RESUMEN
The most commonly reported vector-borne and tick-borne disease in the United States is Lyme disease. Individuals with Lyme disease may present with a wide array of symptoms with resultant musculoskeletal, neurological, and cardiac manifestations that may cause them to seek physical therapist services. The symptoms may develop insidiously and with a variable presentation among individuals. Many persons with Lyme disease do not recall a tick bite or present with an erythema migrans rash, which is considered pathognomonic for the disease. Even if they do, they may fail to associate either with their symptoms, making the diagnosis elusive. It is important to diagnose individuals early in the disease process when antibiotic treatment is most likely to be successful. Physical therapists are in a unique position to recognize the possibility that individuals may have Lyme disease and refer them to another practitioner when appropriate. The purpose of this article is to (1) present an overview of the etiology, incidence, and clinical manifestations of Lyme disease, (2) review evaluation findings that should raise the index of suspicion for Lyme disease, (3) discuss the use of an empirically validated tool for differentiating those with Lyme disease from healthy individuals, (4) discuss the current state of diagnostic testing, and (5) review options for diagnosis and treatment available to individuals for whom referral is recommended.
Asunto(s)
Toma de Decisiones Clínicas , Enfermedad de Lyme/diagnóstico , Modalidades de Fisioterapia , Derivación y Consulta , Humanos , Enfermedad de Lyme/fisiopatología , Enfermedad de Lyme/terapiaAsunto(s)
Antibacterianos/uso terapéutico , Enfermedad de Lyme/tratamiento farmacológico , Enfermedad de Lyme/fisiopatología , Vías de Administración de Medicamentos , Humanos , Repelentes de Insectos/administración & dosificación , Enfermedad de Lyme/complicaciones , Enfermedad de Lyme/prevención & controlRESUMEN
Background and objective: Lyme disease, also known as Lyme borreliosis (LB), is a tick-borne infectious disease caused by the spirochete bacteria Borrelia. The risk of infection depends on the geographical area, ecological factors, and human behavior. Clinical manifestations of Lyme borreliosis have a wide range, but the most frequent clinical symptom, which is also a diagnostic symptom, is a skin rash called erythema migrans (EM). The disease is very common worldwide. In Lithuania, the disease frequency is 99.9 cases per 100,000 population (Centre for Communicable Diseases and AIDS, Lithuania, 2017). The main aim of this study was to obtain the baseline characteristics of the disease regarding the infected Lithuanian population. Materials and Methods: We analyzed data from the Centre for Communicable Diseases and AIDS about all Lyme disease (A69.2) diagnosed patients over a three-year period (from 2014 to 2016) in Lithuania. Results: In 2014-2016, 7424 (crude incidence rate 85.4) cases with LB were diagnosed in Lithuania. Most of them (4633 (62.4%)) were identified in women. Older people were more likely to suffer from LB. Urban residents were 2.6 times more often affected that those living in villages. Tick bites were primarily observed in high season months, from May to September (90%), with the highest peak in July. There was a higher number of observed tick bites (p = 0.003) in the urban residents. Erythema migrans occurred in 75.6% LB cases, while other symptoms did not exceed a quarter of all LB cases. There were 7353 (99.6%) cases where LB was confirmed via clinical symptoms and/or laboratory tests. Also, 1720 (23.2%) patients were tested for LB immunoglobulins. Conclusions: This study found a high incidence of Lyme disease in Lithuania. We elucidated the baseline characteristics regarding the infected Lithuanian population which may ease medical clinicians' work on new Lyme diagnoses.
Asunto(s)
Enfermedades Endémicas , Enfermedad de Lyme/epidemiología , Adulto , Anciano , Femenino , Humanos , Incidencia , Lituania/epidemiología , Enfermedad de Lyme/fisiopatología , Masculino , Persona de Mediana Edad , Estaciones del AñoRESUMEN
Lyme borreliosis is the most common zoonosis in Germany with an incidence of up to 138/100â000. More than 90â% of all cases show dermatological manifestations. Early manifestations are erythema migrans, multiple erythemata migrantia, and (less frequently) borrelial lymphocytoma. A typical late manifestation is acrodermatitis chronica atrophicans. Lyme neuroborreliosis is much less common with an incidence of about 0.8/100â000 inhabitants in Germany. Bannwarth's syndrome (painful radiculoneuritis) is the most common manifestation of Lyme neuroborreliosis in adults followed by meningitis. International case definitions exist regarding the likelihood of Lyme neuroborreliosis on the basis of diagnostic test results. A CSF analysis should be performed in patients with suspected Lyme neuroborreliosis. The first line treatment for dermatological manifestations of Lyme borreliosis is doxycycline, in children and pregnant women amoxicillin. Doxycycline and beta-lactam antibiotics show similar efficacy regarding neurological symptoms and adverse effects for treatment of neurological manifestations. Treatment duration for early manifestations is 10 to 14 days, in Lyme neuroborreliosis it should not exceed 21 days. All manifestations, also Lyme neuroborreliosis, usually show a favourable prognosis after antibiotic treatment. Antibiotic treatment does not show any efficacy in patients with unspecific symptoms and concurrent positive anti-borrelial serology.
