From 1981 through 1993, tick infestations and serum antibodies reactive to Ehrlichia chaffeensis, the causative agent of human ehrlichiosis, were monitored among white-tailed deer (Odocoileus virginianus) at Whitehall Experimental Forest, Clarke County, Georgia (USA). Neither ticks nor E. chaffeensis antibodies were detected during the first two years of the study. Infestations of the lone star tick (Amblyomma americanum), a suspected vector of E. chaffeensis, first were noted on deer in 1983. Prevalence and intensity of A. americanum sharply increased from 1985 to 1989, and prevalence was 100% from 1990 to 1993. Antibodies reactive to E. chaffeensis were first detected in 7% of deer sampled in 1986. Antibody prevalence increased to 21% in 1987 and was 100% from 1988 to 1993. This temporal association between the establishment of A. americanum and the appearance of E. chaffeensis antibodies provides evidence to support the concept that A. americanum could be a natural vector of E. chaffeensis. The high prevalence of antibodies among all age classes of deer also reaffirms that white-tailed deer may be sensitive natural sentinels for monitoring the distribution of E. chaffeensis.

The prevalence and intensity of Parelaphostrongylus tenuis was determined by examining the head and a fecal sample from each of 379 white-tailed deer (Odocoileus virginianus) of known age that had been killed by vehicles in northeastern Minnesota (USA), November 1991 to May 1993. Small numbers of adult worms (mean ± SD, 3.2 ± 2.2; maximum, 13) were found in the cranium of 311 (82%); but over a third (118 of 311) of the infected deer were not passing larvae in their feces. Most occult infections were sterile because only one sex of the parasite was present. Adult P. tenuis were not found in the vertebral canal of deer. Prevalence of adult worms and larvae was lower in fawns (68% and 35%, respectively) than in older age classes of deer (89% and 63%, respectively). Forty-three of 45 deer between 7 and 15 yr old were infected. Mean (±SD) intensity of adult worms was lower in fawns (2.7 ± 1.8) and yearlings (3.0 ± 2.1) than in deer 7 to 15 yr (4.1 ± 2.5). Conversely, the mean (±SD) number of larvae in feces was higher in fawns (103 ±119 larvae/g) than in adults 2 to 6 yr old (36.2 ± 46 larvae/g) and 7 to 15 yr old (35.6 ± 60 larvae/g). Mean (±SD) fecundity of female worms was greatest in fawns (51.6 ± 64.8 larvae/g of feces/female worm). Deer of all ages passed more larvae in the spring. Deer from an area where year-round density was 30 deer/km² had a mean (±SD) of 3.5 (±1.8) adult worms; deer from the study area, with a summer density 2 deer/km², had 3.2 (±2.2) worms; however, deer at the greater density passed a greater mean number of larvae (93.8 and 57.1 larvae/g, respectively). Based on our results we propose that P. tenuis is a long-lived parasite and that most deer become infected in their first or second summer of life, and acquire few additional worms thereafter.

A protocol for the adrenocorticotropic (ACTH) stimulation test in American black ducks (Anas rubripes) was established with synthetic ACTH, cosyntropin (Cortrosyn^®); ACTH stimulation testing was conducted on 31 adult ducks (14 males, 17 females) in September 1993. Plasma corticosterone concentrations were measured on heparinized blood samples collected 30 min, and 1, 2, and 4 hr post-injection. In comparison with saline controls, cosyntropin (0.25 mg/duck) produced a two- to three-fold increase in corticosterone 30 min after administration. Maximal concentrations ranged from 132 to 312 ng/ml and occurred between 1 and 2 hr post-injection. Corticosterone concentrations declined to basal, pre-injection values after 4 hr. Endogenous ACTH release in response to handling stress was evident in control ducks after saline injection but did not interfere with interpretation of the stimulation test. Recommendations for the ACTH stimulation test in black ducks include a 30 min acclimatization period for recently captured or relocated ducks and determination of plasma corticosterone concentration 1 to 2 hr following intramuscular injection with 0.25 mg cosyntropin.

