Soft Tick Species Research Articles

Molecular characterization of hard ticks from Romania by sequences of the internal transcribed spacers of ribosomal DNA

In the present study, four hard tick species and one soft tick species, namely, Dermacentor marginatus, Haemaphysalis punctata, Haemaphysalis parva, Ixodes ricinus, and Dermanyssus gallinae, from south-western Romania were characterized genetically by the first (ITS-1) and second (ITS-2) internal transcribed spacers (ITS) of nuclear ribosomal DNA (rDNA), using a hard tick, Haemaphysalis longicornis, from China for comparative purposes. The ITS rDNA was amplified by polymerase chain reaction (PCR) and sequenced from individual ticks. The lengths of the ITS-1 sequences were 238–1819 bp, and the lengths of ITS-2 were 137–1695 bp, respectively, for all ticks sequenced. While sequence variation within a hard tick species was 0–1.5%, nucleotide differences between hard tick species ranged 2–25.2%, indicating that ITS rDNA sequences provide genetic markers for the differentiation of hard ticks from Romania. Hence, a PCR-linked restriction fragment length polymorphism approach was developed for their unequivocal differentiation based on ITS-1 rDNA. This is the first characterization of ticks from Romania using a genetic approach, which provides the foundation for further studies on ticks in Romania and has implications for studying the population genetic structure of the Romanian ticks and for identification and differentiation of closely related ticks.

Congenital tick-borne relapsing fever: report of a case with transplacental transmission in the Islamic Republic of Iran

Tick-borne relapsing fever (TBRF) is an arthropod-borne infection found in the Middle East, Africa, Europe and North America. The disease is caused by several species of Borrelia and transmitted by various species of soft ticks [1,2]. Specific relationships usually exist between Borrelia species, the vector ticks and the distribution area [3]. Ornithodoros tholozani is distributed in the Middle East and is known as the main vector and sole reservoir for B. persica, which is often responsible for old-world TBRF. Ticks of this species live in close proximity with humans host and feed for short periods, through a painless bite, often at night [4]. TBRF is endemic in the north-west of the Islamic Republic of Iran where clinical and epidemiological studies have been conducted [5,6]. It is more prevalent in children under 5 years and pregnant women. In infected pregnant women, transplacental transfer of the microorganism is possible, which leads to neonatal infection. Although the mothers may have nonspecific febrile illnesses, the infected infants may present with severe disease. Most of the previous studies concern children and adults, whereas no studies have been published on neonatal borreliosis in the Islamic Republic of Iran [6,7]. In this study, we report the clinical and laboratory results of a neonate infected with B. persica.

Molecular characterization of hard and soft ticks from Romania by sequences of the internal transcribed spacers of ribosomal DNA

In the present study, four hard tick species and one soft tick species, namely, Dermacentor marginatus, Haemaphysalis punctata, Haemaphysalis parva, Ixodes ricinus, and Dermanyssus gallinae, from south-western Romania were characterized genetically by the first (ITS-1) and second (ITS-2) internal transcribed spacers (ITS) of nuclear ribosomal DNA (rDNA), using a hard tick, Haemaphysalis longicornis, from China for comparative purposes. The ITS rDNA was amplified by polymerase chain reaction (PCR) and sequenced from individual ticks. The lengths of the ITS-1 sequences were 238-1819 bp, and the lengths of ITS-2 were 137-1695 bp, respectively, for all ticks sequenced. While sequence variation within a hard tick species was 0-1.5%, nucleotide differences between hard tick species ranged 2-25.2%, indicating that ITS rDNA sequences provide genetic markers for the differentiation of hard ticks from Romania. Hence, a PCR-linked restriction fragment length polymorphism approach was developed for their unequivocal differentiation based on ITS-1 rDNA. This is the first characterization of ticks from Romania using a genetic approach, which provides the foundation for further studies on ticks in Romania and has implications for studying the population genetic structure of the Romanian ticks and for identification and differentiation of closely related ticks.