Asunto(s)
Enfermedad de Lyme , Antibacterianos/uso terapéutico , Niño , Doxiciclina/uso terapéutico , Eritema Crónico Migrans , Femenino , Dedos/patología , Alemania/epidemiología , Humanos , Incidencia , Enfermedad de Lyme/diagnóstico , Enfermedad de Lyme/tratamiento farmacológico , Enfermedad de Lyme/epidemiología , Enfermedad de Lyme/fisiopatología , Masculino , Embarazo , Piel/patologíaAsunto(s)
Enfermedad de Lyme/complicaciones , Mordeduras de Garrapatas/complicaciones , Dolor Abdominal/etiología , Animales , Diarrea/etiología , Humanos , Enfermedad de Lyme/etiología , Enfermedad de Lyme/fisiopatología , Masculino , Persona de Mediana Edad , Mordeduras de Garrapatas/fisiopatología , Garrapatas/patogenicidadRESUMEN
Lyme disease is an emerging problem in Poland. Analysis has been undertaken of the medical documentation of 86 patients hospitalized in the Infectious Diseases Department, University Hospital in Cracow in 2013-2016, suspected of Lyme arthritis. It has especially considered medical history including potential exposure to the infection, detailed characteristics of the symptoms, diagnostic challenges and results of the treatment. Only some patients had a history of erythema migrans and not all of them recalled tick-bite. The majority of the patients had affected large joints, especially knee joints, and polyarthritis was rarely observed. Symptoms were resolved completely or partially after antibiotic treatment in most patients. The diagnosis of Lyme arthritis in areas endemic for Lyme disease is still a diagnostic challenge in patients with other rheumatic diseases, including osteoarthritis.
Asunto(s)
Artritis Infecciosa/tratamiento farmacológico , Eritema Crónico Migrans/tratamiento farmacológico , Enfermedad de Lyme/tratamiento farmacológico , Antibacterianos/uso terapéutico , Artritis Infecciosa/diagnóstico , Artritis Infecciosa/fisiopatología , Ceftriaxona/uso terapéutico , Diagnóstico Diferencial , Doxiciclina/uso terapéutico , Eritema Crónico Migrans/diagnóstico , Eritema Crónico Migrans/etiología , Femenino , Articulaciones del Pie , Articulaciones de la Mano , Articulación de la Cadera , Hospitalización , Hospitales Universitarios , Humanos , Articulación de la Rodilla , Enfermedad de Lyme/complicaciones , Enfermedad de Lyme/diagnóstico , Enfermedad de Lyme/fisiopatología , Masculino , Persona de Mediana Edad , Osteoartritis/diagnóstico , Polonia , Articulación del Hombro , Mordeduras de Garrapatas , Resultado del TratamientoRESUMEN
Lyme disease is caused by the spirochete Borrelia burgdorferi and is increasing in incidence in the United States. Patient education and early recognition and treatment of the disease are critical to reduce the impact of chronic long-term infection.
Asunto(s)
Antibacterianos/uso terapéutico , Borrelia burgdorferi , Enfermedad de Lyme/diagnóstico , Enfermedad de Lyme/tratamiento farmacológico , Guías de Práctica Clínica como Asunto , Garrapatas , Animales , Vectores Arácnidos , Humanos , Incidencia , Enfermedad de Lyme/epidemiología , Enfermedad de Lyme/fisiopatología , Estados Unidos/epidemiologíaRESUMEN
Atrophoderma of Pasini and Pierini is a skin atrophy presenting as single or multiple sharply demarcated, hyperpigmented, non-indurated patches, with a slight depression of the skin, that can converge and form a confluent area with atrophy as a consequence. The condition was first described by Pasini in 1923 and subsequently by Pierini in 1936. They distinguished this form of atrophy from other diseases and conditions in which the atrophy is morphologically and clinically different. The disease was initially associated with Borrelia burgdorferi infection; however, at present, various theories have emerged for the appearance of the disease, linked to genetic, neurogenetic, and immunological factors. Here we present a patient that was admitted to the hospital due to disseminated lesions on the skin of the lower limbs, with slightly pigmented and atrophic skin along with irregular borders varying in size, from several mm to a few cm, clearly demarcated from the healthy skin, with no history of a tick bite or a family history of similar skin disorders.
