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PubMed2006

Babesia spp. identified by PCR in ticks collected from domestic and wild ruminants in southern Switzerland.

Concurrent infections with vector-borne pathogens affected a cattle herd in Switzerland, and one of the pathogens was identified as Babesia bigemina, which had never been observed in this country before. Therefore, a survey of the occurrence of ruminant Babesia spp. and their tick vectors in Switzerland was conducted. A total of 2,017 ticks were collected from sheep, goats, cattle, and wild ruminants (deer, roe deer, and chamois) in southern parts of Switzerland and identified morphologically. The vast majority of the ticks (99.2%) were Ixodes ricinus, but 14 ticks from sheep and goats were identified as Dermacentor marginatus and two ticks from wild ruminants were identified as Hemaphysalis punctata. PCR analyses of 700 ticks revealed the presence of Babesia divergens (n = 6), Babesia sp. genotype EU1 (n = 14), and B. major (n = 2), whose suggested occurrence was confirmed in this study by molecular analysis, and the presence of novel Babesia sp. genotype CH1 (n = 4), which is closely related to B. odocoilei and to Babesia sp. genotype RD61 reported from North America. The identification of B. divergens and B. major in ticks collected from wild ruminants cast doubt on the postulated strict host specificity of these bovine Babesia species. Furthermore, the zoonotic Babesia sp. genotype EU1 was detected in ticks collected from domestic animals but was obtained predominantly from ticks collected from wild ruminants. More than one tick containing DNA of different Babesia spp. were collected from two red deer. Hence, the role of these game animals as reservoir hosts of Babesia spp. seems to be important but requires further investigation.

Animals↗
PubMed2003

Detection of Ehrlichia spp., Anaplasma spp., Rickettsia spp., and other eubacteria in ticks from the Thai-Myanmar border and Vietnam.

A total of 650 ticks, including 13 species from five genera, were collected from animals, from people, or by flagging of the vegetation at sites on the Thai-Myanmar border and in Vietnam. They were tested by PCR to detect DNA of bacteria of the order RICKETTSIALES: Three Anaplasma spp. were detected in ticks collected in Thailand, including (i) Anaplasma sp. strain AnDa465, which was considered a genotype of Anaplasma platys (formerly Ehrlichia platys) and which was obtained from Dermacentor auratus ticks collected from dogs; (ii) Anaplasma sp. strain AnAj360, which was obtained from Amblyomma javanense ticks collected on a pangolin; and (iii) Anaplasma sp. strain AnHl446, which was closely related to Anaplasma bovis and which was detected in Haemaphysalis lagrangei ticks collected from a bear. Three Ehrlichia spp. were identified, including (i) Ehrlichia sp. strain EBm52, which was obtained from Boophilus microplus ticks collected from cattle from Thailand; (ii) Ehrlichia sp. strain EHh324, which was closely related to Ehrlichia chaffeensis and which was detected in Haemaphysalis hystricis ticks collected from wild pigs in Vietnam; and (iii) Ehrlichia sp. strain EHh317, which was closely related to Ehrlichia sp. strain EBm52 and which was also detected in H. hystricis ticks collected from wild pigs in Vietnam. Two Rickettsia spp. were detected in Thailand, including (i) Rickettsia sp. strain RDla420, which was detected in Dermacentor auratus ticks collected from a bear, and (ii) Rickettsia sp. strain RDla440, which was identified from two pools of Dermacentor larvae collected from a wild pig nest. Finally, two bacteria named Eubacterium sp. strain Hw124 and Eubacterium sp. strain Hw191 were identified in Haemaphysalis wellingtoni ticks collected from chicken in Thailand; these strains could belong to a new group of bacteria.

Anaplasma↗
PubMed2002

Ticks parasitizing dogs in northwestern Georgia.

From January 1998 through September 1999, 324 dogs in three northwestern Georgia counties were examined for ticks. Six species of ticks were recovered. The three most commonly collected ticks were the American dog tick, Dermacentor variabilis (Say) (310 male male, 352 female female; prevalence, 97%; mean intensity 2.1); the brown dog tick, Rhipicephalus sanguineus (Latreille) (118 male male, 119 female female, 38 nymphs; prevalence, 22%; mean intensity, 3.8); and the lone star tick, Amblyomma americanum (L.) (8 male male 26 female female, 2 nymphs; prevalence, 5%; mean intensity, 2.4). Other ticks recovered were Ixodes cookei Packard (3 female female); the Gulf Coast tick, Amblyomma maculatum Koch (2 female female); and the blacklegged tick, Ixodes scapularis Say (1 female). Another adult female specimen of I scapularis was recovered from a cat, further reinforcing that this medically important tick is present in northwestern Georgia.

