Parasitic manipulation or side effects? The effects of past Toxoplasma gondii and Borrelia spp. infections on human personality and cognitive performance are not mediated by impaired health

Bacteria Borrelia burgdorferi s. l. and even more the protist Toxoplasma gondii Nicolle et Manceaux, 1908, are known to affect the behaviour and mental health of their animal and human hosts. Both pathogens infect a significant fraction of human population, both are neurotropic and survive in the host's body for a long time. While latent infections were thought to be clinically asymptomatic, recent studies suggest otherwise, revealing adverse effects on human health. It was hypothesised that the specific behavioural effects of these pathogens may be side effects of general health impairments in infected individuals. This hypothesis was tested using about one hour-long survey consisting of questionnaires and performance tests on a cohort of 7,762 members of the internet population. Results showed that individuals infected with T. gondii reported worse physical and mental health, and those infected with Borrelia spp. reported worse physical health than uninfected controls. Furthermore, infected and noninfected individuals differed in several personality traits, including conscientiousness, pathogen disgust, injury disgust, Machiavellianism, narcissism, tribalism, anti-authoritarianism, intelligence, reaction time, and precision. While the majority of behavioural effects associated with Borrelia infection were similar to those associated with Toxoplasma infection, some differences were observed, such as performance in the Stroop test. Path analyses and nonparametric partial Kendall correlation tests showed that these effects were not mediated by impaired health in infected individuals, contradicting the side effects hypothesis.

Nervous System Lyme Disease-Facts and Fallacies

The central or peripheral nervous systems may be involved in up to 15% of patients with untreated infection with B burgdorferi sensu lato, characteristic involvement including meningitis, cranial neuritis, and radiculoneuritis. Diagnosis, based on a logical combination of clinical context and antibody-based testing, is usually straightforward, as is treatment. Misconceptions about what does and does not constitute neurologic disease, and about laboratory testing in this infection, have resulted in widespread anxiety that a broad range of other disorders may be attributable to nervous system Lyme disease. This article will review the reasons for these misunderstandings and the arguments against them.

Non-infectious mechanisms of neurological damage due to infection

Infections of the nervous system is a growing aspect of clinical neurology. Accumulating knowledge in early diagnosis, course, therapy and prognosis is enlarging the clinical tools required for effective therapy. Of special importance is the ability to differentiate between proper infections, where anti-microbial agents, when available, should be introduced and used and post infectious conditions where therapy is mainly directed against the host immune system. The two conditions sometimes overlap, a situation that requires the ability to combine clinical skills with the use of laboratory tools such as polymerase chain reaction (PCR), serology, and antigenic detection. In the era of the SARS-CoV-2 pandemic, the need to make this distinction is emphasized as correct diagnosis of post infectious conditions and expedited therapy is important and sometimes lifesaving. We here attempt to present several infectious agents and their possible indirect damage to the nervous system causing in some cases significant neurological deficits. We try to limit our focus on those mechanisms which do not involve the direct tissue damage by the infectious agents but rather are connected to para- and post-infectious mechanisms. We attempt to delineate the features that will enable to tailor the correct diagnosis and following the effective therapy.

Assessing the Need for Multiplex and Multifunctional Tick-Borne Disease Test in Routine Clinical Laboratory Samples from Lyme Disease and Febrile Patients with a History of a Tick Bite

Human polymicrobial infections in tick-borne disease (TBD) patients is an emerging public health theme. However, the requirement for holistic TBD tests in routine clinical laboratories is ambiguous. TICKPLEX® PLUS is a holistic TBD test utilized herein to assess the need for multiplex and multifunctional diagnostic tools in a routine clinical laboratory. The study involved 150 specimens categorized into Lyme disease (LD)-positive (n = 48), LD-negative (n = 30), and febrile patients from whom borrelia serology was requested (n = 72, later "febrile patients") based on reference test results from United Medix, Finland. Reference tests from DiaSorin, Immunetics, and Mikrogen Diagnostik followed the two-tier LD testing system. A comparison between the reference tests and TICKPLEX® PLUS produced 86%, 88%, and 87% positive, negative, and overall agreement, respectively. Additionally, up to 15% of LD and 11% of febrile patients responded to TBD related coinfections and opportunistic microbes. The results demonstrated that one (TICKPLEX® PLUS) test can aid in a LD diagnosis instead of four tests. Moreover, TBD is not limited to just LD, as the specimens produced immune responses to several TBD microbes. Lastly, the study indicated that the screening of febrile patients for TBDs could be a missed opportunity at reducing unreported patient cases.

