indicate that factors contributing to nutritional deprivation in calves were the major cause of neonatal mortality; however, factors affecting stillbirth, abortion, or the urogenital system may have major effects on neonatal caribou and warrant further investigation.

Serum concentrations of the enzymes creatine kinase (CK) and aspartate aminotransferase (AST) were measured in captive and wild mallards (Anas platyrhynchos) as indicators of muscle damage. Baseline values for both enzymes were determined from six captive male mallards. During winter 1990 to 1991, six diets (including controls) representative of food available in the Mississippi alluvial valley were fed to captive female mallards housed in an outdoor aviary at the White River National Wildlife Refuge, Arkansas County, Arkansas (USA). Controlled handling of penned mallards resulted in elevated serum CK x̄ = 1,352 IU/liter; SD = 1,212) and AST x̄ = 101 IU/liter; SD = 95) concentrations consistent with myopathies. These serum enzyme elevations were not affected (P > 0.3) by dietary selenium concentrations in the six diets or by energy malnutrition suffered by birds fed soybeans. Capture of wild mallards with an entanglement type rocket net resulted in serum CK and AST concentrations x̄ = 12,035 and 330 IU/liter; SD = 8,125 and 171, respectively) that were higher (P < 0.001) than those reported after capture with an enveloping type rocket net. Baseline values, controlled handling values, and entanglement rocket net values for serum CK and AST all differed (P < 0.0001).

The Bionic^® trap equipped with a 10 cm aperture bait cone and cocked to eight notches quickly killed nine of nine fishers (Martes pennanti) in simulated natural conditions. Mean (±SE) estimated times to loss of consciousness and heartbeat were ≤55 sec and 305 (±8) sec, respectively, after firing the trap. This study confirmed that the Bionic^® trap can be expected to render ≥70% of captured fishers irreversibly unconscious in ≤3 min (P < 0.05).

Mechanically improved Conibear 220™ traps failed to render irreversibly unconscious in ≤3 min fishers single-struck in the head-neck region, or double-struck in the neck and thorax regions. Although the Conibear 220™ trap is often recommended as an alternative to the steel leghold trap, it is unlikely that it has the potential to humanely kill fisher.

The Kania^® trap equipped with side wings and baited with a pine cone quickly killed nine of nine red squirrels (Tamiasciurus hudsonicus) in enclosures. Mean times to loss of consciousness and heartbeat were estimated at ≤65 sec and ≤91 sec, respectively, after firing the trap. Thus the Kania^® can be expected to render ≥70% of captured red squirrels irreversibly unconscious in ≤3 min (P < 0.05).

Canine parvovirus infected wild canids more than a decade ago, but no population effect has been documented. In wild Minnesota wolves (Canis lupus) over a 12-yr period, the annual percent population increase and proportion of pups each were inversely related to the percentage of wolves serologically positive to the disease. Although these effects did not seem to retard this large extant population, similar relationships in more isolated wolf populations might hinder recovery of this endangered and threatened species.

Edwardsiella tarda, an opportunistic bacterial pathogen, was isolated from dying largemouth bass (Micropterus salmoides) during an epizootic in a eutrophic lake system, Lochloosa Lake, Florida, USA. Approximately 1,500 adult fish died over a 6-wk period during the late summer and early fall of 1991. A mixed population of aerobic bacteria (E. tarda, Aeromonas hydrophila, and Pseudomonas sp.) was isolated from deep cutaneous ulcers and intestines of moribund bass. However, E. tarda in pure culture was the only bacterium isolated from several viscera of several fish; E. tarda may be the etiologic agent responsible for some episodes of seasonal mortality in largemouth bass.

The prevalence of Trichinella sp. in arctic foxes (Alopex lagopus) from Svalbard was studied from 1983 to 1989. Diaphragms of 697 foxes were examined for larvae; 59 foxes (8.5%) were infected. The prevalence of Trichinella sp. increased from 4% in juveniles to 36% in foxes aged more than 6 years of age. There were no significant correlations when condition and body weight each were correlated to the occurrence and number of larvae of Trichinella sp. More foxes were infected in the northern than in the central part of Svalbard. There were only minor differences in prevalence among years.

Antibodies to Encephalitozoon cuniculi were found in wild arctic foxes (Alopex lagopus), feral mink (Mustela vison), wood mice (Apodemus sylvaticus) and house mice (Mus musculus) in Iceland. Animals with antibodies were found throughout the country. No lesions attributable to encephalitozoonosis were found in adult animals necropsied. However, one arctic fox cub with a neurological disorder had pathological and serological evidence of encephalitozoonosis.

An 8-yr-old male capybara (Hydrochoerus hydrochaeris), a resident of an urban zoological collection in upstate New York (USA), had a mass posteroventral to its left stifle; it was of unknown duration. The mass was a fibrosarcoma based on invasive sheets of interwoven spindle-shaped neoplastic cells with moderate associated extracellular matrix composed of collagen fibers. Supportive immunohistochemical staining was positive for vimentin but negative for cytokeratins, desmin, and myoglobin. The animal subsequently died of unknown causes. This is the first known report of a neoplasm in a capybara.

Ingested shotgun pellets were found in 13 of 56 hunter-killed wild waterfowl between October and December 1991 from two hunting grounds in Japan. Four of 33 other waterfowl found dead in lightly hunted areas between January 1991 and March 1992 were diagnosed as having lead poisoning. We propose that lead poisoning maybe a threat to waterfowl in Japan.

Significant differences in levels of blood haptoglobin occurred between river otters (Lutra canadensis) inhabiting oiled x̄ = 361 mg/100 ml, SD = 38, n = 6) and nonoiled x̄ = 306 mg/100 ml, SD = 87, n = 8) areas of Prince William Sound, Alaska (USA) following the Exxon Valdez oil spill in 1989. Additionally, male river otters from oiled areas had significantly lower body mass (1.13 kg) than male otters from nonoiled areas. We propose oil-related causes for these differences.

A pseudohermaphrodite American bison (Bison bison) behaved like an adult male when interacting with adult females, but like an adult female when interacting with adult males. Its chromosomes were a normal 60, XX and it had a uterus; but it had bilateral testes rather than ovaries. Skull measurements were intermediate between a bull and a cow. Gonadotrophs levels were typical of overiectomized domestic cows or steers.

We observed the displacement of the first compartment of the stomach through the diaphragmatic hiatus into the thoracic cavity in an immature harbor porpoise (Phocoena phocoena). This hiatal hernia, coupled with a severe pneumonia, contributed to the emaciation and death of the animal.