Animals↗
PubMed2001

Factors affecting the virulence of entomopathogenic nematodes to engorged female Boophilus annulatus ticks.

The laboratory trials rank the virulence of entomopathogenic nematode strains (3 heterorhabditids and 6 steinernematids) to engorged female Boophilus annulatus ticks according to 3 parameters of the infection process: the effect of exposure time on tick mortality, the quantity of nematodes that penetrate ticks, and the rate of tick mortality after the injection of 1, 2, or 3 nematodes. Exposure of the ticks to heterorhabditid strains for 6 hr resulted in >80% mortality, but only 20 or 65% mortality after exposure to most steinernematids. The quantity of nematodes recovered per tick exposed to nematodes for 6 days averaged from 16 to 141. For steinernematids, a negative correlation was obtained between tick mortality and the average quantity of nematodes recovered. Injecting 1 infective juvenile from 1 of 2 heterorhabditid strains into each tick resulted in close to 100% mortality. Increasing the quantity of nematodes injected into each tick had little or no additive effect on tick mortality.

Animals↗
PubMed1982

Antibody- and cell-mediated immune resistance by guinea pigs to adult Amblyomma americanum ticks.

Naive and actively and passively sensitized guinea pigs were infested with adult Amblyomma americanum ticks. Naive hosts allowed for 75-81% tick yield, 518-581 mg mean tick weight and an average tick feeding period of 12-13 days. Actively sensitized and challenged hosts, however, allowed only 47% tick yield (38.9% rejection), replete individuals were significantly reduced in weight (66.1% weight decrease) and required slightly longer time to feed (14 days). Passively sensitized hosts were given either serum or peritoneal exudate cells (PEC) harvested from actively sensitized and challenged guinea pigs which had expressed resistance. Recipients of immune serum allowed 56% tick yield (27.3% rejection), replete individuals had a mean weight of 376 mg (35.3% reduction) and required an average feeding period of 15 days. However, recipients of immune PEC were conferred with stronger protection allowing only 50% tick yield (35.1% rejection) with a mean tick weight of 413 mg (28.9% reduction) and females required an average feeding period of 15 days to become replete. Cutaneous cellular responses to tick feeding in naive animals were dominated by neutrophils in both female and male attachment sites (62-64%), with the cellular response (lesion) in female sites being 10 times that of male sites. In actively sensitized and challenged (resistant) hosts, cutaneous cellular responses to both females and males were dominated by basophils (53-59%), and lesion size was nearly 20 times greater than in primary feedings, indicating heightened sensitivity to tick bite.

Animals↗
PubMedDate not supplied

[Tick-borne encephalitis in Europe (author's transl)].

Tick-borne encephalitis is the major european arbovirosis. It is observed in Soviet Union, Central and Western Europe and Scandinavian countries. In France, natural foci have been detected in Alsace (more specialy in Illkirch forest, near Strasbourg). In the United Kingdom exists a sheep encephalomyelitis (loupingill) caused by an arbovirus not much different from the tick-born encephalitis virus. The tick-born encephalitis virus is a flavivirus transmitted by tick bites. Tick is also a virus reservoir; it remains infected all along its life, through its metamorphosises and transmits the virus to its progeny. Vector-ticks belong to various species of a same genus; Ixodes persulcatus in Far-Eastern Soviet Union, Ixodes ricinus in other european foci. Small rodents (field-mouse, vole) are mainly the prime vertebrate hosts. Man is more often infected by the tick bite, more rarely by ingestion of new milk from infected domestic animals. Prognosis of the disease is under geographical variations: severe in Far-Eastern Russia and much milder in Central Europe. Natural foci are detected by serological surveys in patients recovering from neurologic diseases, human populations and in domestic animals. Natural foci beeing localized, isolation and identification of the virus from ticks and local rodents are tried. Extension and creation of new natural foci are caused by big mammalians and by migratory birds which carry over virus and vector ticks. Prophylaxis for people going to or living in registered natural foci, consists of avoiding ticks bites by wearing tight clothes and using repellents. Immunization by a recent vaccine produced in Austria from cultures on chicken embryo has given promising results.

