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 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.     

Prevalence of chronic wasting disease and bovine tuberculosis in free-ranging deer and elk in South Dakota

Heads of hunter-harvested deer and elk were collected throughout South Dakota (USA) and within established chronic wasting disease (CWD) surveillance areas from 1997-2002 to determine infection with CWD and bovine tuberculosis (TB). We used immunohistochemistry to detect CWD-infected individuals among 1,672 deer and elk sampled via geographically targeted surveillance. A total of 537 elk (Cervus elaphus nelsoni), 813 white-tailed deer (Odocoileus virginianus), and 322 mule deer (O. hemionus) was sampled for CWD. Estimated overall prevalence and associated confidence intervals (95%) in white-tailed deer was 0.001% (0-0.007%). Similarly, estimated overall prevalence in elk and mule deer was 0.0% (0-0.004%) and 0.0% (0-0.011%), respectively. A total of 401 elk, 1,638 white-tailed deer, and 207 mule deer was sampled for TB. Estimated overall prevalence of infection with TB in elk harvested in South Dakota was 0.0% (0-0.009%). Similarly, estimated overall prevalence of TB in white-tailed deer and mule deer harvested throughout South Dakota was 0.0% (0-0.002%) and 0.0% (0-0.018%), respectively.     

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.     

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.     

Sarcocystis of deer in South Dakota

The prevalence of Sarcocystis in white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus) in South Dakota was determined through microscopic examination of tongue samples. The percentage of Sarcocystis infection for both species of deer was determined for prairies east of the Missouri River, west of the Missouri River, and Black Hills of western South Dakota. Sixteen percent (N = 62) of the white-tailed deer tongues from East River, 69% (N = 42) from West River, and 74% (N = 23) from the Black Hills were infected. Prevalence for mule deer was 88% (N = 24), 78% (N = 63), and 75% (N = 12) from East River, West River, and the Black Hills, respectively. Of 50 tongue samples obtained from both species of deer during a special antlerless deer hunt in the Black Hills in 1978, 66% were infected. Coyotes (Canis latrans), dogs (Canis familiaris), red foxes (Vulpes vulpes), a gray fox (Urocyon cinereoargenteus), bobcat (Felis rufus), and raccoon (Procyon lotor) were fed muscle from white-tailed deer and mule deer naturally infected with Sarcocystis to determine their role as definitive hosts. All coyotes, dogs, and the gray fox shed sporocysts, while none were recovered from the other animals. Sporocysts shed by coyotes were counted and concentrated into an inoculum and administered to a white-tailed deer fawn, which was necropsied 85 days after inoculation. Sections of heart, tongue, esophagus, diaphragm, and skeletal muscle were found to be heavily infected with sarcocysts, while sarcocysts were not detected in a control fawn.     

Identification of dorsal-spined larvae from free-ranging wapiti (Cervus elaphus) in southwestern Manitoba, Canada

Dorsal-spined first-stage larvae recovered from feces of free-ranging wapiti (Cervus elaphus) were passaged through snails (Triodopsis multilineata) and two hand-raised white-tailed deer fawns (Odocoileus virginianus). A total of 74 adult Parelaphostrongylus tenuis were recovered from the fawns; no other protostrongylid nematodes were recovered. The study indicates that wapiti may be infected with natural infections of meningeal worm and pass larvae suitable for transmission to gastropod intermediate hosts. Wapiti from areas endemic with P. tenuis should not be translocated to areas currently free of the parasite.     

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.     

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.     

Gastropod availability and habitat utilization by wapiti and white-tailed deer sympatric on range enzootic for meningeal worm

Gastropod occurrence and the utilization of habitat by sympatric populations of wapiti (Cervus elephus) and white-tailed deer (Odocoileus virginianus) on range enzootic for meningeal worm (Parelaphostrongylus tenuis) were studied on Cookson Hills Wildlife Management Area (WMA) in eastern Oklahoma. Visual observations and fecal pellet group transect data indicated that wapiti spent the majority of their time in open fields and meadows where we recovered the least numbers of gastropods. Although deer were frequently observed in open areas, visual sightings and transect data indicated that they spent more time in forested areas where we recovered the most gastropods. Gastropods harbored low numbers of P. tenuis larvae (0.00 to 0.06 larvae/gastropod) in all habitat types with the greatest recovery from red oak white oak-hickory forests (0.34 larvae/gastropod). Our results indicate that the reason a viable wapiti herd exists on Cookson Hills WMA in a P. tenuis enzootic area is at least partially because of the habitat preference by wapiti and the reduced availability of infected gastropods in the selected areas prefered by the wapiti. We were not able to detect any free-ranging wapiti that were shedding P. tenuis larvae nor were we able to detect past or sub-clinical infections with P. tenuis in wapiti.     

