Concurrent infection of the central nervous system by Borrelia burgdorferi and Bartonella henselae: evidence for a novel tick-borne disease complex

Combining Double-Dose and High-Dose Pulsed Dapsone Combination Therapy for Chronic Lyme Disease/Post-Treatment Lyme Disease Syndrome and Co-Infections, Including Bartonella: A Report of 3 Cases and a Literature Review

Three patients with relapsing and remitting borreliosis, babesiosis, and bartonellosis, despite extended anti-infective therapy, were prescribed double-dose dapsone combination therapy (DDDCT) for 8 weeks, followed by one or several two-week courses of pulsed high-dose dapsone combination therapy (HDDCT). We discuss these patients' cases to illustrate three important variables required for long-term remission. First, diagnosing and treating active co-infections, including Babesia and Bartonella were important. Babesia required rotations of multiple anti-malarial drug combinations and herbal therapies, and Bartonella required one or several 6-day HDDCT pulses to achieve clinical remission. Second, all prior oral, intramuscular (IM), and/or intravenous (IV) antibiotics used for chronic Lyme disease (CLD)/post-treatment Lyme disease syndrome (PTLDS), irrespective of the length of administration, were inferior in efficacy to short-term pulsed biofilm/persister drug combination therapy i.e., dapsone, rifampin, methylene blue, and pyrazinamide, which improved resistant fatigue, pain, headaches, insomnia, and neuropsychiatric symptoms. Lastly, addressing multiple factors on the 16-point multiple systemic infectious disease syndrome (MSIDS) model was important in achieving remission. In conclusion, DDDCT with one or several 6-7-day pulses of HDDCT, while addressing abnormalities on the 16-point MSIDS map, could represent a novel effective clinical and anti-infective strategy in CLD/PTLDS and associated co-infections including Bartonella.

Exploring the relationship of supernumerary recurrent renal calculi formation and tick-borne infections: a case report

A 51-year-old male with a history of Cacchi-Ricci disease and long-standing infection with various species of Borrelia, Babesia, and Bartonella presented with recurrent symptoms of right-sided flank pain. Numerous renal calculi were identified on imaging. The etiology of the calculi had not been previously elucidated. Symptoms intermittently date back to 2002 when uric acid stones were identified. Subsequent calculi analysis revealed calcium oxalate stones. Despite the commonality of nephrolithiasis in patients with Cacchi-Ricci disease, the extreme number of calculi and recurrent presentation of symptoms persisted despite a plethora of medical evaluations, dietary changes, and hereditary testing. This case raises questions of etiology including possible immune deficiency and whether his uncommon microbial history contributes to recurrent stone formation.

Bartonella- and Borrelia-Related Disease Presenting as a Neurological Condition Revealing the Need for Better Diagnostics

The diagnostic tests available to identify vector-borne pathogens have major limitations. Clinicians must consider an assortment of often diverse symptoms to decide what pathogen or pathogens to suspect and test for. Even then, there are limitations to the currently available indirect detection methods, such as serology, or direct detection methods such as molecular tests with or without culture enrichment. Bartonella spp., which are considered stealth pathogens, are particularly difficult to detect and diagnose. We present a case report of a patient who experienced a spider bite followed by myalgia, lymphadenopathy, and trouble sleeping. She did not test positive for Bartonella spp. through clinically available testing. Her symptoms progressed and she was told she needed a double hip replacement. Prior to the surgery, her blood was submitted for novel molecular testing, where Bartonella spp. was confirmed, and a spirochete was also detected. Additional testing using novel methods over a period of five years found Bartonella henselae and Borrelia burgdorferi in her blood. This patient's case is an example of why new diagnostic methods for vector-borne pathogens are urgently needed and why new knowledge of the variable manifestations of Bartonellosis need to be provided to the medical community to inform and heighten their index of suspicion.

Comparison of the Efficacy of Longer versus Shorter Pulsed High Dose Dapsone Combination Therapy in the Treatment of Chronic Lyme Disease/Post Treatment Lyme Disease Syndrome with Bartonellosis and Associated Coinfections

Twenty-five patients with relapsing and remitting Borreliosis, Babesiosis, and bartonellosis despite extended anti-infective therapy were prescribed double-dose dapsone combination therapy (DDDCT), followed by one or several courses of High Dose Dapsone Combination Therapy (HDDCT). A retrospective chart review of these 25 patients undergoing DDDCT therapy and HDDCT demonstrated that 100% improved their tick-borne symptoms, and patients completing 6-7 day pulses of HDDCT had superior levels of improvement versus 4-day pulses if Bartonella was present. At the completion of treatment, 7/23 (30.5%) who completed 8 weeks of DDDCT followed by a 5-7 day pulse of HDDCT remained in remission for 3-9 months, and 3/23 patients (13%) who recently finished treatment were 1 ½ months in full remission. In conclusion, DDDCT followed by 6-7 day pulses of HDDCT could represent a novel, effective anti-infective strategy in chronic Lyme disease/Post Treatment Lyme Disease Syndrome (PTLDS) and associated co-infections, including Bartonella, especially in individuals who have failed standard antibiotic protocols.

Viability and Desiccation Resistance of Bartonella henselae in Biological and Non-Biological Fluids: Evidence for Pathogen Environmental Stability

Pathogen environmental stability is an often-neglected research priority for pathogens that are known to be vector-transmitted. Bartonella henselae, the etiologic agent of Cat Scratch Disease, has become a "pathogen of interest" in several serious human illnesses, which include neoplastic, cardiovascular, neurocognitive, and rheumatologic conditions. Survival in the flea gut and feces as well as the association with a biofilm in culture-negative endocarditis provides insight into this organism's ability to adjust to environmental extremes. The detection of B. henselae DNA in blood and tissues from marine mammals also raises questions about environmental stability and modes of pathogen transmission. We investigated the ability of B. henselae to survive in fluid matrices chosen to mimic potential environmental sources of infective materials. Feline whole blood, serum and urine, bovine milk, and physiologic saline inoculated with a laboratory strain of B. henselae San Antonio 2 were subsequently evaluated by culture and qPCR at specified time intervals. Bacterial viability was also assessed following desiccation and reconstitution of each inoculated fluid matrix. Bartonella henselae SA2 was cultured from feline urine up to 24 h after inoculation, and from blood, serum, cow's milk, and physiologic saline for up to 7 days after inoculation. Of potential medical importance, bacteria were cultured following air-desiccation of all fluid inoculates. The viability and stability of Bartonella within biological and non-biological fluids in the environment may represent a previously unrecognized source of infection for animals and human beings.

