Site Of Tick Bite Research Articles

Differential expression of Ixodes ricinus salivary gland proteins in the presence of the Borrelia burgdorferi sensu lato complex

In Europe, Ixodes ricinus is the main vector of Lyme borreliosis. Their salivary glands play a critical role in the biological success of ticks. To better understand the cross-talk between Borrelia burgdorferi and tick salivary glands, we analyzed protein expression in the salivary glands of I. ricinus adult ticks that were infected by various strains of the B. burgdorferi sl complex. iTRAQ allowed the identification of more than 120 proteins, providing the first proteomic data pertaining to I. ricinus salivary glands. Among these proteins, only 12 were modulated in the presence of various Borrelia strains. Most of them are up-regulated and are involved in cell defense and protein synthesis and processing. Down-regulated proteins are mostly implicated in the cytoskeleton. The DIGE analysis allowed us to identify 35 proteins and showed the down-regulation of 4 proteins. All 15 proteins were not modulated by all strains. Overall, these observations showed that the presence of Borrelia in tick salivary glands is a factor of stress for the protein machinery, and also that some Borrelia strains produce a dysregulation of cytoskeletal proteins. Interestingly, a protein from Borrelia, OspA, was found in infected salivary glands. The consequence of its presence in salivary glands is discussed. Lyme borreliosis is still the most prevalent arthropod-borne disease in the temperate regions of the northern hemisphere. The geographical distribution of Lyme borreliosis is expanding, especially towards higher altitudes and latitudes. Human pathogenic spirochetes causing Lyme borreliosis belong to the B. burgdorferi sensu lato complex. They are extracellular pathogens transmitted to humans through the bite of Ixodes spp. ticks. The bioactive molecules present in tick saliva not only promote tick feeding, but also create an advantageous microenvironment at the tick bite site for survival and replication of Borrelia bacteria. Investigation of the tick-host-pathogen interface would provide new strategies to control tick-borne infections. We chose to analyze the interaction of several strains of the B. burgdorferi sensu lato complex with I. ricinus salivary glands. We also investigated the presence of bacterial proteins in salivary glands. For these purposes, we undertook a proteomic study implying the complementary approaches of iTRAQ and DIGE. Our study allowed identifying several salivary markers of infection that were shown to vary according to the strain. Moreover, OspA, a bacterial protein was shown to be expressed in salivary glands and may be implied in the pathogenicity of some Borrelia strains.

Efficacy of an Experimental Azithromycin Cream for Prophylaxis of Tick-Transmitted Lyme Disease Spirochete Infection in a Murine Model

As an alternative to oral prophylaxis for the prevention of tick transmission of Borrelia burgdorferi, we tested antibiotic cream prophylactic formulations in a murine model of spirochete infection. A 4% preparation of doxycycline cream afforded no protection, but a single application of 4% azithromycin cream was 100% protective when applied directly to the tick bite site at the time of tick removal. Indeed, the azithromycin cream was 100% effective when applied at up to 3 days after tick removal and protected 74% of mice exposed to tick bite when applied at up to 2 weeks after tick removal. Azithromycin cream was also protective when applied at a site distal to the tick bite site, suggesting that it was having a systemic effect in addition to a local transdermal effect. Mice that were protected from tick-transmitted infection did not seroconvert and did not infect larval ticks on xenodiagnosis. Azithromycin cream formulations appear to hold promise for Lyme disease prophylaxis.

