An Exotic Hitchhiker: A Case Report of Importation into Connecticut from Africa of the Human Parasitizing Tick, Hyalomma truncatum (Acari: Ixodidae).

We report the importation into Connecticut, U.S.A., of an exotic tick, Hyalomma truncatum (Koch) (Acari: Ixodidae), on a human with recent travel history to Africa. The tick was identified using key morphological characters and through DNA sequencing. This case report highlights continuing risk associated with the importation of exotic tick vectors of medical and veterinary significance on international travelers returning to the United States from abroad.

Embryo Development and Morphology of the Rocky Mountain Wood Tick (Acari: Ixodidae).

Dermacentor andersoni Stiles embryogenesis was observed using fluorescent and scanning electron microscopy for eggs held under laboratory conditions (25°C and at 93% relative humidity). Early embryonic cell divisions appeared to be synchronous and holoblastic, giving rise to a uniform blastoderm surrounding the yolk. The cells of the blastoderm became concentrated on one side of the embryo, forming the segmented germ band. Distinct opisthosomal and prosomal segment morphologies, which are characteristic of chelicerate embryos, were observed during germ band elongation. Mouth and leg appendages grew from the prosomal segments. As development progressed, the segments were fused into the idiosoma and capitulum of the free-living larval form. An embryo staging system was established based on embryo developmental morphology and the timing of morphogenetic events. The staging system will serve as a basis for future studies directed at understanding morphogenetic mechanisms or for observing the impact of abiotic factors, such as temperature or humidity, on tick development.

Comparative morphology and ultrastructure of the prosomal salivary glands in the unfed larvae Leptotrombidium orientale (Acariformes, Trombiculidae), a possible vector of tsutsugamushi disease agent.

The prosomal salivary glands of the unfed larvae Leptotrombidium orientale (Schluger) were investigated using transmission electron microscopy. In total, four pairs of the prosomal glands were identified--three pairs, the lateral, the medial and the anterior, belong to the podocephalic system, and one pair, the posterior, is separate having an own excretory duct. All glands are simple alveolar/acinous with prismatic cells arranged around a relatively small intra-alveolar lumen with the duct base. The cells of all glands besides the lateral ones contain practically mature electron-dense secretory granules ready to be discharged from the cells. The secretory granules in the lateral glands undergo formation and maturation due to the Golgi body activity. The cells of all gland types contain a large basally located nucleus and variously expressed rough endoplasmic reticulum. Specialized duct-forming cells filled with numerous freely scattered microtubules are situated in the middle zone of each gland's acinus and form the intra-alveolar lumen and the duct base. Both the acinar (secretory) and the duct-forming cells contact each other via gap junctions and septate desmosomes. Axons of nerve cells come close to the basal extensions of the duct-forming cells where they form the bulb-shaped synaptic terminations. The process of secretion is under the control of the nerve system that provides contraction of the duct-forming cells and discharge of secretion from the secretory cells into the intra-alveolar lumen and further to the exterior. Unfed larvae of L. orientale, the potential vector of tsutsugamushi disease agents, contain the most simply organized salivary secretory granules among known trombiculid larvae, and this secretion, besides the lateral glands, does not undergo significant additional maturation. Thus, the larvae are apparently ready to feed on the appropriate host just nearly after hatching.

What ticks do under your skin: two-photon intravital imaging of Ixodes scapularis feeding in the presence of the lyme disease spirochete.

Lyme disease, due to infection with the Ixodes-tick transmitted spirochete Borrelia burgdorferi, is the most common tick-transmitted disease in the northern hemisphere. Our understanding of the tick-pathogen-vertebrate host interactions that sustain an enzootic cycle for B. burgdorferi is incomplete. In this article, we describe a method for imaging the feeding of Ixodes scapularis nymphs in real-time using two-photon intravital microscopy and show how this technology can be applied to view the response of Lyme borrelia in the skin of an infected host to tick feeding.

Morphological characteristics and developmental changes of the ovary in the tick Haemaphysalis longicornis Neumann.

Haemaphysalis longicornis (Ixodida: Ixodidae) is an important vector of transovarially transmitted parasites of the genus Babesia (Piroplasmida: Babesiidae). In the present study, we investigated the morphological characteristics and developmental changes of the ovary of H. longicornis. We show that the ovary of H. longicornis has a single tubular structure and is surrounded by a tunica propria. There is a longitudinal groove along one side of the ovary. During feeding and after engorgement, great changes can be observed in the ovary of H. longicornis and two rapid growth phases can be detected. The number of major protein bands of the ovary is significantly increased from day 3 of feeding and reaches a maximum on the day of engorgement. Therefore, the great diversity of proteins in the ovaries of H. longicornis can facilitate the identification of new targets for vaccine development.

