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PubMed2002

Risk of acquiring tick bites in south-eastern Sweden.

The incidence and the temporal pattern of tick bites were studied in a population frequently out-of-doors in a tick-endemic area in south-eastern Sweden between May 2000 and March 2001. The participants, who were well aware of tick-borne diseases, inspected their skin daily from May until September and completed a diary sheet, registering visited geographical places, time out-of-doors, observed tick bites, etc. The participants were also given questionnaires in both the initial and final stages of the study, asking questions about their earlier history of tick bites, previous tick-borne diseases and out-of-doors activities. The incidence was 0.04 [95% confidence interval (95% CI) 0.02-0.061 tick-bitten participants/10 h spent out-of-doors. In total, the participants registered 1767 tick bites, i.e. an incidence of 0.14 (95% CI 0.10-0.18) tick bites/10 h out-of-doors. Within 6 months after the registration period, 8/235 (3%) had been treated for physician-diagnosed Lyme borreliosis. In conclusion, this study found a 4% risk of being tick-bitten per 10 h spent out-of-doors. The risk of contracting Lyme borreliosis was 1/221 tick bites (0.5%, 95% CI 0.44-0.56). Thus, the results indicate a low risk of acquiring Lyme borreliosis when using daily tick checks and we underline the opinion of not recommending routine prophylactic treatment for observed tick bites.

Adolescent↗
PubMed1997

Enema infusion technique inappropriate for evaluating viral competence of ticks.

To determine whether anal infusion of virus simulates the natural route of infection rather than intracoelomic injection, we compared the course of Venezuelan equine encephalitis (VEE) virus infection in Amblyomma cajennense (F.) ticks that had been exposed to virus by enema infusion with that in ticks fed on a viremic host or exposed by intracoelomic inoculation. Although virus was detected in virtually all ticks 14 d after exposure, orally exposed ticks contained significantly less virus (10(1.9) plaque-forming units [PFU] per tick) than did ticks infected by enema (10(4.1) PFU per tick) or intracoelomically (10(4.2) PFU per tick). At 42 d after virus exposure, only 1% of 512 orally exposed ticks contained virus, but most enema (77%, n = 43) or intracoelomically (79%, n = 29) exposed ticks were infected. Replication of VEE virus in A. cajennense ticks exposed to virus by enema infusion, therefore, appeared more similar to that of ticks inoculated intracoelomically than to those exposed orally. Thus, because enema infusion may bypass potential midgut infection and escape barriers, this procedure may not be appropriate for determining vector competence in ixodid ticks.

Animals↗
PubMed2006

Strategies for development of vaccines for control of ixodid tick species.

Ticks are distributed worldwide and impact human and animal health, as well as food animal production. Control of ticks has been primarily by application of acaricides, which has resulted in selection of resistant ticks and environmental pollution. Vaccines have been shown to be a feasible tick control method that offers a cost-effective, environmentally friendly alternative to chemical control. However, identification of tick-protective antigens remains the limiting step in vaccine development. Tick antigens exposed naturally to the host during tick feeding and those concealed have both shown promise as candidate vaccine antigens. Development of vaccines against multiple tick species may be possible using highly conserved tick-protective antigens or by antigens showing immune cross-reaction to different tick species. Vaccines made from a combination of key protective antigens may greatly enhance vaccine efficacy. Preliminary studies have suggested the possibility of vaccine strategies directed toward both tick control and the blocking of pathogen transmission. Characterization of the tick genomes will have a great impact on the discovery of new protective antigens. The future of research directed toward tick vaccine development is exciting because of new and emerging technologies for gene discovery, and vaccine formulation and delivery.

Animals↗
PubMed2004

Tick immunobiology.

Ticks are of vast medical and veterinary public health importance due to direct damage caused by feeding and their roles in transmitting well known and emerging infectious agents. Ticks and tick-borne pathogens stimulate the immune system of the host. Those immune interactions are of importance in tick biology, pathogen transmission and control of ticks and tick-borne diseases. Both innate and specific acquired immune defenses are involved in the responses of vertebrate hosts to infestation. Ticks have evolved countermeasures to circumvent host immune defenses. This review addresses the immunobiology of the tick-host interface from the perspectives of the pharmacology of tick saliva; relationship of tick saliva to pathogen transmission; host immune responses to infestation; tick modulation of host immune defences; and genomic/proteomic strategies for studying tick salivary gland molecules.