Rickettsia aeschlimanniiInfection in a Man, Greece

<i>Rickettsia aeschlimannii</i>Infection in a Man, Greece

Scalp Eschar and Neck Lymphadenopathy Caused byRickettsia massiliae

Scalp Eschar and Neck Lymphadenopathy Caused by<i>Rickettsia massiliae</i>

Autochthonous Lyme Borreliosis in Humans and Ticks in Korea

ObjectiveThis study aimed at finding epidemiological and clinical features of autochthonous Lyme borreliosis in humans through epidemiological investigations and identifying its vectors and pathogens through analysis of ticks. MethodEpidemiological investigations, including review of the retrospective medical records and patient interviews, were conducted in two cases that occurred in 2012. To identify the vectors and pathogens, ticks were collected between September 23 and October 6, 2012 from the area where the tick bite in the first patient occurred. The ticks were classified, and polymerase chain reaction (PCR) tests and cultures were performed. ResultsThe first patient, a 46-year-old female, visited a forest in Gangwon province, which was 900 m above sea level, where the tick bite occurred. Two weeks after the tick bite, erythema migrans (12 × 6 cm2 in size) appeared on the site of tick bite, along with fever, chill, fatigue, myalgia, and arthralgia on shoulders, knees, and hips. The second patient, a 44-year-old male, visited a mountain in Gangwon province, which was 1200 m above sea level, where a tick bite occurred. One month after the tick bite, erythema migrans appeared at the site of the tick bite, along with fatigue, myalgia, and arthralgia on the right shoulder and temporomandibular joint. Indirect fluorescent antibody testing and Western blotting were carried out in these two cases for diagnosis, and positive findings were obtained. As a result, Lyme borreliosis could be confirmed. To estimate the pathogens and vectors, the ticks were collected. A total of 122 ticks were collected and only two species, Haemaphysalis japonica and Haemaphysalis flava, were identified. PCR and culture were performed on ticks. However, Borrelia burgdorferi sensu lato was not isolated from any collected ticks. ConclusionsThis study is significant to confirm Lyme borreliosis officially at first by the national surveillance system, although identification of the mites and pathogens failed.

Tick Bite on Glans Penis: The Role of Dermoscopy

Dear Editor: Since the first report of a human tick infestation in 19821, about 40 human cases have been reported in the Korean literature. The causative ticks reported in Korea were 7 species, and tick bites from Amblyomma testudinarium has been reported once in Korea2. Dermoscopy is a useful technique that allows the visualization of magnified submacroscopic structures, and by using dermoscopy, we could identify the biting tick and detect the residual part of the tick. A 75-year-old Korean man who lived in Tongyeong city, Gyeongsangnamdo, Korea presented with a small, blackish nodule on his glans penis (Fig. 1A). He had worked on a chili pepper farm the previous day. We noticed that the nodule was a tick by using dermoscopy and removed it with forceps. When we were removing the tick, the mouthpart of tick tore off. We identified the remaining part of the tick by using dermoscopy (Fig. 1B), and the tick bite site was excised. Histopathologic findings showed wedge-shaped necrosis at the site of penetration of the mouthparts, and remnants of the mouthparts of the tick. Fig. 1 (A) A tick attached to the glans penis. Inset: Dermoscopic findings revealed a female Amblyomma testudinarium. (B) Dermoscopic findings showed the remaining part of the tick. The tick was examined stereoscopically and identified as a female A. testudinarium based on the morphological characteristics as described previously3. The tick was about 18 mm in length, having 4 pairs of legs. The dorsal scutum was seen as a small shield ornamented with dark brown spots. The eyes were located on the lateral edges of the scutum (Fig. 2A). An anal groove was observed on the posterior portion of the anus (Fig. 2B). The external spur of coxa I was longer than the internal spur of coxa I. A comma-shaped spiracular plate and genital aperture were seen on the ventral side. Fig. 2 (A) Dorsal scutum was seen as a small shield ornamented with dark brown spots. The eyes (arrows) were located on the lateral edges of the scutum (×25). (B) Anal groove (arrow) was observed on the posterior portion of the anus (×25). Human tick bites by A. testudinarium have been reported mainly in regions with a warm and humid climate. In addition, A. testudinarium tends to attach to the axillary or inguinal region, which are rich in apocrine glands4. The reason why A. testudinarium prefers these sites is unknown, but it has been suggested that this tick reacts strongly to the odor from the apocrine glands. In our case, Tongyeong city is located in the southern coastal area of the Korean peninsula and has an oceanic climate. The external genitalia is rich in apocrine glands and blood supply, but the glans penis has no apocrine glands. As the patient's glans penis was not covered by a prepuce after a circumcision, we suggest that the patient's glans penis was easily approached by the tick. The usefulness of dermoscopy for diagnosing tick infestations was proposed previously. Especially, dermoscopy can determine whether or not the tick has been completely removed5. In our case, we could identify the biting tick and easily made a preliminary identification of the species of the tick. We also detected the remaining mouthpart of the tick by using dermoscopy. When patients present with a small nodular lesion on the glans penis, dermoscopy can be a useful diagnostic tool. In our report, A. testudinarium was identified stereoscopically. Furthermore, the dermoscopic findings helped to make a diagnosis and detect remnants of the tick. We report the second human case of a tick bite from A. testudinarium in Korea for which dermoscopy was used as an adjuvant diagnostic tool.