Meningeal worm is a long-lived parasitic nematode in white-tailed deer

A natural infection of the meningeal worm, Parelaphostrongylus tenuis, persisted for at least 3.7 yr in a white-tailed deer (Odocoileus virginianus). The deer was 5-7 yr old and was shedding dorsal-spined nematode larvae at the time of quarantine. Larvae were extracted from all fecal samples collected up to 730 days post-quarantine (dpq) and thereafter only at 862 dpq and at necropsy (1,350 dpq). Live adults of P. tenuis, one male and one female, were recovered from the cranium at necropsy. Parelaphostrongylus tenuis infections are long lived and latent periods may be extended. Our findings reaffirm the need for reliable antemortem diagnosis to identify non-patent P. tenuis infections to prevent inadvertent introduction of infected animals to non-endemic areas.     

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.     

Mortality of Rocky Mountain elk in Michigan due to meningeal worm

Mortality from cerebrospinal parelaphostrongylosis caused by the meningeal worm (Parelaphostrongylus tenuis) has been hypothesized to limit elk (Cervus elaphus nelsoni) populations in areas where elk are conspecific with white-tailed deer (Odocoileus virginianus). Elk were reintroduced into Michigan (USA) in the early 1900s and subsequently greatly increased population size and distribution despite sympatric high-density (>or=12/km2) white-tailed deer populations. We monitored 100 radio-collared elk of all age and sex classes from 1981-94, during which time we documented 76 mortalities. Meningeal worm was a minor mortality factor for elk in Michigan and accounted for only 3% of mortalities, fewer than legal harvest (58%), illegal kills (22%), other diseases (7%), and malnutrition (4%). Across years, annual cause-specific mortality rates due to cerebrospinal parelaphostrongylosis were 0.033 (SE=0.006), 0.029 (SE=0.005), 0.000 (SE=0.000), and 0.000 (SE=0.000) for calves, 1-yr-old, 2-yr-old, and >or=3-yr-old, respectively. The overall population-level mortality rate due to cerebrospinal parelaphostrongylosis was 0.009 (SE=0.001). Thus, meningeal worm had little impact on elk in Michigan during our study despite greater than normal precipitation (favoring gastropods) and record (>or=14 km2) deer densities. Further, elk in Michigan have shown sustained population rates-of-increase of >or=18%/yr and among the highest levels of juvenile production and survival recorded for elk in North America, indicating that elk can persist in areas with meningeal worm at high levels of population productivity. It is likely that local ecologic characteristics among elk, white-tailed deer, and gastropods, and degree of exposure, age of elk, individual and population experience with meningeal worm, overall population vigor, and moisture determine the effects of meningeal worm on elk populations.     

Meningeal worm in a reintroduced elk population in Kentucky

Meningeal worm (Parelaphostrongylus tenuis) has been implicated in the failure of several elk (Cervus elaphus) restoration attempts in the eastern United States. However, limited post-release monitoring and a paucity of published literature prevents a clear understanding of this parasite's role in past failures. During winters of 1997-2001, the Kentucky Department of Fish and Wildlife Resources translocated 1,044 elk from western states to eastern Kentucky (USA) in an effort to restore a free-ranging population. We monitored 521 radio-collared elk over 4 yr to determine the impact meningeal worm had on population establishment. Thirty (23%) of 129 non-capture related mortalities were attributed to meningeal worm. Twenty-two (73%) of these meningeal worm-caused mortalities were animals < 3 yr old. If younger elk born in Kentucky suffer higher mortality rates than older translocated elk, the population growth observed during the initial years of restoration may be temporary. Additional research is necessary to determine the influence meningeal worm will have on elk population growth in Kentucky.     

Serological diagnosis of Parelaphostrongylus tenuis infection in white-tailed deer and identification of a potentially unique parasite antigen

Serological diagnosis of Parelaphostrongylus tenuis infection should offer many advantages over the currently used method of fecal analysis that relies on a patent infection. Toward this end, we investigated the presence of P. tenuis-specific antibodies in experimentally infected white-tailed deer (WTD) and of unique P. tenuis antigens that may be exploited for serodiagnosis. WTD infected with 6, 20 or 100-150 P. tenuis third-stage larvae (L3) had anti-parasite antibodies from as early as 21 days postinoculation (dpi) until the end of the experiment (147 dpi). Peak anti-P. tenuis enzyme-linked immunosorbent assay (ELISA) titers in individual animals ranged from 1:70 to 1:5,700. Serum from infected WTD reacted with 5 distinct P. tenuis L3 antigens (105, 45, 37, 32, and 19 kDa) as detected by the immunoblotting technique. Serum from caribou infected with Parelaphostrongylus andersoni or Elaphostrongylus rangiferi reacted with all antigens except the 37-kDa antigen of L3, indicating that it may be unique to P. tenuis and can serve as a serodiagnostic antigen. The 37-kDa antigen appears to be present in the adult P. tenuis but not adult E. rangiferi or E. cervi. The development of an ELISA utilizing the unique antigen of P. tenuis should lead to a reliable diagnostic assay for P. tenuis infection in WTD.     

Mortality of fallow deer (Dama dama) experimentally-infected with meningeal worm, Parelaphostrongylus tenuis.

