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Isolation of Beauveria bassiana and Metarhizium anisopliae var. anisopliae from Boophilus microplus tick (Canestrini, 1887), in Rio de Janeiro State, Brazil.

The objective of this work were to isolate and identify strains of entomopathogenic fungi from ingurgitated female Boophilus microplus ticks, collected from the soil in the municipality of Paracambi, Rio de Janeiro State, Brazil. The ingurgitated females were inoculated in the selective medium oat dodine agar (oda), where 49 colonies of Beauveria bassiana (71%) and 20 of Metarhizium anisopliae var. anisopliae (29%) were isolated. These isolated strains characterize for the first time in Brazil the natural occurrence of these species of fungi in this tick, and will be used to conduct bioassays to evaluate the pathogenicity and virulence of these strains for ticks of the genus Boophilus microplus.

Animals↗

Immunization effect of recombinant P27/30 protein expressed in Escherichia coli against the hard tick Haemaphysalis longicornis (Acari: Ixodidae) in rabbits.

We investigated the induction of resistance to Haemaphysalis longicornis infestation in rabbits that had been immunized with recombinant H. longicornis P27/30 protein. The success of immunological control methods is dependent upon the use of potential key antigens as tick vaccine candidates. Previously, we cloned a gene encoding 27 kDa and 30 kDa proteins (P27/30) of H. longicornis, and identified P27/30 as a troponin I-like protein. In this study, rabbits that were immunized with recombinant P27/30 expressed in Escherichia coli showed the statistically significant longer feeding duration for larval and adult ticks (P<0.05), low engorgement rates in larval ticks (64.4%), and an apparent reduction in egg weights, which suggest that H. longicornis P27/30 protein is a potential candidate antigen for a tick vaccine. These results demonstrated that the recombinant P27/30 protein might be a useful vaccine candidate antigen for biological control of H. longicornis.

Animals↗

Difference in pathogenesis between herpes simplex virus type 1 encephalitis and tick-borne encephalitis demonstrated by means of cerebrospinal fluid markers of glial and neuronal destruction.

We determined the extent of neuronal and glial cell destruction in 13 patients with herpes simplex type 1 (HSV-1) encephalitis, 15 patients with tick-borne encephalitis (TBE), and 20 noninfectious controls by analyzing the cerebrospinal fluid (CSF) concentrations of neurofilament protein (a marker of neurons, mainly axons), neuron-specific enolase (a marker of neurons, mainly somas), glial fibrillary acidic protein, and S-100 protein (markers of astrocytes). In addition, in patients with HSV-1 encephalitis CSF samples were collected serially before 7, 8-14, and 18-49 days and 3-10 months after the onset of neurological symptoms. In the acute stage of HSV-1 encephalitis we found markedly higher CSF levels of the cell damage markers than in patients with TBE. The concentration of cell damage markers in HSV-1 encephalitis decreased within 45 days after acute infection, except for neurofilament protein. The CSF concentrations of neurofilament protein increased during the second week, remained extremely high throughout the next month, and decrease thereafter. The changes in these markers of neuronal and glial destruction demonstrate the neuronal and astroglial cell damage during the first month after HSV-1 encephalitis. In contrast, most patients with TBE had signs only of slight astrogliosis, except for two patients with paresis.

Adult↗

Immunization of cattle with Anaplasma marginale derived from tick cell culture.

Anaplasmosis is a hemolytic disease of cattle caused by the ehrlichial tick-borne pathogen Anaplasma marginale. Killed vaccines used for control of anaplasmosis in the US used antigen harvested from infected bovine erythrocytes which was often contaminated with bovine cells and other pathogens. In this study, we performed an initial cattle trial to test A. marginale harvested from tick cell culture as an immunogen for cattle. Eleven yearling Holstein cattle were immunized with the cell culture-derived A. marginale and 11 cattle were non-immunized contact controls. Each vaccine dose contained approximately 2 x 10(10) A. marginale in an oil-based adjuvant. Two immunizations were administered subcutaneously 4 weeks apart and the cattle were challenge-exposed 10 weeks after the second immunization with A. marginale infected blood. Maximum antibody levels as determined by an A. marginale specific competitive ELISA were observed 2 weeks after the last immunization. Antibody responses against major surface proteins (MSPs) 1a and 1beta1 were also characterized and immunized cattle demonstrated a preferential recognition for MSP1beta1. Cattle immunized with the cell culture-derived A. marginale had a significantly lower percent reduction in the packed cell volume (P<0.05) after challenge exposure as compared with the controls and did not display clinical anaplasmosis. The cell culture-derived A. marginale shows promise for use as antigen in development of a new killed vaccine for anaplasmosis.