Neutrophil Extracellular Traps Entrap and KillBorrelia burgdorferiSensu Stricto Spirochetes and Are Not Affected byIxodes ricinusTick Saliva

Lyme disease is caused by spirochetes of the Borrelia burgdorferi sensu lato complex. They are transmitted mainly by Ixodes ricinus ticks. After a few hours of infestation, neutrophils massively infiltrate the bite site. They can kill Borrelia via phagocytosis, oxidative burst, and hydrolytic enzymes. However, factors in tick saliva promote propagation of the bacteria in the host even in the presence of a large number of neutrophils. The neutrophil extracellular trap (NET) consists in the extrusion of the neutrophil's own DNA, forming traps that can retain and kill bacteria. The production of reactive oxygen species is apparently associated with the onset of NETs (NETosis). In this article, we describe NET formation at the tick bite site in vivo in mice. We show that Borrelia burgdorferi sensu stricto spirochetes become trapped and killed by NETs in humans and that the bacteria do not seem to release significant nucleases to evade this process. Saliva from I. ricinus did not affect NET formation by human neutrophils or its stability. However, it greatly decreased neutrophil reactive oxygen species production, suggesting that a strong decrease of hydrogen peroxide does not affect NET formation. Finally, round bodies trapped in NETs were observed, some of them staining as live bacteria. This observation could help contribute to a better understanding of the early steps of Borrelia invasion and erythema migrans formation after tick bite.

Failure of Topical Antibiotics to Prevent Disseminated Borrelia burgdorferi Infection Following a Tick Bite in C3H/HeJ Mice

A prior study in mice has shown that the timely application of topical antibiotics to the skin at the tick bite site could eradicate Borrelia burgdorferi infection. That study, however, did not evaluate antibiotic preparations that are considered suitable for use in humans. In this murine study, topical application of 2% erythromycin and 3% tetracycline preparations that are acceptable for use in humans was found to be ineffective in eliminating B. burgdorferi from the tick bite site or in preventing dissemination to other tissues. Reasons for the discrepant findings are discussed.

A patient who developed toe necrosis due to poor blood circulation after an interdigital tick bite

A 71-year-old female had worked on a farm in the mountains and noticed itching of the left 3rd toe. She visited a local hospital due to a color change to purple in this area. Attachment of a tick was observed between the left 2nd and 3rd toes, and it was extracted. However, due to persistent pain, she was referred to our department of cardiovascular medicine for close examination and treatment. Lower extremity angiography showed that vascular visualization was poor in the area supplied by the arteries distal to the tick bite site, but the other blood vessels of the toe were clearly visualized. Toe amputation was performed and pathological examination of a surgical specimen revealed that most blood vessels near the necrosis were occluded by thrombi. We speculated that tick bite reactions were associated with thrombogenic vasculopathy. This report shows a patient who developed toe necrosis due to poor blood circulation after an interdigital tick bite.

