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Maria A Diukwasser - One of the best experts on this subject based on the ideXlab platform.
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vertical transmission a vector independent transmission pathway of Babesia microti in the natural reservoir host peromyscus leucopus
The Journal of Infectious Diseases, 2021Co-Authors: Danielle M Tufts, Maria A DiukwasserAbstract:BACKGROUND Babesia microti, a malaria-like pathogen, is increasing in mammal and human populations in endemic areas and is unlikely to be the sole result of horizontal pathogen transmission. METHODS Peromyscus leucopus mice, natural reservoir hosts, were infected via Ixodes scapularis nymphs. Infected parental females (n = 6) produced F1 offspring (n = 36) that were screened for B. microti using quantitative PCR. Xenodiagnostic larvae were fed on infected offspring to determine horizontal transmission and pathogen viability. Fifty engorged larvae were screened; the rest were allowed to molt and then screened to determine transstadial transmission. Infected F1 generation offspring were placed in breeding groups, producing 34 F2 offspring and screened for B. microti infection. Chronic infection was monitored in parental females since time of initial vector infection. RESULTS Vertical transmission of B. microti was 74% efficient in offspring born in the first 6 months. Horizontal transmission occurred in larvae (61% prevalence) and molted nymphs (58% prevalence); these nymphs were able to infect susceptible hosts. F2 generation offspring infection prevalence was 38%. Chronic infection persisted for 1 year in some adults. CONCLUSIONS These results demonstrate that vertical transmission is an important nonvector-mediated pathway of B. microti transmission in the natural reservoir host.
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vertical transmission a vector independent transmission pathway of Babesia microti in the natural reservoir host peromyscus leucopus
The Journal of Infectious Diseases, 2020Co-Authors: Danielle M Tufts, Maria A DiukwasserAbstract:BACKGROUND Babesia microti, a malaria-like pathogen, is increasing in mammal and human populations in endemic areas and is unlikely to be the sole result of horizontal pathogen transmission. METHODS Peromyscus leucopus mice, natural reservoir hosts, were infected via Ixodes scapularis nymphs. Infected parental females (n = 6) produced F1 offspring (n = 36) that were screened for B. microti using quantitative PCR. Xenodiagnostic larvae were fed on infected offspring to determine horizontal transmission and pathogen viability. Fifty engorged larvae were screened; the rest were allowed to molt and then screened to determine transstadial transmission. Infected F1 generation offspring were placed in breeding groups, producing 34 F2 offspring and screened for B. microti infection. Chronic infection was monitored in parental females since time of initial vector infection. RESULTS Vertical transmission of B. microti was 74% efficient in offspring born in the first 6 mo. Horizontal transmission occurred in larvae (61% prevalence) and molted nymphs (58% prevalence); these nymphs were able to infect susceptible hosts. F2 generation offspring infection prevalence was 38%. Chronic infection persisted for 1 yr in some adults. CONCLUSIONS These results demonstrate that vertical transmission is an important non-vector mediated pathway of B. microti transmission in the natural reservoir host.
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transplacental transmission of tick borne Babesia microti in its natural host peromyscus leucopus
Parasites & Vectors, 2018Co-Authors: Danielle M Tufts, Maria A DiukwasserAbstract:Babesia microti is an emerging tick-borne pathogen and the causative agent of human babesiosis. Mathematical modeling of the reproductive rate of B. microti indicates that it cannot persist in nature by horizontal tick-host transmission alone. We hypothesized that transplacental transmission in the reservoir population contributes to B. microti persistence and emergence in North American rodent populations. Peromyscus leucopus were collected from Connecticut and Block Island, Rhode Island and analyzed using a highly specific quantitative PCR (qPCR) assay for infection with B. microti. In April, 100% (n = 103) of mice were infected with B. microti. Females exhibited significantly higher parasitemia than their offspring (P < 0.0001) and transplacental transmission was observed in 74.2% of embryos (n = 89). Transplacental transmission of B. microti is thus a viable and potentially important infectious pathway in naturally infected rodent species and should be considered in future theoretical and empirical studies. To our knowledge, this study is the first to report transplacental transmission of B. microti occurring in its natural reservoir host, P. leucopus, in the United States and the only study that provides a quantitative estimate of parasitemia. This vector-independent pathway could contribute to the increased geographic range of B. microti or increase its abundance in endemic areas.