Some hematological changes in chickens infected with ectoparasites

The study was conducted to identify different ectoparasites infesting 280 chicken (native breed out door house reared layers, 6 months – 2 years old), from various regions of Mosul city (poultry market, Hadba' Flock, and six flocks at Kogialli village), for one year. Total percentage of ectoparasites in chickens were 19.3 % of which (54 positive case out of 280 chicken) 81% were single infections and 19 % mixed infections. Lice infestation (12.5 %) and four types of chewing lice were classified (Menacanthus stramineus , Cuclotogaster hetrographus , Goniocoteus gallinae , and Columbicola columbae ). One species of flies (1.4%) ( Pseudolynchia canariensis ). One species of mites (4.3%) ( Dermanyssus gallinae ) were seen. One species of soft ticks (6.8%) ( Argas persicus ) were seen. Parasitological findings of skin and feathers examination for all types of ectoparasites on chicken showed three degrees of infestation depending on the number of these ectoparasites on each bird (low degree 1–50/ bird, moderate degree 51–100/ bird, and heavy degree more than 100/ bird). Clinical signs of the infected chicken with ectoparasites especially severe infection were itching, annoyance, loss of sleep, general weakness, loss of appetite, restless, allergy, drop of egg production in layers and anemia. It clear from results of blood examinations the presence of anemia in infected birds blood sucking ectoparasites with significant decrease in PCV % , TRBC and Hb concentration in chicken especially in severe (heavily) infestation with soft ticks and mites. Results also showed increase in total white blood cells (Leucocytosis) with increase in heterophils, and eosinophils in infected chicken with ticks, mites and lice, with bad nutrition and unhygienic management as compared with non-infected chicken control group.

The tick fauna of Sulawesi, Indonesia (Acari: Ixodoidea: Argasidae and Ixodidae)

Twenty-six species of ticks are reported from the island of Sulawesi (Celebes), Indonesia. These include two species of soft ticks (Argasidae), Carios batuensis and C. vespertilionis, and the following 24 species of hard ticks (Ixodidae): Amblyomma babirussae, A. breviscutatum, A. cordiferum, A. fimbriatum, A. helvolum, A. testudinarium, A. trimaculatum, A. varanense, Dermacentor atrosignatus, D. steini, Haemaphysalis celebensis, H. hystricis, H. kadarsani, H. papuana, H. psalistos, H. renschi, H. toxopei, H. wellingtoni, Ixodes cordifer, I. granulatus, Rhipicephalus haemaphysaloides, R. (Boophilus) microplus, R. pilans and R. sanguineus. This represents an almost three-fold increase in the number of tick species recorded (9) from Sulawesi since the last available list in 1950. The tick records reported herein represent a culmination of data from specimens in the U.S. National Tick Collection, new records of ticks from endemic tarsiers and associated vertebrates, and literature reviews. Collectively, the tick fauna of Sulawesi shows most affinities with the fauna of southeast Asia but there are distinct faunal elements that show relationships with other Indonesian islands, the Philippines or Australasia, as well as a few tick species with widespread geographical distributions. Some ticks known from Sulawesi have known or potential medical-veterinary significance. These include R. (B.) microplus which is a significant pest of cattle and a vector of the agents of bovine anaplasmosis, I. granulatus which is a vector of Langat virus and Lyme disease spirochetes and has been shown to harbor pathogenic rickettsiae in other parts of its range, and R. sanguineus which is a globally widespread ectoparasite of canines and a vector of canine pathogens and parasites.

Characterization of anti-hemostatic factors in the argasid, Argas monolakensis: Implications for the evolution of blood-feeding in the soft tick family

To date, the only anti-hemostatic factors characterized for softs ticks are for Ornithodoros moubata and Ornithodoros savignyi, ticks that feeds mainly on mammals. This includes thrombin (ornithodorin and savignin), fXa (TAP and fXaI) and platelet aggregation (disagegin and savignygrin) inhibitors that belong to the BPTI-Kunitz protein family. This raises the question on how well anti-hemostatic factors will be conserved in other soft tick genera that feeds on other vertebrates such as birds. We characterized the anti-hemostatic factors from Argas monolakensis, a soft tick that feeds mainly on Californian gulls. The main anti-clotting factor (monobin) is an ortholog of ornithodorin and savignin and shows similar slow tight-binding kinetics. The main anti-platelet activities are apyrase and fibrinogen receptor antagonists (monogrins). The monogrins are orthologs of disagregin and savignygrin and like savignygrin presents the RGD integrin-recognition motif on the BPTI substrate-binding presenting loop. This implies that the anti-hemostatic factors evolved in the ancestral soft tick lineage and has been maintained in soft tick species from two distinct genera with different host preferences. The Argas derived anti-hemostatic factors bind to mammalian targets with affinities similar to that observed for their orthologs in the Ornithodoros genus. This cross-reactivity could have facilitated the switching of soft ticks from avian to mammalian hosts and can explain in part the ability of Argas ticks, to feed on humans, thereby remaining a possible health risk.

