White-tailed deer as hosts of cattle fever-ticks

A penned study for obtaining definitive information on the status of white-tailed deer (Odocoileus virginianus) as a host for cattle feverticks (Boophilus microplus) was conducted on St. Croix of the U.S. Virgin Islands. Four generations of fever-ticks were propagated on one deer during a six month period. Nine wild white-tailed deer also were collected from four insular estates to evaluate the carrier status of these animals on an island where cattle fever-ticks are indigenous. Two deer were infested with B. microplus where contact with domestic livestock had not occurred for 20 years; five deer were free of B. microplus where a vigorous cattle dipping program had been practiced for three years; and, two deer were infested with B. microplus where contact with fever-tick infested cattle occurred at irregular intervals. It was concluded that white-tailed deer constitute a host species for B. microplus and must be considered in future fever tick eradication endeavors. This study also suggested that, through routine dipping of cattle, fever ticks may be eradicated from an area where cattle and deer cohabit the same premises.     

Microgeographic distribution of immature Ixodes dammini ticks correlated with that of deer

In order to determine whether the small-scale distribution of immature Ixodes dammini Spielman et al. corresponds closely to the activity patterns of white-tailed deer, Odocoileus virginianus (Zimmerman), these relationships were examined in a site on Long Island, New York, U.S.A. We first determined the extent and temporal pattern of adult ticks feeding on deer by examining twenty-three resident deer tranquilized during September-December 1985. I. dammini adults infested deer throughout this fall period, most abundantly during October and November. With radio-telemetry collars attached to deer we determined the relative frequency that they occupied 0.25 ha quadrats of the study site. During the following summer, we examined white-footed mice, Peromyscus leucopus (Rafinesque), that inhabited these quadrats and removed immature ticks from each. 8975 larval and 163 nymphal I. dammini were removed from 208 mice trapped in forty-three such quadrats. The frequency of deer using these quadrats was positively correlated with both the number of larval and of nymphal ticks per mouse. These results suggest that risk of I. damminiborne zoonotic disease may be decreased by locally reducing deer density in sites that experience intense human activity.     

Attachment site selection of ticks on roe deer, <Emphasis Type="Italic">Capreolus capreolus</Emphasis>

The spatio-temporal attachment site patterns of ticks feeding on their hosts can be of significance if co-feeding transmission (i.e. from tick to tick without a systemic infection of the host) of pathogens affects the persistence of a given disease. Using tick infestation data on roe deer, we analysed preferred attachment sites and niche width of Ixodes ticks (larvae, nymphs, males, females) and investigated the degree of inter- and intrastadial aggregation. The different development stages showed rather consistent attachment site patterns and relative narrow feeding site niches. Larvae were mostly found on the head and on the front legs of roe deer, nymphs reached highest densities on the head and highest adult densities were found on the neck of roe deer. The tick stages feeding (larvae, nymphs, females) on roe deer showed high degrees of intrastadial spatial aggregation, whereas males did not. Male ticks showed large feeding site overlap with female ticks. Feeding site overlap between larval-female and larval-nymphal ticks did occur especially during the months May–August on the head and front legs of roe deer and might allow pathogen transmission via co-feeding. Tick density, niche width and niche overlap on roe deer are mainly affected by seasonality, reflecting seasonal activity and abundance patterns of ticks. Since different tick development stages occur spatially and temporally clustered on roe deer, transmission experiments of tick-borne pathogens are urgently needed.     

Effect ofDermacentor albipictus (Acari: Ixodidae) on blood composition,weight gain and hair coat of moose,Alces alces

The physiological effects of the winter tick,Dermacentor albipictus, on moose,Alces alces, were investigated. Blood composition, weight gain, food intake and change in the hair coat of moose calves, four infested withD. albipictus larvae, and eight uninfested, were monitored. Infested moose groomed extensively, apparently in response to feeding nymphal and adult ticks, and developed alopecia. Other clinical signs included: chronic weight loss, anemia, hypoalbumenemia, hypophosphatemia, and transient decreases in serum asparate transaminase and calcium during the period of nymphal and adult female tick engorgement. Infested animals did not become anorexic. Two moose with severe hair loss had increases in gamma globulin shortly after the onset of female tick engorgement. Results suggest that alopecia is associated with tick resistance. Animals that groom and develop hair loss likely carry fewer ticks and therefore suffer less severely from blood loss.     