Complete Remission in Paralytic Late Tick-Borne Neurological Disease Comprising Mixed Involvement of Borrelia, Babesia, Anaplasma, and Bartonella: Use of Long-Term Treatments with Antibiotics and Antiparasitics in a Series of 10 Cases

This study aimed to demonstrate that severe neurological motor deficits in the context of late tick-borne disease with mixed microorganism involvement are eligible for long-term combined antibiotic/antiparasitic treatments. The inclusion criteria were: 1. neurological limb paralysis with a disability score >4 according to the EDSS Kurtzke disability scale; 2. serological tests pointing to an involvement of the main tick-borne microorganisms Borrelia burgdorferi s.l., Babesia, Anaplasma, and Bartonella; 3. a general disease for more than 6 months with fatigue, pain and subjective cognitive deficit. The patients were administered long-term treatments with repeated cycles (at least three) of 35-day IV ceftriaxone and repeated oral regimens of azithromycin-doxycycline and azithromycin-doxycycline-rifampicin. For Babesia, repeated courses of atovaquone-azithromycin were administered. Ten patients had intractable or severe motor deficits before treatment in the context of Borrelia (two cases) Borrelia-Babesia (four cases), Borrelia-Babesia-Anaplasma (two cases), Borrelia-Babesia-Anaplasma-Bartonella (one case) and Babesia-Anaplasma (one case). For several months, five had been in wheelchairs, and four had been walking with sticks. Seven patients out of 10 (70%) showed complete remission after a mean active treatment duration of 20.1 + 6.6 months, with a mean number of 4 ceftriaxone cycles. Three patients showed an initial remission but suffered secondary antibiotic/antiparasitic-resistant motor recurrences. Among the nine patients with Borrelia serologic positivity, treatments obtained complete remission in seven cases (77%). The findings of this ten-case series suggest the usefulness of long-term antibiotic/antiparasitic treatments in patients with severe late tick-borne neurological deficits with highly significant elements of tick-borne involvement.

Tracking tick-borne diseases in Mongolian livestock using next generation sequencing (NGS)

The livestock industry in Mongolia accounts for 24% of national revenue, with one third of the population maintaining a pastoral lifestyle. This close connection between Mongolian population and livestock is a major concern for pathogen transfer, especially given the increase in vector-borne diseases globally. This study examines blood samples from livestock to assess the prevalence of tick-borne bacterial infections across three provinces in Mongolia (Dornogovi, Selenge, Töv). Whole blood samples from 243 livestock (cattle=38, camel=11, goat=85, horse=22, sheep=87) were analyzed with 16S metagenomics next-generation sequencing (NGS) to screen for bacterial pathogens. Positive-NGS samples for Anaplasma, Bartonella, Ehrlichia, Francisella, Leptospira, and Rickettsia were confirmed by conventional PCR and DNA sequencing. Prevalence rates of Anaplasma, Bartonella, and Ehrlichia were 57.6%, 12.8%, and 0.4%, respectively. A significant difference in the prevalence of Anaplasma spp. in livestock by province was observed, with a higher prevalence in Selenge (74.2%, p<0.001) and Töv (64.2% p = 0.006) compared to the semi-arid region of Dornogovi (39.8%). In contrast, no association was observed in Bartonella prevalence by provinces. All Anaplasma sequences (N = 139) were characterized as A. ovis. For Bartonella species characterization, phylogenetic analyses of gltA and rpoB genes identified three Bartonella species including B. bovis, B. melophagi and Candidatus B. ovis. Bartonella bovis was detected in all 22-positive cattle, while B. melophagi and Candidatus B. ovis were found in four and three sheep, respectively. This study identifies a high prevalence of tick-borne pathogens within the livestock population and to our knowledge, is the first time NGS methods have been used to explore tick-borne diseases in Mongolia. Further research is needed in Mongolia to better understand the clinical and economic burdens associated with tick-borne diseases in both livestock and pastoral herder populations.

Seroprevalence of Antibodies against Tick-Borne Pathogens in Czech Patients with Suspected Post-Treatment Lyme Disease Syndrome

The hypothesized importance of coinfections in the pathogenesis of post-treatment Lyme disease syndrome (PTLDS) leads to the use of combined, ongoing antimicrobial treatment in many cases despite the absence of symptoms typical of the presence of infection with specific pathogens. Serum samples from 103 patients with suspected post-treatment Lyme disease syndrome were tested for the presence of antibodies to the major tick-borne pathogens Anaplasma phagocytophilum, Bartonella henselae/Bartonella quinatana, and Babesia microti. Although the presence of anti-Anaplasma antibodies was detected in 12.6% of the samples and anti-Bartonella antibodies in 9.7% of the samples, the presence of antibodies against both pathogens in the same samples or anti-Babesia antibodies in the selected group of patients could not be confirmed. However, we were able to detect autoantibodies, mostly antinuclear, in 11.6% of the patients studied. Our results are in good agreement with previously published studies showing the presence of a wide spectrum of autoantibodies in some patients with complicated forms of Lyme disease and post-treatment Lyme disease syndrome, but they do not reveal a significant influence of co-infections on the development of PTLDS in the studied group of patients.

Anorexia Nervosa Caused by Polymicrobial Tick-Borne Infections: A Case Study

The etiology of anorexia nervosa (AN) is multifactorial, and infections may play a contributory and possibly a prominent role. A case is presented which is indicative of a causal association between tick-borne infections and AN. This adolescent female was diagnosed with AN at an eating disorder clinic after excessive food restriction and an irrational fear of weight gain necessitating nasogastric tube feeding. Her history was consistent with systemic infections and she tested serologically positive to Borrelia burgdorferi, Babesia microti, and Mycoplasma pneumoniae; in addition, her clinical presentation was consistent with a Bartonella infection. After treatment with oral and intravenous antimicrobials, she stopped food restriction and no longer had body image concerns. Physicians should be aware of the possibility that tick-borne infections could underly a diagnosis of AN. The role of tick-borne infections in the etiology of AN warrants further study.

Transmission of Bartonella henselae within Rhipicephalus sanguineus: Data on the Potential Vector Role of the Tick

Bartonella henselae is a fastidious intraerythrocytic, gram-negative bacteria that causes cat scratch disease in humans. Ixodes ricinus has been confirmed to be a competent vector of B. henselae, and some indirect evidences from clinical cases and epidemiological studies also suggested that some other tick species, including Rhipicephalus sanguineus, may transmit the bacteria. B. henselae has been detected in R. sanguineus but no experimental investigations have been performed to evaluate the vector competency of this tick species regarding B. henselae transmission. To this end, this work aimed to assess the transstadial transmission of B. henselae between larvae and nymphs of R. sanguineus as well as transmission by nymphs infected at the larval stage. Four hundred B. henselae negative larvae were fed with B. henselae-infected blood by using an artificial membrane feeding system. After five days of feeding, B. henselae was detected by PCR in 57.1% (8/14) of engorged larval pools, 66.7% (4/6) of semi-engorged larval pools, and 66.7% (2/3) of larval feces pools. After molting, B. henselae DNA was also detected in 10% (1/10) of nymph pools, but not in tick feces. After a pre-fed step of nymphs infected at the larval stage on non-infected blood meal, B. henselae was detected by PCR in blood sample from the feeder, but no Bartonella colonies could be obtained from culture. These findings showed that B. henselae could be transstadial transmitted from R. sanguineus larvae to nymphs, and also suggest that these nymphs may retransmitted the bacteria through the saliva during their blood meal. This is the first study that validated the artificial membrane feeding system for maintaining R. sanguineus tick colony. It shows the possibility of transstadial transmission of B. henselae from R. sanguineus larvae to nymphs.

