RESUMEN
Babesiosis poses a serious threat to immunocompromised individuals and the major etiological species of Babesia for human babesiosis is Babesia microti. Merozoites are a critical stage in the life cycle of Babesia microti. Several merozoite proteins have been demonstrated to play important roles in this process; however, most of the merozoite proteins of B. microti remain unknown. In the present study, we identified a novel merozoite protein of B. microti with similar structure to the thioredoxin (Trx)-like domain of the Trx family, which was named as B. microti Trx-like protein (BmTLP). Western blot assays demonstrated that this protein was expressed by B. microti during the erythrocytic infection process, and its expression peaked on day 7 post-infection in vivo. Immunofluorescence assay further showed that this protein is mainly expressed in B. microti merozoites. BmTLP hold both heparin- and erythrocyte-binding properties, which are critical functions of invasion-related proteins. Immunization with recombinant BmTLP imparted significant protection against B. microti infection in mice. Taken together, these results suggest that the novel merozoite protein, BmTLP, is an important pathogenic molecule of B. microti and may be a possible target for the design of babesiosis control strategy.
Asunto(s)
Babesia microti , Babesiosis , Proteínas Protozoarias , Tiorredoxinas , Animales , Babesia microti/genética , Babesia microti/patogenicidad , Babesiosis/parasitología , Ratones , Proteínas Protozoarias/genética , Tiorredoxinas/genética , VirulenciaRESUMEN
Inadequate sensitivity has been the primary limitation for implementing high-throughput sequencing for studies of tick-borne agents. Here we describe the development of TBDCapSeq, a sequencing assay that uses hybridization capture probes that cover the complete genomes of the eleven most common tick-borne agents found in the United States. The probes are used for solution-based capture and enrichment of pathogen nucleic acid followed by high-throughput sequencing. We evaluated the performance of TBDCapSeq to surveil samples that included human whole blood, mouse tissues, and field-collected ticks. For Borrelia burgdorferi and Babesia microti, the sensitivity of TBDCapSeq was comparable and occasionally exceeded the performance of agent-specific quantitative PCR and resulted in 25 to > 10,000-fold increase in pathogen reads when compared to standard unbiased sequencing. TBDCapSeq also enabled genome analyses directly within vertebrate and tick hosts. The implementation of TBDCapSeq could have major impact in studies of tick-borne pathogens by improving detection and facilitating genomic research that was previously unachievable with standard sequencing approaches.
Asunto(s)
Babesia microti/genética , Babesiosis/microbiología , Borrelia burgdorferi/genética , Técnicas de Genotipaje/métodos , Enfermedad de Lyme/microbiología , Técnicas de Diagnóstico Molecular/métodos , Análisis de Secuencia de ADN/métodos , Animales , Babesia microti/patogenicidad , Babesiosis/diagnóstico , Borrelia burgdorferi/patogenicidad , Genoma Bacteriano , Técnicas de Genotipaje/normas , Humanos , Enfermedad de Lyme/diagnóstico , Ratones , Técnicas de Diagnóstico Molecular/normas , Sensibilidad y Especificidad , Análisis de Secuencia de ADN/normas , Garrapatas/microbiologíaRESUMEN
BACKGROUND: The universal nature of the human-companion animal relationship and their shared ticks and tick-borne pathogens offers an opportunity for improving public and veterinary health surveillance. With this in mind, we describe the spatiotemporal trends for blacklegged tick (Ixodes scapularis) submissions from humans and companion animals in Ontario, along with pathogen prevalence. METHODS: We tested tick samples submitted through passive surveillance (2011-2017) from humans and companion animals for Borrelia burgdorferi, Borrelia miyamotoi, Anaplasma phagocytophilum and Babesia microti. We describe pathogen prevalence in ticks from humans and from companion animals and constructed univariable Poisson and negative binomial regression models to explore the spatiotemporal relationship between the rates of tick submissions by host type. RESULTS: During the study, there were 17,230 blacklegged tick samples submitted from humans and 4375 from companion animals. Tick submission rates from companion animals were higher than expected in several public health units (PHUs) lacking established tick populations, potentially indicating newly emerging populations. Pathogen prevalence in ticks was higher in PHUs where established blacklegged tick populations exist. Borrelia burgdorferi prevalence was higher in ticks collected from humans (maximum likelihood estimate, MLE = 17.5%; 95% confidence interval, CI 16.97-18.09%) than from companion animals (9.9%, 95% CI 9.15-10.78%). There was no difference in pathogen prevalence in ticks by host type for the remaining pathogens, which were found in less than 1% of tested ticks. The most common co-infection B. burgdorferi + B. miyamotoi occurred in 0.11% of blacklegged ticks from humans and animals combined. Borrelia burgdorferi prevalence was higher in unengorged (21.9%, 95% CI 21.12-22.65%) than engorged ticks (10.0%, 95% CI 9.45-10.56%). There were no consistent and significant spatiotemporal relationships detected via regression models between the annual rates of submission of each host type. CONCLUSIONS: While B. burgdorferi has been present in blacklegged ticks in Ontario for several decades, other tick-borne pathogens are also present at low prevalence. Blacklegged tick and pathogen surveillance data can be used to monitor risk in human and companion animal populations, and efforts are under consideration to unite surveillance efforts for the different target populations.