Peter J Krause - One of the best experts on this subject based on the ideXlab platform.
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clofazimine a promising drug for the treatment of Babesia microti infection in severely immunocompromised hosts
The Journal of Infectious Diseases, 2020Co-Authors: Peter J Krause, Edouard Vannier, Bumduuren Tuvshintulga, Dickson Stuart Tayebwa, Sambuu Gantuya, Thillaiampalam Sivakumar, Azirwan Guswanto, Naoaki Yokoyama, Ikuo IgarashiAbstract:Background Persistent and relapsing babesiosis caused by Babesia microti often occurs in immunocompromised patients, and has been associated with resistance to antimicrobial agents such as atovaquone. Given the rising incidence of babesiosis in the United States, novel drugs are urgently needed. In the current study, we tested whether clofazimine (CFZ), an antibiotic used to treat leprosy and drug-resistant tuberculosis, is effective against B. microti. Methods Mice with severe combined immunodeficiency were infected with 107B. microti-infected erythrocytes. Parasites were detected by means of microscopic examination of Giemsa-stained blood smears or nested polymerase chain reaction. CFZ was administered orally. Results Uninterrupted monotherapy with CFZ curtailed the rise of parasitemia and achieved radical cure. B. microti parasites and B. microti DNA were cleared by days 10 and 50 of therapy, respectively. A 7-day administration of CFZ delayed the rise of parasitemia by 22 days. This rise was caused by B. microti isolates that did not carry mutations in the cytochrome b gene. Accordingly, a 14-day administration of CFZ was sufficient to resolve high-grade parasitemia caused by atovaquone-resistant B. microti parasites. Conclusions Clofazimine is effective against B. microti infection in the immunocompromised host. Additional preclinical studies are required to identify the minimal dose and dosage of CFZ for babesiosis.
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Persistence of Babesia microti Infection in Humans.
Pathogens (Basel Switzerland), 2019Co-Authors: Evan M. Bloch, Sanjai Kumar, Peter J KrauseAbstract:Persistent infection is a characteristic feature of babesiosis, a worldwide, emerging tick-borne disease caused by members of the genus Babesia. Persistence of Babesia infection in reservoir hosts increases the probability of survival and transmission of these pathogens. Laboratory tools to detect Babesia in red blood cells include microscopic detection using peripheral blood smears, nucleic acid detection (polymerase chain reaction and transcription mediated amplification), antigen detection, and antibody detection. Babesia microti, the major cause of human babesiosis, can asymptomatically infect immunocompetent individuals for up to two years. Chronically infected blood donors may transmit the pathogen to another person through blood transfusion. Transfusion-transmitted babesiosis causes severe complications and death in about a fifth of cases. Immunocompromised patients, including those with asplenia, HIV/AIDS, malignancy, or on immunosuppressive drugs, often experience severe disease that may relapse up to two years later despite anti-Babesia therapy. Persistent Babesia infection is promoted by Babesia immune evasive strategies and impaired host immune mechanisms. The health burden of persistent and recrudescent babesiosis can be minimized by development of novel therapeutic measures, such as new anti-parasitic drugs or drug combinations, improved anti-parasitic drug duration strategies, or immunoglobulin preparations; and novel preventive approaches, including early detection methods, tick-avoidance, and blood donor screening.
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bmgpac an antigen capture assay for detection of active Babesia microti infection
Journal of Clinical Microbiology, 2018Co-Authors: Jose Thekkiniath, Peter J Krause, Lauren Lawres, Meital Gewirtz, Michel Ledizet, Sara Mootien, Benjamin A Perrin, Scott C Williams, Stone J Doggett, Choukri Ben MamounAbstract:Human babesiosis is an emerging zoonotic infectious disease caused by intraerythrocytic protozoan parasites of the genus Babesia Most cases of human babesiosis are caused by Babesia microti and often manifest in individuals over the age of 50 years or in patients with a compromised immune system. Patients who develop symptomatic B. microti infections usually experience months of asymptomatic infection after the acute infection has resolved. About one-fifth of B. microti-infected adults never develop symptoms. These asymptomatically infected individuals sometimes donate blood and thus can transmit B. microti through blood transfusion. Current assays for detection of active B. microti infections can be used to screen donor blood prior to transfusion, but they rely primarily on microscopy or PCR methods, which have sensitivity and technical limitations. Here we report the development of an antigen capture enzyme-linked immunosorbent assay (BmGPAC) based on a major secreted immunodominant antigen of B. microti (BmGPI12/BmSA1), and we provide evidence that this assay is superior for detection of active B. microti infections, compared to available microscopy methods and serological assays. The assay has been evaluated using supernatants of B. microti-infected erythrocytes cultured in vitro, sera from B. microti-infected laboratory mice, and sera from wild mice and human patients. Our data suggest that the BmGPAC assay is a reliable assay for detection of active B. microti infections and is superior to real-time PCR and antibody assays for diagnosis of acute B. microti infections, screening of the blood supply, and epidemiological surveys of humans and animal reservoir hosts.