We describe optimization of a peripheral blood mononuclear leukocyte proliferation assay and development of an interleukin-2 receptor (IL-2R) expression assay for bottlenose dolphins (Tursiops truncatus). Peripheral blood mononuclear leukocytes obtained from both Sea World (February 1993) and the Naval Command Control and Ocean Surveillance Center (March 1993) (San Diego, California, USA) were stimulated with the mitogens concanavalin A (ConA) and phytohemagglutinin (PHA) and evaluated for optimum proliferation and IL-2R expression. Based on these optimization assays, standard conditions were established and used to assess immune function in a population of apparently healthy, free-ranging bottlenose dolphins from Sarasota Bay, Florida (USA) in June 1993. A positive correlation was observed between proliferation assays using ConA and PHA as the stimulants. However, IL-2R expression induced by both mitogens differed significantly.

Two in vitro functional assays were developed to evaluate mitogen induced responses of peripheral blood mononuclear leukocytes (PBML) from free-ranging harbor seals, Phoca vitulina. Lymphocyte proliferation was measured by a standard blastogenesis assay following optimization of culture conditions including mitogen concentration, cell density, and incubation time. These optimized parameters, with the exception of incubation time, were subsequently employed to measure lymphocyte activation by analytical flow cytometry using fluorochrome-based identification of cell surface interleukin-2 receptor (IL-2r) expression. Baseline values established for free-ranging harbor seals had extensive animal variability; there was evidence that the samples were derived from a group of animals with a normal distribution. Positive correlations were observed between blastogenesis assays, and between blastogenesis and activation assays, when using pokeweed or concanavalin A as the stimulus. However, no relationship was found in the expression of the IL-2r induced by these mitogens. This result supports the contention that the two mitogens stimulate different lymphocyte subpopulations. This was observed only with the IL-2r expression assay because of its unique ability to measure the number of T lymphocytes initially activated rather than the ultimate number of progeny cells identified by blastogenesis. Both assays, used concurrently, should provide a more comprehensive representation of lymphocyte competence and serve as a measure of animal health.

Blood samples were collected from cottontail rabbits (Sylvilagus floridanus), raccoons (Procyon lotor), white-footed mice (Peromyscus leucopus), and white-tailed deer (Odocoileus virginianus) between 1977 and 1991 in southern Connecticut and New York State (USA) and were tested for antibodies against eight strains of Borrelia burgdorferi sensu lato in enzyme-linked immunosorbent assays. Among these spirochetes were six strains of B. burgdorferi sensu stricto, one strain of B. garinii (=IP90) and a strain (IPF) in group VS461. Sera from each study group reacted positively to all strains having origins in North America and Eurasia. Assay sensitivities normally ranged between 85% and 100% for all study groups. The lowest sensitivity (66%) was noted when mouse sera were tested with B. garinii, an isolate from Ixodes persulcatus in the former Soviet Union. Differences in serum reactivity to various strains were noted for all study groups, but because of multiple shared antigens among the closely related spirochetes tested, the selection of a particular North American strain of B. burgdorferi sensu stricto did not appear to be a critical factor for optimal assay performance. Locally obtained strains of this bacterium are preferred as coating antigens for serologic testing because of their availability.

Although Pseudomonas fluorescens was the predominant bacterium associated with Atlantic salmon (Salmo salar) eggs incubated at the White River National Fish Hatchery (Bethel, Vermont) during January 1992, the fish pathogen Cytophaga psychrophila was isolated only from specific lots of eggs that displayed poor survival (35% eye-up).

We inoculated game-farm mallard (Anas platyrhynchos) eggs and 1-day-old birds with Mycoplasma anatis to determine its effect on hatching success and growth rates of ducklings. Inoculations of eggs reduced hatching success, hatchling size, and duckling growth rates, compared to controls. Intratracheal inoculations of 1-day-old birds did not affect growth rates. Hatchlings and 1-day-old ducklings grew much slower for the first 7 to 10 days when raised at 17 to 19 C, compared to controls raised at 30 to 35 C. The effect of cold stress on growth was greater than the effect of M. anatis infection; we found no synergistic effects between cold stress and M. anatis infection.