Asunto(s)
Ixodes/microbiología , Ixodes/parasitología , Mascotas/microbiología , Mascotas/parasitología , Anaplasma phagocytophilum/aislamiento & purificación , Anaplasma phagocytophilum/patogenicidad , Animales , Babesia microti/aislamiento & purificación , Babesia microti/patogenicidad , Borrelia/aislamiento & purificación , Borrelia/patogenicidad , Borrelia burgdorferi/aislamiento & purificación , Borrelia burgdorferi/patogenicidad , Coinfección/microbiología , Coinfección/parasitología , Femenino , Humanos , Masculino , Ontario , Análisis Espacio-TemporalRESUMEN
BACKGROUND: Protozoa in the genus Babesia are transmitted to humans through tick bites and cause babesiosis, a malaria-like illness. Vertical transmission of Babesia spp. has been reported in mammals; however, the exact timing and mechanisms involved are not currently known. The aims of this study were to evaluate the success of vertical transmission of B. microti in female mice infected before pregnancy (mated during the acute or chronic phases of Babesia infection) and that of pregnant mice infected during early and advanced pregnancy; to evaluate the possible influence of pregnancy on the course of parasite infections (parasitaemia); and to assess pathological changes induced by parasitic infection. METHODS: The first set of experiments involved two groups of female mice infected with B. microti before mating, and inseminated on the 7th day and after the 40th day post infection. A second set of experiments involved female mice infected with B. microti during pregnancy, on the 4th and 12th days of pregnancy. Blood smears and PCR targeting the 559 bp 18S rRNA gene fragment were used for the detection of B. microti. Pathology was assessed histologically. RESULTS: Successful development of pregnancy was recorded only in females mated during the chronic phase of infection. The success of vertical transmission of B. microti in this group was 63%. No evidence of pregnancy was found in females mated during the acute phase of infection or on the 4th day of pregnancy. In the group infected on the 12th day of pregnancy, numerous complications including loss of pregnancy and stillbirths were recorded. During the acute phase of infection, parasitaemia was lower in pregnant females in comparison to infected, non-pregnant control females. CONCLUSIONS: Acute B. microti infection prevents the initiation of pregnancy and embryonic development if it occurs during the first trimester, and causes severe complications in foetal BALB/c mice in the second and third trimesters of pregnancy. Chronic B. microti infection has no detrimental impact on the initiation and development of pregnancy, but results in congenital infection of the offspring. Further study is required to determine the extent to which maternal anti-babesial immune responses contribute to compromise pregnancy in the murine model of congenital Babesia infection.
Asunto(s)
Babesia microti/genética , Babesiosis/transmisión , Transmisión Vertical de Enfermedad Infecciosa , Animales , Babesia microti/patogenicidad , Babesiosis/parasitología , Modelos Animales de Enfermedad , Desarrollo Embrionario , Femenino , Masculino , Ratones , Ratones Endogámicos BALB C , Parasitemia , Embarazo , ARN Ribosómico 18S/genéticaRESUMEN
BACKGROUND: Babesia is a protozoan parasite that infects red blood cells in some vertebrates. Some species of Babesia can induce zoonoses and cause considerable harm. As the largest immune organ in mammals, the spleen plays an important role in defending against Babesia infection. When infected with Babesia, the spleen is seriously injured but still actively initiates immunomodulatory responses. METHODS: To explore the molecular mechanisms underlying the immune regulation and self-repair of the spleen in response to infection, this study used data-independent acquisition (DIA) quantitative proteomics to analyse changes in expression levels of global proteins and in phosphorylation modification in spleen tissue after Babesia microti infection in mice. RESULTS: After mice were infected with B. microti, their spleens were seriously damaged. Using bioinformatics methods to analyse dynamic changes in a large number of proteins, we found that the spleen still initiated immune responses to combat the infection, with immune-related proteins playing an important role, including cathepsin D (CTSD), interferon-induced protein 44 (IFI44), interleukin-2 enhancer-binding factor 2 (ILF2), interleukin enhancer-binding factor 3 (ILF3) and signal transducer and activator of transcription 5A (STAT5A). In addition, some proteins related to iron metabolism were also involved in the repair of the spleen after B. microti infection, including serotransferrin, lactoferrin, transferrin receptor protein 1 (TfR1) and glutamate-cysteine ligase (GCL). At the same time, the expression and phosphorylation of proteins related to the growth and development of the spleen also changed, including protein kinase C-δ (PKC-δ), mitogen-activated protein kinase (MAPK) 3/1, growth factor receptor-bound protein 2 (Grb2) and P21-activated kinase 2 (PAK2). CONCLUSIONS: Immune-related proteins, iron metabolism-related proteins and growth and development-related proteins play an important role in the regulation of spleen injury and maintenance of homeostasis. This study provides an important basis for the diagnosis and treatment of babesiosis.