B. henselae is gram-negative bacteria that infects red blood cells of humans and companion animals and causes cat scratch disease in humans. Ticks were considered to be potential vectors of B. henselae for a long time until it was finally experimentally demonstrated for Ixodes ricinus. Since then, no evidence on B. henselae transmission by other tick species was reported. This study was performed 1) to validate the use of artificial membrane system to feed and infect R. sanguineus ticks and 2) to determine the possibility of B. henselae transmission by R. sanguineus, a world-widely distributed ticks. Our results show that the artificial membrane feeding system can be used to maintain R. sanguineus colony in the laboratory, and that B. henselae can be acquired by R. sanguineus during a blood meal on artificial membrane feeding system and can be transmitted from larvae to nymphs that were able to inject bacterial DNA to blood during a new blood meal. However, further investigations are still needed to confirm the viability of bacteria transmitted to blood by nymphs infected at the larval stage in order to validate B. henselae transmission by R. sanguineus.

Accelerating the sustainable development goals through microbiology: some efforts and opportunities

Modernization has thrown humanity and other forms of life on our planet into a ditch of problems. Poverty, climate change, injustice and environmental degradation are a few of the shared global problems. The United Nations Sustainable Development Goals (SDGs) are the blueprint to achieve a better and more sustainable future for all. The SDGs are well structured to address the global challenges we face including poverty, inequalities, hunger, climate change, environmental degradation, peace and justice. Five years into the implementation, the SDGs have been driven mainly by international donors and 'professional' international development organizations. The world is left with 10 years to achieve these ambitious goals and targets. Various reviews show that little has been achieved overall, and the SDGs will not be a reality if a new strategy is not in place to bring inclusion. Microbiology, the scientific discipline of microbes, their effects and practical uses has insightful influence on our day-to-day living. We present how microbiology and microbiologists could increase the scorecard and accelerate these global goals. Microbiology has a direct link to achieving SDGs addressing food security, health and wellbeing, clean energy, environmental degradation and climate change. A non-classical growing relationship exists between microbiology and other SDGs such as peace, justice, gender equality, decent work and economic growth. The pledge of 'Leave No One Behind' will fast track progress and microbiology is in a better position to make this work.

Is Bartonella a Cause of Primary Sclerosing Cholangitis? A Case Study

The etiology of primary sclerosing cholangitis (PSC) is unknown. I present a case which may be indicative of a causal link between Bartonella infection and PSC. The patient presented with complaints of abdominal pain and bloody diarrhea. A colonoscopy demonstrated chronic inflammation and changes consistent with ulcerative colitis. Routine laboratory studies revealed elevated liver function tests (LFTs); ultrasound and magnetic resonance imaging (MRI) confirmed the diagnosis of PSC. Bartonella serology was positive. It is established that Bartonella infection is associated with both gastrointestinal inflammation and autoimmunity; indeed, there is an animal model for Bartonella-induced PSC. Bartonella is susceptible to treatment with vancomycin and there are case reports and small series that demonstrate that PSC responds to treatment with oral vancomycin. Because of this, it is postulated that at least some cases of PSC may be associated with Bartonella infection. The patient in this report was treated with oral vancomycin and, since then, has been in remission for both colitis and PSC. Since vancomycin is not systemically absorbed, the premise is that he suffered from Bartonella colitis and an autoimmune reaction to Bartonella causing PSC. This premise warrants further study.

Essential Oils with High Activity against Stationary Phase Bartonella henselae

Bartonella henselae is a fastidious Gram-negative intracellular bacterium that can cause cat scratch disease, endocarditis in humans and animals, as well as other complications, leading to acute or chronic infections. The current treatment for Bartonella infections is not very effective due to antibiotic resistance and also persistence. To develop better therapies for persistent and chronic Bartonella infections, in this study, with the help of SYBR Green I/PI viability assay, we performed a high-throughput screening of an essential oil library against the stationary phase B. henselae. We successfully identified 32 essential oils that had high activity, including four essential oils extracted from Citrus plants, three from Origanum, three from Cinnamomum, two from Pelargonium, and two from Melaleuca, as well as frankincense, ylang-ylang, fir needle, mountain savory (winter), citronella, spearmint, elemi, vetiver, clove bud, allspice, and cedarwood essential oils. The minimal inhibitory concentration (MIC) determination of these 32 top hits indicated they were not only active against stationary phase non-growing B. henselae but also had good activity against log-phase growing B. henselae. The time-kill assay showed 13 active hits, including essential oils of oregano, cinnamon bark, mountain savory (winter), cinnamon leaf, geranium, clove bud, allspice, geranium bourbon, ylang-ylang, citronella, elemi, and vetiver, could eradicate all stationary phase B. henselae cells within seven days at the concentration of 0.032% (v/v). Two active ingredients, carvacrol and cinnamaldehyde, of oregano and cinnamon bark essential oils, respectively, were shown to be very active against the stationary phase B. henselae such that they were able to eradicate all the bacterial cells even at the concentration ≤ 0.01% (v/v). More studies are needed to identify the active components of some potent essential oils, decode their antimicrobial mechanisms, and evaluate their activity against Bartonella infections in animal models.

Identification of FDA-Approved Drugs with Activity against Stationary Phase Bartonella henselae

Bartonella henselae can cause various infections in humans, ranging from benign and self-limiting diseases to severe and life-threatening diseases as well as persistent infections that are difficult to treat. To develop more effective treatments for persistent Bartonella infections, in this study, we performed a high-throughput screen of an FDA-approved drug library against stationary phase B. henselae using the SYBR Green I/propidium iodide (PI) viability assay. We identified 110 drug candidates that had better activity against stationary phase B. henselae than ciprofloxacin, and among the top 52 drug candidates tested, 41 drugs were confirmed by microscopy to have higher activity than the current frontline antibiotic erythromycin. The identified top drug candidates include pyrvinium pamoate, daptomycin, methylene blue, azole drugs (clotrimazole, miconazole, sulconazole, econazole, oxiconazole, butoconazole, bifonazole), aminoglycosides (gentamicin and streptomycin, amikacin, kanamycin), amifostine (Ethyol), antiviral Lopinavir/ritonavir, colistin, nitroxoline, nitrofurantoin, verteporfin, pentamidine, berberine, aprepitant, olsalazine, clinafloxacin, and clofoctol. Pyrvinium pamoate, daptomycin, methylene blue, clotrimazole, and gentamicin and streptomycin at their respective maximum drug concentration in serum (C_max) had the capacity to completely eradicate stationary phase B. henselae after 3-day drug exposure in subculture studies. While the currently used drugs for treating bartonellosis, including rifampin, erythromycin, azithromycin, doxycycline, and ciprofloxacin, had very low minimal inhibitory concentration (MIC) against growing B. henselae, they had relatively poor activity against stationary phase B. henselae, except aminoglycosides. The identified FDA-approved agents with activity against stationary phase B. henselae should facilitate development of more effective treatments for persistent Bartonella infections.