A survey was conducted at two wildlife management areas of Pennsylvania (USA) to evaluate an antigen capture enzyme-linked immunosorbent assay (AC-ELISA) for the detection of avian influenza viruses (AIV) in cloacal swabs from waterfowl and to determine the influenza A virus subtypes and the distribution of these viruses among waterfowl. We collected 330 cloacal swabs from hunter-killed waterfowl in the fall of 1990 and from cage-captured waterfowl in the summer of 1991. Thirty-one hemagglutinating agents were isolated by chicken embryo inoculation (CEI) of which 27 were influenza A viruses and four Newcastle disease viruses (NDV). The prevalence of AIV infection was 8.2%. Compared to CEI, AC-ELISA was only 15% sensitive and 61% specific. Based on the distribution of AIV by species of waterfowl, mallards (Anas platyrhynchos) and American wigeons (Anas americana) were at equal risk of AIV infection even though most of the AIV isolates came from mallards. Although significant crude effects of sampling site and season on AIV recovery could be established, juvenile age was identified as the primary risk factor of AIV recovery. Twelve AIV subtypes were identified by hemagglutination inhibition (HI) and neuraminidase inhibition (NI) tests. The most prevalent subytpes were H4N8 and H6N8. We concluded that AC-ELISA was not useful for the detection of AIV in cloacal swabs from waterfowl and that CEI, HI, and NI tests remain as the method of choice for AIV screening in waterfowl. Based on the results AIV infected preferentially the young which represent the high risk group in waterfowl populations. The results from the AIV subtyping in our waterfowl survey are consistent with the results from numerous longitudinal studies of waterfowl in North America.

Exposure to the carbamate insecticide carbofuran was detected using brain cholinesterase (ChE) reactivation techniques in heron carcasses collected from a potential pesticide exposure incident. Great egrets (Nycticorax nycticorax), great blue herons (Ardea herodias), and black-crowned night herons (Casmerodius albus) were exposed to carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) either by dermal exposure while wading or through ingestion of contaminated food items. Carcasses may have been in the field up to 5 days prior to collection. Brain ChE, substantially inhibited in most samples, increased 7.9–208% in the reactivation assay after 4 to 96 hours at 37 C, providing evidence of exposure to a carbamate pesticide. Crayfish (Procambarus clarkii) identified in the crops of some herons contained carbofuran residues of up to 0.6 parts per million wet weight, providing additional evidence of exposure. Reactivated brain ChE in several samples approached the range of control values.

The effect of lead exposure on cellular immunity, hematology, and reproductive and body condition in mature cotton rats (Sigmodon hispidus) was examined. Two groups of 36 cotton rats each were exposed to 0, 100, or 1,000 ppm lead in drinking water for either 7 or 13 weeks, between 31 August and 2 December 1990. Specific and non-specific cell mediated immunity was assessed by measuring splenocyte proliferative responses to polyclonal mitogens (Concanavalin A and Pokeweed mitogen), in vivo 24-hr delayed type hypersensitivity, metabolic activity of peritoneal macrophages, spleen mass and cellularity, and immune organ development. General physiological condition was assessed from hematological, morphological, and reproductive measures. Immune function was sensitive to lead exposure based on depressed proliferative responses of cultured splenocytes, smaller popliteal lymph nodes, and larger spleens among cotton rats receiving 1,000 ppm lead. Spleen mass was reduced in cotton rats receiving 100 ppm lead. Total leukocytes, lymphocytes, neutrophils, eosinophils, total splenocyte yield, packed cell volume, hemoglobin, and mean corpuscular hemoglobin were sensitive to lead exposure. Effects of lead exposure on general condition and reproductive parameters included reduced mass of liver, seminal vesicles, and epididymes in males following a 7-week exposure. Histopathologic changes reflected lead toxicity and included altered renal proximal tubular epithelium, renal intranuclear inclusions, and in some cases, lowered numbers of sperm and developing follicles. In general, lesions were more pronounced with increased lead concentration and longer exposure.