Asunto(s)
Babesia microti/patogenicidad , Regulación de la Expresión Génica , Proteínas/genética , Proteómica , Bazo/patología , Bazo/parasitología , Animales , Babesia microti/inmunología , Babesiosis/inmunología , Babesiosis/fisiopatología , Biología Computacional , Femenino , Ratones , Ratones Endogámicos BALB C , Parasitemia , Bazo/inmunología , Factores de TranscripciónAsunto(s)
Ixodes/microbiología , Ixodes/parasitología , Anaplasma phagocytophilum/patogenicidad , Animales , Babesia microti/patogenicidad , Borrelia burgdorferi/patogenicidad , Virus de la Encefalitis Transmitidos por Garrapatas/patogenicidad , Humanos , Infestaciones por Garrapatas/microbiología , Infestaciones por Garrapatas/virología , WisconsinRESUMEN
The number of recognized flea-borne pathogens has increased over the past decade. However, the true number of infections related to all flea-borne pathogens remains unknown. To better understand the enzootic cycle of flea-borne pathogens, fleas were sampled from small mammals trapped in central Pennsylvania. A total of 541 small mammals were trapped, with white-footed mice (Peromyscus leucopus) and southern red-backed voles (Myodes gapperi) accounting for over 94% of the captures. Only P. leucopus were positive for examined blood-borne pathogens, with 47 (18.1%) and ten (4.8%) positive for Anaplasma phagocytophilum and Babesia microti, respectively. In addition, 61 fleas were collected from small mammals and tested for pathogens. Orchopeas leucopus was the most common flea and Bartonella vinsonii subspecies arupensis, B. microti, and a Rickettsia felis-like bacterium were detected in various flea samples. To the best of our knowledge, this is the first report of B. microti DNA detected from a flea and the first report of a R. felis-like bacterium from rodent fleas in eastern North America. This study provides evidence of emerging pathogens found in fleas, but further investigation is required to resolve the ecology of flea-borne disease transmission cycles.
Asunto(s)
Bartonella/patogenicidad , Siphonaptera/parasitología , Animales , Arvicolinae/parasitología , Babesia microti/parasitología , Babesia microti/patogenicidad , Masculino , Mamíferos/parasitología , Pennsylvania , Peromyscus/parasitología , Rickettsia felis/patogenicidad , Sciuridae/parasitologíaRESUMEN
BACKGROUND: Babesiosis is a disease caused by parasites that infect red blood cells; in infants it can be acquired from tick bites, blood transfusions, or congenitally via vertical transmission. It can present with thrombocytopenia, fevers, and parasitemia. CASE REPORT: A case of vertically transmitted babesiosis in an infant is described. Thrombocytopenia and parasitemia > 4% developed in this well-appearing infant. The diagnosis was made by history and blood smear in both infant and mother, and the patient recovered fully with oral antibiotics. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Congenital babesiosis has been reported infrequently in the literature and is reviewed here. It is important to consider congenital tick-borne illness in endemic areas as a cause for febrile thrombocytopenia in neonates.
Asunto(s)
Babesiosis/complicaciones , Babesiosis/diagnóstico , Babesia microti/patogenicidad , Babesiosis/transmisión , Fiebre/etiología , Humanos , Lactante , Transmisión Vertical de Enfermedad Infecciosa , Masculino , Parasitemia/complicaciones , Parasitemia/transmisión , Trombocitopenia/etiologíaRESUMEN
We report a case of babesiosis, caused by Babesia microti, in a missionary who worked in Equatorial Guinea but also visited rural Spain. The initial diagnosis, based on clinical features and microscopy, was malaria. The patient's recovery was delayed until she received appropriate treatment for babesiosis.
