Parelaphostrongylus andersoni (Nematoda: Protostrongylidae) in white-tailed deer from Michigan

Dorsal-spined larvae in fecal samples from free-ranging white-tailed deer (Odocoileus virginianus) in Michigan and Pennsylvania were used as a source of larvae to infect a hand-raised white-tailed deer fawn. The fawn receive 200 third-stage larvae and passed dorsal-spined larvae in feces 66 days later. Muscleworm (Parelaphostrongylus andersoni), and meningeal worm (Parelaphostrongylus tenuis) were recovered at necropsy. Two white-tailed deer and seven wapiti (Cervus elaphus) exposed to larvae of the source from Pennsylvania harbored only P. tenuis. This is the first report of P. andersoni in the midwestern United States and extends the known range of this muscleworm in free-ranging white-tailed deer. Concurrent infections of P. andersoni and P. tenuis have not been established previously in experimentally infected fawns.     

A search for Parelaphostrongylus andersoni in white-tailed deer from Maine.

Longissimus dorsi muscles from 42 white-tailed deer (Odocoileus virginianus) from Maine (USA) were examined for the Parelaphostrongylus andersoni. No adult nematodes were found. Prevalence based on the Poisson approximation of a binomial distribution could have been between 0 and 9% (95% C.I.). However, based on prevalence documented elsewhere (10 to 18%), it is unlikely that P. andersoni occurs in white-tailed deer in central Maine.     

Distribution and ecology of meningeal worm,Parelaphostrongylus tenuis (Nematoda), in northcentral North America

Meningeal worm (Parelaphostrongylus tenuis), a common nematode parasite in white-tailed deer (Odocoileus virginianus) and pathogenic for several species of ungulates in eastern North America, is not known to occur in the west. Heads of 1,902 white-tailed deer were examined for adult meningeal worm to determine geographic distribution of the parasite in Saskatchewan and Manitoba (Canada) and North Dakota (USA). Finding the parasite in a deer in eastern Saskatchewan near the Manitoba border established the current northern and western limits in Canada. Prevalence of infection was < 1, 18.6, and 8.2% in Saskatchewan, Manitoba, and North Dakota, respectively. Infected deer occurred throughout southern Manitoba and eastern North Dakota. Distribution appears to have changed little since the last published survey for P. tenuis in the region in 1972. We examined precipitation, temperature, deer density, and forest cover as likely correlates to prevalence and distribution of P. tenuis. Deer management units used for hunting purposes were the scale of analysis in the three jurisdictions. Presence of P. tenuis was positively correlated with precipitation during frost-free periods and deer density, and it was negatively correlated with winter and spring temperatures. Landscapes with > 25 and < 75% forest cover were most likely to have infected deer. Low rainfall and low density of white-tailed deer likely influence the westernmost limit of P. tenuis.     

Meningeal worm in deer from western Nebraska

One hundred seventy-eight white-tailed deer (Odocoileus virginianus) and 275 mule deer (Odocoileus hemionus) collected from locker plants in the western 2/3 of Nebraska (USA) in November 1997 were examined for the meningeal worm (Parelaphostrongylus tenuis). Parelaphostrongylus tenuis was identified in 17 (10%) of 168 white-tailed deer and in one (<1%) of 273 mule deer. This is the first naturally occurring infection of P. tenuis recorded in a mule deer.     

Repeated low-level infection of white-tailed deer with Parelaphostrongylus andersoni

Two white-tailed deer (Odocoileus virginianus) were given 5 infective larvae of Parelaphostrongylus andersoni each weekday for 13 weeks. At 23 weeks one of these deer and a control were challenged with single doses of 200 third-stage larvae. Repeated low-level infection of P. andersoni resulted in a sustained leukocytosis with an absolute eosinophilia which declined only after administration of larvae ceased, partial failure of worms to become established in the musculature, reduced numbers and reduced viability of eggs in the lungs, and an apparent active immunity which enabled the deer to resist challenge. The results of this study suggest that wild deer become infected with P. andersoni by isolated chance encounters with infected gastropods.     