Samples of serum, liver, kidney, and heart were collected for selenium analysis from 174 white-tailed deer (Odocoileus virginianus) in southern Florida (USA), 1984 to 1988, to determine the selenium status of these animals. Deer were obtained from eight sites and classified by five age-class groups. For serum and the three tissues analyzed, selenium concentrations varied significantly (P < 0.001) among sites. Differences between years (P < 0.0004) were found for heart and kidney, age-class (P < 0.004) for kidney and season (P < 0.02) for liver. Low selenium concentrations were evident, in that 75% of all serum samples analyzed contained less than the critical concentration (<0.06 ppm) by livestock standards, with 50% of serum samples less than 0.03 ppm, evidence of a severe deficiency. Likewise, tissue selenium concentrations (dry basis) were below critical livestock concentrations in 13% of the liver samples (<0.25 ppm), 36% in kidney (<3.0 ppm) and 19% in heart (<0.15 ppm). Based on serum and tissue data, selenium dietary intake was low and may have been deficient for white-tailed deer in southern Florida.

We present baseline values for 12 hematologic and 17 serum chemistry parameters collected from 22 captive lynx (Felis lynx canadensis) in December 1992, at Ronan, Montana (USA). There were no significant differences in hematologic parameters between yearlings and adults or between sexes. Lynx originally captured in the wild had significantly higher mean (±SE) counts of neutrophils (7.7 ± 0.37 × 10³ versus 7.2 ± 0.35 × 10³) and lower counts of lymphocytes (1.1 ± 0.05 × 10³ versus 1.6 ± 0.08 × 10³) compared to lynx born and raised in captivity. Yearling lynx had significantly higher values for alkaline phosphatase than adults (51.0 ± 6.0 IU/1 versus 17.5 ± 0.8 IU/1.

Hemograms were determined for 26 Cooper's (Accipiter cooperii) and 55 sharp shinned hawks (Accipiter striatus) captured during spring migration (27 March to 12 May 1987) on the south shore of Lake Ontario, New York (USA). No significant differences were noted in packed cell volume and estimated total solids between the species. However, Cooper's hawks had significantly higher total white blood cell counts and higher concentrations of heterophils, monocytes, and eosinophils. Proportionally, lymphocytes made up a smaller percentage of the differential count in the Cooper's hawk. Eosinophil concentrations and percentages of the differential count were significantly higher in the females of both species. Both species had a high prevalence of Leucocytozoon toddi and Haemoproteus spp. infection. Haemoproteus nisi and H. elani were identified in both hawks. Trypanosoma avium was identified in a single Cooper's hawk and Plasmodium circumflexum was identified in a sharp-shinned hawk. Prevalence of Leucocytozoon toddi and Haemoproteus spp. infections were significantly higher in the birds caught late in the spring as compared to those caught earlier in the spring; this was evidence for a spring recrudescence of patent parasite infections.

In January 1993 we simulated a conductive hearing loss in three Mexican bighorn sheep (Ovis canadensis mexicana) by placing bone wax or saline solution in their ear canals. Our objective was to test whether lesions of the external auditory canal caused by psoroptic mites (Psoroptes ovis) may lead to conductive hearing loss in bighorn sheep. We assessed the effects of these manipulations using the auditory brainstem response test. Placing saline solution in the external auditory canal, which loads the tympanic membrane, had a more dramatic effect on the auditory brainstem response than did bone wax. We propose that decreased hearing sensitivity or alterations in resonance characteristics of the external auditory canal, due to psoroptic scabies lesions, may make bighorn sheep more susceptible to predation.