Guidelines for diagnosis and treatment in neurology - Lyme neuroborreliosis

Lyme borreliosis is the most common tick-borne infectious disease in Europe. A neurological manifestation occurs in 3–15% of infections and can manifest as polyradiculitis, meningitis and (rarely) encephalomyelitis.

This S3 guideline is directed at physicians in private practices and clinics who treat Lyme neuroborreliosis in children and adults.

Twenty AWMF member societies, the Robert Koch Institute, the German Borreliosis Society and three patient organisations participated in its development. A systematic review and assessment of the literature was conducted by the German Cochrane Centre, Freiburg (Cochrane Germany).

The main objectives of this guideline are to define the disease and to give recommendations for the confirmation of a clinically suspected diagnosis by laboratory testing, antibiotic therapy, differential diagnostic testing and prevention.

Post-treatment Lyme Disease as a Model for Persistent Symptoms in Lyme Disease

It has long been observed in clinical practice that a subset of patients with Lyme disease report a constellation of symptoms such as fatigue, cognitive difficulties, and musculoskeletal pain, which may last for a significant period of time. These symptoms, which can range from mild to severe, have been reported throughout the literature in both prospective and population-based studies in Lyme disease endemic regions. The etiology of these symptoms is unknown, however several illness-causing mechanisms have been hypothesized, including microbial persistence, host immune dysregulation through inflammatory or secondary autoimmune pathways, or altered neural networks, as in central sensitization. Evaluation and characterization of persistent symptoms in Lyme disease is complicated by potential independent, repeat exposures to B. burgdorferi, as well as the potential for co-morbid diseases with overlapping symptom profiles. Antibody testing for B. burgdorferi is an insensitive measure after treatment, and no other FDA-approved tests currently exist. As such, diagnosis presents a complex challenge for physicians, while the lived experience for patients is one marked by uncertainty and often illness invalidation. Currently, there are no FDA-approved pharmaceutical therapies, and the safety and efficacy of off-label and/or complementary therapies have not been well studied and are not agreed-upon within the medical community. Post-treatment Lyme disease represents a narrow, defined, mechanistically-neutral subset of this larger, more heterogeneous group of patients, and is a useful definition in research settings as an initial subgroup of study. The aim of this paper is to review the current literature on the diagnosis, etiology, risk factors, and treatment of patients with persistent symptoms in the context of Lyme disease. The meaning and relevance of existing patient subgroups will be discussed, as will future research priorities, including the need to develop illness biomarkers, elucidate the biologic mechanisms of disease, and drive improvements in therapeutic options.

Cognitive impairments in patients with persistent symptoms attributed to Lyme disease

Background

Persistent symptoms attributed to Lyme borreliosis often include self-reported cognitive impairment. However, it remains unclear whether these symptoms can be substantiated by objective cognitive testing.

Methods

For this observational study, cognitive performance was assessed in 280 adults with persistent symptoms attributed to Lyme borreliosis (as part of baseline data collected for the Dutch PLEASE study). Cognitive testing covered the five major domains: episodic memory, working memory / attention, verbal fluency, information-processing speed and executive function. Patients’ profiles of test scores were compared to a large age-, education- and sex-adjusted normative sample using multivariate normative comparison. Performance validity was assessed to detect suboptimal effort, and questionnaires were administered to measure self-reported cognitive complaints, fatigue, anxiety, depressive symptoms and several other psychological factors.

Results

Of 280 patients, one was excluded as the test battery could not be completed. Of the remaining 279 patients, 239 (85.4%) displayed sufficient performance validity. Patients with insufficient performance validity felt significantly more helpless and physically fatigued, and less orientated. Furthermore, they had a lower education level and less often paid work. Of the total study cohort 5.7% (n = 16) performed in the impaired range. Among the 239 patients who displayed sufficient performance validity, 2.9% (n = 7) were classified as cognitively impaired. No association between subjective cognitive symptoms and objective impairment was found.

Conclusions

Only a small percentage of patients with borreliosis-attributed persistent symptoms have objective cognitive impairment. Performance validity should be taken into account in neuropsychological examinations of these patients. Self-report questionnaires are insufficiently valid to diagnose cognitive impairment.

