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PubMed1999

Sequence variations in the Boophilus microplus Bm86 locus and implications for immunoprotection in cattle vaccinated with this antigen.

Cattle tick infestations constitute a major problem for the cattle industry in tropical and subtropical regions of the world. Traditional control methods have been only partially successful, hampered by the selection of chemical-resistant tick populations. The Boophilus microplus Bm86 protein was isolated from tick gut epithelial cells and shown to induce a protective response against tick infestations in vaccinated cattle. Vaccine preparations including the recombinant Bm86 are used to control cattle tick infestations in the field as an alternative measure to reduce the losses produced by this ectoparasite. The principle for the immunological control of tick infestations relies on a polyclonal antibody response against the target antigen and, therefore, should be difficult to select for tick-resistant populations. However, sequence variations in the Bm86 locus, among other factors, could affect the effectiveness of Bm86-containing vaccines. In the present study we have addressed this issue, employing data obtained with B. microplus strains from Australia, Mexico, Cuba, Argentina and Venezuela. The results showed a tendency in the inverse correlation between the efficacy of the vaccination with Bm86 and the sequence variations in the Bm86 locus (R2 = 0.7). The mutation fixation index in the Bm86 locus was calculated and shown to be between 0.02 and 0.1 amino acids per year. Possible implications of these findings for the immunoprotection of cattle against tick infestations employing the Bm86 antigen are discussed.

Amino Acid Sequence↗
PubMed2001

Prevalence of vectors of the spotted fever group Rickettsiae and murine typhus in a Bedouin town in Israel.

A survey of the vectors of spotted fever group Rickettsiae and of murine typhus was carried out in Rahat, a Bedouin town in the Negev Desert, where the diseases are endemic. Houses with known cases of spotted fever group Rickettsiae or murine typhus were compared with those without reported clinical cases. A neighboring Jewish community, Lehavim, where no cases of spotted fever group Rickettsiae and murine typhus were reported in recent years, was used as a control. In the houses of patients with spotted fever group Rickettsiae in Rahat, an average of 7.4 times more ticks were found than in control houses. Out of 190 ticks isolated from sheep and goats or caught by flagging in Rahat, 90% were Rhipicephalus sanguineus (Latreille), 7.9% Rhipicephalus turanicus Pomerantzev, and 2.1% were Hyalomma sp. In the houses of patients with murine typhus, three times more rats were caught and, on the average, each rat was infested with 2.2 times more fleas than rats in the control houses. Out of 323 fleas collected from 35 Norwegian rats (Rattus norvegicus Berkenhout), 191 were Xenopsylla cheopis Rothschild and 132 Echidnophaga murina Tiraboschi. Thus, there was a six to seven times higher probability of encountering a tick or flea vector where infections had occurred than in control houses in Rahat. The percentage of rats seropositive to Rickettsia typhi was similar in study and control households (78.3 and 76.2, respectively). In the control settlement, Lehavim, only three Mus musculus L. were caught, which were not infested with ectoparasites and their sera were negative for murine typhus. Out of 10 dogs examined in this settlement, 15 R. sanguineus and eight specimens of the cat flea (Ctenocephalides felis felis Bouché) were isolated. No rats were caught in this settlement. These data indicate that there is a correlation among the density of domestic animals, their ectoparasites, and the incidence of spotted fever group Rickettsiae and murine typhus in Rahat.

Animals↗
PubMed2001

Influence of sheep breed and application site on the efficacy of a flumethrin pour-on formulation against ticks.