Meningeal worm in free-ranging deer in Nebraska

The meningeal worm (Parelaphostrongylus tenuis) was found in 22 (7%) of 300 white-tailed deer (Odocoileus virginianus) (257 adults, 43 fawns) examined from Nebraska (USA) during November 1996. None of 53 mule deer (Odocoileus hemionus) (47 adults and 6 fawns) examined were infected. Twenty-two white-tailed deer from 18 counties in eastern Nebraska were infected with Parelaphostrongylus tenuis. This is the first record of P. tenuis in white-tailed deer from this state.     

Distribution of meningeal worm (Parelaphostrongylus tenuis) in South Dakota

Heads of hunter-harvested deer (Odocoileus sp.) and elk (Cervus elaphus) were collected from meat processing plants throughout South Dakota (USA) from 1997 through 1999 to determine distribution of meningeal worm (Parelaphostrongylus tenuis) in eastern and western South Dakota. A total of 2,848 white-tailed deer (WTD) were examined for P. tenuis, of which 578 (20.3%) were infected with the parasite. Of 578 deer infected, 570 (98.6%) were harvested east of the Missouri River. Our results indicate that P. tenuis is widely distributed throughout eastern South Dakota and limited to the southcentral region of western South Dakota. Infected WTD were documented in 37 of 44 counties in eastern South Dakota and three of 22 counties in western South Dakota. No meningeal worms were found on the meninges or cranial surfaces of 215 mule deer ( Odocoileus hemionus) or 344 elk examined. These findings further define the distribution of the parasite throughout the state. We suggest that the Missouri River acts, in part, as a physical barrier to the westward expansion of P. tenuis to the grasslands of western South Dakota.     

Geographic distribution of the muscle-dwelling nematode Parelaphostrongylus odocoilei in North America, using molecular identification of first-stage larvae

Molecular identification of dorsal-spined larvae (DSL) from fecal samples indicates that the protostrongylid parasite Parelaphostrongylus odocoilei occupies a broader geographic range in western North America than has been previously reported. We analyzed 2,124 fecal samples at 29 locations from thinhorn sheep (Ovis dalli dalli and O. d. stonei), bighorn sheep (Ovis canadensis canadensis and O. c. californiana), mountain goats (Oreamnos americanus), woodland caribou (Rangifer tarandus caribou), mule deer (Odocoileus hemionus hemionus), and black-tailed deer (O. h. columbianus). The DSL were recovered from populations of thinhorn sheep south, but not north, of the Arctic Circle, and they were not recovered from any of the bighorn sheep populations that we examined. In total, DSL were recovered from 20 locations in the United States and Canada (Alaska, Yukon Territory, Northwest Territories, British Columbia, Alberta, and California). The DSL were identified as P. odocoilei by comparing sequences of the second internal transcribed spacer (ITS2) region of ribosomal RNA among 9 protostrongylid species validated by adult comparative morphology. The ITS2 sequences were markedly different between Parelaphostrongylus and other protostrongylid genera. Smaller fixed differences served as diagnostic markers for the 3 species of Parelaphostrongylus. The ITS2 sequences (n = 60) of P. odocoilei were strongly conserved across its broad geographic range from California to Alaska. Polymorphism at 5 nucleotide positions was consistent with multiple copies of the ITS2 within individual specimens of P. odocoilei. This work combines extensive fecal surveys, comparative morphology, and molecular diagnostic techniques to describe comprehensively the host associations and geographic distribution of a parasitic helminth.     