Trial registration

ClinicalTrials.gov NCT01207739. Registered 23 September 2010.

Frontotemporal Dementia Misdiagnosed for Post-Treatment Lyme Disease Syndrome or vice versa? A Treviso Dementia (TREDEM) Registry Case Report

We describe the case of a 61-year-old woman diagnosed with Borreliosis at the age of 57. Subsequently, the patient developed depression, anxiety, and behavioral disturbances. A lumbar puncture excluded the condition of Neuroborreliosis. The diagnostic workup included: an MRI scan, a 18F-FDG PET, a 123I-ioflupane-SPECT, an amyloid-β PET, a specific genetic analysis, and a neuropsychological evaluation. Based on our investigation, the patient was diagnosed with probable behavioral-frontotemporal dementia (bvFTD), whereas in the previous years, the patient had been considered firstly as a case of Post-Treatment-Lyme Disease and, secondly, a psychiatric patient. We believe that, in the present case, such initial symptoms of Borrelia infection may have superimposed on those of bvFTD rather than playing as a contributory cause.

Retrospective Evaluation of Horses Diagnosed with Neuroborreliosis on Postmortem Examination: 16 Cases (2004-2015)

BACKGROUND

Equine neuroborreliosis (NB), Lyme disease, is difficult to diagnose and has limited description in the literature.

OBJECTIVE

Provide a detailed description of clinical signs, diagnostic, and pathologic findings of horses with NB.

ANIMALS

Sixteen horses with histologically confirmed NB.

METHODS

Retrospective review of medical records at the University of Pennsylvania and via an ACVIM listserv query with inclusion criteria requiring possible exposure to Borrelia burgdorferi and histologic findings consistent with previous reports of NB without evidence of other disease.

RESULTS

Sixteen horses were identified, 12 of which had additional evidence of NB. Clinical signs were variable including muscle atrophy or weight loss (12), cranial nerve deficits (11), ataxia (10), changes in behavior (9), dysphagia (7), fasciculations (6), neck stiffness (6), episodic respiratory distress (5), uveitis (5), fever (2), joint effusion (2), and cardiac arrhythmias (1). Serologic analysis was positive for B. burgdorferi infection in 6/13 cases tested. CSF abnormalities were present in 8/13 cases tested, including xanthochromia (4/13), increased total protein (5/13; median: 91 mg/dL, range: 25-219 mg/dL), and a neutrophilic (6/13) or lymphocytic (2/13) pleocytosis (median: 25 nucleated cells/μL, range: 0-922 nucleated cells/μL). PCR on CSF for B. burgdorferi was negative in the 7 cases that were tested.

CONCLUSION AND CLINICAL IMPORTANCE

Diagnosis of equine NB is challenging due to variable clinical presentation and lack of sensitive and specific diagnostic tests. Negative serology and normal CSF analysis do not exclude the diagnosis of NB.

Nervous system Lyme disease

Lymphocytic meningitis, cranial neuritis or radiculoneuritis occur in up to 15% of patients with untreated Borrelia burgdorferi infection. Presentations of multifocal PNS involvement can range from painful monoradiculitis to confluent mononeuropathy multiplex. Serologic testing is highly accurate after 4 to 6 weeks of infection. In CNS infection, production of anti-Bburgdorferi antibody is often demonstrable in CSF. Oral antimicrobials are microbiologically curative in virtually all patients, including acute European neuroborreliosis. Severe cases may require parenteral treatment. The fatigue and cognitive symptoms seen in some patients with extra-neurological disease are neither evidence of CNS infection nor specific to Lyme disease.

Posttreatment Lyme disease syndrome

The prognosis following appropriate antibiotic treatment of early or late Lyme disease is favorable but can be complicated by persistent symptoms of unknown cause termed posttreatment Lyme disease syndrome (PTLDS), characterized by fatigue, musculoskeletal pain, and cognitive complaints that persist for 6 months or longer after completion of antibiotic therapy. Risk factors include delayed diagnosis, increased severity of symptoms, and presence of neurologic symptoms at time of initial treatment. Two-tier serologic testing is neither sensitive nor specific for diagnosis of PTLDS because of variability in convalescent serologic responses after treatment of early Lyme disease. Optimal treatment of PTLDS awaits more precise understanding of the pathophysiologic mechanisms involved in this illness and future treatment trials.