Animals↗
PubMed2004

Biology and control of ticks infesting dogs and cats in North America.

At least 15 different infectious agents and diseases are transmitted or produced by ticks parasitizing dogs and cats in North America. Those infectious agents and diseases are distributed among eight different tick species that commonly infest dogs and cats. All but one of these species are hard ticks with a three-host development cycle in which each motile stage (larva, nymph, and adult) feeds on a different host after molting. Tick species, disease occurrence, and peak activity of each tick life stage can vary dramatically depending on geographic and climatic conditions. Gaining an understanding of tick distribution, tick ecology, and seasonal occurrence of different tick life stages can help with the management of tick infestations and reduce the incidence of tick-transmitted diseases in dogs and cats. Control should be based on an understanding and management of ecologic factors responsible for tick infestations and selection of appropriate acaricides. Occasionally, topical acaricides will appear not to have prevented tick infestations. This lack of control may be real or perceived based on reinfestation rates and/or pet owner expectations of product performance.

Animals↗
PubMed2006

Physiological age of field-collected female taiga ticks, Ixodes persulcatus (Acari: Ixodidae), and their infection with Borrelia burgdorferi sensu lato.

In some studies the prevalence of tick infection (infection rate) and the intensity of infection are negatively correlated with unfed tick age (in the broad sense of this term). However, no special research has been carried out to consider the phenomenon thoroughly. The infection indices of the female taiga ticks, Ixodes persulcatus, infected with Borrelia burgdorferi s.l. were related to tick physiological age, an index that more precisely reflects tick physiological state than the time of tick collection in the field or the duration of tick survival under laboratory conditions. A novel quantitative technique of physiological age determination based on the evaluation of the ratios between sizes of the stable (scutum) and the changing (alloscutum) structures of the tick body was used. The age was estimated in accordance with the classical age-grade scale introduced by Balashov and a more fractional scale determined by the new technique. In total, 131 female ticks were examined for their infection and physiological age, 46 of which were infected with B. burgdorferi s.l. (mean infection rate 35.1%). The minimal intensity of infection was 0.4 bacterial cells per 100 fields of view whereas the maximal infection was 172 cells. There was no difference between the prevalence of infection in ticks of different physiological age. The intensity of infection obviously differed between ticks of different age groups in the scale introduced by Balashov but did not significantly differ between ticks of different age groups according to the fractional age-grade scale. The data concerning the relationships between Borrelia burgdorferi and unfed Ixodes ticks are considered.

Age Factors↗
PubMed2002

Hemolymph proteins in ticks.

In comparison to insects and Crustacea, our knowledge of the predominant hemolymph proteins in ticks is minimal. The hemolymph protein most studied in ticks has been vitellogenin (Vg). Vg is synthesized by the tick fat body after female adults obtain a blood meal, is released into the hemolymph and is absorbed by developing oocytes as vitellin (Vn). Much of what we know about Vg is from studies of Vn. In general, the carbohydrate, lipid and amino acid composition is similar to insects except that in the tick, Vg contains heme, most likely from the digestion of host hemoglobin. In the American dog tick, Dermacentor variabilis, Vg is comprised of two native proteins and seven subunits on SDS-PAGE. Vg has been characterized in five tick species but the amino acid sequence is not yet available. Another predominant hemolymph protein, apparently a carrier protein (CP), has recently been studied in two tick species. This protein is found in the hemolymph of both male and females adults, in adult tissues outside of the hemolymph in some tick species, in coxal fluid of soft ticks and in whole body homogenates from eggs, larvae and nymphs. CP from the hard tick, D. variabilis, contains cholesterol, phospholipids, monoacylglycerides, triacylglycerides, free fatty acids, carbohydrate and heme. Under identical assay conditions, the analogous protein in the soft tick, Ornithodoros parkeri, did not contain heme. CP in the American dog tick consists of two subunits, one of which has 61% identity to the biliprotein, artemocyanin, from the fairy shrimp. CP is identical to a heme-lipoprotein (HeLp) from Boophilus microplus. The exact roles of CP and HeLp have not yet been fully determined, but they apparently are important in heme sequestration and as a storage depot for protein and lipid. Macroglobulin, lectin, antimicrobial, JH binding, JH esterase, and other tick hemolymph proteins are also discussed.