Molecular divergences of the Ornithodoros sonrai soft tick species, a vector of human relapsing fever in West Africa

The soft tick Ornithodoros sonrai is recognized as the only vector of Borrelia crocidurae causing human relapsing fever in West Africa. Its determination has been exclusively based on morphological features, geographical distribution and vector competence. Some ambiguities persist in its systematics and may cause misunderstanding about West African human relapsing fevers epidemiology. By amplifying and aligning 16S and 18S rDNA genes in O. sonrai specimens collected from 14 distinct sites in Senegal and Mauritania, we showed the existence of four genetically different subgroups that were morphologically and ecologically identified as belonging to the same species. Within O. sonrai, intraspecific polymorphism was high (pairwise divergence from 0.2% to 16.4%). In all cases, these four subgroups formed a monophyletic clade sharing a common ancestor with East African soft ticks that transmit Borrelia duttoni human relapsing fever. From amplification of the flagellin gene of B. crocidurae we verified that all subgroups of O. sonrai were infected by B. crocidurae and may constitute vectors for this pathogen. All flagellin sequences were identical, refuting the hypothesis suggesting parallel evolution between O. sonrai and B. crocidurae. However, differences in infection rates were significant, suggesting different vector competences between subgroups of O. sonrai.

Larval feeding performance of two Neotropical Ornithodoros ticks (Acari: Argasidae) on reptiles

This paper determines the feeding performance of the larvae of two Neotropical soft tick species namely Ornithodoros rostratus Aragão, 1911 and O. puertoricensis Fox, 1947 on reptiles (Gekkonidae) using rabbits, mice and guinea pigs to provide comparisons with feeding features on mammals. O. puertoricensis produced a larval feeding rate of 63% on reptiles, while that of O. rostratus was only 20%. But the final success (attaching + feeding) was similar, 12.4% for O. puertoricensis and 10.4% for O. rostratus. The feeding time was also very different for both species. In O. puertoricensis, detachment begins at 16th day and lasts until day 27. In O. rostratus detachment begins at 1.5 h and lasts until day 10. These values of feeding on reptiles are different from those obtained on mammals (average 5.6 days for O. puertoricensis and 2.9 for O. rostratus).

Innate Immunity in Ticks: A review

Ticks transmit more different kinds of pathogenic organisms than any other hematophagous arthropod. This paper attempts to review the literature available on the cell-mediated and humoral responses of ticks. The cell-mediated defense responses by invertebrates are simpler than vertebrates, but are effective as a second line of defense against invasion by microorganisms. Hemocytes play a major role in this immune response through phagocytosis, nodule formation and encapsulation of invading foreign materials. These mechanisms appear to function in both soft and hard ticks. Humoral immune responses consist of three main types; humoral encapsulation, hemagglutination and production of antimicrobial proteins. Humoral encapsulation is elicited by the prophenoloxidase activating system and has only been shown to function in the soft tick Ornithodoros moubata. However, recent studies show the hard ticks also have prophenoloxidase activating cofactors indicating humoral encapsulation also functions in these ticks. Tick lectins function in hemagglutination of various microorganisms in both soft and hard ticks and also appear to function as recognition molecules of nonself and possibly in the transmission of pathogenic microorganisms. Ticks also have numerous antimicrobial proteins that can attack the invading microorganisms. Lysozymes have been shown to have bactericidal effects in several tick species and work in concert with other antimicrobial peptides to kill invaders. Cystatins, classic cysteine protease inhibitors, have recently been shown to function in innate immune responses of ticks. Hemoglobin fragments have antimicrobial activity in the midgut of ticks. Defensins show expression up-regulated by blood feeding and are effective antimicrobial agents with some differences between soft and hard ticks. Other novel antimicrobial peptides have been isolated from various species of soft and hard ticks, but their functions remain to be elucidated. Understanding these innate immune mechanisms in ticks is essential to develop strategies for reducing the transmission of diseases to man and animals.

Existence of phenol oxidase in the argasid tick Ornithodoros moubata.

Phenol oxidase (PO, EC 1.10.3.1) activity was detected in the hemolymph of the fourth instar nymphs of the argasid tick, Ornithodoros moubata, with peak levels corresponding to the days before the majority of the nymphs had molted, suggestive of a protective role of PO during the ecdysial phase. Higher PO activity was detected in plasma relative to the hemolymph and was negligible in hemocytes. The concentration of the hemolymph and plasma assayed clearly influenced the level of PO activity, and was significantly reduced ( P<0.005) after treatment with 1-phenyl-2 thiourea, a specific PO inhibitor. This is the first report of the existence of PO in the hemolymph and plasma of a soft tick species. The regulation of PO activity and its precise role in soft tick immunity, particularly during the ecdysial phase, are interesting and need to be examined further.

The use of the nuclear protein-encoding gene, RNA polymerase II, for tick molecular systematics.