Parelaphostrongylus odocoilei in Columbian black-tailed deer from Oregon

Documenting the occurrence of Parelaphostrongylus odocoilei has historically relied on the morphological examination of adult worms collected from the skeletal muscle of definitive hosts, including deer. Recent advances in the knowledge of protostrongylid genetic sequences now permit larvae to be identified. Dorsal-spined larvae (DSLs) collected in 2003-2004 from the lung and feces of six Columbian black-tailed deer (Odocoileus hemionus columbianus) from Oregon were characterized genetically. The sequences from unknown DSLs were compared to those from morphologically validated adults and larvae of P. odocoilei at both the second internal transcribed spacer (ITS-2) of ribosomal DNA and the mitochondrial cytochrome oxidase II gene. We provide the first unequivocal identification of P. odocoilei in Columbian black-tailed deer from Oregon. The broader geographic distribution, prevalence, and pathology of P. odocoilei are not known in populations of Oregon deer.     

Parelaphostrongyliasis in white-tailed deer in Missouri

The heads of 137 white-tailed deer (Odocoileus virginianus) were collected on the opening day of the 1996 Missouri (USA) fire-arms deer season and surveyed for the presence of meningeal worm (Parelaphostrongylus tenuis). Eighteen percent of the deer examined were infected. Mean intensity of infection was 2.0 (range 1-7). There were no significant differences of infection or mean intensity when deer were classified and compared according to sex or age class.     

Demodicosis in a mule deer (Odocoileus hemionus hemionus) from Saskatchewan, Canada

Infestation of deer with Demodex spp. mites has been described in white-tailed deer (Odocoileus virginianus) and in Columbian black-tailed deer (Odocoileus hemionus columbianus) in North America, as well as in four species of deer in Europe. We describe Demodex sp. infestation in an adult female mule deer (Odocoileus hemionus hemionus) with skin lesions found dead near Saskatoon, Saskatchewan, Canada. This is believed to be the first report of demodicosis in mule deer.     

Efficacy of ivermectin against Parelaphostrongylus andersoni (Nematoda, Metastrongyloidea) in white-tailed deer (Odocoileus virginianus)

Ivermectin was injected subcutaneously at 200 and 400 micrograms/kg of body weight into seven white-tailed deer (Odocoileus virginianus) in an attempt to control the muscle nematode Parelaphostrongylus andersoni. Counts of first-stage larvae in feces dropped to zero at 17 to 18 days posttreatment. Larvae reappeared in feces 1.5 to 6 wk later in six deer. Four deer were treated again approximately 9 wk after the first treatment; larval counts dropped to zero in 12 to 18 days. Larvae reappeared in low numbers 45 to 55 days after the second treatment. Because deer were held indoors on cement and the prepatent period of these worms is approximately 2 mo, the reappearance of larvae was not due to reinfection by accidental ingestion of gastropod intermediate hosts. Results suggest that ivermectin at dosages of 200 or 400 micrograms/kg of body weight suppressed larval production by adult female nematodes for several weeks or destroyed first-stage larvae in the lungs.     

Differential and interacting impacts of invasive plants and white-tailed deer in eastern U.S. forests

Biological Invasions - Forests in eastern North America are experiencing high densities of white-tailed deer (Odocoileus virginianus) and encroachment by invasive plants, both of which threaten...     

An update on the distribution of Parelaphostrongylus tenuis in the southeastern United States

An update is presented on the distribution of the meningeal worm (Parelaphostrongylus tenuis) of white-tailed deer (Odocoileus virginianus) in the southeastern United States. The parasite is widely distributed and common in all or much of Arkansas, Kentucky, Louisiana, Maryland, North Carolina, Tennessee, Virginia and West Virginia. It is also common in the northern half of Alabama and Georgia. In contrast, it is rare or absent along the Atlantic and Gulf coastal plains of Alabama, Georgia, Mississippi and South Carolina. It has been collected from a single deer in Florida.     

Failure to detect infection in fallow deer (Cervus dama) exposed to Theileria cervi from white-tailed deer

A frozen stabilate was produced from Theileria cervi sporozoites in salivary glands of adult Amblyomma americanum. The stabilate was inoculated into three fallow deer (Cervus dama) and two white-tailed deer (Odocoileus virginianus). Following inoculation, the white-tailed deer developed parasitemias as determined by blood smear examination at 11 and 13 days postexposure. Repeat examination of blood from the three fallow deer for 30 days postexposure failed to reveal observable piro-plasms. These findings indicate that fallow deer are not as susceptible to the Theileria cervi found in white-tailed deer from North America. Thus, there are some questions regarding the taxonomic position of this organism.     