Asunto(s)
Hiperpigmentación/patología , Extremidad Inferior , Enfermedades de la Piel/patología , Atrofia/patología , Atrofia/fisiopatología , Biopsia con Aguja , Humanos , Hiperpigmentación/fisiopatología , Inmunohistoquímica , Kosovo , Enfermedad de Lyme/fisiopatología , Masculino , Enfermedades Raras , Medición de Riesgo , Enfermedades de la Piel/fisiopatología , Enfermedades de la Piel/terapia , Adulto JovenRESUMEN
The carboxy-terminal domain of the BBK32 protein from Borrelia burgdorferi sensu stricto, termed BBK32-C, binds and inhibits the initiating serine protease of the human classical complement pathway, C1r. In this study we investigated the function of BBK32 orthologues of the Lyme-associated Borrelia burgdorferi sensu lato complex, designated BAD16 from B. afzelii strain PGau and BGD19 from B. garinii strain IP90. Our data show that B. afzelii BAD16-C exhibits BBK32-C-like activities in all assays tested, including high-affinity binding to purified C1r protease and C1 complex, and potent inhibition of the classical complement pathway. Recombinant B. garinii BGD19-C also bound C1 and C1r with high-affinity yet exhibited significantly reduced in vitro complement inhibitory activities relative to BBK32-C or BAD16-C. Interestingly, natively produced BGD19 weakly recognized C1r relative to BBK32 and BAD16 and, unlike these proteins, BGD19 did not confer significant protection from serum killing. Site-directed mutagenesis was performed to convert BBK32-C to resemble BGD19-C at three residue positions that are identical between BBK32 and BAD16 but different in BGD19. The resulting chimeric protein was designated BXK32-C and this BBK32-C variant mimicked the properties observed for BGD19-C. To query the disparate complement inhibitory activities of BBK32 orthologues, the crystal structure of BBK32-C was solved to 1.7Å limiting resolution. BBK32-C adopts an anti-parallel four-helix bundle fold with a fifth alpha-helix protruding from the helical core. The structure revealed that the three residues targeted in the BXK32-C chimera are surface-exposed, further supporting their potential relevance in C1r binding and inhibition. Additional binding assays showed that BBK32-C only recognized C1r fragments containing the serine protease domain. The structure-function studies reported here improve our understanding of how BBK32 recognizes and inhibits C1r and provide new insight into complement evasion mechanisms of Lyme-associated spirochetes of the B. burgdorferi sensu lato complex.
Asunto(s)
Proteínas Bacterianas/genética , Borrelia burgdorferi/genética , Vía Clásica del Complemento/genética , Proteínas Bacterianas/inmunología , Proteínas Bacterianas/ultraestructura , Borrelia burgdorferi/inmunología , Grupo Borrelia Burgdorferi , Complemento C1r/metabolismo , Vía Clásica del Complemento/fisiología , Proteínas del Sistema Complemento/metabolismo , Humanos , Enfermedad de Lyme/fisiopatología , Dominios Proteicos/fisiología , Proteínas Recombinantes , Análisis de Secuencia de ProteínaRESUMEN
Lyme disease is a continuing threat to military personnel operating in arboriferous and mountainous environments. Here we present the case of a 24-year-old Second Lieutenant, a recent graduate from the United States Military Academy, with a history of Lyme disease who developed recurrent knee effusions following surgery to correct a hip impingement. Although gonococcal arthritis was initially suspected from preliminary laboratory results, a comprehensive evaluation contradicted this diagnosis. Despite antibiotic therapy, aspiration of the effusions, and steroid treatment to control inflammation, the condition of the patient deteriorated to the point where he was found to be unfit for duty and subsequently discharged from active military service. This case illustrates the profound effect that latent Lyme disease can have on the quality of life and the career of an active duty military member. It highlights the need for increased surveillance for Borrelia burgdorferi (B. burgdorferi) in military training areas and for the early and aggressive diagnosis and treatment of military personnel who present with the symptoms of acute Lyme disease.
