Vegetation structure influences the burden of immature Ixodes dammini on its main host, Peromyscus leucopus.

To determine whether the relative abundance of immature Ixodes dammini (the vector of Lyme disease and human babesiosis) is related to habitat structure, we examined tick burdens on their main host, the white-footed mouse (Peromyscus leucopus), in 4 structurally diverse sites on Great Island, Massachusetts, USA. Vegetation structure at each site was quantified with respect to 25 habitat variables. Principal components analysis was used to reduce this set of habitat variables to seven new and orthogonal variables. Immature tick abundance varied widely among grids. Regression analysis of tick burdens on the habitat principal components showed that larval burdens were related strongly to the density of woody vegetation and negatively to herbaceous vegetation. Nymphal burdens were related negatively to herbaceous vegetation, but the relationship was not as strong as in the case of larvae. An experimental reduction in the abundance of white-tailed deer (Odocoileus virginianus), the main host of adult ticks, substantially reduced tick burdens and altered their relationships to habitat structure. Nymphal burdens were unrelated to habitat structure following deer removal. Manipulating habitat structure may have utility as a control strategy against this important vector.

Clustering of host-seeking nymphal deer ticks (Ixodes dammini) infected by Lyme disease spirochetes (Borrelia burgdorferi).

In areas where the agent of Lyme disease is intensely enzootic, the mouse reservoirs may be universally infected. Because a large proportion of the vector tick population appears to feed upon these hosts, the prevalence of infection in the vectors should approach 100%. However, infection in host-seeking nymphal ticks in nature rarely exceeds 40%. To help reconcile this apparent paradox, we examined whether estimates of prevalence might differ if we did not assume that infected ticks are randomly or uniformly distributed within a site. Nymphal Ixodes dammini were collected by dragging a series of 10-meter replicates within an intensely enzootic site. Estimates of the prevalence of spirochetal infection, based upon the monthly means of individual 10-meter collections, were then compared with estimates derived by pooling all samples. Host-seeking ticks tended to cluster. The Lyme disease spirochete was present in 15.6% of 469 pooled ticks. When the prevalence estimate was based solely on ticks in clusters that contained one or more infected ticks, however, at least 50% of the ticks were infected. We conclude that nymphal deer ticks infected by Lyme disease spirochetes tend to aggregate spatially in nature, and that prevalence estimates based upon a mean value for pools may be misleading.

New host of Ixodes dentatus (Acari: Ixodidae), and first record in Tennessee.

Two specimens of Ixodes dentatus Marx were found in southwestern Tennessee in Shelby County during a 14-mo tick survey. This was the first record for this tick in Tennessee. An adult female was found on a dry ice trap and one larva was found on a live-trapped Peromyscus leucopus, the first time this tick has been reported from P. leucopus. This may be another combination of vector and host in the ecology and transmission of B. burgdorferi in the wild.

Ectoparasites of the blackbuck antelope (Antilope cervicapra).

Fifty-two free-ranging blackbuck antelope (Antilope cervicapra) from Texas were examined for ectoparasites. Two species of sucking lice (Anoplura), one species of chewing louse (Mallophaga), one species of louse fly (Diptera), and three species of ticks (Acari) were found. This is the first report of the anoplurans Linognathus cervicaprae and L. pithodes from the Western Hemisphere. The southern deer ked (Lipoptena mazamae), the winter tick (Dermacentor albipictus), and the rabbit tick (Haemaphysalis leporispalustris) are reported from blackbuck for the first time. The lone star tick (Amblyomma americanum) and the mallophagan (Damalinia cornuta cornuta) were reported previously from blackbuck in Texas, the latter species under the name Tricholipeurus balanicus balanicus.

Quantitative evaluation of sampling methods for Ixodes dammini and Amblyomma americanum (Acari: Ixodidae).