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Babesia microti from humans and ticks hold a genomic signature of strong population structure in the united states
BMC Genomics, 2016Co-Authors: Emmanuel Cornillot, Peter J Krause, Choukri Ben Mamoun, Ankit Dwivedi, Timothy Lepore, Giovanna Carpi, Katharine S Walter, Andrew Kitchen, Adalgisa CacconeAbstract:Babesia microti is an emerging tick-borne apicomplexan parasite with increasing geographic range and incidence in the United States. The rapid expansion of B. microti into its current distribution in the northeastern USA has been due to the range expansion of the tick vector, Ixodes scapularis, upon which the causative agent is dependent for transmission to humans. To reconstruct the history of B. microti in the continental USA and clarify the evolutionary origin of human strains, we used multiplexed hybrid capture of 25 B. microti isolates obtained from I. scapularis and human blood. Despite low genomic variation compared with other Apicomplexa, B. microti was strongly structured into three highly differentiated genetic clusters in the northeastern USA. Bayesian analyses of the apicoplast genomes suggest that the origin of the current diversity of B. microti in northeastern USA dates back 46 thousand years with a signature of recent population expansion in the last 1000 years. Human-derived samples belonged to two rarely intermixing clusters, raising the possibility of highly divergent infectious phenotypes in humans. Our results validate the multiplexed hybrid capture strategy for characterizing genome-wide diversity and relatedness of B. microti from ticks and humans. We find strong population structure in B. microti samples from the Northeast indicating potential barriers to gene flow.
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expression purification and biological characterization of Babesia microti apical membrane antigen 1
Infection and Immunity, 2015Co-Authors: Prasun Moitra, Peter J Krause, Vivek Anantharaman, Hong Zheng, Kazuyo Takeda, Rajdeep Banerjee, Yukiko Kozakai, Timothy Lepore, L Aravind, Sanjai KumarAbstract:The intraerythrocytic apicomplexan Babesia microti, the primary causative agent of human babesiosis, is a major public health concern in the United States and elsewhere. Apicomplexans utilize a multiprotein complex that includes a type I membrane protein called apical membrane antigen 1 (AMA1) to invade host cells. We have isolated the full-length B. microti AMA1 (BmAMA1) gene and determined its nucleotide sequence, as well as the amino acid sequence of the AMA1 protein. This protein contains an N-terminal signal sequence, an extracellular region, a transmembrane region, and a short conserved cytoplasmic tail. It shows the same domain organization as the AMA1 orthologs from piroplasm, coccidian, and haemosporidian apicomplexans but differs from all other currently known piroplasmida, including other Babesia and Theileria species, in lacking two conserved cysteines in highly variable domain III of the extracellular region. Minimal polymorphism was detected in BmAMA1 gene sequences of parasite isolates from six babesiosis patients from Nantucket. Immunofluorescence microscopy studies showed that BmAMA1 is localized on the cell surface and cytoplasm near the apical end of the parasite. Native BmAMA1 from parasite lysate and refolded recombinant BmAMA1 (rBmAMA1) expressed in Escherichia coli reacted with a mouse anti-BmAMA1 antibody using Western blotting. In vitro binding studies showed that both native BmAMA1 and rBmAMA1 bind to human red blood cells (RBCs). This binding is trypsin and chymotrypsin treatment sensitive but neuraminidase independent. Incubation of B. microti parasites in human RBCs with a mouse anti-BmAMA1 antibody inhibited parasite growth by 80% in a 24-h assay. Based on its antigenically conserved nature and potential role in RBC invasion, BmAMA1 should be evaluated as a vaccine candidate.
