Abnormal morphology of an adult Rocky Mountain wood tick, Dermacentor andersoni (Acari: Ixodidae)

During a collection of ticks from vegetation in March 2006, a single adult male Rocky Mountain wood tick, Dermacentor andersoni (Stiles, 1908), was collected that exhibited unique morphological anomalies, including the absence of a leg on the right side of the body. Coxa IV on the right side also was missing in this specimen. Such teratological changes have not been reported previously for D. andersoni.     

A serologic survey of mule deer and elk in Utah.

Sera from mule deer (Odocoileus hemionus) and elk (Cervus canadensis) in central and northern Utah were tested for the prevalence of antibodies to 11 diseases communicable to man or domestic livestock. Antibodies to Francisella tularensis (at 1:20) were found in 47 of 88 (53.4%) elk and 1 of 89 (1.1%) deer. A screening slide agglutination test for titers to Brucella (at 1:20) showed two reactors in elk but none in deer sera. No positive antibody titers were obtained in tests for anaplasmosis, Colorado tick fever, Rocky Mountain spotted fever, Q-fever, psittacosis, Powassan, western equine encephalitis, St. Louis encephalitis and California encephalitis.     

Some fungi of the cache la Poudre River,Colorado

Summary Samples of water, bottom sediment, bank soil, and upland soil from nine stations on the Cache la Poudre River, Colorado, from Poudre Lake (elevation 10,752 feet) in Rocky Mountain National Park to a point near its confluence with the South Platte River near Greeley, Colorado, on the Great Plains were examined for fungal populations. A total of 128 species of fungi were recovered on four types of bait, agar, and liquid media. While human, animal, and plant pathogenic fungi were present, species found were of wide-spread occurrence and no serious involvement was noted. If streams such as this continue to receive organic enrichment, increasing loads of potentially pathogenic fungi possibly may be found.     

Factors influencing in vitro infectivity and growth of Rickettsia peacockii (Rickettsiales: Rickettsiaceae), an endosymbiont of the Rocky Mountain wood tick, Dermacentor andersoni (Acari, Ixodidae)

Rickettsia peacockii, a spotted fever group rickettsia, is a transovarially transmitted endosymbiont of Rocky Mountain wood ticks, Dermacentor andersoni. This rickettsia, formerly known as the East Side Agent and restricted to female ticks, was detected in a chronically infected embryonic cell line, DAE100, from D. andersoni. We examined infectivity, ability to induce cytopathic effect (CPE) and host cell specificity of R. peacockii using cultured arthropod and mammalian cells. Aposymbiotic DAE100 cells were obtained using oxytetracycline or incubation at 37 degrees C. Uninfected DAE100 sublines grew faster than the parent line, indicating R. peacockii regulation of host cell growth. Nevertheless, DAE100 cellular defenses exerted partial control over R. peacockii growth. Rickettsiae existed free in the cytosol of DAE100 cells or within autophagolysosomes. Exocytosed rickettsiae accumulated in the medium and were occasionally contained within host membranes. R. peacockii multiplied in other cell lines from the hard ticks D. andersoni, Dermacentor albipictus, Ixodes scapularis, and Ixodes ricinus; the soft tick Carios capensis; and the lepidopteran Trichoplusia ni. Lines from the tick Amblyomma americanum, the mosquito Aedes albopictus, and two mammalian cell lines were non-permissive to R. peacockii. High cell densities facilitated rickettsial spread within permissive cell cultures, and an inoculum of one infected to nine uninfected cells resulted in the greatest yield of infected tick cells. Cell-free R. peacockii also were infectious for tick cells and centrifugation onto cell layers enhanced infectivity approximately 100-fold. The ability of R. peacockii to cause mild CPE suggests that its pathogenicity is not completely muted. An analysis of R. peacockii-cell interactions in comparison to pathogenic rickettsiae will provide insights into host cell colonization mechanisms.     