Nervous System Lyme Disease

Nervous system involvement occurs in 10% to 15% of patients infected with the tick-borne spirochetes Borrelia burgdorferi, B afzelii, and B garinii. Peripheral nervous system involvement is common. Central nervous system (CNS) involvement, most commonly presenting with lymphocytic meningitis, causes modest cerebrospinal fluid (CSF) pleocytosis. Parenchymal CNS infection is rare. If the CNS is invaded, however, measuring local production of anti-B burgdorferi antibodies in the CSF provides a useful marker of infection. Most cases of neuroborreliosis can be cured with oral doxycycline; parenteral regimens should be reserved for patients with particularly severe disease.

Lyme neuroborreliosis-epidemiology, diagnosis and management

Lyme disease, caused by the Borrelia burgdorferi bacterium, is the most common vector-borne disease in the northern hemisphere. The clinical presentation varies with disease stage, and neurological manifestations (often referred to as Lyme neuroborreliosis) are reported in up to 12% of patients with Lyme disease. Most aspects of the epidemiology, clinical manifestation and treatment of Lyme neuroborreliosis are well known and accepted; only the management of so-called chronic Lyme disease is surrounded by considerable controversy. This term is used for disparate patient groups, including those who have untreated late-stage infection (for example, late neuroborreliosis), those with subjective symptoms that persist after treatment (termed 'post-treatment Lyme disease syndrome' [PTLDS]), and those with unexplained subjective complaints that may or may not be accompanied by positive test results for B. burgdorferi infection in serum (here called 'chronic Lyme disease'). The incidence of PTLDS is still a matter of debate, and its pathogenesis is unclear, but there is evidence that these patients do not have ongoing B. burgdorferi infection and, thus, do not benefit from additional antibiotic therapy. Chronic Lyme disease lacks an accepted clinical definition, and most patients who receive this diagnosis have other illnesses. Thus, a careful diagnostic work-up is needed to ensure proper treatment.

Nervous system lyme disease

Lyme disease, a multisystem spirochetal infection, continues to be the subject of considerable debate, but not controversy. Recent years have seen improvements in diagnostic tools, better understanding of pathophysiology, and increasing evidence of efficacy of standard treatment regimens. Nervous system involvement is particularly confusing to patients and many physicians. A rational approach based on objective findings can clarify the cause and dictate the best treatment of patients' difficulties. Diagnosis for all but the earliest cases rests on the combination of likely contact with infected Ixodes ticks and laboratory confirmation of exposure to the causative organism, Borrelia burgdorferi (two-tier serology, combining ELISA with a confirmatory Western blot). Treatment is generally with oral antimicrobials such as doxycycline. Parenteral regimens are usually necessary only for the most severe cases.

γδ T Cells and dendritic cells in refractory Lyme arthritis

Lyme disease is a multisystem infection transmitted by tick vectors with an incidence of up to 300,000 individuals/yr in the United States. The primary treatments are oral or i.v. antibiotics. Despite treatment, some individuals do not recover and have prolonged symptoms affecting multiple organs, including the nervous system and connective tissues. Inflammatory arthritis is a common symptom associated with Lyme pathology. In the past decades, γδ T cells have emerged as candidates that contribute to the transition from innate to adaptive responses. These cells are also differentially regulated within the synovia of patients affected by RLA. Here, we review and discuss potential cellular mechanisms involving γδ T cells and DCs in RLA. TLR signaling and antigen processing and presentation will be the key concepts that we review in aid of understanding the impact of γδ T cells in RLA.

Relevance of chronic lyme disease to family medicine as a complex multidimensional chronic disease construct: a systematic review

Lyme disease has become a global public health problem and a prototype of an emerging infection. Both treatment-refractory infection and symptoms that are related to Borrelia burgdorferi infection remain subject to controversy. Because of the absence of solid evidence on prevalence, causes, diagnostic criteria, tools and treatment options, the role of autoimmunity to residual or persisting antigens, and the role of a toxin or other bacterial-associated products that are responsible for the symptoms and signs, chronic Lyme disease (CLD) remains a relatively poorly understood chronic disease construct. The role and performance of family medicine in the detection, integrative treatment, and follow-up of CLD are not well studied either. The purpose of this paper is to describe insights into the complexity of CLD as a multidimensional chronic disease construct and its relevance to family medicine by means of a systematic literature review.