Asunto(s)
Artritis/etiología , Rodilla/anomalías , Enfermedad de Lyme/diagnóstico , Animales , Artritis/fisiopatología , Borrelia burgdorferi/efectos de los fármacos , Borrelia burgdorferi/patogenicidad , Movilidad Laboral , Humanos , Rodilla/fisiopatología , Enfermedad de Lyme/fisiopatología , Masculino , Personal Militar , Garrapatas , Adulto JovenRESUMEN
OBJECTIVES: There is controversy whether non-specific symptoms can be related to previous Lyme borreliosis (LB). Positive serology can be considered a proxy for previous or persistent LB. We assessed non-specific symptoms and serology in patients suspected of LB referred to a Lyme centre. METHODS: Included were adult patients who visited a Lyme centre between 2008 and 2014. Before medical consultation, serum samples were taken and questionnaires on non-specific symptoms completed. The prevalence of non-specific symptoms was calculated for patients with positive and negative IgG serology. Logistic regression was used to obtain odds ratios (ORs) with 95% confidence interval (CI) for an association between positive serology and non-specific symptoms. RESULTS: Of 1439 included patients, 31.6% (455/1439) had positive serology. The most common non-specific symptoms were severe fatigue (61.4%, 883/1439), sleep disturbances (54.8%, 789/1439) and stiffness of neck/back (52.6%, 757/1439). The prevalence of severe fatigue was 53.0% (241/455) in patients with positive serology vs. 65.2% (642/984) in patients with negative serology (OR = 0.74; 95% CI, 0.58-0.94). The prevalence of sleep disturbances was respectively 46.2% (210/455) vs. 58.8% (579/984) (OR = 0.73; 95% CI, 0.58-0.93). The prevalence of stiffness of neck/back was respectively 47.7% (217/455) vs. 54.9% (540/984) (OR = 0.85; 95% CI, 0.67-1.06). CONCLUSIONS: In patients referred to a Lyme centre, non-specific symptoms did not occur more frequently in patients with positive serology compared to patients with negative serology. Hence, a questionnaire on non-specific symptoms cannot be used for identifying patients with possible post-LB symptoms in clinical practice.
Asunto(s)
Enfermedad de Lyme/diagnóstico , Enfermedad de Lyme/fisiopatología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Anticuerpos Antibacterianos/sangre , Borrelia burgdorferi/inmunología , Estudios de Cohortes , Fatiga/etiología , Femenino , Humanos , Inmunoglobulina G/sangre , Enfermedad de Lyme/sangre , Masculino , Persona de Mediana Edad , Países Bajos , Prevalencia , Pruebas Serológicas , Trastornos del Sueño-Vigilia/etiología , Encuestas y Cuestionarios , Adulto JovenRESUMEN
Lyme disease is the most common tick-borne illness in North America. A 23-year-old female presented to our emergency department with a chief complaint of sudden dyspnea and chest pain. An electrocardiogram revealed a third degree heart block. She was a resident of the Northeast region of Mexico and referred a recent travel to an endemic area for Borrelia burgdorferi in the center of Mexico in the past weeks. Lyme carditis was diagnosed after enzyme linked immunosorbent assay for IgM antibodies against B. burgdorferi was reported positive and corroborated by a confirmatory immunoblot analysis. Persistent AV block was the only manifestation in our patient, a presentation scarcely reported in literature.
Asunto(s)
Bloqueo Atrioventricular/diagnóstico , Bradicardia/diagnóstico , Enfermedad de Lyme/diagnóstico , Antibacterianos/uso terapéutico , Bloqueo Atrioventricular/fisiopatología , Bloqueo Atrioventricular/terapia , Bradicardia/fisiopatología , Bradicardia/terapia , Diagnóstico Diferencial , Electrocardiografía , Femenino , Humanos , Enfermedad de Lyme/tratamiento farmacológico , Enfermedad de Lyme/fisiopatología , Marcapaso Artificial , Adulto JovenAsunto(s)
Grupo Borrelia Burgdorferi/inmunología , Grupo Borrelia Burgdorferi/aislamiento & purificación , Enfermedad de Lyme/diagnóstico , Anticuerpos Antibacterianos/sangre , Diagnóstico Diferencial , Errores Diagnósticos , Humanos , Enfermedad de Lyme/microbiología , Enfermedad de Lyme/patología , Enfermedad de Lyme/fisiopatología , Pruebas SerológicasRESUMEN
Lyme disease (borreliosis) is one of the most common vector-borne diseases worldwide. Its incidence and geographic expansion has been steadily increasing in the last decades. Lyme disease is caused by Borrelia burgdorferi sensu lato, a heterogeneous group of which three genospecies have been systematically associated to Lyme disease: B. burgdorferi sensu stricto Borrelia afzelii and Borrelia garinii. Geographical distribution and clinical manifestations vary according to the species involved. Lyme disease clinical manifestations may be divided into three stages. Early localized stage is characterized by erythema migrans in the tick bite site. Early disseminated stage may present multiple erythema migrans lesions, borrelial lymphocytoma, lyme neuroborreliosis, carditis, or arthritis. The late disseminated stage manifests with acordermatitis chronica atrophicans, lyme arthritis, and neurological symptoms. Diagnosis is challenging due to the varied clinical manifestations it may present and usually involves a two-step serological approach. In the current review, we present a thorough revision of the clinical manifestations Lyme disease may present. Additionally, history, microbiology, diagnosis, post-treatment Lyme disease syndrome, treatment, and prognosis are discussed.