Three tick-sampling methods (dry ice-baited tick traps, cloth drags, and ambulatory human host) were evaluated to determine which technique yielded the greatest capture of host-seeking stages of Ixodes dammini Spielman, Clifford, Piesman & Corwin and Amblyomma americanum (L.). The most reliable method, catching more stages and significantly more numbers of I. dammini and A. americanum; was dry ice-baited tick traps. There were no significant differences between the drag and human-host methods for any stage of ticks (I. dammini and A. americanum) collected. The numbers of ticks caught during the study were 5,052 by dry ice-baited tick traps, 199 by cloth drags, and 89 by ambulatory human host.

A comparison of methods for sampling the deer tick, Ixodes dammini, in a Lyme disease endemic area.

The purpose of this study was to compare the trapping and examining of mice, drag sampling, and CO2-baited traps for their ability to detect the presence and abundance of immature deer ticks, Ixodes dammini, in a Lyme disease endemic area in southern New York State. Eight study sites were sampled 14 times between 28 May and 31 August by setting 49 live-traps, four CO2-baited traps, and drag sampling 500 m2. A total of 1540 nymphs and 3079 larvae was collected during the study. Drag sampling collected the most nymphs (705), while more larvae were recovered from CO2-baited traps (1105). Comparisons among the methods showed a significant difference in the numbers of both larval and nymphal ticks collected (P less than 0.01). There was a positive correlation between the numbers of nymphs collected by drag sampling and CO2-baited tick traps (rs = 0.83, P less than 0.05), and between the numbers of larvae collected by drag sampling and mouse trapping (rs = 0.75, P less than 0.05). These results suggest that drag sampling would be the single most reliable method for quantitatively sampling immature I. dammini populations in a Lyme disease endemic area.

First report of Ixodes (Ixodes) minor Neumann (Acari: Ixodidae) from South Carolina.

Previous reports from the literature have indicated the northernmost range of extension of Ixodes minor Neumann to be southern Georgia with the greatest number of collections having been made in the coastal regions of that state. An unpublished record in the U.S. National Tick Collection indicated that I. minor had been collected as far north as South Island, Georgetown County, S.C., as early as 1933. I. minor was collected on three separate occasions in Charleston County, S.C., between October 1990 and February 1991, thus verifying the northern extension of this tick's range and the probable existence of a stable population on the coast of South Carolina. The roof rat (Rattus rattus) is reported for the first time serving as a host for I. minor.

Tick sweep: modification of the tick drag-flag method for sampling nymphs of the deer tick (Acari: Ixodidae).

We describe a version of the standard tick drag-flag modified for use in close-growing and tangled vegetation, as well as under ornamental shrubbery and fallen branches. Two major features of the sweep are: (1) it allows the user to remain upright with the flag parallel to the ground, thus sampling effectively beneath low and fallen branches and around shrubs, as well as capturing host-seeking ticks in advance of the operator; and (2) the use of a flannel rubberized-laminate fabric (crib sheet) for the flag that is snag-proof and highly durable in dense and thorny vegetation. In simultaneous 100-m samples, the sweep was as effective as the 1-m standard tick drag for capturing nymphs of the deer tick, Ixodes dammini Spielman, Clifford, Piesman & Corwin, where understory vegetation was sparse, but was twice as effective in dense vegetation, capturing significantly more I. dammini nymphs. The sweep also captured nymphs of the American dog tick, Dermacentor variabilis (Say); rabbit tick, Haemaphysalis leporispalustris (Packard); and lone star tick, Amblyomma americanum (L.).

Ornithodoros (Alectorobius) capensis Neumann (Acari: Ixodoidea: Argasidae), a parasite of seabirds, established along the southeastern seacoast of the United States.

Ornithodoros (Alectorobius) capensis Neumann, an ectoparasite of seabirds found circumglobally in the tropics and subtropics, has become established along the southeastern seacoast of the United States. The tick has been found feeding primarily on brown pelicans, Pelecanus occidentalis, but also has been found on the laughing gull, Larus atricilla, and the American oystercatcher, Haematopus palliatus. We report here the presence of O. (A.) capensis from New Hanover and Brunswick counties (near the mouth of the Cape Fear River) in North Carolina, to the Charleston Harbor area of South Carolina and thence south to Cumberland Island (a barrier island) in Camden County, Georgia, just north of the Florida state line.

