Reduction In Number Of Ticks Research Articles

Anti-tick and pathogen transmission blocking vaccines.

Ticks and tick-borne diseases are a challenge for medical and veterinary public health and often controlled through the use of repellents and acaricides. Research on vaccination strategies to protect humans, companion animals, and livestock from ticks and tick-transmitted pathogens has accelerated through the use of proteomic and transcriptomic analyses. Comparative analyses of unfed versus engorged and uninfected versus infected ticks have provided valuable insights into candidates for anti-tick and pathogen transmission blocking vaccines. An intricate interplay between tick saliva and the host's immune system has revealed potential antigens to be used in vaccination strategies. Immunization of hosts with targeted anti-tick vaccines would ideally lead to a reduction in tick numbers and prevent transmission of tick-borne pathogens. Comprehensive control of tick-borne diseases would come from successful anti-tick vaccination, vaccination preventing transmission of tick-borne diseases or a combination. Due to the close interaction with wildlife and ticks, with wildlife reservoirs enabling propagation of pathogens between ticks, the vaccination of these reservoirs is an attractive target to reduce human contact with ticks and tick-borne diseases through a one-health approach. Wildlife vaccination presents formulation and regulatory challenges which should be considered early in the development of reservoir-targeted vaccines.

A combination of antibodies against Bm86 and Subolesin inhibits engorgement of Rhipicephalus australis (formerly Rhipicephalus microplus) larvae in vitro

BackgroundRhipicephalus microplus is a hard tick species that has a high impact on cattle health and production in tropical and subtropical regions. Recently, ribosomal DNA and morphological analysis resulted in the reinstatement of R. australis as a separate species from R. microplus. Both feed on cattle and can transmit bovine pathogens such as Anaplasma and Babesia species. The current treatment with acaricides is becoming increasingly less effective due to the emergence of resistant tick strains. A promising alternative can be found in the form of anti-tick vaccines. The available commercial vaccines can be used to control tick infestation, but the lack of a knockdown effect (> 90% reduction in tick numbers as seen with effective acaricides) hampers its widespread use, hence higher efficacious vaccines are needed. Instead of searching for new protective antigens, we investigated the efficacy of vaccines that contain more than one (partially) protective antigen. For screening vaccine formulations, a previously developed in vitro feeding assay was used in which R. australis larvae are fed sera that were raised against the candidate vaccine antigens. In the present study, the efficacy of the Bm86 midgut antigen and the cytosolic Subolesin (SUB) antigen were evaluated in vitro.ResultsAntiserum against recombinant Bm86 (rBm86) partially inhibited larval engorgement, whereas antiserum against recombinant SUB (rSUB) did not have any effect on feeding of larvae. Importantly, when larvae were fed a combination of antiserum against rBm86 and rSUB, a synergistic effect on significantly reducing larval infestations was found. Immunohistochemical analysis revealed that the rBm86 antiserum reacted with gut epithelium of R. australis larvae, whereas the antiserum against rSUB stained salivary glands and rectal sac epithelium.ConclusionsCombining anti-Bm86 and anti-subolesin antibodies synergistically reduced R. australis larval feeding in vitro. Rhipicephalus australis is a one host tick, meaning that the larvae develop to nymphs and subsequently adults on the same host. Hence, this protective effect could be even more pronounced when larvae are used for infestation of vaccinated cattle, as the antibodies could then affect all three developmental stages. This will be tested in future in vivo experiments.

Avaliação da eficácia de produtos isoterápicos no controle de Rhipicephalus (Boophilus) microplus