Asunto(s)
Antiprotozoarios/uso terapéutico , Atovacuona/uso terapéutico , Azitromicina/uso terapéutico , Babesia microti/efectos de los fármacos , Babesiosis/diagnóstico , Malaria/diagnóstico , Proguanil/uso terapéutico , Adulto , Artemisininas/farmacología , Babesia microti/crecimiento & desarrollo , Babesia microti/patogenicidad , Babesiosis/tratamiento farmacológico , Babesiosis/parasitología , Errores Diagnósticos , Combinación de Medicamentos , Guinea Ecuatorial , Femenino , Humanos , Malaria/tratamiento farmacológico , Malaria/parasitología , Primaquina/farmacología , España , ViajeRESUMEN
The blacklegged tick, Ixodes scapularis, is the primary vector to humans in the eastern United States of the deer tick virus lineage of Powassan virus (Powassan virus disease); the protozoan parasite Babesia microti (babesiosis); and multiple bacterial disease agents including Anaplasma phagocytophilum (anaplasmosis), Borrelia burgdorferi and Borrelia mayonii (Lyme disease), Borrelia miyamotoi (relapsing fever-like illness, named Borrelia miyamotoi disease), and Ehrlichia muris eauclairensis (a minor causative agent of ehrlichiosis). With the notable exception of Powassan virus, which can be transmitted within minutes after attachment by an infected tick, there is no doubt that the risk of transmission of other I. scapularis-borne pathogens, including Lyme disease spirochetes, increases with the length of time (number of days) infected ticks are allowed to remain attached. This review summarizes data from experimental transmission studies to reinforce the important disease-prevention message that regular (at least daily) tick checks and prompt tick removal has strong potential to reduce the risk of transmission of I. scapularis-borne bacterial and parasitic pathogens from infected attached ticks. The most likely scenario for human exposure to an I. scapularis-borne pathogen is the bite by a single infected tick. However, recent reviews have failed to make a clear distinction between data based on transmission studies where experimental hosts were fed upon by a single versus multiple infected ticks. A summary of data from experimental studies on transmission of Lyme disease spirochetes (Bo. burgdorferi and Bo. mayonii) by I. scapularis nymphs indicates that the probability of transmission resulting in host infection, at time points from 24 to 72â¯h after nymphal attachment, is higher when multiple infected ticks feed together as compared to feeding by a single infected tick. In the specific context of risk for human infection, the most relevant experimental studies therefore are those where the probability of pathogen transmission at a given point in time after attachment was determined using a single infected tick. The minimum duration of attachment by single infected I. scapularis nymphs required for transmission to result in host infection is poorly defined for most pathogens, but experimental studies have shown that Powassan virus can be transmitted within 15â¯min of tick attachment and both A. phagocytophilum and Bo. miyamotoi within the first 24â¯h of attachment. There is no experimental evidence for transmission of Lyme disease spirochetes by single infected I. scapularis nymphs to result in host infection when ticks are attached for only 24â¯h (despite exposure of nearly 90 experimental rodent hosts across multiple studies) but the probability of transmission resulting in host infection appears to increase to approximately 10% by 48â¯h and reach 70% by 72â¯h for Bo. burgdorferi. Caveats to the results from experimental transmission studies, including specific circumstances (such as re-attachment of previously partially fed infected ticks) that may lead to more rapid transmission are discussed.
Asunto(s)
Babesiosis/transmisión , Infecciones Bacterianas/transmisión , Encefalitis Transmitida por Garrapatas/transmisión , Ixodes/fisiología , Anaplasma phagocytophilum/aislamiento & purificación , Anaplasma phagocytophilum/patogenicidad , Anaplasmosis/transmisión , Animales , Babesia microti/aislamiento & purificación , Babesia microti/patogenicidad , Babesiosis/epidemiología , Babesiosis/prevención & control , Infecciones Bacterianas/epidemiología , Infecciones Bacterianas/prevención & control , Borrelia/aislamiento & purificación , Borrelia/patogenicidad , Ehrlichia/aislamiento & purificación , Ehrlichia/patogenicidad , Ehrlichiosis/transmisión , Virus de la Encefalitis Transmitidos por Garrapatas/aislamiento & purificación , Virus de la Encefalitis Transmitidos por Garrapatas/patogenicidad , Encefalitis Transmitida por Garrapatas/epidemiología , Encefalitis Transmitida por Garrapatas/prevención & control , Femenino , Humanos , Ixodes/microbiología , Ixodes/parasitología , Enfermedad de Lyme/transmisión , Fiebre Recurrente/transmisión , Factores de TiempoRESUMEN