Cytotoxic effects of permethrin in salivary glands of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) semi-engorged females.

Because of the medical and veterinary importance of ticks and the wide use of synthetic chemical substances such as permethrin (active ingredient of Advantage® Max3 - Bayer)for their control, this study evaluated the effects of different concentrations (206, 1031 and 2062 ppm) of the acaricide on the salivary glands of Rhipicephalus sanguineus semi-engorged females. Results showed that permethrin is a potent substance that acts morpho-physiologically in the tick glandular tissue, causing changes in the acini shape intense vacuolation in acinar cells, and disruption of the tissue by cell death process, with subsequent formation of apoptotic bodies, especially at higher concentrations, thus precluding the accurate identification of different types of acini. Importantly, it is demonstrated that permethrin acts on salivary gland tissue, as well as affecting the nervous system, accelerating the process of glandular degeneration, and interfering with the engorgement process of female ticks, preventing them from completing the feeding process.

Ultrastructural evidence of the ehrlichial developmental cycle in naturally infected Ixodes persulcatus ticks in the course of coinfection with Rickettsia, Borrelia, and a flavivirus.

Ehrlichiae are small gram-negative obligately intracellular bacteria that multiply within vacuoles of their host cells and are associated for a part of their life cycle with ticks, which serve as vectors for vertebrate hosts. Two morphologically and physiologically different ehrlichial cell types, reticulate cells (RC) and dense-cored cells (DC), are observed during experimental infection of cell cultures, mice, and ticks. Dense-cored cells and reticulate cells in vertebrate cell lines alternate in a developmental cycle. We observed ultrastructure of RC and DC of Ehrlichia muris in morulae in salivary gland cells and coinfection with Borrelia burgdorferi sensu lato (sl), "Candidatus Rickettsia tarasevichiae," and a flavivirus (presumably, tick-borne encephalitis virus [TBEV]) of Ixodes persulcatusticks collected in the Cis-Ural region of Russia. Polymerase chain reaction revealed 326 (81.5%) of 400 ticks carrying at least one infectious agent, and 41.5% (166 ticks) were coinfected with two to four agents. Ehrlichiae and rickettsiae were identified by sequencing of 359 bp of the 16S rRNA gene of E. muris and of 440 bp of the 16S rRNA gene and 385 bp of the gltA gene of "R. tarasevichiae." Different organs of the same tick harbored different microorganisms: TBEV in salivary gland and borreliae in midgut; E. muris in salivary gland; and "R. tarasevichiae" in midgut epithelium. Salivary gland cells contained both RC and DC, a finding that confirmed the developmental cycle in naturally infected ticks. Dense-cored cells in tick salivary glands were denser and of more irregular shape than DC in cell cultures. Ehrlichia-infected salivary gland cells had lysed cytoplasm, suggesting pathogenicity of E. muris for the tick host at the cellular level, as well as potential transmission during feeding. Rickettsiae in the midgut epithelial cells multiplied to significant numbers without altering the host cell ultrastructure. This is the first demonstration of E. muris, "R. tarasevichiae," and the ehrlichial developmental cycle in naturally infected I. persulcatus sticks.

Amblyomma cajennense (Acari: Ixodidae): salivary gland cells of partially engorged females ticks and the production of lipid by their mitochondria.

Morphologically, the salivary glands of ticks are paired structures consisting of a secretory and an excretory portion, lacking a reservoir for the storage of the secretion. The secretory portion is composed in females by cells that form acini classified into the types I, II, and III. The excretory possess a major duct, from which arise several intermediate ducts that then subdivide to form the canaliculi or acinal tubules, which end at the acini from where they collect the secretion. The present study describes the ultrastructural changes that occur in the mitochondria of cells of the acini I, II, and III in the salivary glands of partially engorged females of the Cayenne tick Amblyomma cajennense. The results show that this organelle exhibits completely disarrayed crests due to the presence of lipidic material inside the matrix and between the crests, thus demonstrating their participation in the production of the lipids that would be used structurally by the cells. These organelles with ultrastructural changes were denominated derived mitochondria.

Acaricidal efficacy of Myrrh (Commiphora molmol) on the fowl tick Argas persicus (Acari: Argasidae).