Human Bartonellosis: An Underappreciated Public Health Problem?

Bartonella spp. bacteria can be found around the globe and are the causative agents of multiple human diseases. The most well-known infection is called cat-scratch disease, which causes mild lymphadenopathy and fever. As our knowledge of these bacteria grows, new presentations of the disease have been recognized, with serious manifestations. Not only has more severe disease been associated with these bacteria but also Bartonella species have been discovered in a wide range of mammals, and the pathogens’ DNA can be found in multiple vectors. This review will focus on some common mammalian reservoirs as well as the suspected vectors in relation to the disease transmission and prevalence. Understanding the complex interactions between these bacteria, their vectors, and their reservoirs, as well as the breadth of infection by Bartonella around the world will help to assess the impact of Bartonellosis on public health.

Precision medicine: retrospective chart review and data analysis of 200 patients on dapsone combination therapy for chronic Lyme disease/post-treatment Lyme disease syndrome: part 1

PURPOSE

We collected data from an online survey of 200 of our patients, which evaluated the efficacy of dapsone (diaminodiphenyl sulfone, ie, DDS) combined with other antibiotics and agents that disrupt biofilms for the treatment of chronic Lyme disease/post-treatment Lyme disease syndrome (PTLDS). We also collected aggregate data from direct retrospective chart review, including laboratory testing for Lyme, other infections, and associated tick-borne coinfections. This helped us to determine the frequency of exposure to other infections/coinfections among a cohort of chronically ill Lyme patients, evaluate the efficacy of newer "persister" drug regimens like DDS, and determine how other infections and tick-borne coinfections may be contributing to the burden of chronic illness leading to resistant symptomatology.

PATIENTS AND METHODS

A total of 200 adult patients recruited from a specialized Lyme disease medical practice had been ill for at least 1 year. We regularly monitored laboratory values and participants' symptom severity, and the patients completed the online symptom questionnaire both before beginning treatment and after 6 months on DDS combination therapy (DDS CT). Paired-samples t-tests and Wilcoxon signed-rank nonparametric test were performed on each of eight major Lyme symptoms, both before DDS CT and after 6 months of therapy.

RESULTS

DDS CT statistically improved the eight major Lyme symptoms. We found multiple species of intracellular bacteria including rickettsia, Bartonella, Mycoplasma, Chlamydia, Tularemia, and Brucella contributing to the burden of illness and a high prevalence of Babesia complicating management with probable geographic spread of Babesia WA1/duncani to the Northeast. Borrelia, Bartonella, and Mycoplasma species, as well as Babesia microti had variable manifestations and diverse seroreactivity, with evidence of persistence despite commonly prescribed courses of anti-infective therapies. Occasional reactivation of viral infections including human herpes virus 6 was also seen in immunocompromised individuals.

CONCLUSION

DDS CT decreased eight major Lyme symptoms severity and improved treatment outcomes among patients with chronic Lyme disease/PTLDS and associated coinfections.

Anti-NMDAR Encephalitis in Association with Herpes Simplex Virus and Viral and Bacterial Zoonoses

Multiple co-infections can predispose a patient to autoimmune encephalitis. Out of thirty cases of N-methyl-D-aspartate receptor (NMDAR) encephalitis seen at a single tertiary referral center, only two cases of co-infection with NMDAR encephalitis were identified. One of these cases was highly interesting due to the presence of more than one co-infections along with the presence of cortical dysfunction, seizures, and orofacial dyskinesias at the onset in a male in the absence of tumors, which was refractory to initial treatment.

Combination of microbiome analysis and serodiagnostics to assess the risk of pathogen transmission by ticks to humans and animals in central Germany

BACKGROUND

Arthropod-borne diseases remain a major health-threat for humans and animals worldwide. To estimate the distribution of pathogenic agents and especially Bartonella spp., we conducted tick microbiome analysis and determination of the infection status of wild animals, pets and pet owners in the state of Hesse, Germany.

RESULTS

In total, 189 engorged ticks collected from 163 animals were tested. Selected ticks were analyzed by next generation sequencing (NGS) and confirmatory PCRs, blood specimens of 48 wild animals were analyzed by PCR to confirm pathogen presence and sera of 54 dogs, one cat and 11 dog owners were analyzed by serology. Bartonella spp. were detected in 9.5% of all ticks and in the blood of 17 roe deer. Further data reveal the presence of the human and animal pathogenic species of genera in the family Spirochaetaceae (including Borrelia miyamotoi and Borrelia garinii), Bartonella spp. (mainly Bartonella schoenbuchensis), Rickettsia helvetica, Francisella tularensis and Anaplasma phagocytophilum in ticks. Co-infections with species of several genera were detected in nine ticks. One dog and five dog owners were seropositive for anti-Bartonella henselae-antibodies and one dog had antibodies against Rickettsia conorii.

CONCLUSIONS

This study provides a snapshot of pathogens circulating in ticks in central Germany. A broad range of tick-borne pathogens are present in ticks, and especially in wild animals, with possible implications for animal and human health. However, a low incidence of Bartonella spp., especially Bartonella henselae, was detected. The high number of various detected pathogens suggests that ticks might serve as an excellent sentinel to detect and monitor zoonotic human pathogens.

Neuropsychiatric Lyme Borreliosis: An Overview with a Focus on a Specialty Psychiatrist's Clinical Practice

There is increasing evidence and recognition that Lyme borreliosis (LB) causes mental symptoms. This article draws from databases, search engines and clinical experience to review current information on LB. LB causes immune and metabolic effects that result in a gradually developing spectrum of neuropsychiatric symptoms, usually presenting with significant comorbidity which may include developmental disorders, autism spectrum disorders, schizoaffective disorders, bipolar disorder, depression, anxiety disorders (panic disorder, social anxiety disorder, generalized anxiety disorder, posttraumatic stress disorder, intrusive symptoms), eating disorders, decreased libido, sleep disorders, addiction, opioid addiction, cognitive impairments, dementia, seizure disorders, suicide, violence, anhedonia, depersonalization, dissociative episodes, derealization and other impairments. Screening assessment followed by a thorough history, comprehensive psychiatric clinical exam, review of systems, mental status exam, neurological exam and physical exam relevant to the patient's complaints and findings with clinical judgment, pattern recognition and knowledgeable interpretation of laboratory findings facilitates diagnosis. Psychotropics and antibiotics may help improve functioning and prevent further disease progression. Awareness of the association between LB and neuropsychiatric impairments and studies of their prevalence in neuropsychiatric conditions can improve understanding of the causes of mental illness and violence and result in more effective prevention, diagnosis and treatment.