Ticks transmit a greater variety of pathogenic agents that cause disease in humans and animals than any other haematophagous arthropod, including Lyme disease, Rocky Mountain spotted fever, human granulocytic anaplasmosis, babesiosis, tick-borne encephalitis, Crimean Congo haemorhagic fever, and many others (Gulia-Nuss et al., 2016). Although diverse explanations have been proposed to explain their remarkable vectorial capacity, among the most important are their blood feeding habit, their long term off-host survival, the diverse array of bioactive molecules that disrupt the host's natural hemostatic mechanisms, facilitate blood flow, pain inhibitors, and minimize inflammation to prevent immune rejection (Hajdusek et al., 2013). Moreover, the tick's unique intracellular digestive processes allow the midgut to provide a relatively permissive microenvironment for survival of invading microbes. Although tick-host-pathogen interactions have evolved over more than 300 million years (Barker and Murrell, 2008), few microbes have been able to overcome the tick's innate immune system, comprising both humoral and cellular processes that reject them. Similar to most eukaryotes, the signaling pathways that regulate the innate immune response, i.e., the Toll, IMD (Immunodeficiency) and JAK-STAT (Janus Kinase/ Signal Transducers and Activators of Transcription) also occur in ticks (Gulia-Nuss et al., 2016). Recognition of pathogen-associated molecular patterns (PAMPs) on the microbial surface triggers one or the other of these pathways. Consequently, ticks are able to mount an impressive array of humoral and cellular responses to microbial challenge, including anti-microbial peptides (AMPs), e.g., defensins, lysozymes, microplusins, etc., that directly kill, entrap or inhibit the invaders. Equally important are cellular processes, primarily phagocytosis, that capture, ingest, or encapsulate invading microbes, regulated by a primordial system of thioester-containing proteins, fibrinogen-related lectins and convertase factors (Hajdusek et al., 2013). Ticks also express reactive oxygen species (ROS) as well as glutathione-S-transferase, superoxide dismutase, heat shock proteins and even protease inhibitors that kill or inhibit microbes. Nevertheless, many tick-borne microorganisms are able to evade the tick's innate immune system and survive within the tick's body. The examples that follow describe some of the many different strategies that have evolved to enable ticks to transmit the agents of human and/or animal disease.
Asunto(s)
Interacciones Huésped-Patógeno/inmunología , Inmunidad Innata/inmunología , Enfermedades por Picaduras de Garrapatas/inmunología , Enfermedades por Picaduras de Garrapatas/microbiología , Garrapatas/inmunología , Garrapatas/microbiología , Anaplasma phagocytophilum/inmunología , Anaplasma phagocytophilum/patogenicidad , Animales , Babesia microti/inmunología , Babesia microti/patogenicidad , Borrelia burgdorferi/inmunología , Borrelia burgdorferi/patogenicidad , Humanos , Rickettsia rickettsii/inmunología , Rickettsia rickettsii/patogenicidadRESUMEN
Real-time PCR assays have recently been implemented in diagnostics for many bacterial pathogens, allowing rapid and accurate detection, which ultimately results in improved clinical intervention. Here, we describe a sensitive method of detection for three common tick-borne pathogens Borrelia burgdorferi, Anaplasma phagocytophilum, and Babesia microti since coinfections with these pathogens have started occurring with increasing frequency over the last several years in both North America and Europe. A shared geographic region, the same tick vectors, and similar transmission cycle all favor simultaneous transmission of these three tick-borne pathogens. Furthermore, early symptoms of the diseases are often similar and somewhat nonspecific leading to poor clinical identification. The multiplex real-time PCR assay we describe here utilizes gene-specific primers, molecular beacon probes tagged with different fluorophores, and optimized PCR conditions to detect even small amounts of specific pathogen DNA without interference. Application of this detection method will offer better diagnostics for acute and persistent infection compared to the two-tier serological tests that are currently approved in North America and Europe, which do not necessarily detect active infection.
Asunto(s)
Sangre/microbiología , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Enfermedades por Picaduras de Garrapatas/microbiología , Anaplasma phagocytophilum/genética , Anaplasma phagocytophilum/patogenicidad , Animales , Artefactos , Babesia microti/genética , Babesia microti/patogenicidad , Borrelia burgdorferi/genética , Borrelia burgdorferi/patogenicidad , Cartilla de ADN , Humanos , Enfermedad de Lyme/sangre , Enfermedad de Lyme/microbiología , Ratones , Sensibilidad y Especificidad , Enfermedades por Picaduras de Garrapatas/sangreRESUMEN
Infections of Toxoplasma gondii and Babesia microti are reported in many wild animals worldwide, but information on their incidence and molecular detection in Korean wild fields is limited. In this study, the prevalence of T. gondii and B. microti infection in blood samples of 5 animal species (37 Chinese water deer, 23 raccoon dogs, 6 roe deer, 1 wild boar, and 3 Eurasian badgers) was examined during 2008-2009 in Gangwon-do (Province), the Republic of Korea (=Korea) by using serological and molecular tests. The overall seropositivity of T. gondii was 8.6% (6/70); 10.8% in Chinese water deer, 4.3% in raccoon dogs, and 16.7% in roe deer. PCR revealed only 1 case of T. gondii infection in Chinese water deer, and phylogenic analysis showed that the positive isolate was practically identical to the highly pathogenetic strain type I. In B. microti PCR, the positive rate was 5.7% (4/70), including 2 Chinese water deer and 2 Eurasian badgers. Phylogenetic analysis results of 18S rRNA and the ß-tubulin gene showed that all positive isolates were US-type B. microti. To our knowledge, this is the first report of B. microti detected in Chinese water deer and Eurasian badger from Korea. These results indicate a potentially high prevalence of T. gondii and B. microti in wild animals of Gangwon-do, Korea. Furthermore, Chinese water deer might act as a reservoir for parasite infections of domestic animals.