Borrelia Burgdorferi Sensu Lato in Ixodes Ricinus Ticks and Rodents in a Recreational Park in South-Western Ireland

Ixodes ricinus ticks infected with Borrelia burgdorferi sensu lato were numerous on the edges of paths and roads in a recreational park in south-western Ireland. The abundance of ticks at different sites was related to the presence of deer, but a negative relationship was shown between tick abundance and tick infection rates. This is thought to be due to the deposition of large numbers of uninfected ticks by deer, which are apparently not good reservoir hosts of B. burgdorferi s.l. Blood meal analysis only detected deer DNA in uninfected nymphs. Reservoir competent rodents, Apodemus sylvaticus and Clethrionomys glareolus, were abundant at all sites and a high proportion of captured specimens were infested with larval ticks. However, very few rodents were infected with B. burgdorferi s.l. and none of the unfed infected nymphs analysed for the identity of their larval blood meal had fed on rodents. The spirochaetes detected in I. ricinus in the study area may be poorly adapted to rodents or are not transmitted readily because of the absence of nymphal infestation. The majority of spirochaetes in these ticks were apparently acquired from non-rodent hosts, such as birds.     

不同饲养条件下海南坡鹿幼体春季昼间行为时间分配及活动节律

2003 年2 月至4 月间, 在海南甘什岭自然保护区采用瞬时扫描取样法对10 头海南坡鹿幼体昼间行为时间分配和活动节律进行了初步研究。结果表明: 坡鹿幼体昼间行为时间分配中摄食、卧息和反刍占有较大的比例;人工圈养和半散放条件下摄食、卧息、反刍、站立和运动行为的昼间时间分配差异性显著( P < 0.01), 半散放条件下幼鹿每天用于摄食和运动的时间比人工圈养的多, 而用于卧息、反刍和站立的时间较少, 其余行为时间比较接近; 在昼间活动节律方面, 圈养条件下摄食有3 个高峰期(09:00～10:00, 11:00～12:00, 16:00～18:00) , 卧息有2 个高峰期(10:00～11:00, 13:00～16: 00) ; 半散放条件下没有明显的摄食高峰期, 主要原因是大部分时间花费在食物的搜索和处理上, 而其卧息高峰出现在14:00 以后。     

Tick infestations of white-tailed deer in Alabama.

Four species of ticks were collected from 537 white-tailed deer (Odocoileus virginianus), examined during the hunting seasons (November to January) of 1988-89 and 1989-90 at selected locations in Alabama (USA). Ixodes scapularis was the most common tick recovered (2,060 specimens) and infested 54% of the deer. Dermacentor albipictus was the second most frequent tick (1,253 specimens) and infested 15% of the deer. Amblyomma americanum was the third most frequent tick (315 specimens) and infested 24% of the deer; this was the only species of tick collected from deer at all sampling locations. Amblyomma maculatum was an infrequent parasite (five specimens) and infested only 1% of the deer; this tick species was only recorded during the 1989-90 season. Year-to-year and geographical differences in tick infestation parameters were noted. The data are compared with those reported for previous surveys of ticks infesting white-tailed deer in Alabama and adjacent states.     

Natural and experimental infection of white-tailed deer (Odocoileus virginianus) from the United States with an Ehrlichia sp. closely related to Ehrlichia ruminantium