Control of Lyme borreliosis and other Ixodes ricinus-borne diseases

Lyme borreliosis (LB) and other Ixodes ricinus-borne diseases (TBDs) are diseases that emerge from interactions of humans and domestic animals with infected ticks in nature. Nature, environmental and health policies at (inter)national and local levels affect the risk, disease burden and costs of TBDs. Knowledge on ticks, their pathogens and the diseases they cause have been increasing, and resulted in the discovery of a diversity of control options, which often are not highly effective on their own. Control strategies involving concerted actions from human and animal health sectors as well as from nature managers have not been formulated, let alone implemented. Control of TBDs asks for a “health in all policies” approach, both at the (inter)national level, but also at local levels. For example, wildlife protection and creating urban green spaces are important for animal and human well-being, but may increase the risk of TBDs. In contrast, culling or fencing out deer decreases the risk for TBDs under specific conditions, but may have adverse effects on biodiversity or may be societally unacceptable. Therefore, in the end, nature and health workers together must carry out tailor-made control options for the control of TBDs for humans and animals, with minimal effects on the environment. In that regard, multidisciplinary approaches in environmental, but also medical settings are needed. To facilitate this, communication and collaboration between experts from different fields, which may include patient representatives, should be promoted.

Empirical validation of the Horowitz Multiple Systemic Infectious Disease Syndrome Questionnaire for suspected Lyme disease

PURPOSE

Lyme disease is spreading worldwide, with multiple Borrelia species causing a broad range of clinical symptoms that mimic other illnesses. A validated Lyme disease screening questionnaire would be clinically useful for both providers and patients. Three studies evaluated such a screening tool, namely the Horowitz Multiple Systemic Infectious Disease Syndrome (MSIDS) Questionnaire. The purpose was to see if the questionnaire could accurately distinguish between Lyme patients and healthy individuals.

METHODS

Study 1 examined the construct validity of the scale examining its factor structure and reliability of the questionnaire among 537 individuals being treated for Lyme disease. Study 2 involved an online sample of 999 participants, who self-identified as either healthy (N=217) or suffering from Lyme now (N=782) who completed the Horowitz MSIDS Questionnaire (HMQ) along with an outdoor activity survey. We examined convergent validity among components of the scale and evaluated discriminant validity with the Big Five personality characteristics. The third study compared a sample of 236 patients with confirmed Lyme disease with an online sample of 568 healthy individuals.

RESULTS

Factor analysis results identified six underlying latent dimensions; four of these overlapped with critical symptoms identified by Horowitz - neuropathy, cognitive dysfunction, musculoskeletal pain, and fatigue. The HMQ showed acceptable levels of internal reliability using Cronbach's coefficient alpha and exhibited evidence of convergent and divergent validity. Components of the HMQ correlated more highly with each other than with unrelated traits.

DISCUSSION

The results consistently demonstrated that the HMQ accurately differentiated those with Lyme disease from healthy individuals. Three migratory pain survey items (persistent muscular pain, arthritic pain, and nerve pain/paresthesias) robustly identified individuals with verified Lyme disease. The results support the use of the HMQ as a valid, efficient, and low-cost screening tool for medical practitioners to decide if additional testing is warranted to distinguish between Lyme disease and other illnesses.

Seroprevalence of Bartonella Species in Patients with Ocular Inflammation

Bartonella species, vector-borne etiologic agents of many systemic or self-limited infections, are responsible for a widening spectrum of diseases in humans, including inflammatory conditions of the eye. The aim of this study was to determine whether there is any relationship between uveitis and the evidence of Bartonella spp. infection in the serum, ocular fluid, and cataract mass in patients with intraocular inflammation. Polymerase chain reaction (PCR)-based tests and DNA sequencing were performed on surgery-extracted specimens of intraocular fluid and lens mass of 33 patients. Sera from 51 patients and 101 control subjects were tested for the presence of specific antibodies against Bartonella spp. Neither IgM-class antibodies against Bartonella spp. nor Bartonella spp. DNA were detected. A specific IgG-class antibody was found in 33.3% of the patients with uveitis. The rate of positive Bartonella serology was higher among the uveitis patients than that in control subjects. This high rate may in part result from unrecognized indirect mechanisms rather than the immediate presence and multiplication of Bartonella spp. in the eyeball. Nonetheless we believe that screening for Bartonella spp. should become part of the diagnostic workup in uveitis.

Bartonella spp. - a chance to establish One Health concepts in veterinary and human medicine

Infectious diseases remain a remarkable health threat for humans and animals. In the past, the epidemiology, etiology and pathology of infectious agents affecting humans and animals have mostly been investigated in separate studies. However, it is evident, that combined approaches are needed to understand geographical distribution, transmission and infection biology of “zoonotic agents”. The genus Bartonella represents a congenial example of the synergistic benefits that can arise from such combined approaches: Bartonella spp. infect a broad variety of animals, are linked with a constantly increasing number of human diseases and are transmitted via arthropod vectors. As a result, the genus Bartonella is predestined to play a pivotal role in establishing a One Health concept combining veterinary and human medicine.

Human pathogens associated with the blacklegged tick Ixodes scapularis: a systematic review

BACKGROUND

The blacklegged tick Ixodes scapularis transmits Borrelia burgdorferi (sensu stricto) in eastern North America; however, the agent of Lyme disease is not the sole pathogen harbored by the blacklegged tick. The blacklegged tick is expanding its range into areas of southern Canada such as Ontario, an area where exposure to blacklegged tick bites and tick-borne pathogens is increasing. We performed a systematic review to evaluate the public health risks posed by expanding blacklegged tick populations and their associated pathogens.

METHODS

We followed PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines for conducting our systematic review. We searched Ovid MEDLINE, Embase, BIOSIS, Scopus and Environment Complete databases for studies published from 2000 through 2015, using subject headings and keywords that included "Ixodes scapularis", "Rickettsia", "Borrelia", "Anaplasma", "Babesia" and "pathogen." Two reviewers screened titles and abstracts against eligibility criteria (i.e. studies that included field-collected blacklegged ticks and studies that did not focus solely on B. burgdorferi) and performed quality assessments on eligible studies.

RESULTS

Seventy-eight studies were included in the final review, 72 were from the US and eight were from Canada (two studies included blacklegged ticks from both countries). Sixty-four (82%) studies met ≥ 75% of the quality assessment criteria. Blacklegged ticks harbored 91 distinct taxa, 16 of these are tick-transmitted human pathogens, including species of Anaplasma, Babesia, Bartonella, Borrelia, Ehrlichia, Rickettsia, Theileria and Flavivirus. Organism richness was highest in the Northeast (Connecticut, New York) and Upper Midwest US (Wisconsin); however, organism richness was dependent on sampling effort. The primary tick-borne pathogens of public health concern in Ontario, due to the geographic proximity or historical detection in Ontario, are Anaplasma phagocytophilum, Babesia microti, B. burgdorferi, Borrelia miyamotoi, deer tick virus and Ehrlichia muris-like sp. Aside from B. burgdorferi and to a much lesser concern A. phagocytophilum, these pathogens are not immediate concerns to public health in Ontario; rather they represent future threats as the distribution of vectors and pathogens continue to proliferate.