Histologic and quantitative techniques were compared in an evaluation of the intensity of Pneumocystis carinii infection in common shrews (Sorex araneus) at Espoo, southern Finland, from September 1992 to May 1993. The histological scores were comparable to the results of the cyst count technique. The number of P. carinii cysts found in common shrews was low compared to those reported by others in clinically ill laboratory rats. The inflammatory changes detected in the lung sections had no significant relation to the presence of P. carinii infection.

Nodular lesions containing Hepatozoon sp. schizonts or merozoite gametocytes were found in the tissues of 67 (96%) of 70 wild caught martens (Martes melampus) examined in Gifu, Japan, 1991 and 1992. The heart was the most commonly parasitized organ (96%), followed by the perirenal adipose tissue (36%); the diaphragm, mesentery, tongue, omentum and perisplenic adipose tissue generally had a prevalence of 10 to 15%. In the heart, two types of nodular lesions were differentiated based on developmental stages: nodules containing schizonts and nodules consisting of an accumulation of phagocytes containing merozoites or gamonts. Under electron microscopy, mature schizonts contained membrane-bound merozoites with a single nucleus and small scattered electrondense cytoplasmic granules in the schizont nodules; the merozoites and gamonts were engulfed in a phagosome-like vacuole of phagocytes with the nucleus compressed to one side due to the parasite in the merozoite-gamont nodule.

Two isolates of encephalomyocarditis (EMC) virus (ZRC 276RA/90 and ZRC 292RA/90) were isolated from two dormice (Myoxus glis) in Tuscany, Italy. The two isolates were lethal for laboratory mice and caused a rapid cytopathic effect characterized by rounded and wrinkled cells in both baby hamster kidney cells (BHK21) and African green monkey kidney cells (Vero). We found neutralizing antibodies against EMC virus in 408 (77%) of 529 domestic pigs (Sus scrofa scrofa) and in 165 (49%) of 338 wild boars (S. scrofa ferus majori) in Tuscany.

Cytopathogenic pestiviruses were isolated from two seronegative free-ranging roe deer (Capreolus capreolus) from northern Germany (Schleswig-Holstein): an adult female and a young buck collected on 6 December 1990 and 26 July 1991, respectively. The two isolates were identified by polymerase chain reaction as pestiviruses. However, they were negative when primers specific for bovine virus diarrhea virus or classical swine fever virus were used, indicating that the two isolates might belong to a separate group of pestiviruses of wild ruminants different from BVDV.

From 1990 until 1992, 355 bloodsamples of roe deer (Capreolus capreolus) (n =123), red deer (Cervus elaphus) (n = 60), fallow eer (Darna dama) (n= 87) and other cervid pecies (n = 85) from three different habitats (n = 180) and 11 wildlife parks or zoos (n = 75) in Germany were tested for prevalence of estivirus antibodies. Seventeen samples were seropositive for bovine viral diarrhea virus (BVDV); only one animal had antibodies for Border disease virus. Microneutralization test titers ranged from 1:5 to 1:125. We found no significant difference in antibody prevalence among deer in habitats with high, intermediate and low density of cattle. There were significantly more seropositive individuals in roe deer compared to fallow deer. Significantly more seropositive individuals were found among juvenile animals than among adults. Antibody prevalence in free-ranging cervids was significantly higher compared with that of deer in enclosures. Antibody prevalence in summer was significantly higher than in winter.

Notoedric mange (Notoedres cati) was found in a neonate Florida panther (Felis concolor coryi) and presumably its mother on 22 June 1992 and 8 February 1993, respectively, in Collier County, Florida (USA). Both infestations were treated successfully with 0.2 mg/kg ivermectin. This is the first known case of notoedric mange in the endangered Florida panther.