小児日本紅斑熱9 例の臨床的検討

To clarify the clinical manifestations of pediatric Japanese spotted fever (JSF), which remain unclear, we retrospectively reviewed the records of 9 consecutive hospitalized children 5 boys and 4 girls aged 0-15 years (median: 2.3) whose diagnosis was patients with JSF who were serologically confirmed from April 2008 to October 2009. We initially studied the polymerase chain reaction (PCR) assay validity for specific Rickettsia japonica DNA in the blood. We also studied febrile duration, the history of contact with tick-infested areas, body temperature, eschars at tick bite sites, skin rash, treatment drugs, and laboratory data. Five of the 9 (56%) had positive PCR tests. Prehospitalization febrile duration was 1-5 days. Five had had contact with tick-infested areas and 4 had not despite living near such areas. Body temperature was 40 degrees C in 7. Only 4 had eschars at bite sites. Characteristic spotted palmar and/or plantar erythema seen in 8 was useful in diagnosis. Laboratory studies showed typical hyponatremia of < 135mEq/L in 6 JSF was diagnosed easily at hospitalization in 7. Diagnosis in a 2-month-old infant proved difficults, however, worsening the child's condition and causing hepatosplenomegaly, thrombocytopenia, anemia, and hyperferritinema. The infant was treated with high-dose gamma-globulin and azithromycin (AZM) followed by minocycline (MINO). Another case was difficult to diagnose due to clinical manifestations consistent with Kawasaki disease. The child was treated with high-dose gamma-globulin and AZM. Three of the 9 were treated with MINO alone and 4 with combined MINO and new quinolones. Fever was resolved within 2 days of treatment in all cases. Our findings show that children with high fever and spotted palmar and/or plantar erythema should be treated immediately for JSF in prevalent areas, even in the absence of eschars.

A morphological and molecular study of Anaplasma phagocytophilum transmission events at the time of Ixodes ricinus tick bite

BackgroundAnaplasma phagocytophilum is the causative agent of human granulocytic anaplasmosis (HGA) in humans and tick-borne fever (TBF) in ruminants. The bacterium invades and replicates in phagocytes, especially in polymorphonuclear granulocytes.MethodsIn the present study, skin biopsies and ticks (Ixodes ricinus) were collected from tick feeding lesions on 38 grazing lambs between two and three weeks after access to pastures. The histopathological changes associated with tick bites and A. phagocytophilum infection, were described. In addition the skin biopsies were examined by immunohistochemistry. Furthermore, samples from blood, skin biopsies and ticks were examined by serology, PCR amplification of msp2 (p44), genotyping of rrs (16S rRNA) variants, and compared with the results obtained from histological and immunohistochemical investigations.ResultsTick bites were associated with chronic and hyperplastic inflammatory skin lesions in this study. A. phagocytophilum present in skin lesions were mainly associated with neutrophils and macrophages. Bacteria were occasionally observed in the Tunica media and Tunica adventitia of small vessels, but were rarely found in association with endothelial cells. PCR and genotyping of organisms present in blood, ticks and skin biopsies suggested a haematogenous and a local spread of organisms at the tick attachment sites.ConclusionsThe present study describes different aspects of A. phagocytophilum infection at the site of tick bite, and indicates that A. phagocytophilum rarely associates with endothelium during the early pathogenesis of infection.

DIFFERENTIAL DIAGNOSIS OF RADICULOPATHY IN LYME BORRELIOSISAND DYSTROPHIC LESIONS OF THE VERTEBRAL COLUMN

Subjects and methods. Thirty patients, including 9 (30.0%) men and 21 (70.0%) women, with signs of radiculopathy (RP) in late-stages Lyme borreliosis (LB) were examined. A control group comprised 30 patients with vertebrogenic RP in the presence of dystrophic changes in the vertebral column. Results. 56.7% of the patients with LB were observed to have its primary chronic course in the absence of the acute period of LB. The latter with the signs of RP showed a topic association between the pain location and the tick bite site in 43.3% of the patients. A gradual disease development was more frequently (63.3%) observed in LB while the periods of remission and exacerbation were more typical (56.7%) in vertebrogenic RP. In the patients with LB, pain syndrome depended on posture and physical exercise less frequently (30.0%) than in those with vertebrogenic RP (96.7%). Bilateral pain irradiation was more characteristic of RP in LB than in dystrophic lesions of the vertebral column. The symptoms of tonic muscle tension and limited movement volume in the afflicted part of the vertebral column were significantly less common in the patients with LB than in those with vertebrogenic RP. LB was marked by a concomitance of radicular and polyneuritic disorders (83.3%) and vertebrogenic RP was characterized by a preponderance of the radicular-type of sensitivity disorder (100%). Systemic inflammatory syndrome and polysystemacy of manifestations were more characteristic of LB. The benefits of nonsteriodal antiinflammatory drugs in LB patients with RP were significantly worse than in those with vertebrogenic RP; regression of symptoms in LB was seen only after a course of specific antibiotic therapy.