CONCLUSIONS

Our review is the first systematic assessment of the literature on the human pathogens associated with the blacklegged tick. As Lyme disease awareness continues to increase, it is an opportune time to document the full spectrum of human pathogens transmittable by blacklegged ticks.

Bartonella henselae in eastern Poland: the relationship between tick infection rates and the serological response of individuals occupationally exposed to tick bites

To explore the potential role of Ixodes ricinus as the presumed vector of Bartonella henselae in eastern Poland, ticks collected in various geographic locations were examined for the presence of B. henselae, and the results were matched against the prevalence of anti-B. henselae antibodies in individuals occupationally exposed to tick bites. The presence of Bartonella DNA was investigated by PCR in a total of 1,603 unfed Ixodes ricinus ticks. The presence of IgG antibodies against B. henselae was investigated in serum samples from 332 people occupationally exposed to tick bites (94 farmers and 238 forestry workers). The total prevalence of B. henselae in ticks was 1.7%; the infection rates in males (3.1%) and females (2.7%) were nearly ten times greater than in nymphs (0.3%). The prevalence of seropositive results in the risk group (30.4%), farmers (27.7%) and forestry workers (31.5%), was significantly greater compared to the control group (8.9%). The results showed a weak positive correlation between the degree of infection of ticks and humans living in the same geographic region. The lack of a direct relationship indicates that exposure to tick bites is only one of the factors contributing to the significant preponderance of a seropositive response to B. henselae in the forestry workers and farmers over the control group. Other factors must be considered, such as contact with cats, which are popular domestic animals in Polish villages, and exposure to cat fleas.

Atypical presentation of cat-scratch disease in an immunocompetent child with serological and pathological evidence

Typical cat-scratch disease (CSD) is characterized by local lymphadenopathy following the scratch or bite from a cat or kitten. An atypical presentation which includes liver and/or spleen lesions is rarely reported in an immunocompetent child. Systemic CSD may mimic more serious disorders like malignancy or tuberculosis. Although a diagnosis is difficult to establish in systemic CSD, an early diagnosis and an appropriate treatment are important to prevent complications. Bartonella henselae is difficult to culture, and culture is not routinely recommended. Clinical, serological, radiological, and pathological findings are used for the diagnosis of CSD. Herein we present a case of systemic CSD presenting with hepatic mass in an immunocompetent child. The differential diagnosis is made by serological and pathological evidence. He was successfully treated with gentamicin (7.5 mg/kg) and rifampin (15 mg/kg) for six weeks.

Chronic coinfections in patients diagnosed with chronic lyme disease: a systematic review

PURPOSE

Often, the controversial diagnosis of chronic Lyme disease is given to patients with prolonged, medically unexplained physical symptoms. Many such patients also are treated for chronic coinfections with Babesia, Anaplasma, or Bartonella in the absence of typical presentations, objective clinical findings, or laboratory confirmation of active infection. We have undertaken a systematic review of the literature to evaluate several aspects of this practice.

METHODS

Five systematic literature searches were performed using Boolean operators and the PubMed search engine.

RESULTS

The literature searches did not demonstrate convincing evidence of: 1) chronic anaplasmosis infection; 2) treatment-responsive symptomatic chronic babesiosis in immunocompetent persons in the absence of fever, laboratory abnormalities, and detectable parasitemia; 3) either geographically widespread or treatment-responsive symptomatic chronic infection with Babesia duncani in the absence of fever, laboratory abnormalities, and detectable parasitemia; 4) tick-borne transmission of Bartonella species; or 5) simultaneous Lyme disease and Bartonella infection.

CONCLUSIONS

The medical literature does not support the diagnosis of chronic, atypical tick-borne coinfections in patients with chronic, nonspecific illnesses.

Review: the important bacterial zoonoses in "one health" concept

An infectious disease that is transmitted from animals to humans, sometimes by a vector, is called zoonosis. The focus of this review article is on the most common emerging and re-emerging bacterial zoonotic diseases. The role of "One Health" approach, public health education, and some measures that can be taken to prevent zoonotic bacterial infections are discussed.

KEY POINTS

A zoonotic bacterial disease is a disease that can be very commonly transmitted between animals and humans. Global climate changes, overuse of antimicrobials in medicine, more intensified farm settings, and closer interactions with animals facilitate emergence or re-emergence of bacterial zoonotic infections.The global "One Health" approach, which requires interdisciplinary collaborations and communications in all aspects of health care for humans, animals, and the environment, will support public health in general.New strategies for continuous dissemination of multidisciplinary research findings related to zoonotic bacterial diseases are hence needed.

Lyme disease: point/counterpoint

Lyme disease represents a growing public health threat. The controversial science and politics of Lyme disease have created barriers to reliable diagnosis and effective treatment of this protean illness. Two major clinical hurdles are the absence of a therapeutic end point in treating Borrelia burgdorferi, the spirochetal agent of Lyme disease, and the presence of tickborne coinfections with organisms such as Babesia, Anaplasma, Ehrlichia and Bartonella that may complicate the course of the disease. From a pathophysiologic standpoint, the affinity of Borrelia burgdorferi for multiple cell types and the presence of nonreplicating forms of the Lyme disease spirochete have contributed to persistent infection and failure of simple antibiotic regimens. Newer approaches to the treatment of Lyme disease should take into account its clinical complexity in coinfected patients and the possible need for prolonged combination therapy in patients with persistent symptoms of this potentially debilitating illness. The optimal antibiotic regimen for chronic Lyme disease remains to be determined.

Laboratory diagnosis of CNS infections by molecular amplification techniques

The initial presentation of symptoms and clinical manifestations of CNS infectious diseases often makes a specific diagnosis difficult and uncertain, and the emergence of polymerase chain reaction-led molecular techniques have been used in improving organism-specific diagnosis. These techniques have not only provided rapid, non-invasive detection of microorganisms causing CNS infections, but also demonstrated several neurologic disorders linked to infectious pathogens. Molecular methods performed on cerebrospinal fluid are recognized as the new 'gold standard' for some of these infections caused by microorganisms that are difficult to detect and identify. Although molecular techniques are predicted to be widely used in diagnosing and monitoring CNS infections, the limitations as well as strengths of these techniques must be clearly understood by both clinicians and laboratory personnel.