An Ehrlichia sp. (Panola Mountain [PM] Ehrlichia sp.) closely related to Ehrlichia ruminantium was recently detected in a domestic goat experimentally infested with lone star ticks (LSTs, Amblyomma americanum) collected from Georgia, USA. The infected goat exhibited pyrexia and mild clinical pathologic abnormalities consistent with ehrlichiosis. At least two other Ehrlichia species (Ehrlichia chaffeensis and Ehrlichia ewingii) are maintained in nature by a cycle involving LSTs as the primary vector and white-tailed deer (Odocoileus virginanus) as a known or suspected reservoir. To investigate the possibility that white-tailed deer are potential hosts of the PM Ehrlichia sp., whole blood samples collected from 87 wild deer from 2000 to 2002 were screened with a species-specific nested PCR assay targeting the citrate synthase gene. In addition, two laboratory-raised white-tailed deer fawns were each infested with 120 wild-caught LST adults from Missouri, USA, and blood samples were periodically collected and tested for the PM Ehrlichia sp. Of 87 deer tested from 20 locations in the southeastern United States, three (3%) deer from Arkansas, North Carolina, and Virginia were positive for the PM Ehrlichia sp. Wild-caught ticks transmitted the PM Ehrlichia sp. to one of two deer fawns, and colony-reared nymphal LSTs acquired the organism from the deer, maintained it transstadially as they molted to adults, and transmitted the PM Ehrlichia sp. to two na?ve fawns. These findings indicate that white-tailed deer are naturally and experimentally susceptible to infection with an Ehrlichia sp. closely related to E. ruminantium and are able to serve as a source of infection to LSTs.     

Attractivity of cattle infested by Amblyomma variegatum (Acari: Ixodidae) for conspecific adult ticks from the field in Guadeloupe

Four field experiments were conducted with creole cattle in Guadeloupe to study the attractivity for adult ticks of animals previously infested with males of Amblyomma variegatum producing aggregation attachment pheromones (AAPs). In each experiment, two groups of cattle were used; the first group was infested with adult A. variegatum and the second group was kept free of ticks and pheromones by acaricidal treatment and by washing the hair and skin of previously infested sites. Both groups were then exposed to natural infestation by ticks present in the environment or by ticks bred in the laboratory and released on the pasture. The number of additional ticks infesting animals were compared between the treated and control groups. There were no significant differences between both groups in the numbers of new male ticks infesting the animals during the first days following the beginning of the experiment. Thereafter, comparison of the slopes of infestation indicated that infested cattle were no more attractive for male ticks than uninfested hosts. Uninfested cattle were spontaneously and rapidly infested by male ticks. It is concluded that carbon dioxide or another host component was a major attractant for A. variegatum males. Female ticks attached on predilection sites exclusively in the presence of AAP-producing males, i.e. 5–10 days after the attachment of the first males. Based on these results we postulate that slow-release devices impregnated with pheromones have no additional attractive effect on A. variegatum males under Caribbean conditions. However, they may be useful in inducing the attachment of females, but only in the first days preceding the arrival of pioneer AAP-producing males. © Rapid Science Ltd. 1998     

Attempted transmission of Ehrlichia chaffeensis among white-tailed deer by Amblyomma maculatum

A deer was needle-exposed intravenously to Ehrlichia chaffeensis (Rickettsiales: Ehrlichieae) in canine macrophage (DH82) cells and 7 days later was infested with laboratory-reared Amblyomma maculatum (Koch) (Acari:Ixodidae) nymphs for acquisition feeding. After molting, the adult ticks were allowed to feed on a naive deer. The organism was reisolated from the needle-exposed deer by cell culture and E. chaffeensis DNA was detected in the deer's blood by PCR. Similar isolation/recovery techniques were used for the tick-exposed deer and no evidence of infection was found. Although these findings must be considered as preliminary owing to inadequate controls, the data suggest that A. maculatum is probably not a suitable vector for E. chaffeensis.     

Experimental evaluation of birds as disseminators of the cosmopolitan tick Rhipicephalus sanguineus (Acari: Ixodidae)

Rhipicephalus sanguineus is believed to be the most widespread tick species of the world and its dissemination seems to rely on the diffusion of its main host, the dog. Empirical observations indicate that several bird species in urban areas regularly steal dog food. Such circumstances create a chance for R. sanguineus ticks to climb on birds and carry ticks to another site. In this work we evaluated experimentally the likelihood of birds (chicks) to either feed and/or carry R. sanguineus ticks from an infested site to another and to infest a host (rabbit) in the new location. Chicks were not suitable hosts for R. sanguineus ticks. Not a single adult tick engorged on chicks, yield as well as weight of engorged larvae and nymphs were very low and feeding period of these ticks was very long. However, a few larvae and, chiefly, nymphs were delivered to a new location either mechanically or after attachment and engorging total or partially on chicks. A few of these ticks fed successfully on rabbits. Further evidence on the capacity of birds to introduce R. sanguineus into non-infested dog settings should be provided by systematic examination of birds from urban areas, close to tick infested households.     