Spatial and Temporal Variability in the Amount and Source of Dissolved Organic Carbon: Implications for Ultraviolet Exposure in Amphibian Habitats

The amount, chemical composition, and source of dissolved organic carbon (DOC), together with in situ ultraviolet (UV-B) attenuation, were measured at 1–2 week intervals throughout the summers of 1999, 2000, and 2001 at four sites in Rocky Mountain National Park (Colorado). Eight additional sites, four in Sequoia and Kings Canyon National Park/John Muir Wilderness (California) and four in Glacier National Park (Montana), were sampled during the summer of 2000. Attenuation of UV-B was significantly related to DOC concentrations over the three years in Rocky Mountain (R² = 0.39, F = 25.71, P < 0.0001) and across all parks in 2000 (R² = 0.44, F = 38.25, P < 0.0001). The relatively low R² values, however, reflect significant temporal and spatial variability in the specific attenuation per unit DOC. Fluorescence analysis of the fulvic acid DOC fraction (roughly 600–2,000 Daltons) indicated that the source of DOC significantly affected the attenuation of UV-B. Sites in Sequoia–Kings Canyon were characterized by DOC derived primarily from algal sources and showed much deeper UV-B penetration, whereas sites in Glacier and Rocky Mountain contained a mix of algal and terrestrial DOC-dominated sites, with more terrestrially dominated sites characterized by greater UV-B attenuation per unit DOC. In general, site characteristics that promoted the accumulation of terrestrially derived DOC showed greater attenuation of UV-B per unit DOC; however, catchment vegetation and soil characteristics, precipitation, and local hydrology interacted to make it difficult to predict potential exposure from DOC concentrations.     

Characterization of an endosymbiont infecting wood ticks, Dermacentor andersoni, as a member of the genus Francisella.

A microorganism (Dermacantor andersoni symbiont [DAS]) infecting Rocky Mountain wood ticks (D. andersoni) collected in the Bitterroot Mountains of western Montana was characterized as an endosymbiont belonging to the genus Francisella. Previously described as Wolbachia like, the organism's DNA was amplified from both naturally infected tick ovarial tissues and Vero cell cultures by PCR assay with primer sets derived from eubacterial 16S ribosomal DNA (rDNA) and Francisella membrane protein genes. The 16S rDNA gene sequence of the DAS was most similar (95.4%) to that of Francisella tularensis subsp. tularensis. Through a combination of Giménez staining, PCR assay, and restriction fragment length polymorphism analysis, 102 of 108 female ticks collected from 1992 to 1996 were infected. Transovarial transmission to female progeny was 95.6%, but we found no evidence of horizontal transmission.     

Detection of PrPCWD in feces from naturally exposed Rocky Mountain elk (Cervus elaphus nelsoni) using protein misfolding cyclic amplification

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy affecting captive and free-ranging cervids. Currently, tests for CWD in live animals involve relatively invasive procedures to collect lymphoid tissue biopsies and examine them for CWD-associated, protease-resistant cervid prion protein (PrP(CWD)) detected by immunohistochemistry (IHC). We adapted an ultrasensitive prion detection system, protein misfolding cyclic amplification (PMCA), to detect PrP(CWD) in Rocky Mountain elk (Cervus elaphus nelsoni) feces. Our PMCA reproducibly detected a 1.2 × 10(7) dilution of PrP(CWD) (a 10% infected brain homogenate diluted 1.2 × 10(6)-fold into 10% fecal homogenates), equivalent to approximately 100 pg of PrP(CWD)/g of feces. We developed a semiquantitative scoring system based on the first PMCA round at which PrP(CWD) was detected and fit a nonlinear regression curve to our serial dilutions to correlate PMCA scores with known PrP(CWD) concentrations. We used this PMCA scoring system to detect PrP(CWD) and estimate its concentration in feces from free-ranging elk from Rocky Mountain National Park, Colorado. We compared our results to PrP(CWD) IHC of rectoanal mucosa-associated lymphoid tissue and obex from the same animals. The PMCA successfully detected PrP(CWD) in feces from elk that were positive by IHC, with estimated prion loads from 100 to 5,000 pg PrP(CWD)/g of feces. These data show for the first time PrP(CWD) in feces from naturally exposed free-ranging elk and demonstrate the potential of PMCA as a new, noninvasive CWD diagnostic tool to complement IHC.     