Journal Article↗
PubMed2002

Investigations on the mode and dynamics of transmission and infectivity of Borrelia burgdorferi sensu stricto and Borrelia afzelii in Ixodes ricinus ticks.

Borrelia burgdorferi sensu lato (sl), the agent of Lyme disease, is transmitted to the host during the blood meal of Ixodes ticks. In most unfed ticks, spirochetes are present in the midgut and migrate during blood feeding to the salivary glands, from which they are transmitted to the host via saliva. In the present study, the efficiency of Ixodes ricinus ticks to transmit B. afzelii and B. burgdorferi sensu stricto (ss) and their infectivity for mice were examined in relation to the duration of the blood meal. In addition, we investigated whether these two Borrelia species can penetrate intact skin. Three modes of infection of mice were studied: tick-bite infection, inoculation of tick homogenates, and transcutaneous infection by topical application of tick homogenates on mouse skin. Transmission of B. burgdorferi sl from I. ricinus nymphs to mouse increased with duration of tick attachment. B. afzelii-infected ticks start to transmit infection earlier (< or = 48 h) than B. burgdorferi ss-infected ticks. As previously shown for B. burgdorferi ss in Ixodes scapularis, B. burgdorferi ss and B. afzelii in unfed I. ricinus were noninfectious for mice when tick homogenates were inoculated. However, the inoculation of homogenates of ticks fed for 24 h readily produced infection in mice. Therefore, B. burgdorferi ss and B. afzelii spirochetes are potentially infectious in the tick before natural transmission can occur. None of the mice (n = 33) became infected by transcutaneous transmission when tick homogenates were applied on mouse skin, showing that B. burgdorferi ss and B. afzelii are unable to penetrate intact skin, in contrast to relapsing fever spirochetes. This study also shows that B. afzelii is transmitted by I. ricinus to the host earlier than B. burgdorferi ss and that I. ricinus seems to be a more efficient vector of B. afzelii than B. burgdorferi ss.

Administration, Oral↗
PubMed1994

DNA typing of rickettsiae in naturally infected ticks using a polymerase chain reaction/restriction fragment length polymorphism system.

We used the polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) rickettsial typing system of Regnery and others to rapidly identify rickettsiae in naturally infected ticks. Unlike previously described methods, our PCR assays type rickettsiae directly from tick tissues without first isolating the organisms. We collected 226 adult Dermacentor andersoni ticks in the Bitterroot Mountains of western Montana and analyzed them for possible rickettsial infection by hemolymph test using the Gimenez stain. Thirteen (5.8%) of these ticks were positive by hemolymph test and selected for further analysis using the above PCR/RFLP typing system. The PCR assays performed using the first primer set (RpCS) resulted in amplification of fragments of the predicted size from nine of the 13 hemolymph test-positive tick samples. Only four of these nine tick samples were also positive in similar PCR assays performed with a second primer set (Rr190) that is presumed to be spotted fever group specific. The RFLP analyses of material amplified from these four ticks indicated they were infected with Rickettsia rickettsii (one sample) and R. rhipicephali (three samples). The PCR/RFLP analyses of the five PCR-positive tick samples that were positive only in assays performed with the RpCS primer set indicated that these ticks were infected with R. bellii. The remaining four of 13 hemolymph test-positive tick samples gave negative PCR results with both the RpCS and Rr190 primer sets. Infected hemocytes from these PCR-negative ticks contained organisms of distinctive bacillary morphology that appeared similar to those described previously as long forms, and it is possible that these organisms belong to a genus other than Rickettsia. We also examined established laboratory isolates of tick-borne rickettsiae from different regions of North America to determine whether this typing system produces consistent results. Multiple isolates of R. montana (nine isolates), R. bellii (five isolates), R. rickettsii (Hlp-like) (four isolates), and R. canada (two isolates) were tested and no significant variations in PCR/RFLP patterns were observed between members of the same serotypes. However, among the five isolates of R. rhipicephali tested, two slightly different RFLP patterns were noted. Our results suggest that this PCR/RFLP typing scheme has wide applicability for identifying rickettsiae directly from D. andersoni or D. variabilis tick tissues.