Study of the sustained speed of kill of the combination of fipronil/amitraz/(S)-methoprene and the combination of imidacloprid/permethrin against Dermacentor reticulatus, the European dog tick

The sustained speed of kill against Dermacentor reticulatus of two topical combinations, one containing fipronil/amitraz/(S)-methoprene and the other, imidacloprid/permethrin, was evaluated in dogs. Two treated groups and one untreated control group of eight adult Beagle dogs each were randomly formed based on pre-infestation rates and bodyweight. Each treatment was administered topically once on Day 0, according to the recommended label dose and instructions for use. All dogs were infested with 50 adult unfed D. reticulatus starting on Day 1, then weekly, for a total of five weeks. While most studies determine tick efficacy at 48 hours (h), in this study, all remaining ticks were counted and categorized 24 h following each infestation. The numbers of ticks (living or dead) that remained attached on treated dogs were compared to those on the control animals. The percent reduction of attached ticks (disruption of attachment) at 24 h on dogs treated with fipronil/amitraz/(S)-methoprene remained above 92% for four weeks. The reduction of attached ticks at 24 h on dogs treated with imidacloprid/permethrin did not reach 80% during the entire study. The number of ticks attached at 24 h was significantly (p<0.05) lower in the fipronil/amitraz/(S)-methoprene group than in the imidacloprid/permethrin group in assessments on Days 2, 15, 22, 29 and 36. When assessing efficacy based upon live ticks on treated versus control dogs, fipronil/amitraz/(S)-methoprene 24 h efficacy was above 95% for four weeks, decreasing to 77.8% at Day 36. The 24 h efficacy of imidacloprid/permethrin ranged from 56.2% to 86.7% through Day 29, never achieving 90% throughout the study. The 24-hour efficacy of fipronil/amitraz/(S)-methoprene was significantly (p<0.05) higher than imidacloprid/permethrin at all time points, including Day 36.     

Permethrin-impregnated bednets reduce nuisance arthropods in Gambian houses

The prevalence of bedbugs (Cimex hemipterus L.), chicken ticks (Argas persicus Oken) and headlice (Pediculus capitis De Geer) was surveyed in a rural area of The Gambia. At the beginning of the study 37.5% of children's beds were infested with bedbugs and 3.9% with chicken ticks, whilst the prevalence rate of pediculosis in children under 10 years old was 28.8%. Both bedbugs and headlice were clustered within compounds. Headlice prevalence increased with hair length and they were more common on girls than boys. Following this cross-sectional survey all bednets in the sixteen hamlets were either dipped in permethrin or a placebo. About 4 months later it was found that bedbugs and chicken ticks had disappeared from homes in which the bednets had been impregnated with permethrin. There was no reduction in hamlets with placebo-treated bednets. The rate of acquiring headlice between the two surveys was reduced by 91.1% in children who slept under insecticide-treated bednets compared with children with placebo-treated bednets. There were also significantly fewer day-flying and crawling insects, except earwigs, in homes of children who slept under insecticide-treated bednets compared with those with placebo-treated nets. These additional benefits of permethrin-treated bednets should contribute to their widespread acceptance and utilization by the community for personal protection.     