The objectives of this study were to determine the influence of application site and sheep breed on the efficacy of a flumethrin (1% m/v) solution for the control of 'bont'-legged (Hyalomma spp.) and red-legged ticks (Rhipicephalus evertsi evertsi). This study was conducted from November 1996 to February 1997 on 3 farms in the southwestern Free State Province. Two trials were conducted on Dorper sheep and 2 on Merino sheep. For each specific application 30 sheep were selected and allocated to 3 groups of 10 animals each using randomisation through minimisation, with pre-treatment total tick count as only criterion. Groups consisted of an untreated control group, a group treated with 3 ml of a flumethrin (1% m/v) solution applied only to the anogenital region, and a group treated at a dose rate of 1 mf flumethrin (1% m/v)/5 kg host body mass. The total dose volume for animals in the last group was divided into 3 equal parts and applied to the brisket/axillae, groin and anogenital regions respectively. Animals grazed under extensive farming conditions and were infested by ticks that occurred naturally in the environment. Ticks were counted and removed weekly over a 6-week period. In all 4 trials, Rhipicephalus e. evertsi was the dominant tick species, followed, in 3 of the trials, by Hyalomma spp. Efficacy (%) of control against ticks for Dorper sheep, treated only on the anogenital region, was variable, ranging between 29.5 and 97%. In Merino sheep the efficacy values ranged between 23.1 and 90 %. The site-spcific (anogenital region) efficacy of control against ticks infesting Merino sheep was in general 100% or almost 100%. In Dorper sheep the efficacy values were >80 % for 3-5 weeks. The efficacy (%) of control against ticks for sheep treated on the brisket/axillae, groin and anogenital regions was always higher compared to sheep treated only on the anogenital region. In Dorper sheep, efficacy of control was >80 % for up to 4 weeks and in Merino sheep >80 % for 6 weeks.

Administration, Topical↗
PubMedDate not supplied

[Structure of parasitic arthropod communities in forest small mammals].

Species composition and structure of ectoparasite arthropod communities were examined all year round six years in the bank vole Clethrionomys glareolus, Ural wood mouse Apodemus uralensis and the common shrew Sorex araneus in forests of the Ilmen'-Volkhov depression. In total, 4500 host samples have been examined and all ectoparasites have been collected. The species composition of ectoparasite community in small mammal species are as follows: the bank vole--29 insect, tick and mite species, the common shrew--23 species, the Ural wood mouse--16 species. In forest biotopes, many temporary ectoparasitic species occur on several host species living in the same habitats under a forest canopy and contacting each other. A parasitic supracommunity in the ecosystem examined has a pool of temporary ectoparasites, which is available for all the community of small mammals. A role of different rodent and shrew species are hosts of insects and ticks changes depending on a density of potential host populations and numerous other environment factors.

Animals↗
PubMed1999

Experimental and field evaluations of two acaracides for control of I. pacificus (Acari: Ixodidae) in northern California.

Use of acaricides for the control of Ixodes pacificus (Cooley & Kohls), the vector of Lyme borreliosis in the western United States, can be a beneficial component in a program to reduce the morbidity of Lyme borreliosis in California. Three commercially available acaricides, carbaryl, chlorpyrifos, and diazinon, were evaluated in laboratory bioassays for their effectiveness against I. pacificus adults. Based on bioassay results, chlorpyrifos and carbaryl were selected for field evaluations. Chlorpyrifos demonstrated the lowest LD50 in the laboratory and the best overall control in the field trials. Chlorpyrifos and carbaryl provided effective control with a residual effect on adult ticks up to 7 wk after a single treatment. A field application timed to coincide with the highest period of adult questing activity proved effective in the control of I. pacificus in a Sierran foothill habitat. Judicious use of either of the acaricides evaluated may help to reduce adult tick densities in a peridomestic environment and thereby reduce the risk of human exposure to Lyme borreliosis and other tick-borne agents.

Animals↗
PubMed2004

Ixodid and argasid tick species and west nile virus.

Control of West Nile virus (WNV) can only be effective if the vectors and reservoirs of the virus are identified and controlled. Although mosquitoes are the primary vectors, WNV has repeatedly been isolated from ticks. Therefore, tick-borne transmission studies were performed with an ixodid (Ixodes ricinus) and an argasid tick species (Ornithodoros moubata). Both species became infected after feeding upon viremic hosts, but I. ricinus ticks were unable to maintain the virus. In contrast, O. moubata ticks were infected for at least 132 days, and the infection was maintained through molting and a second bloodmeal. Infected O. moubata ticks transmitted the virus to rodent hosts, albeit at a low level. Moreover, the virus was nonsystemically transmitted between infected and uninfected O. moubata ticks co-fed upon uninfected hosts. Although ticks are unlikely to play a major role in WNV transmission, our findings suggest that some species have the potential to act as reservoirs for the virus.

Animals↗
PubMed2002

Control of Ixodes scapularis and Amblyomma americanum through use of the '4-poster' treatment device on deer in Maryland.