Asunto(s)
Animales Salvajes/sangre , Animales Salvajes/parasitología , Babesia microti/aislamiento & purificación , Toxoplasma/aislamiento & purificación , Toxoplasmosis Animal/epidemiología , Toxoplasmosis Animal/parasitología , Animales , Anticuerpos Antiprotozoarios/sangre , Babesia microti/genética , Babesia microti/inmunología , Babesia microti/patogenicidad , Reservorios de Enfermedades/parasitología , Reservorios de Enfermedades/veterinaria , Filogenia , Reacción en Cadena de la Polimerasa , Prevalencia , ARN Ribosómico 18S/genética , República de Corea/epidemiología , Toxoplasma/genética , Toxoplasma/inmunología , Toxoplasma/patogenicidad , Tubulina (Proteína)/genéticaRESUMEN
BACKGROUND: Ticks transmit Babesia microti, the causative agents of babesiosis in North America and Europe. Babesiosis is now endemic in Northeastern USA and affects people of all ages. Babesia species infect erythrocytes and can be transmitted through blood transfusion. Whole blood and blood products, which are not tested for Babesia, can cause transfusion-transmitted babesiosis (TTB) resulting in severe consequences in the immuno-compromised patients. The purpose of this study was epidemiological evaluation of babesiosis in a tick-infested state. RESULTS: We examined blood samples from 192 patients who visited clinics during the active tick-borne diseases season, using a newly developed qPCR assay that uses the specific molecular beacon probe. Due to the absence of clear symptomology, clinical laboratories did not test 131 samples by IFA, FISH or microscopic examination of Giemsa-stained blood smears. Babesia infection was detected in all age groups by FISH and microscopy; notably patients >40 years of age represented 64% of tested samples and 13% were younger patients. We tested all samples using qPCR and found that 38% were positive for Babesia. Of 28 samples that were positive by FISH, 27 (96%) were also positive by qPCR indicating high congruency between nucleic acid based tests. Interestingly, of 78 asymptomatic samples not tested by FISH, 22 were positive by our qPCR. Direct detection of Babesia relies upon microscopic examination of patient blood smears, which is labor intensive, difficult to scale up, requires specific expertise and is hence, often not performed. In fact, a clinical laboratory examined only 23 of 86 blood samples obtained from two different counties by microscopy. By considering individuals positive for Babesia infection when results from currently available microscopy, FISH or serological tests were positive, we found that our qPCR is highly sensitive (96.2%) and showed a specificity of 70.5% for Babesia. CONCLUSION: Robust qPCR using specific probes can be highly useful for efficient and appropriate diagnosis of babesiosis in patients in conjunction with conventional diagnostics, or as a stand-alone test, especially for donated blood screening. The use of a nucleic acid amplification test based screening of blood and blood products could prevent TTB.
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Babesia microti/genética , Babesia microti/aislamiento & purificación , Babesiosis/diagnóstico , Babesiosis/epidemiología , Babesiosis/parasitología , Técnicas de Amplificación de Ácido Nucleico/métodos , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Animales , Babesia microti/patogenicidad , Babesiosis/sangre , Secuencia de Bases , Niño , Preescolar , ADN Protozoario , Femenino , Fluoroinmunoensayo/métodos , Humanos , Hibridación Fluorescente in Situ/métodos , Masculino , Microscopía , Persona de Mediana Edad , New England/epidemiología , New Jersey/epidemiología , ARN Ribosómico 18S/genética , Estaciones del Año , Sensibilidad y Especificidad , Garrapatas/genética , Garrapatas/parasitología , Adulto JovenRESUMEN
Babesia microti, a tick-transmitted, intraerythrocytic protozoan parasite circulating mainly among small mammals, is the primary cause of human babesiosis. While most cases are transmitted by Ixodes ticks, the disease may also be transmitted through blood transfusion and perinatally. A comprehensive analysis of genome composition, genetic diversity, and gene expression profiling of seven B. microti isolates revealed that genetic variation in isolates from the Northeast United States is almost exclusively associated with genes encoding the surface proteome and secretome of the parasite. Furthermore, we found that polymorphism is restricted to a small number of genes, which are highly expressed during infection. In order to identify pathogen-encoded factors involved in host-parasite interactions, we screened a proteome array comprised of 174 B. microti proteins, including several predicted members of the parasite secretome. Using this immuno-proteomic approach we identified several novel antigens that trigger strong host immune responses during the onset of infection. The genomic and immunological data presented herein provide the first insights into the determinants of B. microti interaction with its mammalian hosts and their relevance for understanding the selective pressures acting on parasite evolution.