Animals↗
PubMed1978

Acquired resistance to ticks. III. Cobra venom factor and the resistance response.

Guinea-pigs developed resistance to larvae of the ixodid tick, Dermacentor andersoni, after one infestation. Resistant hosts were characterized by allowing significantly fewer larvae to engorge than non-resistant hosts. Larvae engorging on non-resistant hosts had a mean weight six times that of larvae obtained from resistant hosts at the end of a 5-day infestation. This immunologically based resistance was previously shown to have a cell-mediated and a humoral component. In an attempt to ascertain the role of complement in the resistance response, cobra venom factor (CoF) was administered to guinea-pigs producing prolonged (85--95 per cent) depletion of complement titres. CoF was administered during an initial infestation with tick larvae to determine if complement depletion altered the acquisition of tick resistance. CoF was also administered to tick-resistant hosts in an attempt to determine if the expression of tick resistance and the development of the basophil-packed lesion, characteristic of the tick-attachment site in resistant hosts, could be altered by complement depletion. CoF did not alter the acquisition of resistance when complement levels were reduced during a primary infestation. However, complement depletion of an animal which had acquired tick resistance blocked the expression of that resistance during a challenge infestation. In addition to increased numbers and weights of larvae engorging on tick-resistant animals depleted of complement, the basophil packed lesion at the tick attachment site was greatly reduced. Complement plays an important role in the expression of tick resistance in guinea-pigs.

Animals↗
PubMed1996

Acaricidal efficacy of cypermethrine (a new synthetic pyrethroid) against Boophilus annulatus ticks in cattle.

Resistance of ticks to acaricides had spread dramatically in recent years, so changing of acaricides periodically is needed to avoid resistant strains. Cypermethrine is a new pyrethroid acaricide recently introduced in the skin parasites control programs in Egypt. Fourteen crossbred cows (Friesian X Egyptian native) were used to assess the acaricidal efficacy of cypermethrine against Boophilus annulatus ticks. Cows were allocated into treated and control groups, each consists of 7 animals. At day 0 before treatment, ticks of more than 4.5 mm in length attached to both treated and control animals were counted and every week thereafter. The average tick number on vaccinated and control animals were counted and the efficacy percentage of cypermethrine was then determined. The number of ticks which laid eggs were counted in treated and control animals and hatching percentage of eggs were then calculated. Spraying of animals with cypermethrine showed that complete elimination of ticks occurred early on the 7th day post-treatment. The average number of ticks was 1673 and that of controls was 1578 at day 0 before treatment. The maximum efficacy (100%) was sustained for up to 7 weeks post-treatment after which the efficacy was slightly dropped and reached 98%. The results of cypermethrine on oviposition and egg hatchability of the ticks which survived treatment were surprising. The percentage of ticks collected from treated cows that succeeded to lay eggs was 22%, the average number of eggs laid per tick was 259 and hatching rate was 8.6%.

Animals↗
PubMed1998

[Educational status of the Czech population about Lyme borreliosis and experience with tick bites--pilot study].

The incidence of Lyme borreliosis (LB) has a rising trend since 1995. In 1995 6,302 cases were reported, in 1996 4,192 (EPIDAT, SZU). The objective of the present work was to assess in a selected population sample knowledge of ticks and their relationship to Lyme borreliosis. The investigation was based on a survey using questionnaires. 110 respondents were selected according to the following pattern: 19 secondary school students, 32 blood donors, 44 visitors of parks, 15 countryside people. 99.1% of the subjects knew about the existence of ticks in the Czech Republic, 10.9% of the respondents do not know about Lyme borreliosis. More than 80% of the people are in the countryside at least once a week. 87% of the people report they had a tick, 75% removed a tick from another person. Only 6.7% of the respondents never had any contact with ticks. When removing ticks 17% of the subjects use disinfection, 67% use oil. Almost 30% of the respondents remove ticks with bare hands and more than 14% destroy them by squashing them between their fingers. 41% are not aware of the risk of transmission of tick-borne encephalitis. From the investigation a frequent contact of the population with ticks is apparent. Theoretical knowledge of the problem is extensive, practical experience is different. Unfortunately unsuitable habits in removal of ticks persist and this increases the risk of transmission of Lyme borreliosis.

Adult↗
PubMed1997

Sheep and goat tick management.