Detection of Bartonella DNA in roe deer (Capreolus capreolus) and in ticks removed from deer

The potential role of roe deer as a sylvatic reservoir of Bartonella in north-west Poland has been assessed. In addition, ticks infesting roe deer were screened to assess their role as a vector and reservoir of Bartonella. Blood and tissue samples of 72 animals from north-western Poland were PCR-screened. Bartonella DNA was detected by using primers complementary to the intergenic spacer between the 16S and 23S rRNA genes, which is used for identification of over a dozen species of this genus. Products of three different sizes were detected: 230 and 290 bp, representative of two strains of Bartonella capreoli, and 190 bp, identified as Bartonella bovis. All the three amplicons were detected in the blood, spleen and liver from the roe deer. All samples from the heart, lungs and kidneys were PCR negative. In ticks (Ixodes ricinus), only the 290 bp fragment from B. capreoli was present. Generally, Bartonella infection rate in Capreolus capreolus amounted to 27.6% of the roe deer, but it was much higher during winter (62%) than in spring (6.9%). The results show that the roe deer may be a reservoir for B. capreoli and B. bovis. The infection detected in I. ricinus ticks (7.7%) suggests that ticks may act as a Bartonella reservoir and vector.     

Feeding Tactics of Low-ranking Red Deer Stags at Supplementary Feeding Sites

We tested the hypothesis that low-ranking red deer Cervus elaphus stags adjust feeding tactics according to the spatio-temporal availability of the food. We observed free-ranging red deer at two supplementary feeding sites in the Scottish Highlands. It was predicted that at spatially clumped food, low-ranking stags would avoid high-ranking stags, 1. spatially when food is available only for a short period, but 2. temporally when the food is available continuously.
We observed several feeding tactics in low-ranking stags and the prevalence of a feeding tactic was related to the spatial distribution of the food. When food was highly clumped some low-ranking stags rushed in between feeding high-ranking stags, took a bite and retreated to process the bite (sneaking tactic). Bite rate/min did not differ between sneaking (0.29 ± 0.05) and non-sneaking low-ranking stags (0.26 ± 0.05). Compared with non-sneaking low-ranking herd members, sneaking stags took larger bites, as reflected in a significantly longer handling time (125 ± 12.4 s/bite) and thus achieved a higher intake, although still considerably less than high-ranking stags.
The temporal availability of the food did not influence feeding tactics in low-ranking stags. Low-ranking stags always avoided higher-ranking herd members spatially but did not shift their feeding bouts to times of the day when high-ranking stags were not feeding.     

An antivector vaccine protects against a lethal vector-borne pathogen

Vaccines that target blood-feeding disease vectors, such as mosquitoes and ticks, have the potential to protect against the many diseases caused by vector-borne pathogens. We tested the ability of an anti-tick vaccine derived from a tick cement protein (64TRP) of Rhipicephalus appendiculatus to protect mice against tick-borne encephalitis virus (TBEV) transmitted by infected Ixodes ricinus ticks. The vaccine has a "dual action" in immunized animals: when infested with ticks, the inflammatory and immune responses first disrupt the skin feeding site, resulting in impaired blood feeding, and then specific anti-64TRP antibodies cross-react with midgut antigenic epitopes, causing rupture of the tick midgut and death of engorged ticks. Three parameters were measured: "transmission," number of uninfected nymphal ticks that became infected when cofeeding with an infected adult female tick; "support," number of mice supporting virus transmission from the infected tick to cofeeding uninfected nymphs; and "survival," number of mice that survived infection by tick bite and subsequent challenge by intraperitoneal inoculation of a lethal dose of TBEV. We show that one dose of the 64TRP vaccine protects mice against lethal challenge by infected ticks; control animals developed a fatal viral encephalitis. The protective effect of the 64TRP vaccine was comparable to that of a single dose of a commercial TBEV vaccine, while the transmission-blocking effect of 64TRP was better than that of the antiviral vaccine in reducing the number of animals supporting virus transmission. By contrast, the commercial antitick vaccine (TickGARD) that targets only the tick's midgut showed transmission-blocking activity but was not protective. The 64TRP vaccine demonstrates the potential to control vector-borne disease by interfering with pathogen transmission, apparently by mediating a local cutaneous inflammatory immune response at the tick-feeding site.     