Seasonal activity and spatial distribution of host-seeking adults of the tick Dermacentor variabilis

The seasonal temporal and spatial distribution and emergence of overwintering and summer cohorts of host-seeking American dog tick, Dermacentor variabilis (Say) (Acari: Ixodidae), adults were examined for 5 years in the Bluegrass region of Kentucky. Weekly drag cloth sampling was conducted from early March until late September 1992-1995 and early March until the end of May 1996. Overwintering adult cohorts became active in early to mid-April followed by bimodal host-seeking activity each year, with the duration and intensity of the first activity period being related to the previous year's summer cohort activity. The first activity peak extended from mid-April through late May and the second activity peak occurred in July. All host-seeking activity ceased by early August, except in 1995, when activity ended on 22 August. Laboratory survival of adults, collected weekly during 1993-1996, was used to estimate the emergence of summer adult cohorts. Summer adult cohorts became active in late May or early June and overlapped with overwintering adult host-seeking activity. The termination of host-seeking activity in overwintering adults could not be determined using the methods employed in this study and is most likely to have continued for the entire season. Host-seeking adults displayed contagious distribution patterns along trails bordering ecotone habitats, as determined by fitting a negative binomial frequency distribution to weekly sampling data. These patterns did not vary from year to year. In addition, the location of D. variabilis activity did not change from year to year, which suggests that microhabitats within apparently homogeneous environments enhance adult survival and lead to 'hot spots' of tick activity despite the ability of vertebrate hosts to disperse D. variabilis populations more widely. These data better define our understanding of D. variabilis adult seasonal and spatial host-seeking activity, estimate for the first time the intensity of summer cohort host-seeking activity, and relate summer cohort activity with spring activity the following year.     

Association of different genetic types of Francisella-like organisms with the rocky mountain wood tick (Dermacentor andersoni) and the American dog tick (Dermacentor variabilis) in localities near their northern distributional limits

Dermacentor andersoni and Dermacentor variabilis from allopatric and sympatric populations near their northern distributional limits were examined for the presence of Francisella species using molecular techniques that targeted 373 bp of the 16S rRNA gene. Although there was no evidence for the presence of Francisella tularensis in any tick, Francisella-like endosymbionts (FLEs) were common in D. andersoni and D. variabilis adults and immatures. A significantly greater proportion of female ticks contained FLEs compared to male ticks. In addition, significantly more D. variabilis adult individuals contained multiple FLE sequence types than did D. andersoni adults. Ten different types of FLEs were identified based on the sequence data, which has implications for diagnostic tests and epidemiological studies of F. tularensis in tick populations in Canada. The three most prevalent types of FLEs have been detected previously in D. andersoni or D. variabilis from other parts of their distributional ranges, whereas the other seven FLE types have not been reported previously. A comparison of the FLEs from both allopatric and sympatric populations of these two tick species provided insight into the relative host-specificity and the modes of transmission of these tick-borne bacteria. In general, each FLE type was specific for one tick species, suggesting vertical transmission of each bacterium. However, there were a few instances of potential cross-transfer of two FLE types to the other tick species at locations where D. andersoni and D. variabilis occurred in sympatry, suggesting that there may be occasional horizontal transmission of some FLEs.     

Dot-ELISA assessment of guinea pig antibody responses to repeated Dermacentor andersoni infestations

Acquired resistance to ixodid tick infestation is expressed by cattle and laboratory animals. Humoral factors appear to be involved in host acquired resistance to tick bite; however, specific immune responses have yet to be fully characterized. This study examined tick resistance expressed by Hartley guinea pigs upon repeated infestation with Dermacentor andersoni, and describes longitudinal development of antigen specific immunoglobulin over approximately 180 days. Guinea pigs were infested either 4 times with D. andersoni adults, or twice with nymphs. Both infestation groups, adults and nymphs, demonstrated a significant level of resistance to re-infestation, following initial exposure. Dot enzyme-linked immunosorbent assay (Dot-ELISA) was employed to detect antibody reactive with D. andersoni salivary gland antigens (SGA). Animals infested with adults had antibody that increased at a relatively constant rate until the fourth infestation, which was differentiated by a sharp increase in titer, that was maintained for approximately 2 wk. Guinea pigs that received nymph infestations had SGA-specific antibody; however, titers were lower than those in the adult infestation group. Antibody levels continued to increase approximately 80 days beyond the final (second) infestation for this group. A direct correlation between resistance and antibody titer was not evident, since resistance was relatively stable after the second infestation in both infestation groups, and tick-specific immunoglobulin levels continually increased.     

Prevalence of Dictyocaulus viviparus infection in Rocky Mountain elk in Teton County, Wyoming.

Dictyocaulus viviparus infections in Rocky Mountain elk (Cervus canadensis of Teton Countywere surveyed by fecal analyses during spring, summer and winter and by fecal analyses and necropsies during fall hunting seasons, 1968-1973. Prevalance of the lungworms was relatively high: 32-70% during the spring; slightly lower, 30-47%, during the summer; 21-39% in the fall; and declined to the annual low of 8-19% during the winter. Conversely, elk summering on Big Game Ridge showed an increase in prevalance of D. viviparus from 1969 to 1973. Decreases in prevalance of lungworms were noted on the National Elk Refuge at Jackson after management changes were effected in 1971.     