Establishment of adult Parelaphostrongylus tenuis, patent infections, and acquired immunity after experimental infection of white-tailed deer (Odocoileus virginianus) and red deer (Cervus elaphus elaphus)

Experimental Parelaphostrongylus tenuis infections were established in white-tailed deer (Odocoileus virginianus) and an atypical host, red deer (Cervus elaphus elaphus). Groups of deer were fed 10, 25, or 100 third-stage larvae (L3) of P. tenuis and received a single equivalent challenge exposure at varying intervals. Infections were monitored up to 6 yr in white-tailed deer and up to 2.8 yr in red deer. The prepatent period in white-tailed deer varied from 91 to 1,072 days (381 +/- 374) and in red deer from 105 to 358 days (167 +/- 77). Adult worms lived for up to 6 yr in white-tailed deer. Although most had patent infections until necropsy, latent periods were observed regardless of season. Adult worms lived for up to 2.8 yr in red deer, and patent infections persisted for 20-363 days (152 +/- 106). Patent infections were correlated with the presence of adult worms in blood vessels and sinuses of both deer species. Worms were restricted to the subdural space in all deer with latent and occult infections. Adult worm recovery in white-tailed deer fed 10 or 25 L3 corresponded to the mean intensities reported in natural infections of white-tailed deer Recovery from deer fed 100 L3 was not typical of natural infection intensities. Adult P. tenuis established in all groups of red deer, but neurologic disease was restricted to animals fed 100 L3. Acute neurologic disease was associated with subdural hemorrhage and occurred at 11 mo postinfection in 2 red deer. The absence of postchallenge patent periods and the persistence of occult infections indicated that challenge exposures did not establish. These data indicate that acquired immunity to P. tenuis was established by 6 mo postinfection in both white-tailed and red deer. Latent periods in white-tailed deer and latent infections in red deer reinforce the need for a reliable diagnostic assay.     

Seed dispersal by white-tailed deer: implications for long-distance dispersal,invasion, and migration of plants in eastern North America

For many plant species in eastern North America, short observed seed dispersal distances (ranging up to a few tens of meters) fail to explain rapid rates of invasion and migration. This discrepancy points to a substantial gap in our knowledge of the mechanisms by which seeds are dispersed long distances. We investigated the potential for white-tailed deer (Odocoileus virginianus Zimm.), the dominant large herbivore in much of eastern North America, to disperse seeds via endozoochory. This is the first comprehensive study of seed dispersal by white-tailed deer, despite a vast body of research on other aspects of their ecology. More than 70 plant species germinated from deer feces collected over a 1-year period in central New York State, USA. Viable seeds included native and alien herbs, shrubs, and trees, including several invasive introduced species, from the full range of habitat types in the local flora. A mean of >30 seeds germinated per fecal pellet group, and seeds were dispersed during all months of the year. A wide variety of presumed dispersal modes were represented (endo- and exozoochory, wind, ballistic, ant, and unassisted). The majority were species with small-seeded fruits having no obvious adaptations for dispersal, underscoring the difficulty of inferring dispersal ability from diaspore morphology. Due to their broad diet, wide-ranging movements, and relatively long gut retention times, white-tailed deer have tremendous potential for effecting long-distance seed dispersal via ingestion and defecation. We conclude that white-tailed deer represent a significant and previously unappreciated vector of seed dispersal across the North American landscape, probably contributing an important long-distance component to the seed shadows of hundreds of plant species, and providing a mechanism to help explain rapid rates of plant migration.Electronic Supplementary Material Supplementary material is available in the online version of this article at     

Intracranial abscessation in white-tailed deer of North America.