RESUMO O Rhipicephalus (Boophilus) microplus é responsável por consideráveis perdas na pecuária brasileira. O controle desse parasita tem sido feito, principalmente, com o uso de carrapaticidas, sendo os isoterápicos uma alternativa para seu combate. Objetivou-se neste trabalho analisar a eficiência da utilização da isopatia como ferramenta de controle alternativo do carrapato-do-boi. Foram utilizadas 18 fêmeas bovinas de raça europeia, mantidas em sistema de pecuária extensiva, no município de Canguçu, Rio Grande do Sul. Os animais foram divididos em grupo controle (Lote A) e grupo tratado com isoterápico (Lote B). O sal mineral foi utilizado como veículo para a administração da isopatia, sendo que o Lote A recebeu sal mineral com placebo (açúcar) e o Lote B sal mineral com isopatia. Os animais foram infestados artificialmente com 10 mil larvas deR. (B.) microplus , e no 20º, 21º e 22º dias pós-infestação, foram realizadas contagem e coleta de fêmeas ingurgitadas. As teleóginas de cada lote foram divididas ao acaso em nove grupos de dez indivíduos para análise dos parâmetros biológicos e posterior cálculo do Índice Nutricional e Índice de Eficácia Reprodutiva. Para comparação da média de teleóginas de cada grupo, foi empregada análise de variância e Teste LSD. Os bovinos tratados com isopatia apresentaram uma redução de 53,4% do número médio de teleóginas, quando comparados com o grupo não tratado (p = 0,001). Quanto aos padrões biológicos, não houve diferença estatística. Conclui-se que o uso de isopatia foi capaz de reduzir a infestação de R.(B.) microplus , mostrando-se uma alternativa promissora para o controle deste ixodídeo.

Acaricidal Treatment of White-Tailed Deer to ControlIxodes scapularis(Acari: Ixodidae) in a New York Lyme Disease-Endemic Community

The efficacy of topically treating white-tailed deer with an acaricide was evaluated in a Lyme disease-endemic community of southern New York State. Twenty-four 4-Poster feeders were placed in a 5.2 km(2) treatment area in Bedford, NY, while a site in Lewisboro, NY, 4.8 km distant, served as control. Treatment periods ran from 15 September to 15 December each fall from 1997 to 2001, and from 15 March to 15 May each spring from 1998 to 2002. Corn consumption averaged 15,779 kg in fall sessions and 9054 kg in spring sessions, and a mean of 89.6% of deer in the study area showed evidence of using the feeders. Deer densities, estimated by aerial snow counts, averaged 22 and 28 deer per km(2) in Bedford and Lewisboro, respectively, over a 3-year period. Significant reductions in tick numbers on deer captured in the treatment area were noted in fall 1999 compared to deer captured at the control site. Drag sampling for nymphal host-seeking ticks indicated 63.6% control in 2001, which dropped to 54.8% the following year, but reached 80% in 2003. Higher-than-normal acorn production in 2001 that likely caused a drop in deer visitation to the feeders may have reduced efficacy against larval ticks in 2002. The 4-Poster effectively reduced the density of Ixodes scapularis, though the level of control is dependent on environmental factors that affect feeding behavior of white-tailed deer.

Evaluation of the efficacy and safety of a novel formulation of metaflumizone plus amitraz in dogs naturally infested with fleas and ticks in Europe

The efficacy and safety of a novel spot-on formulation of metaflumizone plus amitraz (ProMeris ®/ProMeris Duo ® for Dogs, Fort Dodge Animal Health, Overland Park, KS) was assessed in dogs naturally infested with ticks and/or fleas in a multiregional, clinical field study. Nineteen veterinary clinics in Germany and 11 clinics in France enrolled patients to the study. One hundred eighty one dogs with tick infestation and 170 dogs with flea infestation (plus three dogs harboring both ticks and fleas) qualified as primary patients and were randomly allocated to one of two treatments in a ratio of approximately 2:1 for metaflumizone plus amitraz (minimum dosage of 20 plus 20 mg/kg) or fipronil (at the recommended label rate). Clinical examinations and baseline parasite counts were performed on Day 0 prior to treatment. Tick and/or flea counts and safety evaluations were repeated at intervals of about 2 weeks for 8 weeks. Both products resulted in consistent reductions in tick numbers (>81%) throughout the study, with metaflumizone plus amitraz giving consistently higher reductions in tick numbers. The efficacy against tick count compared with Day 0 was 97.6%, 93.5%, 89% and 94% at Day 14, 28, 42 and 56, respectively, for metaflumizone plus amitraz. The corresponding efficacies for fipronil were 86.3%, 81.1%, 84.8% and 86.1%. Within groups, the tick reduction was highly significant ( P < 0.0001) compared to baseline at all observation periods. Both treatments resulted in consistent (>89%) and highly significant ( P < 0.0001) reductions in flea numbers relative to the baseline counts throughout the study, although fipronil resulted in numerically higher reductions on each count day. The efficacy against fleas compared to baseline was 91.8%, 88.7%, 91.5% and 92.0% at Day 14, 28, 42 and 56, respectively, for metaflumizone plus amitraz. The corresponding efficacies for fipronil were 98.2%, 96.3%, 95.9% and 96.7%. Metaflumizone plus amitraz was highly effective in controlling existing infestations of fleas and ticks on dogs and was effective against reinfestation for at least 56 days. Metaflumizone plus amitraz showed a good tolerance profile in dogs.