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Babesia microti/patogenicidad , Babesiosis/genética , Polimorfismo Genético , Proteómica , Animales , Babesia microti/genética , Babesiosis/parasitología , Babesiosis/transmisión , Regulación de la Expresión Génica , Genoma de Protozoos , Genómica , Interacciones Huésped-Parásitos/genética , Humanos , Ixodes/genética , Ixodes/parasitología , Análisis por Micromatrices , New EnglandRESUMEN
Babesia microti and Borrelia burgdorferi, the respective causative agents of human babesiosis and Lyme disease, are maintained in their enzootic cycles by the blacklegged tick (Ixodes scapularis) and use the white-footed mouse (Peromyscus leucopus) as primary reservoir host. The geographic range of both pathogens has expanded in the United States, but the spread of babesiosis has lagged behind that of Lyme disease. Several studies have estimated the basic reproduction number (R0) for B. microti to be below the threshold for persistence (<1), a finding that is inconsistent with the persistence and geographic expansion of this pathogen. We tested the hypothesis that host coinfection with B. burgdorferi increases the likelihood of B. microti transmission and establishment in new areas. We fed I. scapularis larva on P. leucopus mice that had been infected in the laboratory with B. microti and/or B. burgdorferi. We observed that coinfection in mice increases the frequency of B. microti infected ticks. To identify the ecological variables that would increase the probability of B. microti establishment in the field, we integrated our laboratory data with field data on tick burden and feeding activity in an R0 model. Our model predicts that high prevalence of B. burgdorferi infected mice lowers the ecological threshold for B. microti establishment, especially at sites where larval burden on P. leucopus is lower and where larvae feed simultaneously or soon after nymphs infect mice, when most of the transmission enhancement due to coinfection occurs. Our studies suggest that B. burgdorferi contributes to the emergence and expansion of B. microti and provides a model to predict the ecological factors that are sufficient for emergence of B. microti in the wild.
Asunto(s)
Babesia microti/patogenicidad , Babesiosis/transmisión , Borrelia burgdorferi/patogenicidad , Animales , Coinfección/microbiología , Coinfección/parasitología , Ixodes/microbiología , Ixodes/parasitología , New England , Peromyscus/microbiología , Peromyscus/parasitologíaRESUMEN
Animal and plant species differ dramatically in their quality as hosts for multi-host pathogens, but the causes of this variation are poorly understood. A group of small mammals, including small rodents and shrews, are among the most competent natural reservoirs for three tick-borne zoonotic pathogens, Borrelia burgdorferi, Babesia microti, and Anaplasma phagocytophilum, in eastern North America. For a group of nine commonly-infected mammals spanning >2 orders of magnitude in body mass, we asked whether life history features or surrogates for (unknown) encounter rates with ticks, predicted reservoir competence for each pathogen. Life history features associated with a fast pace of life generally were positively correlated with reservoir competence. However, a model comparison approach revealed that host population density, as a proxy for encounter rates between hosts and pathogens, generally received more support than did life history features. The specific life history features and the importance of host population density differed somewhat between the different pathogens. We interpret these results as supporting two alternative but non-exclusive hypotheses for why ecologically widespread, synanthropic species are often the most competent reservoirs for multi-host pathogens. First, multi-host pathogens might adapt to those hosts they are most likely to experience, which are likely to be the most abundant and/or frequently bitten by tick vectors. Second, species with fast life histories might allocate less to certain immune defenses, which could increase their reservoir competence. Results suggest that of the host species that might potentially be exposed, those with comparatively high population densities, small bodies, and fast pace of life will often be keystone reservoirs that should be targeted for surveillance or management.