Animals↗
PubMed2006

Prevalence of Borrelia burgdorferi genospecies in Ixodes ricinus ticks from Lublin region (eastern Poland).

The objective of the study was to determine the prevalence rate of 3 Borrelia burgdorferi genospecies in Ixodes ricinus ticks collected from wooded areas of the Lublin region (eastern Poland). A group of 1,813 I. ricinus ticks from 6 districts were examined for the presence of Borrelia burgdorferi sensu lato (B.b.s.l.) by polymerase chain reaction (PCR). Another group of 438 I. ricinus ticks collected from 4 districts were examined for the presence of B.b.s.l. by culture on BSKH liquid medium confirmed by PCR, and for the presence of Borrelia spp. by dark field microscopy (DFM). Borrelia burgdorferi genospecies (Borrelia burgdorferi sensu stricto, Borrelia afzelii and Borrelia garinii) were determined by nested-PCR in 113 ticks lysates showing presence of B.b.s.l. (in PCR or in culture and PCR). 5.4 % of I. ricinus ticks examined by PCR showed the presence of B.b.s.l. DNA. The infection rate was highest in females (12.1 %), lower in males (6.0 %) and the lowest in nymphs (1.7 %) (p < 0.001). The minimum infection rate of I. ricinus ticks with B.b.s.l. determined by culture was 3.4 %, whereas the minimum infection rate of ticks with motile spirochetes morphologically resembling Borrelia spp., determined by DFM, amounted to 11.2 %. The presence of all 3 Borrelia burgdorferi genospecies under investigation was found in ticks collected from 5 out of 6 examined districts. In 81.4 % of infected ticks only single infection with 1 genospecies was observed, while coinfections with 2 or 3 genospecies were detected respectively in 16.8 % and 1.8 % of infected ticks. Borrelia burgdorferi sensu stricto was the dominant genospecies in all examined tick stages and districts, both in single infections and in coinfections, and found in a total of 62.8 % of I. ricinus ticks infected with B.b.s.l. Borrelia afzelii and Borrelia garinii were less frequent and observed in respectively 39.8 % and 17.8 % of infected ticks.

Animals↗
PubMed2003

Identification of Borrelia burgdorferi sensu lato, Anaplasma and Ehrlichia species, and spotted fever group Rickettsiae in ticks from Southeastern Europe.

Prevalence data for tick-borne pathogens are used to assess the risk for human health. In this study the presence and identity of Borrelia burgdorferi sensu lato, Ehrlichia, Anaplasma, and Rickettsia species in Bulgarian Ixodes ricinus ticks and in non- Ixodes ticks from Turkey and Albania was determined by polymerase chain reaction (PCR) and reverse line blot hybridization. In the adult Bulgarian ticks, the prevalence of Borrelia burgdorferi sensu lato infection was approximately 40%, while Borrelia afzelii was the predominant species, representing more than half of all Borrelia-positive ticks. Ehrlichia and Anaplasma species were detected in 35% of the adult Ixodes ricinus ticks and in 10% of the nymphs. Sequence analysis of PCR products reacting with the Anaplasma phagocytophila probe revealed a 16S rRNA gene identical to that of the Anaplasma phagocytophila prototype strain. Ehrlichia and Anaplasma species were found in approximately 7% of the non- Ixodes ticks. Sequence analysis of some of these samples revealed the presence of Anaplasma ovis, Ehrlichia canis, and a species closely resembling Ehrlichia chaffeensis. About half of all adult ticks examined and approximately 20% of all nymphs were infected with Rickettsia species. In Ixodes ricinus ticks, Rickettsia helvetica and a Rickettsia species designated as IRS3 were found in high prevalence. Rickettsia conorii was found in virtually all non- Ixodes tick species from Albania and Turkey. The results of this study show that many tick-borne diseases are most probably endemic in the Balkan area. Furthermore, the results suggest that there is a considerable chance for simultaneous transmission of tick-borne pathogens to human beings.

Albania↗
PubMed2004

Risk factors for tick attachment to smallholder dairy cattle in Tanzania.