Asunto(s)
Grupo Borrelia Burgdorferi/fisiología , Enfermedad de Lyme , Enfermedades Cutáneas Bacterianas , Animales , Antibacterianos/uso terapéutico , Grupo Borrelia Burgdorferi/clasificación , Grupo Borrelia Burgdorferi/efectos de los fármacos , Técnicas de Laboratorio Clínico , Humanos , Ixodes/clasificación , Ixodes/microbiología , Enfermedad de Lyme/diagnóstico , Enfermedad de Lyme/tratamiento farmacológico , Enfermedad de Lyme/patología , Enfermedad de Lyme/fisiopatología , Pronóstico , Enfermedades Cutáneas Bacterianas/diagnóstico , Enfermedades Cutáneas Bacterianas/tratamiento farmacológico , Enfermedades Cutáneas Bacterianas/patología , Enfermedades Cutáneas Bacterianas/fisiopatología , Resultado del TratamientoRESUMEN
Lyme disease (LD), caused by bacteria of the Borrelia burgdorferi sensu lato species complex, is the most common vector-borne disease in North America and Europe. A systematic review (SR) was conducted to summarize the global literature on adverse birth outcomes associated with gestational LD in humans. The SR followed an a priori protocol of pretested screening, risk of bias, and data extraction forms. Data were summarized descriptively and random effects meta-analysis (MA) was used where appropriate. The SR identified 45 relevant studies, 29 describing 59 cases reported as gestational LD in the United States, Europe, and Asia (1969-2017). Adverse birth outcomes included spontaneous miscarriage or fetal death (n = 12), newborn death (n = 8), and newborns with an abnormal outcome (e.g. hyperbilirubinemia, respiratory distress and syndactyly) at birth (n = 16). Only one report provided a full case description (clinical manifestations in the mother, negative outcome for the child, and laboratory detection of B. burgdorferi in the child) that provides some evidence for vertical transmission of B. burgdorferi that has negative consequences for the fetus. The results of 17 epidemiological studies are included in this SR. Prevalence of adverse birth outcomes in an exposed population (defined by the authors as: gestational LD, history of LD, tick bites or residence in an endemic area) was compared to that in an unexposed population in eight studies and no difference was reported. A meta-analysis of nine studies showed significantly fewer adverse birth outcomes in women reported to have been treated for gestational LD (11%, 95%CI 7-16) compared to those who were not treated during pregnancy (50%, 95%CI 30-70) providing indirect evidence of an association between gestational LD and adverse birth outcomes. Other risk factors investigated; trimester of exposure, length of LD during pregnancy, acute vs. disseminated LD at diagnosis, and symptomatic LD vs. seropositive women with no LD symptoms during pregnancy were not significantly associated with adverse birth outcomes. This SR summarizes evidence from case studies that provide some limited evidence for transplacental transmission of B. burgdorferi. There was inconsistent evidence for adverse birth outcomes of gestational LD in the epidemiological research, and uncommon adverse outcomes for the fetus may occur as a consequence of gestational LD. The global evidence does not fully characterize the potential impact of gestational LD, and future research that addresses the knowledge gaps may change the findings in this SR. Given the current evidence; prompt diagnosis and treatment of LD during pregnancy is recommended.