Rhipicephalus (Boophilus) microplus: Clotting time in tick-infested skin varies according to local inflammation and gene expression patterns in tick salivary glands

Ticks deposit saliva at the site of their attachment to a host in order to inhibit haemostasis, inflammation and innate and adaptive immune responses. The anti-haemostatic properties of tick saliva have been described by many studies, but few show that tick infestations or its anti-haemostatic components exert systemic effects in vivo. In the present study, we extended these observations and show that, compared with normal skin, bovine hosts that are genetically susceptible to tick infestations present an increase in the clotting time of blood collected from the immediate vicinity of haemorrhagic feeding pools in skin infested with different developmental stages of Rhipicepahlus microplus; conversely, we determined that clotting time of tick-infested skin from genetically resistant bovines was shorter than that of normal skin. Coagulation and inflammation have many components in common and we determined that in resistant bovines, eosinophils and basophils, which are known to contain tissue factor, are recruited in greater numbers to the inflammatory site of tick bites than in susceptible hosts. Finally, we correlated the observed differences in clotting times with the expression profiles of transcripts for putative anti-haemostatic proteins in different developmental stages of R. microplus fed on genetically susceptible and resistant hosts: we determined that transcripts coding for proteins similar to these molecules are overrepresented in salivary glands from nymphs and males fed on susceptible bovines. Our data indicate that ticks are able to modulate their host’s local haemostatic reactions. In the resistant phenotype, larger amounts of inflammatory cells are recruited and expression of anti-coagulant molecules is decreased tick salivary glands, features that can hamper the tick’s blood meal.

Membranous glomerulonephritis secondary to Borrelia burgdorferi infection presenting as nephrotic syndrome.

Sir, A few months following a tick bite an adult patient presented with progressive oedema, hypoalbuminaemia and nephrotic range proteinuria. Serology was positive for Borrelia burgdorferi and renal biopsy confirmed secondary membranous glomerulonephritis (MGN). A 64-year-old male sustained a tick bite on his left leg whilst holidaying on an island near Stockholm. There was no localized reaction or febrile illness associated with the bite. Over the next few months he experienced progressive oedema. Blood tests showed elevated serum creatinine at 147 μmol (106 μmol 2 months prior to holiday), serum albumin 11 g/L and serum cholesterol/HDL ratio 28.8. Urine dipstick showed 4+ of protein and 1+ of blood. Twenty-four-hour urinary collection for protein excretion was 15.46 g/24 h (<0.15 g/24 h). Hepatitis serology and autoimmune screen were negative and complement levels were normal. Initial enzyme immunoassay to Borrelia C6 peptide was reactive. This was followed by western immunoblot which was Borrelia burgdorferi IgG antibody positive and IgM antibody negative, consistent with recent infection. The patient was treated with doxycycline 100 mg twice daily for 1 month. Ultrasound of the renal tract revealed normal sized kidneys and a renal biopsy was performed. Histological examination showed diffuse thickening of the glomerular basement membrane (GBM). Immunohistology demonstrated IgG and C3 in a diffuse granular intensive reaction along the GBM in a membranous pattern. Electron microscopy revealed large electron dense deposits on the mesangial surface. The patient is on an angiotensin-converting enzyme inhibitor to reduce the intraglomerular pressure, thereby reducing the rate of his disease progression, and on warfarin therapy to reduce the risk of thrombotic complications. His oedema has subsided and the proteinuria has decreased to 650 mg/mmol/L on a recent urine PCR (protein/creatinine ratio) determined in our clinic. Lyme disease is caused by the tick-borne spirochete Borrelia burgdorferi [1]. Clinical manifestations of Lyme disease include a slowly expanding skin lesion, erythema migrans, which occurs at the site of tick bite. The skin lesion is frequently accompanied by malaise, headache, arthralgia, fever or regional lymphadenopathy, followed within days or weeks by disseminated infection that affects the nervous system, heart or joints [2]. Infection with Borrelia burgdorferi is well described as a cause of glomerulonephritis in animals, particularly canines [3]. This is rarer in humans, and association of Lyme disease with membranoproliferative glomerulonephritis (MPGN) in humans has been described in the literature only twice [4,5]. Most membranous glomerulonephritis is idiopathic but MGN may be secondary to immunological conditions, infections (hepatitis B and C, malaria), neoplasms or drugs. To our knowledge, this is the first case of membranous glomerulopathy and Borrelia burgdorferi infection as a possible aetiology. The outcome of MGN is variable as the degree of renal recovery is dependent on the causative infectious agent and treatment modalities available. Conflict of interest statement. None declared.