Tick and tick-borne disease (TBD) problems of sheep and goats are less well studied than those of cattle. Nevertheless, small ruminants are able to acquire worthwhile resistance to most tick species and the principles of enzootic stability and the need to preserve it are similar to those with cattle. In practice, sheep and goats are often grazed nomadically and initial TBD infections may be delayed. This may well account for losses from Nairobi sheep disease and heartwater. Sheep and goats are also affected by direct tick damage including tick bite abscesses, tick paralysis, tick-induced dermatophilosis, etc. Otherwise direct damage is believed to be only slight and stress from dipping causes reductions in liveweight gain greater than those caused by the ticks. Even "pour-on" preparations produce no economic benefit in studied situations despite the lack of stress. A pragmatic approach to tick management is needed for varying situations although the need to preserve enzootic stability is of paramount importance.

Animals↗
PubMed1998

Tick bites and Lyme disease in an endemic setting: problematic use of serologic testing and prophylactic antibiotic therapy.

CONTEXT: The use of serologic testing to diagnose Lyme disease (LD) is a source of controversy. Expert recommendations also discourage the routine use of antibiotic therapy for prophylaxis of LD following tick bites, but the extent to which physicians in endemic areas have adopted these recommendations is not known. OBJECTIVE: To assess the pattern of use of serologic testing and antibiotic therapy for tick bites and LD and associated charges for management in an endemic area. DESIGN: Active surveillance of patient-physician encounters for tick bites and LD. SETTING: Primary care practices on the Eastern Shore of Maryland. PATIENTS: Consecutive sample of 232 patients with tick bites, LD (defined by physician diagnosis in medical record), and suspected LD (physician notation of possible, but not definite LD) seen in 1995. MAIN OUTCOME MEASURES: Serologic testing for LD, test results, antibiotic therapy, and direct costs of management. RESULTS: Surveillance identified 142 patients (61.2%) with diagnoses of tick bites, 40 patients (17.2%) with LD, and 50 patients (21.6%) with suspected LD. Of the 142 patients seen for tick bites, 95 (67%) underwent serologic testing for LD. Of these, 93 patients had initial negative or equivocal results; 24 (26%) of the 93 had convalescent testing, with 1 seroconversion. Seventy-eight patients (55%) with a diagnosis of tick bite received antibiotic therapy. No patients with tick bite developed clinical LD. Serologic testing for LD was performed for 36 patients (90%) with a diagnosis of LD and 46 patients (92%) with suspected LD. In most cases, antibiotics were prescribed before serologic test results became available. Convalescent testing was not performed for 37 (86%) of the 43 patients with suspected LD who had initial negative or equivocal results. Of these 37 patients, 25 (68%) did not receive antibiotic therapy. Direct charges for treatment of these 232 patients totaled $47 595, one third of which was attributable to serologic testing. A total of 32% of direct charges were for patients with tick bites, 48% were for patients with LD, and 20% were for patients with suspected LD. CONCLUSIONS: In this setting, most patients consulting physicians for tick bites received prophylactic antibiotic therapy of unproven efficacy and underwent unnecessary, costly serologic testing. Despite almost universal use in this study, serologic testing for LD did not appear to influence treatment of patients diagnosed as having LD.

Animals↗
PubMed1996

Amblyomma variegatum (Acari: Ixodidae): mechanism and control of arbovirus secretion in tick saliva.

Saliva is considered to be the conduit by which pathogens are transmitted from blood-sucking arthropod vectors to their vertebrate hosts, but supporting evidence for this is fragmentary. To determine if Thogoto (THO) virus, a tick-borne member of the influenza virus family, is transmitted via tick saliva, and whether virus replication is a prerequisite for such transmission, two experimental conditions were compared: (1) "biological transmission" and (2) "mechanical transmission." In (1), THO virus was allowed to infect and replicate in a natural vector, Amblyomma variegatum: virus was detected in saliva collected from 3/22 (14%) ticks. In (2), virus was inoculated directly into the hemocoel with the drug used to induce salivation and saliva was collected immediately to preclude the possibility of virus replication: virus was detected in saliva collected from 31/170 (18%) ticks. The results demonstrate that THO virus is secreted in tick saliva and that virus can pass from the hemolymph to the salivary glands independently of viral replication within the tick. The comparatively low numbers of ticks that yielded virus-positive saliva samples together with the results from assays of serial saliva samples suggested that virus secretion may not be a continuous process during salivation. Ticks in which THO virus had established an infection showed an impaired secretory response compared with uninfected ticks and ticks used for mechanical transmission.