Deer self-treatment devices ('4-posters') were evaluated for their efficacy in reducing populations of blacklegged ticks, Ixodes scapularis, and lone star ticks, Amblyomma americanum. At each of three locations in Maryland, 25 '4-posters' were operated in study areas of approximately 5.18 km2. Populations of host-seeking ticks were monitored by flagging of treated areas and similar untreated control areas without '4-posters.' From 1998 to 2002 the percent mortalities achieved were 69, 75.8 and 80 at the three study sites infested with I. scapularis nymphs, and 99.5 and 95.3 for A. americanum nymphs at the two sites where this species occurred.

Animals↗
PubMed2004

Evolution of duplicate control regions in the mitochondrial genomes of metazoa: a case study with Australasian Ixodes ticks.

To investigate the evolution pattern and phylogenetic utility of duplicate control regions (CRs) in mitochondrial (mt) genomes, we sequenced the entire mt genomes of three Ixodes species and part of the mt genomes of another 11 species. All the species from the Australasian lineage have duplicate CRs, whereas the other species have one CR. Sequence analyses indicate that the two CRs of the Australasian Ixodes ticks have evolved in concert in each species. In addition to the Australasian Ixodes ticks, species from seven other lineages of metazoa also have mt genomes with duplicate CRs. Accumulated mtDNA sequence data from these metazoans and two recent experiments on replication of mt genomes in human cell lines with duplicate CRs allowed us to re-examine four intriguing questions about the presence of duplicate CRs in the mt genomes of metazoa: (1) Why do some mt genomes, but not others, have duplicate CRs? (2) How did mt genomes with duplicate CRs evolve? (3) How could the nucleotide sequences of duplicate CRs remain identical or very similar over evolutionary time? (4) Are duplicate CRs phylogenetic markers? It appears that mt genomes with duplicate CRs have a selective advantage in replication over mt genomes with one CR. Tandem duplication followed by deletion of genes is the most plausible mechanism for the generation of mt genomes with duplicate CRs. Once duplicate CRs occur in an mt genome, they tend to evolve in concert, probably by gene conversion. However, there are lineages where gene conversion may not always occur, and, thus, the two CRs may evolve independently in these lineages. Duplicate CRs have much potential as phylogenetic markers at low taxonomic levels, such as within genera, within families, or among families, but not at high taxonomic levels, such as among orders.

Animals↗
PubMed1991

Effectiveness of selected granular acaricide formulations in suppressing populations of Ixodes dammini (Acari: Ixodidae): short-term control of nymphs and larvae.

Applications of selected granular acaricide formulations to the shrub layer of forested habitats during the peak activity periods of Ixodes dammini Spielman, Clifford, Piesman & Corwin nymphs and larvae significantly reduced the abundance of these stages on Peromyscus leucopus. The granules effectively penetrated growing vegetation and suppressed populations of subadult ticks questing in the leaf litter. The use of granular acaricide formulations provides the only documented method of control of free-living I. dammini nymphs and larvae in dense vegetation. As such, this technique will serve as a major component of any integrated control program against this vector tick species.

Animals↗
PubMed2005

Effectiveness of Metarhizium anisopliae (Deuteromycetes) against Ixodes scapularis (Acari: Ixodidae) engorging on Peromnyscus leucopus.

With the incidence of Lyme disease increasing throughout the United States, reducing risk of exposure to the disease is of the utmost concern. In the northeastern U.S., the blacklegged tick, Ixodes scapularis, is the primary vector and the white-footed mouse, (Peromyscus leucopus), the primary reservoir for Borrelia burgdorteri, the bacterium causing Lyme disease. Targeting I. scapularis engorging on white-footed mice with an effective biological control agent, such as the fungus Metarhizium anisopliae, could be an effective and relatively safe control technique. In 2002-2003, we performed laboratory and field experiments to determine whether M anisopliae-treated nesting material could effectively control larval I. scapularis ticks engorging on white-footed mice, and therefore reduce the number of infected nymphal I. scapularis questing the following summer. Our laboratory experiment demonstrated a strong negative effect of M. anisopliae-treated nesting material on survival of I. scapularis larvae feeding on P. leucopus, with 75% versus 35% larval mortality in treatment versus control nests. Our field trials caused only modest, localized reductions in nymphal abundance and had no effect on the proportion of nymphal I. scapularis infected with B. burgdorferi. Field results probably could be improved by increasing the density of nestboxes to allow fungal delivery to a higher proportion of the mouse population and by deploying nestboxes in an area with lower mammalian diversity, such as a suburban landscape.