Thermal characteristics of Metarhizium anisopliae isolates important for the development of biological pesticides for the control of cattle ticks

Experiments were conducted to determine if Metarhizium anisopliae isolates which are capable of growth at cattle surface temperatures could produce pathogenicity to Boophilus microplus in laboratory and field studies. The diurnal temperature fluctuation on the surface of cattle was monitored. The temperature tolerance of M. anisopliae isolates (ARSEF3297 and IMI386697) was determined and their pathogenicity to B. microplus compared at a standard bioassay temperature (28 °C) and at a temperature similar to the cattle surface (31–35 °C). The effect of the two isolates on the B. microplus population on cattle under field conditions was determined. The temperature of the fore udder, rear udder, ribs and neck regions of the mixed Holstein cattle fluctuated between 30 and 35 °C, in a similar pattern to the prevailing environmental temperature. However, wider fluctuations were obtained on the ears (28–35 °C) and spine (30–41 °C). The colony radius of both isolates declined as temperature increased, however, the growth of IMI386697 was five times greater than ARSEF3297 at 34 °C. At 28 °C, the pathogenicity of both isolates to B. microplus was similar, however, at 31–35 °C, IMI386697 was more pathogenic than ARSEF3297. Both isolates reduced the B. microplus population on cattle in comparison to the control formulation. However, IMI386697 (8.5 ± 0.64 ticks/animal) produced a greater reduction in tick numbers than ARSEF3297 (19.1 ± 0.64 ticks/animal). M. anisopliae was re-isolated from 8.9% of the ticks collected from IMI386697 treated cattle as compared to 2.8% of ticks from ARSEF3297 treated cattle.

Eprinomectin pour-on for control of Boophilus microplus (Canestrini) ticks (Acari: Ixodidae) on cattle

The efficacy of a commercial pour-on formulation of eprinomectin, a macrocyclic lactone, against experimental infestations of Boophilus microplus (Canestrini) ticks was evaluated in two trials involving 27 Bos taurus calves. The first trial was designed to evaluate the effects of a single treatment at a dose of 0.5 mg/kg of body weight against standard size B. microplus females (4.5–8.0 mm long). A significant reduction in tick numbers ( P < 0.05, Wilcoxon test) was observed between treated calves as compared to untreated ones from Day 3 (44% efficacy) after treatment to the end of the trial on Day 28 (96.9%), with a peak efficacy of 97.1% on Day 21. In the second trial the effect of eprinomectin on standard size tick numbers, engorgement weight and fertility of female ticks from calves with a single treatment dose of 1 mg/kg on Day 0 and calves treated twice at a dose of 0.5 mg/kg on Days 0 and 4 was evaluated. An efficacy >93% was obtained from Day 2 to Day 28 after treatment in calves treated twice at 0.5 mg/kg, and to the end of the trial (Day 35) in calves treated once with 1 mg/kg. The 1 mg/kg treatment provided >98% residual efficacy for at least 7 days. During the first part of the second trial the efficacy of eprinomectin resulted from a dramatic adverse effect on engorgement weight and fertility of female ticks, with 100% control on Day 5 (dosage of 1 mg/kg) and on Days 6 and 7 (two doses of 0.5 mg/kg). Following Day 7, most of the effect was due to reduction in the number of standard size female ticks.

Disease reservoirs in complex systems: a comment on recent work by Laurenson et al.