Five concentrations of purified extract of Myrrh from Commiphora molmol tree were prepared to study its effects on the fowl tick Argas persicus under laboratory conditions. The results revealed that Myrrh had dependant dose toxic effect on the adult female of A. persicus. Toxicity increased gradually daily post treatment. The LC50 was 1.28%, 0.88%, 0.84%, 0.50% and 0.42% at Ist, 2nd, 3rd, 6th and 12th days respectively. At 12th day, the recorded mortality rates were 63, 67, 76, 87 and 94% for concentrations, 0.625, 1.25, 2.5, 5 and 10%, respectively against 5% in control. Histopathological and Transmission election microscope (TEM) examinations showed the lysing of epithelial gut cells in treated groups. The lysed epithelial gut cells showed irregularly distributed nucleus, commonly at low concentrations and rarely in high concentrations of Myrrh. The lysed epithelial gut cells, without nucleus or with aggregated one beside the basal lamina, were common at high concentrations and rare in low concentrations of Myrrh. Consequently, Myrrh can rapidly penetrate the cuticle to body cavity, destroy the epithelial gut cells and finally cause the death of ticks.

[Ticks (Acarina: Ixodidae) as vectors and reservoirs of pathogen microorganisms in Spain]. / Las garrapatas (Acarina: Ixodida) como transmisores y reservorios de microorganismos patógenos en España.

Hard and soft-ticks are obligate haematophagous arachnids of medical and veterinary significance mainly because of the animal disease agents transmitted by them, which include an array of different pathogens (virus, bacteria, protozoa and nematodes). Ticks transmit microbes by several routes including salivary secretions, coxal fluids, regurgitation and faeces. Among the biological factors that contribute to the high vector potential of ticks are their living habits and characteristic properties of their saliva secretions and blood digestion. In the Iberian Peninsula, the prostriata tick Ixodes ricinus, and the metastriata Dermacentor marginatus, Rhipicephalus sanguineus and Hyalomma marginatum are the main species that could bite man, and are involved in the transmission of Borrelia burgdorferi sensu lato, several genoespecies of Rickettsia (R. conorii, R. slovaca, R. aeschlimannii) and Anaplasma phagocytophila.

Aponomma hydrosauri, the reptile-associated tick reservoir of Rickettsia honei on Flinders Island, Australia.

Rickettsia honei is the etiologic agent of Flinders Island (Australia) spotted fever. The tick Aponomma hydrosauri is associated with reptiles and is the arthropod reservoir for this rickettsia on Flinders Island. The rickettsia appears to be maintained in the tick via vertical transmission. Of 46 ticks examined, 29 (63%) were positive for spotted fever group rickettsiae by detection of the citrate synthase gene by a polymerase chain reaction (PCR). From the positive tick samples, seven were sequenced and found to be 100% homologous with R. honei. Of 17 reptiles examined, none had evidence of rickettsiae by PCR or culture of blood.

Ultrastructural study of the infection process of Rickettsia conorii in the salivary glands of the vector tick Rhipicephalus sanguineus.

This work was designed to study the infection process of Rickettsia conorii in the salivary glands of experimentally infected Rhipicephalus sanguineus ticks. One hundred six uninfected engorged nymphs were intracelomically inoculated with approximately 2 x 10(3) plaque-forming units of a rickettsial suspension. After the molt, unfed and fed adults were dissected, and the salivary glands were extracted and processed for transmission electron microscopy observation. Three different uninfected control groups were used for (1) evaluating the impact of the inoculation procedure, (2) establishing the feeding period of infected ticks, and (3) ultrastructural characterization of the salivary glands. Overall, 75.5% (80 of 106) of the nymphs inoculated with rickettsiae died during the molt or soon after hatching into adult instars; 50% (12 of 24) of the remaining infected adults showed severe malformations compromising their viability. In apparently healthy specimens, time of engorgement was longer. The contrast with the negative control groups was statistically significant, suggesting that R. conorii exerts a strong negative effect on the vector ticks. The ultrastructural study showed that in the salivary glands of infected ticks, rickettsial growth occurs preferentially in central, peripheral, and interstitial acini cells.

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.

Pathogenicity of the entomopathogenic fungus Metarhizium anisopliae (Deuteromycetes) to Ixodes scapularis (Acari: Ixodidae).

The entomopathogenic fungus Metarhizium anisopliae is highly pathogenic to the black-legged tick, Ixodes scapularis. Spore concentrations of 10(8)/ml for engorged larvae and 10(7)/ml for engorged females resulted in 100% tick mortality, 2 wk postinfection. The LC50 value for engorged larvae (concentration to kill 50% of ticks) was 10(7) spores/ml. Metarhizium anisopliae shows considerable potential as a microbial control agent for the management of Ixodes scapularis.