Chronic Lyme Disease and Co-infections: Differential Diagnosis

In Lyme disease concurrent infections frequently occur. The clinical and pathological impact of co-infections was first recognized in the 1990th, i.e. approximately ten years after the discovery of Lyme disease. Their pathological synergism can exacerbate Lyme disease or induce similar disease manifestations. Co-infecting agents can be transmitted together with Borrelia burgdorferi by tick bite resulting in multiple infections but a fraction of co-infections occur independently of tick bite. Clinically relevant co-infections are caused by Bartonella species, Yersinia enterocolitica, Chlamydophila pneumoniae, Chlamydia trachomatis, and Mycoplasma pneumoniae. In contrast to the USA, human granulocytic anaplasmosis (HGA) and babesiosis are not of major importance in Europe. Infections caused by these pathogens in patients not infected by Borrelia burgdorferi can result in clinical symptoms similar to those occurring in Lyme disease. This applies particularly to infections caused by Bartonella henselae, Yersinia enterocolitica, and Mycoplasma pneumoniae. Chlamydia trachomatis primarily causes polyarthritis. Chlamydophila pneumoniae not only causes arthritis but also affects the nervous system and the heart, which renders the differential diagnosis difficult. The diagnosis is even more complex when co-infections occur in association with Lyme disease. Treatment recommendations are based on individual expert opinions. In antibiotic therapy, the use of third generation cephalosporins should only be considered in cases of Lyme disease. The same applies to carbapenems, which however are used occasionally in infections caused by Yersinia enterocolitica. For the remaining infections predominantly tetracyclines and macrolides are used. Quinolones are for alternative treatment, particularly gemifloxacin. For Bartonella henselae, Chlamydia trachomatis, and Chlamydophila pneumoniae the combination with rifampicin is recommended. Erythromycin is the drug of choice for Campylobacter jejuni.

Co-infection of Borrelia afzelii and Bartonella spp. in bank voles from a suburban forest

We report the molecular detection of Borrelia afzelii (11%) and Bartonella spp. (56%) in 447 bank voles trapped in a suburban forest in France. Adult voles were infected by significantly more Borrelia afzelii than juveniles (p<0.001), whereas no significant difference was detected in the prevalence of Bartonella spp. between young and adult individuals (p=0.914). Six percent of the animals were co-infected by both bacteria. Analysis of the bank vole carrier status for either pathogen indicated that co-infections occur randomly (p=0.94, CI(95)=[0.53; 1.47]). Sequence analysis revealed that bank voles were infected by a single genotype of Borrelia afzelii and by 32 different Bartonella spp. genotypes, related to three known species specific to rodents (B. taylorii, B. grahamii and B. doshiae) and also two as yet unidentified Bartonella species. Our findings confirm that rodents harbor high levels of potential human pathogens; therefore, widespread surveillance should be undertaken in areas where humans may encounter rodents.

Molecular evidence of vector-borne pathogens coinfecting dogs from Poland

Ticks of the genus Ixodes are vectors for many pathogens, including Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum and Rickettsia spp., and may also serve as vectors for Bartonella spp. However, the role of ticks in Bartonella transmission requires additional studies. The aim of this study was to investigate whether coinfection with two or more vector-borne pathogens can occur in the following three groups of dogs: I - dogs with suspected borreliosis (N = 92), II - dogs considered healthy (N = 100), and III - dogs with diagnosed babesiosis (N = 50). Polymerase chain reactions were performed to detect DNA of Anaplasma phagocytophilum, Rickettsia spp. and Bartonella spp. in the blood of dogs. In dogs of Group I, the DNA of both A. phagocytophilum and Bartonella sp. was detected (14% and 1%, respectively). In eight dogs, coinfection was indicated: A. phagocytophilum or Bartonella sp. with B. burgdorferi s.l. (the presence of antibodies against and/or DNA B. burgdorferi s.l.). In the case of five dogs positive for A. phagocytophilum DNA, no coinfection with B. burgdorferi s.l. was shown. In Group II, the DNA of A. phagocytophilum was detected in four dogs. In Group III, no pathogenic agents possibly transmitted by ticks were confirmed. No DNA of R. helvetica was detected in any of the groups studied.

Vector competence of the tick Ixodes ricinus for transmission of Bartonella birtlesii

Bartonella spp. are facultative intracellular vector-borne bacteria associated with several emerging diseases in humans and animals all over the world. The potential for involvement of ticks in transmission of Bartonella spp. has been heartily debated for many years. However, most of the data supporting bartonellae transmission by ticks come from molecular and serological epidemiological surveys in humans and animals providing only indirect evidences without a direct proof of tick vector competence for transmission of bartonellae. We used a murine model to assess the vector competence of Ixodes ricinus for Bartonella birtlesii. Larval and nymphal I. ricinus were fed on a B. birtlesii-infected mouse. The nymphs successfully transmitted B. birtlesii to naïve mice as bacteria were recovered from both the mouse blood and liver at seven and 16 days after tick bites. The female adults successfully emitted the bacteria into uninfected blood after three or more days of tick attachment, when fed via membrane feeding system. Histochemical staining showed the presence of bacteria in salivary glands and muscle tissues of partially engorged adult ticks, which had molted from the infected nymphs. These results confirm the vector competence of I. ricinus for B. birtlesii and represent the first in vivo demonstration of a Bartonella sp. transmission by ticks. Consequently, bartonelloses should be now included in the differential diagnosis for patients exposed to tick bites.

Bartonella species and their ectoparasites: selective host adaptation or strain selection between the vector and the mammalian host?

A wide range of blood-sucking arthropods have either been confirmed or are suspected as important vectors in Bartonella transmission to mammals, including humans. Overall, it appears that the diversity of Bartonella species DNA identified in ectoparasites is much broader than the species detected in their mammalian hosts, suggesting a mechanism of adaptation of Bartonella species to their host-vector ecosystem. However, these mechanisms leading to the fitness between the vectors and their hosts still need to be investigated.

Lyme disease: the next decade

Although Lyme disease remains a controversial illness, recent events have created an unprecedented opportunity to make progress against this serious tick-borne infection. Evidence presented during the legally mandated review of the restrictive Lyme guidelines of the Infectious Diseases Society of America (IDSA) has confirmed the potential for persistent infection with the Lyme spirochete, Borrelia burgdorferi, as well as the complicating role of tick-borne coinfections such as Babesia, Anaplasma, Ehrlichia, and Bartonella species associated with failure of short-course antibiotic therapy. Furthermore, renewed interest in the role of cell wall-deficient (CWD) forms in chronic bacterial infection and progress in understanding the molecular mechanisms of biofilms has focused attention on these processes in chronic Lyme disease. Recognition of the importance of CWD forms and biofilms in persistent B. burgdorferi infection should stimulate pharmaceutical research into new antimicrobial agents that target these mechanisms of chronic infection with the Lyme spirochete. Concurrent clinical implementation of proteomic screening offers a chance to correct significant deficiencies in Lyme testing. Advances in these areas have the potential to revolutionize the diagnosis and treatment of Lyme disease in the coming decade.

Occurrence of Bartonella henselae and Borrelia burgdorferi sensu lato co-infections in ticks collected from humans in Germany

Bartonella (B.) henselae is the zoonotic agent of cat scratch disease. B. henselae has been associated with therapy-resistant Lyme disease in humans suggesting that B. henselae and Borrelia burgdorferi sensu lato might be transmitted concurrently by ticks. In the present study we found that 16 (6.9%) of 230 Ixodes ricinus collected from humans harboured DNA of Bartonella spp. Fifteen positive ticks were infected with B. henselae and one tick with B. clarridgeiae. Twenty-five percent of the 16 Bartonella positive ticks were co-infected with Borrelia burgdorferi sensu lato. Our data show that B. henselae is present in Ixodes ricinus and that ticks may serve as source of infection for humans.