Phylogenetic studies of ticks have been increasing in recent years, particularly in the use of molecular data. However, all of the studies to date are either limited to the mitochondrial genome or to a few nuclear ribosomal genes. There is a need to explore the use of nuclear protein-encoding genes because these genes direct most aspects of the phenotypic traits in the development of an organism. We report here the test of a nuclear protein-encoding gene, RNA polymerase II, for the phylogenetic study of ticks. Thirty-eight ticks representing 26 species of hard and soft ticks were chosen for the study. The pairwise divergences among sampled species are ranged from 0.3 to 15.2% and most of the substitutions are transitions. In addition, the nucleotide composition is not obviously biased in POL II gene. The trees inferred from the POL II sequences using maximum parsimony (MP), neighbor joining (NJ), and maximum likelihood (ML) by PAUP* and MrBayes are largely concordant with the existing phylogenies. Our study demonstrated that POL II gene sequences contain strong phylogenetic signals in ticks at the generic and higher levels. POL II has proven to be a useful gene for resolving tick phylogeny.

Quantification of Host Immunoglobulin in the Hemolymph of Ticks

The inhibition of tick enzymes and neutralization of their hormones with specific antibodies have been suggested as methods for interfering with tick feeding and development (Roberts, 1968, Journal of Parasitology 54: 657-662; Galun, 1978, Control of livestock pests by interference in their development, Bogota, Colombia, UC/AID Pest Management and Relative Environmental Protection Progress Report; Allen and Humphreys, 1979, Nature 280: 491-493; Ackerman et al., 1980, Journal of Medical Entomology 17: 391-397; McGowan et al., 1980, Journal of Parasitology 66: 42-48). Antibodies of mammalian hosts, imbibed with a blood meal, have been demonstrated in the hemolymph of several soft and hard tick species. Human and rabbit immunoglobulin G (IgG) were found in the hemolymph of Dermacentor variabilis (Say) (Ackerman et al., 1981, Journal of Parasitology 67: 737-740). Hemolysin antibodies were detected in the hemolymph of Ixodes ricinus (L.) following a blood meal on rabbits immunized with sheep red blood cells (Bossard and Rais, 1984, Experientia 40: 561-563). Bovine IgG specific for Theileria sergenti was found in the hemolymph of both Ornithodoros moubata (Murray) and Haemaphysalis longicornis Neumann (Fujisaki et al., 1984, Annals of Tropical Medicine and Parasitology 78:449-450). Specific (antiovalbumin) rabbit IgG was found in the hemolymph of 0. moubata following a blood meal on rabbits immunized with ovalbumin (Minoura et al., 1985, Experimental Parasitology 60: 355363). The hemolymph samples tested in the above studies were usually pooled from several ticks, and therefore provided no information about individual variation in the presence of IgG in the hemolymph. Furthermore, when hemolymph samples from individual ticks were assayed (Brossard and Rais, 1984, loc. cit.), only a small fraction contained hemolysin antibodies. Though the concentration of host antibodies in tick he-

東海地方における不快動物としてのアブラコウモリ, およびそれに由来する有害節足動物

The Japanese pipistrelle, Pipistrellus abramus (Temminck, 1840), usually roosts in human houses in Japan and has been commonly known as the house bat. Due probably to an increase of the local populations of this bat around the Tokai district for the last few years, some of the inhabitants became nervous to the bats that roosted in the ceiling, shutter-box, garret, crevice of the wainscot, or under the floor of their houses. Some of these people complained of squeaking noises of the bats at night, of the filth and carcasses occasionally found in the neighborhood of the houses. Certain circles, moreover, became apprehensive of the occurrence of arthropod-bites or communicable diseases that might be transmitted by these bats. Therefore, we investigated the inhabitants who had made appeals as described above, but we did not confirm any serious symptoms. At present we regard this bat as one of the so-called "nuisances." However, our examination of arthropods on these bats and in the dust or dirt collected at their roosting sites revealed at least 20 acarine and four insect species (Table 1). Of these, a species of soft ticks, Argas vespertilionis (Latreille), has been well known to bite man; and a mesostigmatid, Steatonyssus longispinosus Wang, can be responsible for dermatitis cases of undetermined origin.

Lack of specificity in assembly pheromones of soft ticks (Acari: Argasidae).

Assembly pheromones are demonstrated in 2 species of soft ticks, Ornithodoros tholozani (Laboulbene & Megnin) and Argas brumpti Neumann. Interspecific response is observed between Argas persicus (Oken) and the following species: A. brumpti, O. tholozani, Ornithodoros savignyi (Audouin). Feeding increased pheromone production and decreased tick response to pheromone. The role of assembly pheromones in host location is considered.