Ectoparasites from river otters in Pennsylvania.

Twenty-three livetrapped and two trapper-caught river otters (Lutra canadensis) from northeastern Pennsylvania (USA) were examined for ectoparasites immediately after their captures during 1981 to 1985. Ectoparasites were collected from both trapper-caught otters, but from only one livetrapped otter. One species of tick (Ixodes cookei) and one flea (Oropsylla arctomys) were collected.

Parasite burdens and host susceptibility of Zebu and N'Dama cattle in village herds in Gambia.

Helminth and tick burdens of N'Dama cattle kept in village herds were compared with parasite burdens in Zebu cattle introduced into the same herds. The animals were monitored regularly for tick and helminth burdens, and blood samples were examined for differential white cell counts. The Zebu were found to have significantly higher numbers of endo- and ectoparasites. The N'Dama had significantly higher levels of circulating eosinophils than the Zebu during peak parasite burdens. No difference in antibody levels to Amblyomma variegatum infestation could be detected between the two breeds. It is suggested that observed differences in susceptibility to endo- and ectoparasites between the two breeds cannot be totally attributed to environmental naivety of the Zebu, but must be partially owing to enhanced innate resistance factors in the N'Dama.

First record of Ixodes brunneus in Kansas.

A single specimen, a partially engorged female, of Ixodes brunneus was recovered from a common grackle (Quiscalus quiscula) in Butler County, near El Dorado, Kansas (USA). The discovery of this tick in Kansas represents a new state record.

Ticks (Ixodidae) parasitizing humans in four provinces of north-western Argentina.

In four provinces of north-western Argentina (Catamarca, Jujuy, Salta and Tucumán), between March 1976 and March 1990, 514 ticks were found on humans. They were identified as Rhipicephalus sanguineus group (1 male), Boophilus microplus (6 male, 1 female), Amblyomma parvum (9 male, 13 female), A. cajannense (35 male, 30 female, 81 nymphs), A. neumanni (33 male, 41 female, 144 nymphs) and Amblyomma spp. (10 nymphs, 110 larvae). Most of the ticks were from the phytogeographical region of Chaco, one (B. microplus) was from an ecotone between the Chaco and the Andean Patagonia region, and the remainder of the ticks were from the Amazon region.

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.

Parasites of domestic and wild animals in South Africa. XXVII. Ticks on helmeted guineafowls in the eastern Cape Province and eastern Transvaal Lowveld.

Seventy-six helmeted guineafowls (Numida meleagris) were shot in the Andries Vosloo Kudu Reserve and on an adjacent farm in the eastern Cape Province during the period May 1985 to January 1987 and their tick burdens determined. A total of 10 ixodid tick species were recovered, of which Amblyomma hebraeum, Amblyomma marmoreum and Haemaphysalis silacea were the most abundant. The seasonal abundances of these 3 species and of Hyalomma marginatum rufipes were ascertained. A marked difference between the total number of A. hebraeum recovered from the birds in the reserve and those on the farm is ascribed to the treatment of domestic stock on the farm with an acaricide. The tick burdens of 118 helmeted guineafowls, shot in the southern part of the Kruger National Park, eastern Transvaal Lowveld, from August 1988 to August 1990, were also determined. Ten ixodid tick species and the larvae of an argasid species were recovered. A. hebraeum, A. marmoreum and the Argas sp. were the most abundant and their seasonal abundances and that of Rhipicephalus zambeziensis were determined. Only 2 of the 54,659 ixodid ticks recovered from the birds at the 3 localities were adults and the presence of these is ascribed to accidental infestations.

The geographic spread and temporal increase of the Lyme disease epidemic.