Animals↗
PubMed1991

[Anti-Borrelia burgdorferi antibody in dogs: Lyme disease as zoonosis].

To obtain epidemiological data on human Lyme disease (LD) in Japan, anti Borrelia burgdorferi (Borrelia) antibody was measured in dogs by enzyme-linked immunosorbent assay (ELISA). The anti-Borrelia antibody titer was high in 106 (27.3%) of 387 clinically healthy dogs that may have a chance of tick bite but not in any of 31 negative control dogs not exposed to ticks; the difference of the antibody titer between two groups was significant. However, no signs of arthritis were observed in any of the 106 dogs with a high anti-Borrelia antibody titer. The antibody titer was also significantly differed between the age groups less than 1 year old and 1 year old or more, the group maintained indoors and that maintained outdoors, the group with tick bites and that without tick bites, and hounds and the other dogs but not between males and females or the group vaccinated and that unvaccinated with leptospires. According to districts, high antibody titers were observed in 20% of the dogs or more in Hokkaido, Saitama, Kanagawa, Niigata, Kyoto, Kochi, and Fukuoka Prefectures. These districts were nearly consistent with the distribution of the ticks. Western blot analysis of serum samples with a high anti-Borrelia antibody titer showed 31-, 41-, 66-, and 83-Kd bands, which are also observed in sera of human patients with LD. Though no dog had clinical signs of LD, dogs serologically positive for Borrelia were detected throughout the country. The data suggested that there were the dogs infected by Borrelia burgdorferi in Japan. The data on anti-Borrelia antibody in dogs obtained by ELISA may be very useful for studying the epidemiology of LD in humans.

Animals↗
PubMed2000

Effect of ivermectin on the brown dog tick, Rhipicephalus sanguineus.

Ivermectin (Ivomec) proved to be effective in controlling R. sanguineus. All brown dog ticks infesting the treated dogs (subcutaneous injections) with 1.5 ml or 2 ml/50 kg dropped off within 4 or 3 days respectively. The dropped off ticks were completely inactive and died within one day or two. Ticks exposed to filter papers impregnated with 100 micrograms/ml (66.67%) died within four days. A dose of 1.5-2 microliters/50 kg eradicated Toxocara canis infection in four dogs, and caused shrinkage of Dipylidium caninum gravid segments in three. A general discussion was given with special reference to the contraindications and side effects of ivermectin particularly for human usage.

Animals↗
PubMed2003

Effect of moxidectin against natural infestation of the cattle tick Boophilus microplus (Acarina: Ixodidae) in the Mexican tropics.

The study was divided in to two trials and carried out in a ranch in eastern Yucatan state, Mexico. In the first trial, two groups of 15 BostaurusxBosindicus heifers, 6-12 month of age and naturally infested with Boophilus microplus ticks were used. Heifers in Group 1 were treated with a 1% injectable formulation of moxidectin at the dose of 0.20mg/kg body weight by subcutaneous injection. The other group remained as untreated controls. Number of immature and engorging female ticks were assessed on days 0, 7, 14, 21, 28 and 35 post-treatment (PT). The efficacy of moxidectin on adult ticks from day 7 to 28 PT was greater than 95%. The efficacy decreased to 74.9% by day 35. In the second trial, animals in Group 1 were treated with the moxidectin product as before, while cattle in Group 2 were treated according to the routine procedure for the control of ticks on that property (125 g/l amitraz as a dip). Treatment of all cattle was repeated four times at intervals of 28 days. The efficacy of the experimental moxidectin treatment was similar to that of the routine amitraz treatment, i.e., greater than 99%.

Administration, Topical↗
PubMed1997

Studies on the comprehensive control of babesiasis in cattle and buffaloes.