Bartonella spp. transmission by ticks not established

A review found no well-documented case of transmission by deer ticks.

Bartonella spp. infect humans and many animal species. Mainly because PCR studies have demonstrated Bartonella DNA in ticks, some healthcare providers believe that these microorganisms are transmitted by ticks. B. henselae, in particular, is regarded as being present in and transmissible by the Ixodes scapularis tick. The presence of a microbial agent within a tick, however, does not imply that the tick might transmit it during the course of blood feeding and does not confer epidemiologic importance. After a critical review of the evidence for and against tick transmission, we conclude that transmission of any Bartonella spp. by ticks, to animals or humans, has not been established. We are unaware of any well-documented case of B. henselae transmission by I. scapularis ticks.

Potential for tick-borne bartonelloses

Although possible, tick transmission to a vertebrate host has not been proven.

As worldwide vectors of human infectious diseases, ticks are considered to be second only to mosquitoes. Each tick species has preferred environmental conditions and biotopes that determine its geographic distribution, the pathogens it vectors, and the areas that pose risk for tick-borne diseases. Researchers have identified an increasing number of bacterial pathogens that are transmitted by ticks, including Anaplasma, Borrelia, Ehrlichia, and Rickettsia spp. Recent reports involving humans and canines suggest that ticks should be considered as potential vectors of Bartonella spp. To strengthen this suggestion, numerous molecular surveys to detect Bartonella DNA in ticks have been conducted. However, there is little evidence that Bartonella spp. can replicate within ticks and no definitive evidence of transmission by a tick to a vertebrate host.

Prevalence of Bartonella henselae and Borrelia burgdorferi sensu lato DNA in ixodes ricinus ticks in Europe

Bartonella spp. can cause persistent bloodstream infections in humans and animals. To determine whether Bartonella henselae is present in questing Ixodes ricinus ticks, we analyzed the prevalence of B. henselae DNA among tick stages compared to the prevalence of DNA from Borrelia burgdorferi sensu lato, the pathogen most frequently transmitted by ticks. B. henselae DNA was present with a prevalence of up to approximately 40% in tick populations sampled in four European sites (Eberdingen, Germany; Klasdorf, Germany; Lembach, France; and Madeira, Portugal). The odds of detecting B. henselae DNA in nymphal ticks was approximately 14-fold higher than in adult ticks. No tick was found to be coinfected with B. henselae and B. burgdorferi sensu lato. Taken together, our data indicate that ticks might serve as a vector for the transmission of B. henselae to humans.

Insights in Bartonella host specificity

The genus Bartonella comprises a unique group of emerging gram-negative, intracellular bacteria that can cause a long-lasting intraerythrocytic bacteremia in their reservoir hosts. In recent years, the widespread occurrence and diversity of these bacteria has been increasingly recognized. This has resulted in a dramatic expansion of the genus Bartonella to 24 currently described species or subspecies, among which at least half have been associated with human disease. Bartonella infections have been observed in virtually all species examined, extending from humans to carnivores, ungulates, rodents, lagomorphs, insectivores, and bats. Adaptation by Bartonellae to such a diverse range of mammals has resulted in host specificity, and all validated Bartonella species described to date are capable of parasitizing only a limited number of animal species. In this review, the possible mechanisms explaining the specificity of each Bartonella species for its reservoir host are discussed.

Ecological fitness and strategies of adaptation of Bartonella species to their hosts and vectors

Bartonella spp. are facultative intracellular bacteria that cause characteristic hostrestricted hemotropic infections in mammals and are typically transmitted by blood-sucking arthropods. In the mammalian reservoir, these bacteria initially infect a yet unrecognized primary niche, which seeds organisms into the blood stream leading to the establishment of a long-lasting intra-erythrocytic bacteremia as the hall-mark of infection. Bacterial type IV secretion systems, which are supra-molecular transporters ancestrally related to bacterial conjugation systems, represent crucial pathogenicity factors that have contributed to a radial expansion of the Bartonella lineage in nature by facilitating adaptation to unique mammalian hosts. On the molecular level, the type IV secretion system VirB/VirD4 is known to translocate a cocktail of different effector proteins into host cells, which subvert multiple cellular functions to the benefit of the infecting pathogen. Furthermore, bacterial adhesins mediate a critical, early step in the pathogenesis of the bartonellae by binding to extracellular matrix components of host cells, which leads to firm bacterial adhesion to the cell surface as a prerequisite for the efficient translocation of type IV secretion effector proteins. The best-studied adhesins in bartonellae are the orthologous trimeric autotransporter adhesins, BadA in Bartonella henselae and the Vomp family in Bartonella quintana. Genetic diversity and strain variability also appear to enhance the ability of bartonellae to invade not only specific reservoir hosts, but also accidental hosts, as shown for B. henselae. Bartonellae have been identified in many different blood-sucking arthropods, in which they are typically found to cause extracellular infections of the mid-gut epithelium. Adaptation to specific vectors and reservoirs seems to be a common strategy of bartonellae for transmission and host diversity. However, knowledge regarding arthropod specificity/restriction, the mode of transmission, and the bacterial factors involved in arthropod infection and transmission is still limited.

Transmission of Bartonella henselae by Ixodes ricinus

The causative agent of cat-scratch disease in humans can be transmitted by this tick through saliva.

Bartonella spp. are facultative intracellular bacteria associated with several emerging diseases in humans and animals. B. henselae causes cat-scratch disease and is increasingly associated with several other syndromes, particularly ocular infections and endocarditis. Cats are the main reservoir for B. henselae and the bacteria are transmitted to cats by cat fleas. However, new potential vectors are suspected of transmitting B. henselae, in particular, Ixodes ricinus, the most abundant ixodid tick that bites humans in western Europe. We used a membrane-feeding technique to infect I. ricinus with B. henselae and demonstrate transmission of B. henselae within I. ricinus across developmental stages, migration or multiplication of B. henselae in salivary glands after a second meal, and transmission of viable and infective B. henselae from ticks to blood. These results provide evidence that I. ricinus is a competent vector for B. henselae.

Bartonella sp. bacteremia in patients with neurological and neurocognitive dysfunction

We detected infection with a Bartonella species (B. henselae or B. vinsonii subsp. berkhoffii) in blood samples from six immunocompetent patients who presented with a chronic neurological or neurocognitive syndrome including seizures, ataxia, memory loss, and/or tremors. Each of these patients had substantial animal contact or recent arthropod exposure as a potential risk factor for Bartonella infection. Additional studies should be performed to clarify the potential role of Bartonella spp. as a cause of chronic neurological and neurocognitive dysfunction.