Toxoplasmosis was diagnosed in a free-ranging wild turkey (Meleagris gallopavo) from West Virginia (USA) in June 1993. Gross findings included emaciation, splenomegaly, multifocal necrotizing hepatitis and splenitis, and crusting dermatitis on the head and neck. Histologically, multifocal necrosis with mononuclear inflammation was present in kidney, liver, spleen, heart, lungs, and pancreas. Toxoplasma gondii was confirmed in sections of liver by avidin-biotin immunohistochemical analysis. Subsequently, a retrospective serosurvey of wild turkeys for T. gondii antibodies was conducted using turkey sera collected between 1984 and 1989. An antibody prevalence of 10% was detected in 130 birds from 21 locations in the southeastern United States. While wild turkeys in the Southeast have T. gondii antibodies, this is only the second natural case of fatal toxoplasmosis reported; it appears that wild turkeys infrequently develop clinical disease when infected with T. gondii.

Ten trapped Rocky Mountain elk (Cervus elaphus nelsoni) were successfully immobilized with a combination of 500 mg Telazol® and 60 mg xylazine hydrochloride (HCl) from 9 July to 25 August 1993 in Custer State Park, South Dakota (USA). Mean (SD) dosages of 2.5 (0.6) mg/kg Telazol^® and 0.3 (0.1) mg/kg xylazine HCl, respectively, were administered, resulting in a mean (SD) induction time of 4.6 (0.8) min. Induction time varied with weight and dosage. Respiratory rate (breaths/ min) increased following injection of Telazol^® and xylazine HCl and remained elevated or continued to increase through 10 min post-injection and then declined. There were no mortalities in this study. Forty mg of yohimbine HCl was used as an antagonist in eight elk, resulting in a mean (SD) recovery time of 14.0 (9.9) min when administered intravenously (n =6), and 124.7 (9.5) min when given intramuscularly (n = 2). Recovery time varied with weight and dosage of yohimbine. Elk given 2.1 to 2.6 mg/kg Telazol^® and 0.1 to 0.3 mg/kg xylazine HCl responded to yohimbine HCl when administered intravenously.

Brain cholinesterase activity was measured to evaluate pesticide exposure in wild birds. Thermal reactivation of brain cholinesterase was used to differentiate between carbamate and organophosphorus pesticide exposure. Brain cholinesterase activity was compared with gas chromatography and mass spectrometry of stomach contents. Pesticides were identified and confirmed in 86 of 102 incidents of mortality from 29 states within the USA from 1986 through 1991. Thermal reactivation of cholinesterase activity was used to correctly predict carbamates in 22 incidents and organophosphates in 59 incidents. Agreement (P < 0.001) between predictions based on cholinesterase activities and GC/MS results was significant.

Lead poisoning was diagnosed in four spectacled eiders (Somateria fischeri) and one common eider (Somateria mollissima) found dead or moribund at the Yukon Delta National Wildlife Refuge, Alaska (USA) in 1992, 1993, and 1994. Ingested lead shot was found in the lower esophagus of one spectacled eider and in the gizzard of the common eider. Lead concentrations in the livers of the spectacled eiders were 26 to 38 ppm wet weight, and 52 ppm wet weight in the liver of the common eider. A blood sample collected from one of the spectacled eiders before it was euthanized had a lead concentration of 8.5 ppm wet weight. This is the first known report of lead poisoning in the spectacled eider, recently listed as a threatened species by the U.S. Fish and Wildlife Service.

Two solid bacteriologic media were compared for cultivating Aeromonas spp. from piscine sources: the Rimler Shotts (RS) medium and a starch-glutamate-ampicillin-penicillin-based medium (SGAP-10C) used for the recovery of Aeromonas spp. from water samples. The selective and differential capacities of the media were assessed March through October 1992 by recovery rate and phenotype of 99 isolates representing 15 genera of bacteria. Recovery frequency of Aeromonas spp. (n = 62) was similar at 97% on RS and 95% on SGAP-10C. The SGAP-10C medium proved to be more specific than RS toward Aeromonas species (P ≤ 0.005). Use of SGAP-10C at 24 C for 48 hr offers a better choice for the laboratory recovery of Aeromonas spp. from clinical fish specimens.