Isolation of a spotted fever group Rickettsia, Rickettsia peacockii, in a Rocky Mountain wood tick, Dermacentor andersoni, cell line

An embryonic cell line (DAE100) of the Rocky Mountain wood tick, Dermacentor andersoni, was observed by microscopy to be chronically infected with a rickettsialike organism. The organism was identified as a spotted fever group (SFG) rickettsia by PCR amplification and sequencing of portions of the 16S rRNA, citrate synthase, Rickettsia genus-specific 17-kDa antigen, and SFG-specific 190-kDa outer membrane protein A (rOmpA) genes. Sequence analysis of a partial rompA gene PCR fragment and indirect fluorescent antibody data for rOmpA and rOmpB indicated that this rickettsia was a strain (DaE100R) of Rickettsia peacockii, an SFG species presumed to be avirulent for both ticks and mammals. R. peacockii was successfully maintained in a continuous culture of DAE100 cells without apparent adverse effects on the host cells. Establishing cell lines from embryonic tissues of ticks offers an alternative technique for isolation of rickettsiae that are transovarially transmitted.     

Genetic structure of California's elk: a legacy of extirpations,reintroductions, population expansions,and admixture

California, USA, is home to 3 subspecies of North American elk (Cervus canadensis): Roosevelt (C. c. roosevelti), Rocky Mountain (C. c. nelsoni), and tule (C. c. nannodes). Effective management requires a baseline understanding of each subspecies' range, admixture zones, and geographic patterns of genetic diversity. To address these questions, we genotyped 1,271 individual elk from California (n = 1,204) and reference populations of Rocky Mountain and Roosevelt elk from Nevada (n = 32) and Oregon (n = 35), USA. Using 19 polymorphic microsatellite loci, we detected admixture between Roosevelt and Rocky Mountain elk at a contact zone in northern California, and between Roosevelt and tule elk in north-coastal California and central-coastal California. We identified a genetically distinct population of Roosevelt elk in northwestern California, likely reflecting the remnant population that survived a large demographic decline from overhunting during the 1800s. Tule elk exhibited lower levels of heterozygosity (0.44 ± 0.03 [SD]) and allelic richness (2.9 ± 0.2) than Rocky Mountain (0.58 ± 0.05, 4.9 ± 0.4, respectively) and Roosevelt (0.50 ± 0.06, 4.4 ± 0.6, respectively) elk. Among tule elk populations, heterozygosity varied, with the lowest heterozygosity (0.23 ± 0.05) corresponding to the oldest enclosed herd used over the past century as a source of translocations. Among tule elk populations, genetic structure revealed several cases of successful and unsuccessful reintroduction or augmentation attempts. Results provide an essential baseline for future monitoring and decisions about harvest management, translocations to preserve genetic diversity, and landscape-level conservation planning to maintain, enhance, or obstruct connectivity of elk populations. Genome-wide sequencing and analyses are needed to quantify inbreeding absolutely and assess genetic load and the age of admixture where subspecies currently exchange genes.     

An enigmatic heteronemertean from the Gulf of Mexico

The effects of acid (HNO3) on drift and survival of benthic invertebrate communities were assessed in stream microcosms over a 7-day exposure period. Communities were obtained from the Cache la Poudre River, Colorado, using artificial substrates colonized in the stream for 30 days and then transferred to stream microcosms. Streams receiving the highest acid concentration (pH 4.0) contained significantly fewer individuals ( F = 378.42, p < 0.0001) and taxa ( F = 7.8, p = 0.0123) at the end of the experiment compared to the other two treatments (pH 5.5, 6.5) and the control (pH 7.4). Reduced macroinvertebrate abundance resulted primarily from reduced abundance of mayflies (Ephemeroptera) which were particularly sensitive. Comparisons of Plecoptera, Trichoptera, and Diptera abundances showed no statistically significant differences among treatments. Analysis of invertebrate drift samples, collected after 2, 6, 18, and 42 h exposure, revealed that percent drift in the most acidic streams was nine times that of control streams. Ephemeroptera was the only aquatic insect order to exhibit a significant drift response, and timing and magnitude of responses varied among mayfly taxa. Differences in sensitivity to acid among aquatic insect orders observed in our experimental streams were similar to those reported from field studies in other regions. Effects of acid on drift and survival of benthic invertebrate communities were also similar to effects of heavy metals, one of the primary water quality concerns in the Rocky Mountain region. These results suggest a general pattern of responses to chemical stressors in benthic communities from Rocky Mountain streams. This revised version was published online in July 2006 with corrections to the Cover Date.     