L.), anda vector of the louping-ill virus. They go on to showthat a reduction in hare density was coincident with areduction in tick numbers, a reduction in louping-illseroprevalence in grouse and an increase in grousebreeding success. They concluded that, in the presenceof mountain hares, ‘it may not be possible to take largeharvests of red grouse’, and make moorland manage-ment for grouse uneconomic. Their case for mountainhares being important in the persistence of louping-illis weakened by the lack of a rigorous experimentaldesign but, moreover, they have failed to demonstratethat the removal of mountain hares has any effect onthe potential harvest of red grouse, making their con-clusions unreliable. We argue that the impact of loupingill on grouse dynamics, and the role that hares play inthis, needs further investigation before any firm con-clusions can be drawn or recommendations made forgrouse-moor management with respect to the cullingof mountain hares.

Reduction in tick numbers ( Haemaphysalis longicornis), mortality and incidence of Theileria sergenti infection in field-grazed calves treated with flumethrin pour-on

The effectiveness of the pour-on formulation of flumethrin was tested on grazing cattle. Flumethrin was applied once a month from April to October from 1990 to 1995 to cattle grazing in the Aso area of Kumamoto Prefecture in Japan. Both the number of ticks in the field and the number of ticks feeding on cattle decreased remarkably in relation to the number of years flumethrin was applied. Ticks in the field were not detected in 1994 and 1995, and ticks feeding on cattle decreased to 4% in 1995. Mortality due to Theileria sergenti infection also decreased significantly after more than 3 years of flumethrin pour-on application, although overall mortality did not change. At the end of the trial the incidence of T. sergenti had decreased to one-fifth of the pretrial value, although total incidence of disease had not changed. These results indicated that multiple-year seasonal application of flumethrin pour-on to grazing cattle effectively decreased the number of ticks and decreased both mortality and incidence of T. sergenti.

Evaluation of TickGARD PLUS, a novel vaccine against Boophilus microplus, in lactating Holstein–Friesian cows

The effects of vaccination with the Bm 86 vaccine TickGARD PLUS against infestation with cattle tick ( Boophilus microplus) and of holding cattle on a feedpad until 09:00 hours after the morning milking was tested on 40 mid lactation Holstein cattle using a factorial design. Vaccination resulted in a 56% reduction in tick numbers in the field over one generation, and a 72% reduction in laboratory measures of the reproductive efficiency of ticks. The liveweight gain of vaccinated cattle over 27 weeks was 18.6 kg higher than that of controls, and vaccinated cattle tended to have lower somatic cell count in milk (SCC). There were no other significant differences in measures of production. Cattle kept on the feedpad after the morning milking carried 26% more ticks than those returned immediately to their paddocks.

Control of Ticks

A number of different acaricides provide highly effective control of tick populations on dogs and cats. These acaricides are formulated as sprays, dips, dusts, or shampoos for use on the animal. Further protection of the animal from reinfestation with ticks can be achieved with the use of acaricide-impregnated flea and tick collars. Some of these acaricides are registered with the EPA for indoor and outdoor use as controls for free-living populations of ticks. Caution should be used when applying these materials. The label directions for the application of the acaricide and disposal of the acaricide containers should always be followed. Removal of underbrush and leaf litter, thinning trees, and frequently mowing grasses help reduce the number of free-living ticks. Any reduction in the amount of wildlife food sources and cover areas potentially decreases populations of ticks and thus reduces the potential of these ticks parasitizing a dog or cat. Application of an acaricide for area-wide control of free-living ticks in the spring, summer, and autumn also reduces the number of ticks. New approaches to area-wide control of ticks by use of acaricides that are focused on controlling the ticks attached to small mammal hosts are discussed. Although research has shown that reductions in tick numbers can be achieved using these methods, acceptance of these methods by regulatory agencies and the public requires further research.

Failure of White-Tailed Deer, Odocoileus virginianus L., to Sustain a Population of Cattle Ticks, Boophilus annulatus (Say), through Successive Generations

Cattle ticks, Boophilus annulatus (Say), previously reared only on cattle, were placed on 3 white-tailed deer, Odocoileus virginianus L. Ticks were maintained through successive generations solely on the same deer as they aged (3, 6, and 9 mo of age) and received repeated challenges (0, 1, and 2 previous challenges). Cattle were infested simultaneously to assess tick viability and provide a comparison of tick numbers, female weight, egg mass weight, and egg hatch. The initial infestation (3,000 larvae/animal) produced a mean of 12.7 and 506.7 females from deer and cattle, respectively. Ticks recovered from deer weighed less, laid smaller egg masses, and had lower egg hatchability than cattle-reared ticks. A second infestation (3,000 larvae/animal) produced a 6.3-fold reduction in tick numbers on deer (means = 2.0 females/deer), whereas the number on cattle increased (means = 578.0 females/calf). Ticks reared on the deer were again smaller, laid fewer eggs, and had lower egg hatch, although differences were not significant. A third infestation of deer (1,900 larvae/deer) produced only 1 engorged female tick and no viable eggs, thus eliminating the population of deer-reared ticks within 3 generations. Results of the study suggest that a population of B. annulatus will not be sustained indefinitely through time solely on deer; thus, efforts to reduce deer populations severely as a means of eradicating ticks are unnecessary.