Serological evidence of Rickettsia parkeri as the etiological agent of rickettsiosis in Uruguay

We report three new rickettsiosis human cases in Uruguay. The three clinical cases presented clinical manifestations similar to previous reported cases of Rickettsia parkeri in the United States; that is mild fever (< 40 degrees C), malaise, headache, rash, inoculation eschar at the tick bite site, regional lymphadenopathy, and no lethality. Serological antibody-absorption tests with purified antigens of R. parkeri and Rickettsia rickettsii, associated with immunofluorescence assay indicated that the patients in two cases were infected by R. parkeri. Epidemiological and clinical evidences, coupled with our serological analysis, suggest that R. parkeri is the etiological agent of human cases of spotted fever in Uruguay, a disease that has been recognized in that country as cutaneous-ganglionar rickettsiosis.

Spotted fever group rickettsioses documented in Morocco

Mediterranean spotted fever (MSF) is caused by Rickettsia conorii conorii transmitted by the brown dog tick Rhipicephalus sanguineus. It is endemic in the Mediterranean area, where most of the cases are encountered during the summer, when the tick vectors are highly active [1]. In Morocco, MSF has been the sole human tick-borne rickettsiosis known by clinicians, and cases that are clinically recognized are rarely documented [2]. Our aim is to describe the clinical and epidemiological characteristics of confirmed cases of MSF in Casablanca and in the surrounding regions of Morocco.

Activation of several key components of the epidermal differentiation pathway in cattle following infestation with the cattle tick, Rhipicephalus (Boophilus) microplus

The cattle tick, Rhipicephalus (Boophilus) microplus, and the diseases it transmits pose a persistent threat to tropical beef production. Genetic selection of host resistance has become the method of choice for non-chemical control of cattle tick. Previous studies have suggested that larval stages are most susceptible to host resistance mechanisms. To gain insights into the molecular basis of host resistance that occurs during R. microplus attachment, we assessed the abundance of proteins (by isobaric tag for relative and absolute quantitation (iTRAQ) and Western blot analyses) and mRNAs (by quantitative reverse transcription PCR (qRT-PCR)) in skin adjacent to tick bite sites from high tick-resistant (HR) and low tick-resistant (LR) Belmont Red cattle following challenge with cattle tick. We showed substantially higher expression of the basal epidermal keratins KRT5 and KRT14, the lipid processing protein, lipocalin 9 (LCN9), the epidermal barrier catalysing enzyme transglutaminase 1 (TGM1), and the transcriptional regulator B lymphocyte-induced maturation protein 1 (Blimp1) in HR skin. Our data reveals the essential role of the epidermal permeability barrier in conferring greater resistance of cattle to tick infestation, and suggest that the physical structure of the epidermal layers of the skin may represent the first line of defence against ectoparasite invasion.