A cross-sectional study was conducted in Tanga and Iringa regions of Tanzania, and a longitudinal study in Tanga, to investigate tick-control methods and other factors influencing tick attachment to the cattle of smallholder dairy farms. Most farmers reported applying acaricides at intervals of 1-2 weeks, most used acaricides that require on-farm dilution and most farmers incorrectly diluted the acaricides. Rhipicephalus appendiculatus and Boophilus spp. ticks were those most-frequently encountered on the cattle, but few cattle carried ticks of any species (only 13 and 4.6% of tick counts of the cattle yielded adult R. appendiculatus and Boophilus spp., respectively). Animals were more likely to carry one or more adult Boophilus spp. ticks if they also carried one or more R. appendiculatus adults (OR=14.4, CI=9.2, 22.5). The use of pour-on acaricides was associated with lower odds that animals carried a R. appendiculatus tick (OR=0.29, CI=0.18, 0.49) but higher odds that they carried a Boophilus spp. tick (OR=2.48, CI=1.55, 3.97). Animals >4 months old and those with a recent history of grazing had higher odds of carrying either a R. appendiculatus (ORs=3.41 and 2.58, CIs=2.34, 4.98 and 1.80, 3.71), or a Boophilus spp. tick (ORs=5.70 and 2.18, CIs=2.34, 4.98 and 1.49. 3.25), but zero-grazing management did not prevent ticks attaching to cattle even when combined with high-frequency acaricide treatments. The odds that animals carried ticks varied amongst the agro-ecological zones (AEZs) and administrative districts where the farms were situated-but there was still considerable residual variation in tick infestation at the farm level.

Animal Husbandry↗
PubMed2002

The natural history of ticks.

Ticks have evolved to become one of the most important groups of arthropod vectors of human pathogens. One or more of the approximately 840 known species of ticks are found in most terrestrial regions of the earth. Ticks are a highly specialized group of obligate, bloodsucking, nonpermanent ectoparasitic arthropods that feed on mammals, birds, and reptiles. They are classified into two major families, Ixodidae (hard-bodies ticks) and Argasidae (soft-bodied ticks). The Ixodidae is the largest and most important family. There are many taxonomic keys for identifying ticks to assist the serious investigator. Their life cycles are often complex, and even though ticks are associated with their parasitic habits, ticks spend most of their life off hosts and in vegetation or soil. Maintenance of water balance during periods of overhydration while feeding and periods of dehydration while fasting is significant in the distribution, survival, activity, and transmission of disease-causing pathogens to humans and animals. Ticks attach to skin of the host by using their hypostome as an anchor and create a feeding lesion to ingest blood or tissue fluids. Soft-bodied ticks feed relatively rapidly (hours or less) and ingest only blood. Hard-bodied ticks take days to complete feeding and feed on blood, lymph, and lysed tissues from a pool that forms around the mouthparts. Feeding causes direct damage to the skin of the host. Disease-causing organisms may be ingested or expelled during feeding. Ingestion of relatively enormous quantities of blood is characteristic of ticks.

Animals↗
PubMed2002

Prevention of tick-borne diseases.

Ticks are a part of the landscape where humans live, work, and play. Because ticks carry a wide range of organisms that potentially can cause disease in humans, many studies have focused on ways to reduce risk of these diseases. Ticks have biologically complex interactions with microorganisms and with their vertebrate hosts, on whom they depend for blood meals and survival. To consider ways to reduce the burden of tick-borne diseases in humans, it is necessary to understand the biology and ecology of ticks and their interface with humans. In many areas, changes in land use, reforestation, and patterns of human settlements have led to more abundant tick populations, increasing rates of infections in ticks, and increasing contact with human populations. Warmer winter temperatures in temperate regions may extend the transmission season for some ticks and pathogens. Although much of the discussion in this article has focused on I. scapularis and the Lyme disease spirochete (because they have been studied extensively), other tick-pathogen pairs may differ in risk factors for infection and transmission dynamics. Interventions studied to reduce the burden of tick-borne diseases include changing the environment, controlling vertebrate hosts, killing ticks, altering the behavior of humans, treating tick bites, and trying to protect humans through immunologic means (vaccine). All of these approaches have limitations and drawbacks. From a public health perspective, a plan that employs multiple strategies may be most effective. This article has reviewed what is known about preventive interventions, including the vaccine.