Anaplasma↗

In vitro titration of Theileria parva tick derived stabilates.

Immunization against the protozoan Theileria parva by infection and treatment has proved to be very efficient for the control of East Coast fever, an acute and often-fatal lymphoproliferative tick-borne disease of cattle in Eastern, Central and Southern Africa. The immunizing dose of live T. parva sporozoites used in this method is usually determined by in vivo titration. An alternative in vitro method of quantification of sporozoites in whole tick-derived stabilates is proposed. The method consists of incubating serially diluted T. parva stabilates with bovine peripheral blood lymphocytes, the host cell that is infected naturally. Allowing the cultures to incubate undisturbed for the full cultivation period (10 days) reduced the variability among replicate titrations. Fungal contaminations were avoided by centrifuging stabilates at 400 g prior to the incubation, which did not precipitate sporozoites significantly. Fungistatics, Nystatin and Flucytosine, did not appear to interfere with the in vitro development of T. parva but their effect on fungal growth was limited. In vitro titration data were compared to in vivo infection data for 2 stabilates. In vitro titration of T. parva sporozoites should allow more ethical and efficient research on the preparation and storage of T. parva tick-derived stabilates.

Animals↗

Isolation and characterization of an anticoagulant present in the salivary glands of the bont-legged tick, Hyalomma truncatum.

A low molecular mass anticoagulant (17 kDa) was isolated from the salivary glands of prefed female Hyalomma truncatum ticks by means of reverse phase and anion-exchange HPLC. Trypsin digestion and amino acid analysis confirmed the protein nature of the anticoagulant. The inhibitor appears to be uncompetitive with a Ki of 6.9 x 10(-10)M. The target of the anticoagulant is factor Xa at the junction of the extrinsic and intrinsic pathways. This may be crucial for the survival of the tick, making it feasible to investigate the possibility of vaccination with this antihaemostatic against tick feeding. In addition, tick anticoagulants may possibly have therapeutic application in controlling thrombosis.

Amino Acids↗

Distribution and phenology of ixodid ticks in southern Zambia.

Distribution data for epidemiologically important ticks (Acari: Ixodidae) in the Southern Province of Zambia, one of the main cattle areas of the country, are presented. Boophilus microplus (Canestrini) was not recorded in southern Zambia, whereas Boophilus decoloratus (Koch) is present throughout the area. New distribution patterns for less economically important ixodid ticks are also discussed. Southern Zambia is a transition zone because it is the most northern area in Africa where mixed Rhipicephalus appendiculatus Neumann and Rhipicephalus zambeziensis Walker, Norval & Corwin populations were reported. Although a second generation of adult R. appendiculatus/R. zamnbeziensis was encountered, simulations indicated that this phenomenon is very rare in southern Zambia, mainly because of the colder temperatures during the early dry season and lower rainfall. These simulations were supported by a development trial under experimental conditions. Tick body size measurements showed that southern Zambian ticks are larger than eastern Zambian R. appendiculatus. It is hypothesized that body size is related to diapausing intensity in this species. The epidemiological consequences are that a different approach to control Theileria parva (Theiler) (Piroplasmida: Theileriidae) and other tick-borne diseases is needed in southern Zambia, compared to the one adopted in eastern Zambia.

Animals↗

Experimental induction of chronic borreliosis in adult dogs exposed to Borrelia burgdorferi-infected ticks and treated with dexamethasone.

OBJECTIVE: To develop a method to experimentally induce Borrelia burgdorferi infection in young adult dogs. ANIMALS: 22 healthy Beagles. PROCEDURE: All dogs were verified to be free of borreliosis. Twenty 6-month-old dogs were exposed to Borrelia burgdorferi-infected adult ticks and treated with dexamethasone for 5 consecutive days. Two dogs not exposed to ticks were treated with dexamethasone and served as negative-control dogs. Clinical signs, results of microbial culture and polymerase chain reaction (PCR) testing, immunologic responses, and gross and histologic lesions were evaluated 9 months after tick exposure. RESULTS: Predominant clinical signs were episodic pyrexia and lameness in 12 of 20 dogs. Infection with B burgdorferi was detected in microbial cultures of skin biopsy specimens and various tissues obtained during necropsy in 19 of 20 dogs and in all 20 dogs by use of a PCR assay. All 20 exposed dogs seroconverted and developed chronic nonsuppurative arthritis. Three dogs also developed mild focal meningitis, 1 dog developed mild focal encephalitis, and 18 dogs developed perineuritis or rare neuritis. Control dogs were seronegative, had negative results for microbial culture and PCR testing, and did not develop lesions. CONCLUSIONS AND CLINICAL RELEVANCE: Use of this technique successfully induced borreliosis in young dogs. Dogs with experimentally induced borreliosis may be useful in evaluating vaccines, chemotherapeutic agents, and the pathogenesis of borreliosis-induced arthritis.