Ir-LBP, an Ixodes ricinus Tick Salivary LTB4-Binding Lipocalin, Interferes with Host Neutrophil Function

BackgroundDuring their blood meal, ticks secrete a wide variety of proteins that can interfere with their host's defense mechanisms. Among these proteins, lipocalins play a major role in the modulation of the inflammatory response.Methodology/Principal FindingsWe previously identified 14 new lipocalin genes in the tick Ixodes ricinus. One of them codes for a protein that specifically binds leukotriene B4 with a very high affinity (Kd: ±1 nM), similar to that of the neutrophil transmembrane receptor BLT1. By in silico approaches, we modeled the 3D structure of the protein and the binding of LTB4 into the ligand pocket. This protein, called Ir-LBP, inhibits neutrophil chemotaxis in vitro and delays LTB4-induced apoptosis. Ir-LBP also inhibits the host inflammatory response in vivo by decreasing the number and activation of neutrophils located at the tick bite site. Thus, Ir-LBP participates in the tick's ability to interfere with proper neutrophil function in inflammation.Conclusions/SignificanceThese elements suggest that Ir-LBP is a “scavenger” of LTB4, which, in combination with other factors, such as histamine-binding proteins or proteins inhibiting the classical or alternative complement pathways, permits the tick to properly manage its blood meal. Moreover, with regard to its properties, Ir-LBP could possibly be used as a therapeutic tool for illnesses associated with an increased LTB4 production.

Guinea Pigs Develop Cutaneous Basophilia after Repeated Infestations by Nymphs of the Tick Amblyomma triste

This study investigated the development of resistance in guinea pigs to nymphs of Amblyomma triste ticks after repeated infestations. Guinea pigs were infested thrice, at 30-day intervals, with 30 nymphs of A. triste per animal per infestation. Acquisition of resistance was evaluated by determining: nymph yielding rate, engorgement period, and weight. Skin biopsies of tick bite sites were collected at 24, 48, and 96 h after tick attachment for inflammatory cell counts. Engorged nymphs weighed 5.53 mg +/- 1.9 in re-infested hosts (56.6% less than in primary infestation) and took 6.9 days +/- 2.16 to feed in the third infestation (14.5% more than in the first infestation). Guinea pigs yielded 78%+/- 7.2 of nymphs in the re-infestation (11.6% less than in the primary infestation). In addition, a marked increase in basophil influx was observed from the first infestation onward; 69% of infiltrated cells were basophils in re-infested hosts 24 h after tick attachment. No basophils were seen at this time in primary infested animals. That number increased to 84.7% 48 h post attachment in re-infested hosts (73.2% more than in the primary infested ones) and decreased markedly 96 h post attachment in both groups (2.6% and 1% of basophils in the third and first infestation, respectively). We conclude that guinea pigs acquire resistance against nymphs of A. triste ticks after repeated infestations and that a cutaneous basophilia must play a crucial role in such a mechanism.

Cutaneous Basophilia in the Resistance of Goats to Amblyomma cajennense Nymphs after Repeated Infestations

The acquisition of resistance in goats against Amblyomma cajennense after repeated infestations and the role of inflammatory cells in this mechanism were investigated. Ten naive goats aged 6 months were distributed into two groups: test (n= 5), infested thrice at 30-day intervals; and control (n= 5), infested once. Nymphs (n= 115 per animal per infestation) were released inside alimentary chambers glued to the animal's dorsum and the following biological parameters were evaluated: yielding rate, nymphal engorgement weight, engorgement period, ecdise rate, and ecdise period. Skin fragments of tick bite sites were collected at 24, 48, 72, and 120 h post attachment for histopathology and inflammatory cells counts. The engorgement weight decreased significantly (P < 0.05) from the first infestation onward; nymphs weighed 41.7% and 37.1% less after the second and third infestations, respectively, as compared to those collected after the first infestation (12.55 mg +/- 3.21). Furthermore, the ecdise period increased significantly (P < 0.05) in the third infestation (18 days +/- 2.83) in comparison with the first infestation (15 days +/- 0.82) and the ecdise rate was significantly lower after the second infestation (71.91%+/- 17.38) in comparison with the first infestation (96.89%+/- 3.38). There were no significant differences with regard to both the engorgement period and yielding rate. A cutaneous basophilia was evidenced between 48 and 72 h (P < 0.05) after both the second and third infestations. We conclude that goats develop resistance against nymphs of A. cajennense and that basophils may play an important role in such a mechanism.