Six fallow deer (Dama dama) fawns died after receiving 25 to 150 infective larvae of Parelaphostrongylus tenuis. Fawns given higher doses usually died sooner (6 to 23 days) than those given lower doses (54 to 67 days). Early deaths were associated with severe acute peritonitis resulting from perforation of the intestinal wall; later deaths were associated with paralysis and inability to rise. Numerous adult P. tenuis were found within neural tissues of the brain and spinal cord in the three fawns with paralysis. One white-tailed deer (Odocoileus virginianus) exposed to infective larvae from the same source survived infection without exhibiting clinical signs and began passing larvae in feces 88 days post-exposure. At the doses used in this study, meningeal worm caused fatal infections in fallow deer. Results are compared to published observations of fallow deer naturally-infected with P. tenuis.     

Experimental infection of some North American wild ruminants and domestic sheep with Mycobacterium paratuberculosis: clinical and bacteriological findings

Mycobacterium paratuberculosis originally isolated from bighorn sheep (Ovis canadensis) with spontaneous paratuberculosis was used to orally inoculate Rocky Mountain elk (Cervus elaphus nelsoni) calves, mule deer (Odocoileus hemionus) fawns, white-tailed deer (Odocoileus virginianus) fawns, bighorn X mouflon (Ovis musimon) hybrid lambs, and domestic lambs. All experimentally exposed animals became infected. During the first year of infection, hybrid and domestic sheep were able to control the infection but infection was progressive in elk and deer. Clinical paratuberculosis occurred only in mule deer.     

Prevalence of Parelaphostrongylus tenuis in white-tailed deer in northern New York.

The prevalence and distribution of "brainworm" (Parelaphostrongylus tenuis) were examined in northern New York (USA) from 1986 to 1989. Sixty nine (46%) of 151 white-tailed deer (Odocoileus virginianus) heads examined, contained adult P. tenuis. The proportion of infected individuals was not significantly different between males and females. Prevalence was significantly greater in the adult age class as compared to the juvenile age class (P less than 0.01). Deer pellet samples were examined for prevalence of P. tenuis-like larvae. Pellet samples in New York had an overall prevalence of 60%. The effects of precipitation and host density on prevalence of P. tenuis in deer was not significant.     

Survival of Pronghorns in Western South Dakota

Abstract: Survival and cause-specific mortality of pronghorns (Antilocapra americana) have been well-documented in several western states and Canadian provinces. However, no information has been collected in western South Dakota, USA, where mixed-grass prairie habitats characterize rangelands. The objectives of our study were to determine survival and cause-specific mortality of adult (>18 months) and yearling (6-18 months) pronghorns and to determine monthly and summer (Jun-Aug) survival for neonatal (<1 month of age) pronghorns in South Dakota. We radiocollared 93 adult female and 142 neonatal pronghorns on 3 areas in western South Dakota. We used bed sites from initial neonate captures to collect microhabitat information throughout Harding and Fall River counties. We measured vegetation understory and overstory height, shrub canopy, and distance to nearest concealment cover to the nearest centimeter inside 1-m² quadrats by collecting measurements at 15 random points within a 30-m radius of the bed site. We documented that coyote (Canis latrans) predation was the primary cause of mortality for neonates in western South Dakota and that microhabitat characteristics at neonate bed sites differed between northwestern and southwestern South Dakota. More intensive aerial predator control may increase neonate survival in Fall River County. Management of rangelands by state and federal employees throughout western South Dakota and Wind Cave National Park that maximizes height of overstory and understory vegetation would provide neonates with adequate concealment cover for protection from predators, thereby increasing 4-week and 12-week postcapture survival. Our study provides South Dakota game managers with region-specific, annual and seasonal survival rates that were previously only estimated, thus improving the accuracy of simulated pronghorn population model output. Hunting was the primary cause of mortality (26%) for adult females in Harding and Fall River counties, thereby confirming the continued use of annual harvest by South Dakota game managers as the primary management tool for maintaining pronghorn populations within statewide population management goals.     

Movements of white-tailed deer in riparian habitat: Implications for infectious diseases

Movements of male white-tailed deer (Odocoileus virginianus) are of great concern with respect to spread of chronic wasting disease (CWD) across landscapes because most yearlings males disperse and adult males have higher prevalence of CWD than do females and younger deer. We radiocollared and monitored 85 male white-tailed deer in the middle Missouri River Valley of eastern Nebraska and western Iowa, USA from 2004 to 2008. Average size (±SE) of fixed-kernel annual home ranges (95%) and core areas (50%) for resident deer were 449 (±32) ha and 99 (±7) ha, respectively. Resident deer exhibited a high-degree of fidelity to their home ranges. Mean overlap between consecutive annual home ranges and core areas was 81% and 74%, respectively. Average dispersal distance was 17.7 ± 4.5 km (range = 3–121 km) for 22 radio-marked and 6 ear-tagged yearlings. Mean spring dispersal distance (25 km) was 150% greater than fall (10 km). Dispersal direction from Desoto National Wildlife Refuge (DNWR) was bimodal on a northwest to southeast axis that followed the Missouri River corridor. Of 22 yearlings that dispersed, 18 (82%) established adult home ranges within the river valley. Dispersal movements of yearling males represent the greatest risk for rapid spread of diseases from infected source populations. Disease management efforts in riparian habitats should target male fawns and yearling males for removal in areas within or immediately adjacent to river corridors. © 2011 The Wildlife Society.