Typhus-like Fevers of Unknown Ætiology,with Special Reference to the Malay States

Typhus exanthematicus, Rocky Mountain fever, and the tsutsugamushi disease have been classified in the "typhus group" by Megaw, as louse-typhus, tick-typhus, and mite-typhus. He has added a fourth-class, comprising typhus-like fevers, with unknown vectors. It is the diseases of this class with which this paper is concerned.Endemic typhus (Brill's disease) is very closely related to typhus fever; the Weil-Felix reaction is positive, typhus-like vascular lesions are present, and there is cross-immunity with typhus. In the exanthematic fever of Marseilles the relationship is more superficial; there is neither cross-immunity nor vascular lesion, and the Weil-Felix reaction is negative. Some, e.g., the scrub-typhus of Malaya (vector probably a mite), are more nearly related to tsutsugamushi than to typhus; others, e.g., Indian "tick-typhus" (vector probably a tick), to Rocky Mountain fever.All are non-contagious, non-epidemic, warm-weather diseases. They are unassociated with dirt, squalor, or lice, and are restricted to definite foci. Probably rodents or other animals are the reservoirs of the virus. On the question of identity with typhus, health authorities decide that notification is unnecessary; typhus introduced into America spreads, Brill's disease does not.These typhus-like diseases are not the same in all the countries where they occur. There are two main groups: (1) an urban group, more closely related to typhus, in which the Weil-Felix reaction is positive; (2) a rural group, more closely related to tsutsugamushi and Rocky Mountain fever, in which the Weil-Felix reaction is negative. There is a special non-indologenic strain of B. proteus, which is agglutinated in some of the fevers belonging to the second group.TROPICAL TYPHUS IN THE MALAY STATES: (1) urban form, or "shop-typhus," resembling Brill's disease; (2) rural form or "scrub-typhus." Peculiar association with oil-palms and coarse grass.     

Elk grazing and vegetation responses following a late season fire in Yellowstone National Park

We studied responses of aboveground production, grazing by elk and the availability of eight elements (Ca, Fe, K, Mg, N, Na, P, Zn) in a Yellowstone National Park sagebrush grassland following a fire in 1992. We compared four areas of differing fire history: (1) an area burned in 1992, (2) an area burned in 1992 and 1988, (3) an area burned in 1988 and (4) an area with no recent fire history. The year after burning, graminoids produced more aboveground biomass on burned areas compared with unburned areas. Forages growing on burned soils were highly concentrated with all nutrients, except Ca, when elk grazed the site. Despite nutrient-rich forage on burned areas, elk consumed little forage in these areas. We hypothesized that elk ate less than expected in burned areas because of a large bloom of lupine (Lupinus sericeus), which may be unpalatable to elk.     

Brucellosis in captive Rocky Mountain bighorn sheep (Ovis canadensis) caused by Brucella abortus biovar 4

Nine (four female, five male) captive adult Rocky Mountain bighorn sheep (Ovis canadensis) contracted brucellosis caused by Brucella abortus biovar 4 as a result of natural exposure to an aborted elk (Cervus elaphus) fetus. Clinical signs of infection were orchitis and epididymitis in males and lymphadenitis and placentitis with abortion in females. Gross pathologic findings included enlargement of the testes or epididymides, or both, and yellow caseous abscesses and pyogranulomas of the same. Brucella abortus biovar 4 was cultured in all bighorn sheep from a variety of tissues, including testes/epididymides, mammary gland, and lymph nodes. All bighorn sheep tested were positive on a variety of standard Brucella serologic tests. This is the first report of brucellosis caused by B. abortus in Rocky Mountain bighorn sheep. It also provides evidence that bighorn sheep develop many of the manifestations ascribed to this disease and that infection can occur from natural exposure to an aborted fetus from another species. Wildlife managers responsible for bighorn sheep populations sympatric with Brucella-infected elk or bison (Bison bison) should be cognizant of the possibility of this disease in bighorn sheep.