Animals↗

Efficacy of amitraz (Taktic 12.5% EC) as a dip for the control of Boophilus microplus (Canestrini) (Acari: Ixodidae) on cattle.

Four groups of cattle infested with Boophilus microplus (Canestrini) were each dipped in a different concentration of amitraz diluted from a 12.5% EC formulation to determine the efficacy and performance of the product in an 11,400 l dipping vat. Except for the period when heifers were dipped, animals were restrained in stanchions placed individually inside 3.3 x 3.3 m2 stalls within an open-sided barn. The amitraz in the vat was stabilized with hydrated lime to maintain a pH of ca. 12. Analyses of vat samples showed that concentrations of amitraz in the vat were 7.6 to 13% lower than the targeted concentrations of 0.010, 0.015, 0.020, and 0.025% active ingredient (AI) for dilutions prepared according to instructions on the manufacturer's label. The large quantity of hydrated lime added to the vat (10 kg/1000 l) interfered with the HPLC analysis of vat samples. Therapeutic efficacy of each of the four observed concentrations (0.0088, 0.0131, 0.0174, and 0.0231% AI) of amitraz was excellent (> 99% control). However, the rapid detachment of all ticks from an animal within a few hours after treatment with amitraz, that has been frequently observed, was not pronounced in the present study. Only 47% of the B. microplus detached in the first 4 h post-treatment, and 84% detached within the first 24 h. All of the treatments, except the lowest concentration, provided protection of cattle against re-infestation by B. microplus larvae for 14 days post-treatment. Possibly as a result of the formation of a compact layer of lime and amitraz on the bottom after the vat was undisturbed for six weeks, intense agitation was required to re-suspend the active ingredient.

Animals↗

Experimental infestation of llamas (Lama glama) with Boophilus microplus (Acari:Ixodidae).

Two llamas (Lama glama) were infested with approximately 20,000 Boophilus microplus larvae each and maintained under controlled conditions to collect the detached adult ticks. A total of 72 engorged and semi-engorged females were recovered with a mean weight of 163.0 +/- 70.6 mg. Sixty-three (87.5%) of these ticks oviposited and 60 (95.2%) of the egg masses produced larvae. Six of the heaviest females laid 18,838 eggs from which 16,545 (87.8%) hatched. These results show that llamas are able to maintain a population of B. microplus under experimental conditions. Further studies are required to determine the role of llamas as alternative hosts for B. microplus under field conditions.

Animals↗

Lyme disease.

PURPOSE: To review the presentation, treatment, and prevention of Lyme disease in primary care. DATA SOURCES: Selected articles from the scientific literature and the Centers for Disease Control. CONCLUSIONS: Lyme disease is a tick-borne, multisystem inflammatory disease with worldwide distribution caused by the spirochete Borrelia burgdorferi. Lyme disease is initially characterized by a spreading, annular erythema migrans skin rash and can disseminate to the musculoskeletal, neurologic, or cardiovascular system. Stages of the disease present with varying clinical manifestations. IMPLICATIONS FOR PRACTICE: Treatment of Lyme disease with appropriate antimicrobial therapy should be prompt in order to avoid debilitating outcomes. Awareness of the many presentations of Lyme disease in endemic areas may facilitate a timely diagnosis and appropriate treatment.

Anti-Bacterial Agents↗

The effects of war on the control of diseases of livestock in Rhodesia (Zimbabwe).

The disruption of veterinary services in the tribal areas of Rhodesia (now Zimbabwe) during seven years of conflict resulted in serious epidemics of disease. The cessation of dipping was followed by the death of an estimated one million cattle from tick-borne disease. Heavy mortality followed the disruption of control measures for trypanosomiasis. Foot-and-mouth disease and anthrax spread widely in the tribal areas. Rabies, normally restricted to areas bordering Botswana and Mocambique, became widespread. A marked increase in human deaths from anthrax and rabies occurred.