OBJECTIVE: To describe the temporal and geographic progression of the Lyme disease epidemic in New York State from 1977 through 1989. DESIGN: Communicable disease surveillance system. SETTING: Statewide. MAIN OUTCOME MEASURES: The progression of the epidemic was examined by analyzing trends in Lyme disease cases reported to the state surveillance system, town and county Lyme disease incidence rates, Lyme disease hospital discharge rates, and the distribution of Ixodes dammini ticks obtained from surveillance efforts and submitted for identification. MAIN RESULTS: The number of confirmed Lyme disease cases in New York has increased with concurrent increases in the number of hospital discharges. The number of counties endemic for Lyme disease increased from four to eight between 1985 and 1989. The number of counties with documented I dammini ticks increased from four in 1985 to 22 in 1989. Incidence of the disease also increased within known endemic counties. CONCLUSIONS: Tick surveillance indicated that the range of I dammini has expanded annually into areas up to 384 km from the original known endemic areas of Long Island, NY, and Connecticut. Cumulative data from human surveillance resources document both temporal increases and geographic expansion of the Lyme disease epidemic in New York.

Landscape ecology of Lyme disease in a residential area of Westchester County, New York.

The landscape ecology of Lyme disease was studied in 1989 on 67 residences in an endemic area of Armonk, Westchester County, a northern suburb of New York City. Four main habitat types were defined, and each property was surveyed for immature and adult lxodes dammini ticks; 98.6% of 1,790 ticks collected were I. dammini. Overall, 67.3% were collected from woods, 21.6% from ecotone (unmaintained edge), 9.1% from ornamental vegetation, and 2% from lawns. Larval ticks were concentrated in woods, but nymphs and adults were widely dispersed in all habitats. Tick abundance was positively correlated with property size. Larger properties (greater than or equal to 0.5 acre) were more likely to have woodlots and, hence, more ticks. Dark-field and direct fluorescent microscopic examination of tick midgut tissues revealed that 29.6% of nymphs and 49.7% of adults were infected with Borrelia burgdorferi. Infected nymphs and adults were found on 36% and 60% of properties, respectively. These data indicate that the abundance of ticks capable of transmitting Lyme disease spirochetes is related to landscape features of the suburban residential environment.

Parasitization of humans in West Virginia by Ixodes cookei (Acari: Ixodidae), a potential vector of Lyme borreliosis.

In 32 collections, two larvae, 33 nymphs, and one adult female Ixodes cookei Packard were collected from humans in West Virginia from August 1987 to May 1990. Most were attached. The ticks were found in 14 counties and were the most abundant Ixodes found biting humans. One nymphal I. cookei was removed from the left axilla of a 39-yr-old woman who lives and works in Monongalia and Marion counties, W. Va. The bite was the center of an expanding erythematous lesion reaching 4 cm in diameter, clearing centrally, and typical of erythema migrans. This association and the near absence of Ixodes dammini Spielman, Clifford, Piesman & Corwin from the state suggests the possibility that I. cookei may be an important vector of Lyme borreliosis in West Virginia. In five separate collections, five nymphal Ixodes dentatus Marx were removed from humans in four counties, implicating this species as a potential minor vector of Lyme borreliosis in West Virginia.

[Arthropods found on European beaver (Castor fiber L.) in Poland]. / Stawonogi wystepujace na bobrze europejskim (Castor fiber L.) w Polsce.

In July 1988, arthropods from 6 Castor fiber were collected at Popielno near Ruciane. Schizocarpus numerosus Dub., S. fedjushini Dub., S. brachyurus Dub. are new to the fauna of Poland. Ixodes hexagonus Leach (larvae, nymphs, females) is especially numerous. Under-development of the coxa and trochanter of the third left leg was noted in one female. Moreover, Acarus farris (Oud.), Cunaxoides kielczewskii Mich. and unidentified female of the Phytoseiidae were obtained. Cunaxid mites have not been collected hitherto from mammals. At the present time in Poland, 8 species (including Platypsyllus castoris Rit.) of arthropods are found on C. fiber.