To obtain a highly effective method for controlling babesiosis in cattle and buffalo, an epidemiological survey was carried out at Zuiyun village in Hubai Province. On the grounds of the epidemiological data, control measures which included preventive drugs and killing the vectors were devised. After two years of control no clinical cases of bovine babesiosis were found. The average number of ticks on cattle or buffalo decreased from 9-282 to 0-11.3. Good results were obtained in another epidemic area using this control method. These results indicated that this technique of controlling babesiosis is highly effective.

Animals↗
PubMed1994

A survey of the incidence and importance of the tick-borne diseases heartwater, redwater and anaplasmosis in the heartwater-endemic regions of South Africa.

In an almost 50% response to a survey questionnaire, farmers in the heartwater-endemic regions of South Africa indicated that they were experiencing losses of 1.3, 0.3 and 0.2% in cattle due to heartwater, redwater and anaplasmosis, respectively. In small stock, the heartwater mortality was 3.8%. Only 35% of cattle farmers and 15% of farmers keeping sheep and goats, vaccinate their animals against heartwater. It would seem that the present vaccine does not control heartwater adequately and, with 9% of farmers claiming poor protection after immunization, it would be difficult to recommend wider use of the heartwater vaccine. Likewise, vaccination against redwater and anaplasmosis on 11.8 and 14.2% of farms, respectively, appears to have had no beneficial effect on the mortality rates of these diseases. Many farmers still believe that very few or no ticks should be seen on cattle. In fact, it would appear that a considerable proportion of farmers find so few ticks on their cattle, that the frequency of acaricidal treatment is in many cases too high. Although there is no correlation between the incidence of heartwater and the intensity of tick control, there is also no serological evidence to support the possibility of an endemically unstable condition. The concept that endemic stability as a means to control heartwater in cattle can be achieved by allowing more ticks on animals, has not yet been established. The overall impression is that farmers do not regard heartwater in cattle as such a serious problem as it is generally believed to be.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

Oxidative stress impairs heme detoxification in the midgut of the cattle tick, Rhipicephalus (Boophilus) microplus.

In the cattle tick Rhipicephalus (Boophilus) microplus digestion of blood is intracellular, accomplished by the so-called digest cells that fill the midgut lumen. Hydrolysis of hemoglobin in the digestive vesicles of these cells results in the release of large amounts of heme, a pro-oxidant compound, whose iron atom, together with H(2)O(2), may participate in the Fenton reaction and lead to the production of hydroxyl radicals. Here, we investigated the role of catalase, an enzyme responsible for H(2)O(2) detoxification. Fully engorged female ticks injected with 3-amino-1,2,4-triazole (AT), a catalase inhibitor, showed increased H(2)O(2) in the gut, together with diminished life span and lower egg-laying rates. Increased mortality observed upon AT injection was reversed by further injection of exogenous catalase, 2 days after AT treatment, confirming that increased death was due to inhibition of this enzyme by AT. In primary cultures of digest cells, intracellular H(2)O(2) is limited to specific organelles, while treatment with AT in vitro resulted in increased H(2)O(2) spreading all over the cell, confirming the role of catalase in regulating H(2)O(2) levels. Ticks fed on a calf that had been injected with AT showed marked inhibition of catalase activity in the gut and diminished life span, oviposition and engorgement. Digest cells of these ticks had an altered morphology, showing heme spread all over the cytosol, instead of being limited to the hemosomes. The amount of aggregated heme found in isolated hemosome was also strongly decreased in AT-treated cattle. All together, our results indicate that catalase performs an important role in the control of redox balance in R. microplus, which dramatically affects hemosome formation and stability. This enzyme may be a target in the development of new methods for tick control.

Amitrole↗
PubMedDate not supplied

[Sensitivity of the females of Ixodes persulcatus and Dermacentor silvarum (Ixodidae) to baytex and the possibility of their overcoming poisoning with this substance].

Females of I. persulcatus and D. silvarum are very sensitive to baytex, the value of LD50 for both species are similar. The development of injury after exposure to baytex proceeds very quickly and the subsequent stages of injury development correspond to those caused by DDT (Uspensky and Levikov, 1974). The overcoming of baytex poisoning during the sucking of the host's blood is possible only at the initial stage of the injury. The simulatneous feeding on the same rabbit of ticks treated with baytex and control ones has shown a system effect of baytex on the second group of ticks.

Animals↗