Anaplasmosis↗

Use of a duplex PCR/DNA probe assay to monitor Babesia bovis and Babesia bigemina in cattle during a vaccination trial.

A Duplex Polymerase Chain Reaction (DPCR)/DNA probe assay was used to detect Babesia bovis and B. bigemina DNA in cattle undergoing immunization trials. Blood samples were collected from 15 non-splenectomized, 1-2 years old bulls, inoculated with 1 x 10(7) each of culture-derived B. bovis- and B. bigemina-infected erythrocytes. 15 bulls inoculated with normal erythrocytes served as a control group. All cattle were field exposed to tick-transmitted Babesia 21 days (20 animals, Group I) and 60 days (10 animals, Group II) post-inoculation (PI). After immunization, the DPCR/DNA probe assay detected B. bigemina and B. bovis parasite DNA in all inoculated animals from days 4 to 14 PI. At challenge, B. bovis DNA was detected in all control animals as early as day 8 (Group I), or day 11 (Group II) post-introduction to a tick-infested area. The immunized bulls showed B. bovis positive PCR/DNA probe signals from day 0 (Group II) and day 8 (group I), up to day 32 post-exposure to ticks. Positive B. bigemina signals were detected from day 0 (Group I) and day 8 (Group II), up to day 36 post-exposure to ticks. During challenge, it was not possible to clearly define whether the PCR/DNA probe signals detected in the blood from immunized cattle were a result of amplified DNA from the culture-derived parasites, from the tick-transmitted parasites, or both.

Animals↗

Grooming in impala: role of oral grooming in removal of ticks and effects of ticks in increasing grooming rate.

In Experiment 1, five adult female impala were fitted with harnesses that restrained oral self-grooming of the anterior part of the body. At the same time, six cohoused female impala were fitted with control harnesses that allowed normal oral grooming. The impala were allowed to habituate to the harnesses for 10 days, and both groups were then exposed to larval ticks (Boophilus decoloratus) by herding them into a tick-seeding corral. During the third week following tick seeding, when female ticks were estimated to have developed into engorging adults, the impala were immobilized, tick numbers on the animals sampled by patch sampling, and the harnesses removed. Observations continued for 5 days following removal of the harnesses. Twenty-minute focal observations were conducted daily on each impala during the habituation, tick-seeded, and postharness phases. Restrained impala had a median of 20 times more adult female ticks (both engorged and unengorged) than control impala. Oral grooming, which had been suppressed in the restrained impala during habituation and tick-seeded phases, increased 10-fold once the harnesses were removed and occurred 2.5 times more frequently than in control impala during the postharness phase. In Experiment 2, 15 adult female impala were seeded with larval ticks as in Experiment 1; in week 3 after tick seeding all ticks were removed from animals by application of an acaricide. Grooming was recorded during 3 weeks of baseline observations prior to tick seeding, 3 weeks after tick seeding, and then for 3 weeks beginning 1 week after acaricide treatment. Oral grooming and scratch grooming significantly increased from baseline during tick seeding and significantly declined following removal of the ticks with acaracide. Taken together, the two experiments demonstrate that oral grooming is very effective and important in removing fitness-compromising ticks in free-ranging impala. Correspondingly, exposure to, and subsequent infestation by, ticks increases the rate of grooming.

Animals↗

Rapid vaccination protocols for commercial vaccines against tick-borne encephalitis.

Although inactivated viral vaccines have been dramatically successful in controlling many of the world's most devastating diseases, they frequently need several injections to ensure high levels of protection, and thus their efficacy is reduced in many situations. We have developed several rapid vaccination protocols for two commercial vaccine preparations against tick-borne encephalitis virus and studied their efficacy in an experimental murine model. Vaccination protocols as brief as two doses given over two days elicit efficient protection against challenge with potentially fatal doses of virus and this protection is afforded as soon as 5 or as long as 100 days after the first vaccination. The very rapid induction of protection and the poor antibody responses observed would suggest that cell-mediated immune responses are the most important mechanisms for the protection elicited by conventional inactivated vaccines against tick-borne encephalitis.

Animals↗

Experimental infection of white-tailed deer with Anaplasma phagocytophilum, etiologic agent of human granulocytic anaplasmosis.