Analysis of Variance↗
PubMed1994

The effect of rainfall on tick challenge at Kyle Recreational Park, Zimbabwe.

The effect of rainfall pattern on tick challenge was investigated at Kyle Recreational Park, Zimbabwe, from 1991 to 1992 using drag and removal plot methods to sample environmental tick density. The abundance of adults and nymphs of the brown ear-tick Rhipicephalus appendiculatus and larvae of the bont tick Amblyomma hebraeum was positively correlated with monthly rainfall, whereas no relationship with rainfall was revealed for larval R. appendiculatus, adults of the red-legged tick R. evertsi, or larvae of the blue tick Boophilus decoloratus. A comparison between 1991 (490 mm rainfall) and the drought year of 1992 (161 mm) revealed significant differences in the abundance of R. appendiculatus, A. hebraeum, and B. decoloratus. During the wet season, R. appendiculatus adults were 2-3 times more numerous in the environment during the higher rainfall year of 1991. A. hebraeum larval abundance exhibited a similar pattern to that of R. appendiculatus adults, but B. decoloratus larvae were more abundant in the drought year of 1992 during both the wet and dry seasons. Comparable tick abundance data collected at Kyle during the above-average rainfall years of 1975-1977 (mean = 1029 mm) were compared with tick challenge during the below-average rainfall years of 1991-1992 (mean = 326 mm). In grassland sand habitat and all habitats combined R. appendiculatus adults, nymphs, and larvae were much more abundant during the high rainfall years. In contrast, larvae of B. decoloratus were more numerous during the drier years. A hebraeum larvae were also more abundant during the drier years. The strong positive correlation of adult R. appendiculatus abundance with rainfall and the coincidence of increased adult tick challenge with increased rainfall indicate that adult R. appendiculatus tick burden on hosts would be heaviest during the wet season and high rainfall years.

Animals↗
PubMed2004

[Tick-borne human pathogenic microorganisms found in Europe and those considered nonpathogenic. Part II: Bacteria, parasites and mixed infections].

The importance of tick-borne diseases has significantly increased objectively and subjectively during the last few years. This fact was demonstrated by the description of tick-borne viruses, in particular with respect to tickborne encephalitis published in part I. Here in part II, tick-borne bacteria and parasites will be discussed as well the significance of these agents, their vectors, clinical course, diagnostics, prophylaxis, and therapy. Naturally, Lyme borreliosis, one of the most important tick-borne bacterial illnesses of humans, is the center of our interest. In addition to basic understanding, critical practice-relevant advice regarding all agents is presented. Similarly all tick-borne bacterial diseases such as relapsing fever, tularemia, ehrlichiosis, and rickettsiosis including Q fever will be discussed. Tick-borne zoonotic babesiae are parasites whose veterinary importance has been known for the last 100 years but whose relevance for human medicine only became evident in 1957. The fact that multiple and mixed infections caused by ticks are possible has been known for years. Taking into account such a high prevalence of the infectious agents in ticks, such multiple infections were to be expected. During the last few years it has become evident that double and multiple infections of humans caused by tick bites occur far more frequently than has been known so far. As a result, in cases of unclear anamnesis,new diagnostic and therapeutic approaches should be taken. In general one can say that considerable additional scientific research is necessary to effectively reduce the incidence of tick-borne diseases.

Anaplasmosis↗
PubMed2005

RNA interference screening in ticks for identification of protective antigens.

Ticks are ectoparasites of wild and domestic animals and humans, and are considered to be the most important arthropod vector of pathogens in North America. Development of vaccines directed against tick proteins may effect reduction of tick infestations and transmission of tick-borne pathogens. The limiting step for the development of tick vaccines has been the identification of tick protective antigens. Reverse vaccinology approaches aimed at reducing animal experimentation while allowing for the rapid screening of pools of potential tick vaccine candidates would greatly facilitate progress towards the development of tick vaccines. Herein, we describe the screening of Ixodes scapularis cDNAs for identification of tick protective antigens using RNA interference (RNAi). The results of the RNAi screening were similar to those obtained previously using expression library immunization and demonstrated that RNAi could serve as a more rapid and cost-effective tool for vaccine antigen discovery in ticks and in other nonmodel organisms.

Animals↗
PubMed2004

Transfusion-transmitted tick-borne infections: a cornucopia of threats.