Asunto(s)
Feto , Enfermedad de Lyme , Complicaciones del Embarazo , Femenino , Humanos , Recién Nacido , Enfermedad de Lyme/epidemiología , Enfermedad de Lyme/fisiopatología , Embarazo , Complicaciones del Embarazo/epidemiología , Complicaciones del Embarazo/fisiopatología , Resultado del EmbarazoRESUMEN
Lyme disease is the most commonly reported vector-borne disease in the United States. After initial antibiotic treatment for patients with Lyme disease, ongoing symptoms that may persist have considerable long-term impact on healthcare costs. Posttreatment Lyme disease syndrome is characterized by a host of chronic symptoms that can leave patients physically and mentally disabled.
Asunto(s)
Enfermedad de Lyme/enfermería , Diagnóstico de Enfermería , Antibacterianos/uso terapéutico , Costos de la Atención en Salud , Humanos , Enfermedad de Lyme/economía , Enfermedad de Lyme/epidemiología , Enfermedad de Lyme/fisiopatología , Estados Unidos/epidemiologíaAsunto(s)
Encefalitis Antirreceptor N-Metil-D-Aspartato/complicaciones , Encefalitis Antirreceptor N-Metil-D-Aspartato/fisiopatología , Enfermedad de Lyme/complicaciones , Enfermedad de Lyme/fisiopatología , Adulto , Encefalitis Antirreceptor N-Metil-D-Aspartato/diagnóstico , Encefalitis Antirreceptor N-Metil-D-Aspartato/terapia , Diagnóstico Diferencial , Humanos , Enfermedad de Lyme/diagnóstico , Enfermedad de Lyme/terapia , MasculinoRESUMEN
The Ixodes tick is an important arthropod vector in the transmission of human disease. This 3-part review highlights the biology of the Ixodes tick and manifestations of related diseases. Part 1 addresses the Ixodes tick biology and life cycle; local reactions; and Lyme disease, the most prevalent of associated diseases. Part 2 will address human granulocytic anaplasmosis, babesiosis, Powassan virus infection, Borrelia miyamotoi disease, tick-borne encephalitis, and tick paralysis. Part 3 will address coinfection with multiple pathogens as well as methods of tick-bite prevention and tick removal.
Asunto(s)
Babesiosis/fisiopatología , Ixodes/fisiología , Enfermedad de Lyme/fisiopatología , Enfermedades Cutáneas Infecciosas/fisiopatología , Infestaciones por Garrapatas/fisiopatología , Animales , Babesiosis/parasitología , Babesiosis/terapia , Humanos , Ixodes/crecimiento & desarrollo , Ixodes/parasitología , Estadios del Ciclo de Vida , Enfermedad de Lyme/parasitología , Enfermedad de Lyme/terapia , Enfermedades Parasitarias/parasitología , Enfermedades Parasitarias/fisiopatología , Enfermedades Parasitarias/terapia , Mordeduras de Garrapatas/fisiopatología , Mordeduras de Garrapatas/terapia , Infestaciones por Garrapatas/terapiaRESUMEN
Borrelia burgdorferi, the agent of Lyme disease (LD), uses host-derived signals to modulate gene expression during the vector and mammalian phases of infection. Microarray analysis of mutants lacking the Borrelia host adaptation regulator (BadR) revealed the downregulation of genes encoding enzymes whose role in the pathophysiology of B. burgdorferi is unknown. Immunoblot analysis of the badR mutants confirmed reduced levels of these enzymes, and one of these enzymes, encoded by bb0086, shares homology to prokaryotic magnesium chelatase and Lon-type proteases. The BB0086 levels in B. burgdorferi were higher under conditions mimicking those in fed ticks. Mutants lacking bb0086 had no apparent in vitro growth defect but were incapable of colonizing immunocompetent C3H/HeN or immunodeficient SCID mice. Immunoblot analysis revealed reduced levels of proteins critical for the adaptation of B. burgdorferi to the mammalian host, such as OspC, DbpA, and BBK32. Both RpoS and BosR, key regulators of gene expression in B. burgdorferi, were downregulated in the bb0086 mutants. Therefore, we designated BB0086 the Borrelia host adaptation protein (BadP). Unlike badP mutants, the control strains established infection in C3H/HeN mice at 4 days postinfection, indicating an early colonization defect in mutants due to reduced levels of the lipoproteins/regulators critical for initial stages of infection. However, badP mutants survived within dialysis membrane chambers (DMCs) implanted within the rat peritoneal cavity but, unlike the control strains, did not display complete switching of OspA to OspC, suggesting incomplete adaptation to the mammalian phase of infection. These findings have opened a novel regulatory mechanism which impacts the virulence potential of Bburgdorferi.