First description of the male and redescription of the immature stages of Amblyomma rotundatum (Acari: Ixodidae), a recently discovered tick in the U.S.A.

The male of Amblyomma rotundatum is described for the first time, and the nymph and larva are redescribed. This tick is a parthenogenetically reproducing species parasitic on amphibians and reptiles in the warmer areas of the New World. Attempts to mate male and female A. rotundatum under laboratory conditions were unsuccessful.

Development of Anaplasma marginale in male Dermacentor andersoni transferred from parasitemic to susceptible cattle.

The development and transmission of Anaplasma marginale was studied in Dermacentor andersoni males. Laboratory-reared male D andersoni were allowed to feed for 7 days on a calf with ascending A marginale parasitemia. The ticks were then held in a humidity chamber for 7 days before being placed on 2 susceptible calves. Anaplasmosis developed in the calves after incubation periods of 24 and 26 days. Gut and salivary glands were collected from ticks on each day of the 23-day experiment and examined with light and electron microscopy. Colonies of A marginale were first observed in midgut epithelial cells on the sixth day of feeding on infected calves, with the highest density of colonies found in gut cells while ticks were between feeding periods. The first colonies contained 1 large dense organism that subsequently gave rise to many reticulated organisms. Initially, these smaller organisms were electron-lucent and then became electron-dense. On the fifth day after ticks were transferred to susceptible calves for feeding, A marginale colonies were found in muscle cells on the hemocoel side of the gut basement membrane. A final site for development of A marginale was the salivary glands. Colonies were first seen in acinar cells on the first day that ticks fed on susceptible calves, with the highest percentage of infected host cells observed on days 7 to 9 of that feeding. Organisms within these colonies were initially electron-lucent, but became electron-dense.

The presence of the parasite Demodex folliculorum on the skin surface of the eyelid.

It is well established that Demodectic mites can infest the meibomian glands, eyelash and hair follicles of the eyelid. In this study, scanning electron microscopy revealed Demodex folliculorum occurring freely on the skin surface of the eyelid. This indicates some mobility and implies further vector potential. Exoskeletons from these parasites also occur on the eyelid.

Specificity and effects of host resistance on the African tick Rhipicephalus zambeziensis (Acarina: Ixodidae).

Repeated infestations of the rabbit with adult Rhipicephalus zambeziensis ticks resulted in a ten-fold reduction in engorgement weight of adult ticks and a significant decline in engorgement weight of nymphs. There was no evidence of cross-resistance against the South African bont tick, Amblyomma hebraeum. Immunization of rabbits with crude extracts of whole-tick protein significantly influenced engorgement weights and oviposition rates of adult R. zambeziensis. Histological studies of tissues from R. zambeziensis adults fed on resistant rabbits showed severe gut damage; this was associated with the binding of host IgG to mid-gut cells.

Mixed Rickettsia-virus infection in Dermacentor reticulatus imago.

Electron microscopic examination revealed replication and accumulation of Rickettsia sibirica in the fat body of experimentally infected Dermacentor reticulatus ticks. Rickettsia are released from the fat body cells by budding being surrounded with cytoplasm and plasmalemma of the host cell. Eukaryotic cell structures have been detected consisting of lamella layers whirled around the intact rickettsiae. In addition to rickettsia, microorganisms morphologically resembling Francisella tularensis and an orbivirus were found in tick tissues at morphological examination. The morphology of the virus and stages of its morphogenesis are described. Mixed viral and rickettsial infection has been shown to develop in the same ticks and even in the same fat body cells in a very close association.

[The ultrastructure of the interaction of Rickettsia sibirica and R. slovaca with the cells of ixodid ticks]. / Ul'trastruktura vzaimodeistviia Rickettsia sibirica i R. slovaca s kletkami iksodovykh kleshchei.

The ultrastructural aspects of the interaction of R. sibirica and R. slovaca with cells of mites of the species Dermacentor reticulatus, D. marginatus and Ixodes ricinus after their parenteral infection, as well as in the organs of D. marginatus infected naturally in the environment, have been studied. Both rickettsial species have similar morphology in different organs of the vector. These rickettsiae not only multiply, their populations are also partly destroyed in phagolysosomes. The natural mixed infection of R. sibirica and orbivirus in cells of D. reticulatus is described. As shown in this study, both associates pass through the complete ontogenetic cycle of development on the level of the host body and also on the level of an individual cell.