Over the past several decades, the frequency of contact between humans and ticks has increased dramatically. Concomitantly, several newly recognized tick-borne pathogens have emerged joining those already known to be transmitted by ticks. Together these factors have led to an enhanced public health awareness of ticks, tick-borne agents, and their associated diseases. Reports that several of these agents are transmitted by blood transfusion have raised concerns about blood safety. The primary agents of interest are members of the genus Babesia, but Anaplasma phagocytophilum, Rickettsia rickettsii, Colorado tick fever virus, and tick-borne encephalitis virus also have been transmitted by transfusion. In many cases, these agents and their diseases share common features including vectors, symptoms, and diagnosis. Unfortunately, they also share the common problem of insufficient epidemiologic and transmissibility data necessary for making informed decisions regarding potential blood safety interventions. Although further surveillance and epidemiologic studies of tick-borne agents are clearly needed, at present only the Babesia warrant consideration for active intervention; because donor management strategies based on risk-factor questions are inadequate, leukoreduction not effective for agents found in red cells and pathogen inactivation remains problematic for red cell products. Despite the present unavailability of screening assays, some form of serologic and nucleic acid testing may be justified for the Babesia. Given that interactions between humans and ticks are likely to increase in the future, vigilance is required as new and extant tick-borne agents pose potential threats to transfusion safety.

Humans↗
PubMed2005

A serine protease inhibitor (serpin) from Haemaphysalis longicornis as an anti-tick vaccine.

The application of anti-tick vaccine has been shown to be the most promising alternative tick control strategy compared to the current use of acaricides that suffer from a number of limitations. The success of this strategy is dependent on the cloning, and characterization of tick molecules involved in the mediation of tick central physiological roles. Rapid amplification of the cDNA ends (RACE) and primers designed based on a conserved serpin amino acid motif (NAVYFKG) were used to clone a cDNA with high similarity in the reactive center loop (RCL) to representative serpin, heparin cofactor II. We have named this novel gene as Haemaphysalis longicornis serpin-2 (HLS2). RT-PCR analysis showed that HLS2 mRNA transcripts are not expressed in salivary glands but in hemolymph by feeding ticks. HLS2 was not introduced into the bite site as measured by Western blot analysis. The activated partial thromboplastin time (APTT) and the thrombin inhibitory assay using recombinant HLS2 (rHLS2) demonstrated prolonged coagulation time and inhibition of thrombin activity. These results suggested that HLS2 is present only in hemolymph of the feeding ticks and the function of HLS2 is homeostasis in tick physiological compartment. Vaccination of rabbits with rHLS2 conferred protective immunity against ticks, resulting in 44.6 and 43.0% mortality in nymphal and adult ticks, respectively. These results show that rHLS2 could be an important candidate as a component of a cocktail anti-tick vaccine.

Amino Acid Sequence↗
PubMed2006

Identification of the etiologic agent of epizootic bovine abortion in field-collected Ornithodoros coriaceus Koch ticks.

Epizootic bovine abortion (EBA), or foothill abortion as it has often been termed, is a tick-borne disease of pregnant cattle recognized in California, Nevada and Oregon. The primary objective of this study was to better define the relationship of a novel deltaproteobacterium, the putative etiological agent of EBA (aoEBA), with the Pajaroello tick (Ornithodoros coriaceus Koch), the recognized vector of EBA. Three developmental stages of O. coriaceus (larva, nymph, and adult) were collected from five locations in California, Nevada and Oregon. A polymerase chain reaction (PCR), developed for detection of aoEBA, was applied to DNA extracted from ticks. Southern blotting of the PCR products increased the number of ticks determined to be carrying the bacteria by seven-fold, suggesting the majority of infected ticks carry relatively low numbers of the pathogen. An effort was made to determine if an artificial blood meal would stimulate replication of the bacterial pathogen, thereby increasing the frequency in which aoEBA could be identified; no statistically significant effect was evident. The number of ticks determined to be carrying aoEBA varied with geographic location and ranged from 5 to 20%. aoEBA was found in both adults (12% of the males and 12% of the females) and nymphs (13%) but not larvae. Comparative analysis of dissected ticks provided strong evidence that the salivary gland was the most common location of aoEBA in field-collected ticks. No significant correlations were identified between the frequency of infection and tick weight, suggesting that increasing tick age and increased number of blood meals did not increase infectivity.

Abortion, Veterinary↗