Lyme disease and migrating birds in the Saint Croix River Valley

During a study of migrating land birds in 1987, we examined over 9,200 individual birds representing 99 species from the Saint Croix River Valley, a Lyme disease-endemic area of east central Minnesota and northwestern Wisconsin. We found that 250 deer tick (Ixodes dammini) larvae and nymphs infested 58 birds from 15 migrant species; 56 ticks (22.4%) were positive for the Lyme disease spirochete Borrelia burgdorferi. Five ground-foraging migrant bird species favoring mesic habitats, veery (Catharus fuscescens), ovenbird (Seiurus aurocapillus), northern waterthrush (S. novaboracensis), common yellowthroat (Geothlypis trichas), and swamp sparrow (Melospiza georgiana), accounted for nearly three-quarters of parasitized individuals. Nearly half of the spirochete-positive ticks were removed from migrating birds taken in a riparian floodplain forest. Recaptured migrants with infected ticks indicate that they transmit B. burgdorferi to hexapod larvae. We suggest that birds may be both an important local reservoir in the upper Mississippi Valley and long-distance dispersal agents for B. burgdorferi-infected ticks to other regions of the continent.     

Evidence for competition between Ixodes scapularis and Dermacentor albipictus feeding concurrently on white-tailed deer

Competition among ticks, and among ectoparasites generally, has rarely been demonstrated. Ixodes scapularis and Dermacentor albipictus are both hard ticks commonly found feeding on deer harvested at Letterkenny Army Depot, in south central Pennsylvania, USA. The two species have contrasting life histories resulting in D. albipictus spending notably more time on the shared host. We hypothesized that this would give D. albipictus an advantage in locating and occupying optimal attachment sites (highly vascularized areas like the head and ears). Ticks were collected from 224 hunter-killed deer in December 2005 and November 2006 to determine if there is evidence of competition for attachment sites when these two species concurrently infest deer. A timed sample (3?min per region) of representative ticks was collected from the head (ears, face and neck regions) and body (axillae regions). Ixodes scapularis was more abundant and prevalent overall than D. albipictus. Dermacentor albipictus was found almost exclusively on the head, whereas I. scapularis was more evenly distributed, but somewhat more abundant on the body than on the head. The proportion of I. scapularis on the head was reduced at high D. albipictus abundances, but I. scapularis abundance did not alter the distribution of D. albipictus. This study supports the hypothesis of competition for preferred attachment sites between these two species of ticks, and suggests that D. albipictus may be competitively dominant over I. scapularis on the head region of concurrently infested white-tailed deer.     

Lyme disease and migrating birds in the Saint Croix River Valley.

During a study of migrating land birds in 1987, we examined over 9,200 individual birds representing 99 species from the Saint Croix River Valley, a Lyme disease-endemic area of east central Minnesota and northwestern Wisconsin. We found that 250 deer tick (Ixodes dammini) larvae and nymphs infested 58 birds from 15 migrant species; 56 ticks (22.4%) were positive for the Lyme disease spirochete Borrelia burgdorferi. Five ground-foraging migrant bird species favoring mesic habitats, veery (Catharus fuscescens), ovenbird (Seiurus aurocapillus), northern waterthrush (S. novaboracensis), common yellowthroat (Geothlypis trichas), and swamp sparrow (Melospiza georgiana), accounted for nearly three-quarters of parasitized individuals. Nearly half of the spirochete-positive ticks were removed from migrating birds taken in a riparian floodplain forest. Recaptured migrants with infected ticks indicate that they transmit B. burgdorferi to hexapod larvae. We suggest that birds may be both an important local reservoir in the upper Mississippi Valley and long-distance dispersal agents for B. burgdorferi-infected ticks to other regions of the continent.     

The effect of feeding immature Karoo paralysis ticksIxodes rubicundus (Acari: Ixodidae) on the metabolic rate of the rock elephant shrew

The effect of feeding immature Karoo paralysis ticks (Ixodes rubicundus) on the resting metabolic rate (RMR) of their principal natural host, the rock elephant shrew (Elephantulus myurus), was investigated under laboratory conditions. The elephant shrews were artificially infested with numbers of ticks simulating natural burdens. The RMR of the elephant shrews was quantified by measuring the oxygen consumption in an open through-flow system. The RMR of hosts infested only with larvae did not differ from that of the control group. Those infested with nymphs, or nymphs and larvae, had significantly lower RMR's compared to the control animals. There were no signs of paralysis in any of the infested hosts.