Effects of the Gulf Coast tick on blood composition and weights of drylot Hereford steers.

Light weight Hereford steers in a drylot situation when fed a standard ration were infested at 2 levels with Amblyomma maculatum Koch. The effects of high and low tick infestations on the blood composition and weights of the steers were compared with values measured in tick-free animals over a period of 7 weeks. Significant changes occurred in animal weights between treatment groups. High infested animals were 24 kg lighter than control animals at the end of the study whereas low infested animals were 14 kg lighter. Significant increases occurred in the blood parameters of total serum protein, serum globulin, the alpha, beta, and gamma globulin fractions, and plasma fibrinogen values over the course of the study in both infested groups of animals as compared with tick-free animals. Also, in high infested cattle, significant decreases occurred in the total leukocyte cell counts over the study as compared to the other 2 groups. In both groups of tick-infested cattle, decreases occurred over time in the numbers of ticks which attached. The possible causes for these reductions in tick numbers and the changes in animal weights and blood composition are discussed.

Control of the Lone Star Tick on Cattle1

The following treatments sprayed onto cattle gave > 90% reduction of adult lone star ticks, Amblyomma Americanum (L.), at 1 day posttreatment compared with numbers on untreated cattle: 0.25% Banol® (6-chloro-3,4-xylyl methylcarbamate); 0.05-0.25% Bay 39007 ( o -isopropoxyphenyl methylcarbamate); 1% bromophos; 0.5% carbaryl; 0.3% Ciodrin®( alpha -methylbenzyl 3-hydroxycrotonate dimethyl phosphate) ; 0.1% Compound 4072 (2-chloro-l-(2,4-dichlorophenyl) vinyl diethyl phosphate); 0.25% coumaphos; 0,03% diazinon (EC); 0.025-0.1% Dursban® ( O , O- diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate); 0.125-0.25% Imidan® ( O, O -dimethyl S -phthalimidomethyl phosphorodithioate); 0.1-0.5% Shell SD-8447 (2-chloro-1-(2,4,5-trichlorophenyl)vinyl dimethyl phosphate); 0.1% Shell SD 8448 (2-chloro-1-(2,4,5-trichlorophenyl)vinyl diethyl phosphate); 1% trichlorfon; and 0.5% toxaphene (the standard treatment). Treatments giving less than 90% reduction were: 0.1% Banol; 0.1-0.25% Bay 37341 ( O , O -diethyl O -[4-(methylthio)-3,5-xylyl] phosphorothioate); 0.375% bromophos; 0.25% bromophos-ethyl; 0.05% carbophenothion; 0.03% diazinon (wp); 0.1% Dowco® 175 (2,4-dichlorophenyl propyl methylphosphoramidate); 0.01% Dursban; 0.1% fenthion; 0.1% Imidan; and 0.5% menazon. At 1 week posttreatment, the following sprays gave reduction equal to or greater than the 64% reduction given by 0.5% toxaphene: 0.25% Bay 37341,0.1% Bay 39007, 0.5% carbaryl, 0.1% Compound 4072, 0.25% coumaphos, 0.1% Dowco 175, 0.05% Dursban, 0.1 and 0.25% Imidan, 0.1% Shell SD-8448, and 1% trichlorfon. At 2 weeks posttreatment, all treatments except 0.25% coumaphos gave little or no reduction in number of ticks. A pouron of 2% Bay 37341 at 1 oz per cwt gave only 39% reduction at 1 day posttreatment, whereas a pouron of 8% trichlorfon at ½ oz per cwt gave 72% reduction at 1 day and 44% reduction at 1 week posttreatment.