Animals↗
PubMed1991

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.

Animals↗
PubMed1999

Population dynamics of ticks on indigenous cattle in a pastoral dry to semi-arid rangeland zone of Uganda.

Studies on seasonality and population dynamics of ticks on indigenous cattle and their crosses (calves) were carried out in Buruli Ranching Scheme, Nabiswera, Luwero district of Uganda on three treatment groups of animals: group 1 (twice a week dipping), group 2 (once a month dipping) and group 3 (no tick control). During this study, four major species of ticks of economic importance were recorded in decreasing order of abundance: Rhipicephalus appendiculatus, Rhipicephalus evertsi evertsi, Amblyomma variegatum and Boophilus decoloratus. Of these ticks, a seasonal pattern of activity was only observed in R. appendiculatus ticks, with peak activities occurring during rainy seasons. Greater numbers of ticks were recorded on cows than calves in the three treatment groups, with the exception of A. variegatum where the reverse occurred. The mean numbers of ticks per animal were highly significantly different (p < 0.01) when group 1 animals were compared with group 2 and 3 animals. However, no significant differences (p > 0.05) were observed in mean tick numbers between group 2 and 3 animals. Highly significant differences (p < 0.01) were observed in mean tick numbers on cows and calves (more than 12 months old) in different calving seasons. The state of lactation only affected tick counts on cows in group 1; significantly more ticks (p < 0.01) were observed in lactating than non-lactating cows. Furthermore, significantly greater (p < 0.05) numbers of ticks (with the exception of B. decoloratus) were recorded during the second year of study (March 1992-May 1993) than the first year (January 1991-February 1992), despite lower rainfall during the former period.

Animals↗
PubMed1998

Individual host variations in tick infestations of cattle in a resource-poor community.

Relative resistance levels of cattle against tick infestations in the communal grazing area of Botshabelo in the south-eastern Free State were determined. The objective was to establish whether differences in resistance can be exploited to contribute to tick control methods used by small-scale farmers in resource-poor environments. Ten cows (Bos taurus crosses) between the ages of 18 months and four years were used and tick counts were conducted once a month over a period of 12 months to compare their total tick burdens. Tick burdens of the various animals were compared mutually as well as with the mean tick burden of the group as a whole. Tick numbers varied throughout the year on all individuals but some animals consistently tended to have either higher or lower numbers than the mean of the group. Tick burdens on cattle classified as having a relatively low resistance to tick infestations increased eleven-fold from January to June 1996 compared to a six-fold increase on cattle categorized as belonging to the high resistance group. Twenty-eight percent of the cattle in the total study group carried 50% of the ticks collected (60,079). It is recommended that farmers in the region visually assess B. decoloratus burdens, the most abundant tick species, and sell or cull the most susceptible animals first in their normal program of utilization of the animals. This should eventually result in the direct improvement of the overall tick resistance of their cattle herds.

Analysis of Variance↗
PubMed1997

Use of the polymerase chain reaction for identification and quantification of Theileria parva protozoa in Rhipicephalus appendiculatus ticks.

The polymerase chain reaction (PCR) was adapted for detection of Theileria parva sporoblasts in Rhipicephalus appendiculatus ticks by comparison with staining of histological preparations of ticks with methyl green and pyronin (MGP). Two 32mer primers (IL174 and IL179) were used to amplify Theileria parva (Muguga isolate) DNA from the TPR 1 region of the genome by the PCR. Detection of T. parva was carried out with dissected salivary glands and whole ticks preserved in ethanol. Adult ticks which fed as nymphs on a T. parva infected calf were used in three experiments. Firstly, 70 whole ticks divided into 7 batches representing the rising and falling parasitaemia of the calf were used to show that detection of infection by the PCR was significantly correlated with MGP staining. Secondly, 120 dissected ticks were used from 4 different batches representative of the overall infection profile within the ticks to show a high correlation between PCR quantification within tick salivary glands and MGP count data of the paired gland. Thirdly, 120 ticks were used in batches selected for high and low infections. Bloodmeal contaminants from partially fed adult ticks, present in 60 out of the 120 ticks used, did not inhibit the PCR amplification of T. parva DNA. This experiment also showed a great increase in infection detection in partially fed batches of ticks compared to the untreated batches.

Animals↗