Serologic and molecular evidence of Anaplasma phagocytophilum has been demonstrated in white-tailed deer (WTD; Odocoileus virginianus), and deer are an important host for the tick vector Ixodes scapularis. In this study, we describe experimental infection of WTD with A. phagocytophilum. We inoculated four WTD with a human isolate of A. phagocytophilum propagated in tick cells. Two additional deer served as negative controls. All inoculated deer developed antibodies (titers, > or =64) to A. phagocytophilum, as determined by an indirect fluorescent antibody test, between 14 and 24 days postinfection [p.i.]), and two deer maintained reciprocal titers of > or =64 through the end of the 66-day study. Although morulae were not observed in granulocytes and A. phagocytophilum was not reisolated via tick cell culture of blood, 16S reverse transcriptase nested PCR (RT-nPCR) results indicated that A. phagocytophilum circulated in peripheral blood of three deer through at least 17 days p.i. and was present in two deer at 38 days p.i. Femoral bone marrow from one deer was RT-nPCR positive for A. phagocytophilum at 66 days p.i. There was no indication of clinical disease. These data confirm that WTD are susceptible to infection with a human isolate of A. phagocytophilum and verify that WTD produce detectable antibodies upon exposure to the organism. Because adults are the predominant life stage of I. scapularis found on deer and because adult I. scapularis ticks do not transmit A. phagocytophilum transovarially, it is unlikely that WTD are a significant source of A. phagocytophilum for immature ticks even though deer have a high probability of natural infection. However, the susceptibility and immunologic response of WTD to A. phagocytophilum render them suitable candidates as natural sentinels for this zoonotic tick-borne organism.

Anaplasma phagocytophilum↗

Immunization against East Coast fever: the use of selected stocks of Theileria parva for immunization of cattle exposed to field challenge.

Two antigenically different stocks of Theileria parva parva (Kilifi and Marikebuni), previously characterized as belonging to groups A and C respectively on monoclonal antibody (MAb) profiles, were selected for immunization of different breeds of cattle against East Coast fever (ECF) by the infection and treatment method. A total of 52 immunized cattle and 33 susceptible controls of different group sizes were exposed to field challenge by ticks for periods of 42-90 days at three field sites where ECF is endemic on the Kenyan coast. All immunized cattle survived ECF challenge, but 87% of the controls died of the disease. The cattle exposed at one site had been immunized 1 year earlier and maintained tick-free in the intervening period. The level of immunity in these cattle was similar to that of cattle which had been immunized 1 or 2 months prior to exposure. Thus, immunity had not waned over the 1-year period. A study at another site showed that acaricidal treatment of immunized cattle could be safely extended from twice a week to once every three weeks, whereas in susceptible cattle even twice weekly spraying did not control ECF. The isolates made from infected controls during the trials indicated the presence of three T. p. parva stocks as defined by MAb profiles. Of the two stocks used for immunization, T. p. parva Marikebuni induced broader protection. In view of the apparent limited antigenic diversity of T. p. parva strains within the Coast Province it is suggested that the Marikebuni stock might represent a key stock for vaccination in this area.

Animals↗

The role of Rhipicephalus appendiculatus and R. evertsi evertsi males in inducing resistance in laboratory animals: preliminary studies.

Guinea-pigs infested with male ticks of the species Rhipicephalus appendiculatus, and rabbits infested with R. evertsi evertsi, acquired immunity to conspecific female ticks. The hosts were first infested with male ticks and thereafter were challenged with males and females of the same species. The mean weight of the engorged females of R. appendiculatus fed on guinea pigs previously infested with male ticks was 509.0 (+/- 41.4) mg compared with that of females fed on control guinea pigs (651.2 +/- 31.8 mg). Similar weight differences were observed for R.e. evertsi females which fed on rabbits previously infested three times with male ticks. The mean weight of the female ticks which fed on these rabbits was 520.1 (+/- 29.8) mg compared with 640.7 (+/- 30.2) mg of R.e. evertsi females which fed on control hosts. The concentration of gammaglobulins in the sera of rabbits was monitored at various intervals after the first infestation. It was found, for the first time, that infestation of laboratory animals with male ticks conferred immunity, but to a lesser degree than infestation with both sexes. It was also shown that the level of gammaglobulins increased from 3.4 +/- 0.28 g l-1 to 7.3 +/- 0.24 g l-1 in sera of rabbits hosts as a result of the feeding activity of males, but to a lesser extent than in sera of rabbits on which both sexes had fed (10.8 +/- 2.4 g l-1).

Animals↗