From January 1996 through April 1997, the geographic distribution, etiology, demographics, seasonality, and prevalence of an intracranial abscessation/suppurative meningoencephalitits syndrome in white-tailed deer (Odocoileus virginianus) were evaluated by surveying wildlife disease diagnostic laboratories and by examining both natural mortality and hunter-harvested deer skulls from North America. Intracranial abscesses were diagnosed as the cause of death or illness in 97 of nearly 4,500 (2.2%) white-tailed deer examined from 12 states and four Canadian provinces by the diagnostic laboratories. The bacterium Arcanobacterium pyogenes was isolated from 61% of cases; 18 other genera of bacteria also were isolated. The disease was strongly gender-biased (P < 0.01) with 87% of cases occurring in males, and the overall prevalence among males was 4.9%. Cases were most common among antlered males (> or = 1 yr) with few cases among male fawns. Among antlered males, cases were seasonal, primarily occurring from September through April. Four hundred eighteen skulls from deer found dead in the field were examined from southeastern USA, and of the 119 used for further evaluation, 9% had characteristic lesions. Skulls from hunter-harvested males in the southeastern USA had a lesion prevalence of 1.4%. The similarity of disease prevalence among male deer found dead in the field (9.0%) and deer examined as southeastern diagnostic laboratory cases (8.4%) suggests that this disease accounts for slightly < 10% of the natural mortality for yearling and adult male white-tailed deer in the southeastern region. The strong bias for occurrence among males suggests this disease may affect quality deer management strategies.     

Parasites, diseases, and health status of sympatric populations of fallow deer and white-tailed deer in Kentucky

In August 1983, a study on parasites, diseases, and health status was conducted on sympatric populations of fallow deer (Dama dama) and white-tailed deer (Odocoileus virginianus) from Land Between The Lakes, Lyon and Trigg counties, Kentucky. Five adult deer of each species were studied. White-tailed deer had antibodies to epizootic hemorrhagic disease (EHD) virus and Leptospira interogans serovariety icterohemorrhagiae, and fallow deer had antibodies to bluetongue and EHD viruses. Serologic tests for bovine virus diarrhea virus, infectious bovine rhinotracheitis virus, parainfluenza3 virus, and Brucella spp. were negative. One white-tailed deer had an infectious cutaneous fibroma, and one fallow deer had pulmonary mucormycosis. White-tailed deer harbored 16 species of parasites, all of which are considered typical of the parasite fauna of this host in the southeastern United States. Fallow deer harbored nine species of parasites, including eight species known to occur in white-tailed deer on the area and one species (Spiculopteragia assymmetrica) that is not. All fallow deer had inflammatory lesions in the spinal cord and/or brain that were attributed to prior infection with meningeal worm (Parelaphostrongylus tenuis), indicating that P. tenuis infections are not always fatal for this species. The apparent high rate of exposure of Land Between The Lakes fallow deer to P. tenuis without a resultant high rate of clinical cerebrospinal parelaphostrongylosis is hypothesized to be due to a low prevalence and intensity of P. tenuis, partial innate resistance of fallow deer, and acquired immunity.     

Comparative studies of Babesia spp. from white-tailed and sika deer

Babesia odocoilei from white-tailed deer (Odocoileus virginianus) in Texas (USA) and B. capreoli isolated from sika deer (Cervus nippon) in Ireland were compared morphologically and antigenically. Babesia odocoilei and B. capreoli paired pyriforms resembled each other closely when in sika deer, but B. odocoilei pyriforms in white-tailed deer were slightly different. Babesia odocoilei in white-tailed deer also differed from B. odocoilei and B. capreoli in sika deer in the frequency of its developmental forms. Indirect immunofluorescence antibody test titres showed that there was some antigen cross-reactivity, but not as much as between B. capreoli and the bovine parasite, B. divergens. The Babesia spp. from deer that we studied appear to be distinct but related species. The low infectivity of B. odocoilei for a splenectomised sika deer suggests that sika deer in North America are probably not very susceptible to this parasite in the wild.