Asunto(s)
Ixodes/microbiología , Ixodes/parasitología , Enfermedades por Picaduras de Garrapatas/transmisión , Zoonosis/transmisión , Anaplasma phagocytophilum/patogenicidad , Animales , Babesia microti/patogenicidad , Babesiosis/parasitología , Babesiosis/transmisión , Tamaño Corporal , Borrelia burgdorferi/patogenicidad , Reservorios de Enfermedades/microbiología , Reservorios de Enfermedades/parasitología , Ehrlichiosis/microbiología , Ehrlichiosis/transmisión , Humanos , Enfermedad de Lyme/microbiología , Enfermedad de Lyme/transmisión , América del Norte , Densidad de Población , Enfermedades por Picaduras de Garrapatas/microbiología , Enfermedades por Picaduras de Garrapatas/parasitología , Zoonosis/microbiología , Zoonosis/parasitologíaRESUMEN
BACKGROUND: Babesia microti, a transfusion-transmissible intraerythrocytic parasite, is increasing in frequency in the United States with no available FDA-licensed donor screening assay. We utilized investigational arrayed fluorescence immunoassay (AFIA) and polymerase chain reaction (PCR) to detect B. microti antibodies and DNA in blood donors. STUDY DESIGN AND METHODS: AFIA and real-time PCR were performed on frozen paired EDTA plasma (AFIA) and EDTA whole blood (PCR) samples collected from May to September 2010 to 2011 in nonendemic (Arizona [AZ] and Oklahoma [OK]), moderately endemic (Minnesota [MN] and Wisconsin [WI]), and highly endemic (Connecticut [CT] and Massachusetts [MA]) areas of the United States. AFIA utilized B. microti piroplasm as an antigen substrate; PCR primers and probes targeted the B. microti 18S ribosomal RNA gene. Data from AZ and OK were used to calculate specificity. All AFIA- or PCR-positive or -inconclusive donors were deferred, notified, and invited to participate in a follow-up study involving repeat testing and a demographic and risk-factor questionnaire. Recipient tracing was performed for any cellular component transfused at index, at subsequent donation, or within the prior 12 months. RESULTS: Testing of 13,269 paired samples included 4022 from AZ and OK, 4167 from MN and WI, and 5080 from CT and MA. B. microti antibody and/or DNA prevalences were 0.025% (95% confidence interval [CI], 0.00%-0.14%), 0.12% (95% CI, 0.04%-0.28%), and 0.75% (95% CI, 0.53%-1.03%) in the nonendemic, mid-endemic, and high-endemic regions, respectively. Specificities were 99.95% (95% CI, 99.82%-99.99%) at a 1-in-64 AFIA cutoff and 99.98% (95% CI, 99.86%-100.00%) at a 1-in-128 cutoff. CONCLUSIONS: B. microti prevalence followed expected geographical patterns. Screening was feasible with a performance comparable or superior to other infectious disease blood donor screening assays.
Asunto(s)
Babesia microti/patogenicidad , Donantes de Sangre/estadística & datos numéricos , Anticuerpos Antiprotozoarios/sangre , Babesia microti/genética , Babesia microti/inmunología , ADN Protozoario/sangre , Humanos , Reacción en Cadena en Tiempo Real de la Polimerasa , Estados UnidosRESUMEN
BACKGROUND: Babesia infection is caused by intraerythrocytic tick-borne parasites. Cases of transfusion-transmitted babesiosis have been increasingly recognized. To date, no Babesia test has been licensed for screening US blood donors. We conducted a longitudinal study to assess the course and markers of Babesia infection among seropositive donors identified in a seroprevalence study. STUDY DESIGN AND METHODS: Eligible donors had B. microti indirect fluorescent antibody (IFA) titers of 64 or greater. Enrollees were monitored up to 3 years, by IFA and three methods for evidence of parasitemia: B. microti nested polymerase chain reaction (PCR) analysis (at two laboratories), hamster inoculation, and blood-smear examination. RESULTS: Among 115 eligible donors, 84 (73%) enrolled. Eighteen enrollees (21%) had evidence of parasitemia for 30 total specimens (17% of 181), which were collected in 9 different months and tested positive by various approaches: PCR (25 specimens/16 persons), hamster inoculation (13 specimens/8 persons), and blood smear (one specimen positive by all three approaches). Overall, 14 persons had one or more specimen with positive PCR results at both laboratories (12 persons) and/or had parasitologically confirmed infection (eight persons). Three of nine persons who had more than one specimen with evidence of parasitemia had nonconsecutive positives. Several enrollees likely had been infected at least 1 year when their last positive specimen was collected. The final three specimens for seven persons tested negative by all study methods, including IFA. CONCLUSION: Seropositive blood donors can have protracted low-level parasitemia that is variably and intermittently detected by parasitologic and molecular methods. Donor-screening algorithms should include serologic testing and not solely rely on molecular testing.