Anna Bajer - One of the best experts on this subject based on the ideXlab platform.
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bartonella infections in three species of microtus prevalence and genetic diversity vertical transmission and the effect of concurrent Babesia microti infection on its success
Parasites & Vectors, 2018Co-Authors: Katarzyna Tolkacz, Mohammed Alsarraf, Dorota Dwuznik, Maciej Grzybek, Jerzy M Behnke, Maciej Kowalec, Anna BajerAbstract:Background Bartonella spp. cause persistent bacterial infections in mammals. Although these bacteria are transmitted by blood-feeding arthropods, there is also evidence for vertical transmission in their mammalian hosts. We aimed to determine: (i) the prevalence and diversity of Bartonella spp. in a Microtus spp. community; (ii) whether vertical transmission occurs from infected female voles to their offspring; (iii) the effect of concurrent Babesia microti infection on the success of vertical transmission of Bartonella; and (iv) the impact of congenital infection on pup survival.
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prevalence genetic identity and vertical transmission of Babesia microti in three naturally infected species of vole microtus spp cricetidae
Parasites & Vectors, 2017Co-Authors: Katarzyna Tolkacz, Malgorzata Bednarska, Mohammed Alsarraf, Dorota Dwuznik, Maciej Grzybek, Renata Welcfaleciak, Jerzy M Behnke, Anna BajerAbstract:Vertical transmission is one of the transmission routes for Babesia microti, the causative agent of the zoonotic disease, babesiosis. Congenital Babesia invasions have been recorded in laboratory mice, dogs and humans. The aim of our study was to determine if vertical transmission of B. microti occurs in naturally-infected reservoir hosts of the genus Microtus. We sampled 124 common voles, Microtus arvalis; 76 root voles, M. oeconomus and 17 field voles, M. agrestis. In total, 113 embryos were isolated from 20 pregnant females. Another 11 pregnant females were kept in the animal house at the field station in Urwitalt until they had given birth and weaned their pups (n = 62). Blood smears and/or PCR targeting the 550 bp 18S rRNA gene fragment were used for the detection of B. microti. Selected PCR products, including isolates from females/dams and their embryos/pups, were sequenced. Positive PCR reactions were obtained for 41% (89/217) of the wild-caught voles. The highest prevalence of B. microti was recorded in M. arvalis (56/124; 45.2%), then in M. oeconomus (30/76; 39.5%) and the lowest in M. agrestis (3/17; 17.7%). Babesia microti DNA was detected in 61.4% (27/44) of pregnant females. Vertical transmission was confirmed in 81% (61/75) of the embryos recovered from Babesia-positive wild-caught pregnant females. The DNA of B. microti was detected in the hearts, lungs and livers of embryos from 98% of M. arvalis, 46% of M. oeconomus and 0% of M. agrestis embryos from Babesia-positive females. Of the pups born in captivity, 90% were born to Babesia-positive dams. Babesia microti DNA was detected in 70% (35/50) of M. arvalis and 83% (5/6) of M. oeconomus pups. Congenitally acquired infections had no impact on the survival of pups over a 3-week period post partum. Among 97 B. microti sequences, two genotypes were found. The IRU1 genotype (Jena-like) was dominant in wild-caught voles (49/53; 92%), pregnant females (9/11; 82%) and dams (3/5; 60%). The IRU2 genotype (Munich-like) was dominant among B. microti positive embryos (20/27; 74%) and pups (12/17; 71%). A high rate of vertical transmission of the two main rodent genotypes of B. microti was confirmed in two species of naturally infected voles, M. arvalis and M. oeconomus.
Sam R. Telford - One of the best experts on this subject based on the ideXlab platform.
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minimal infectious dose and dynamics of Babesia microti parasitemia in a murine model
Transfusion, 2018Co-Authors: Sonia Bakkour, Daniel M. Chafets, Li Wen, Marcus O. Muench, Sam R. Telford, James L. Erwin, Andrew E. Levin, Deanna SelfAbstract:Background Babesia microti is a parasite that infects red blood cells (RBCs) in mammals. It is transmitted to humans by tick bites, transfusion, organ transplantation, and congenital acquisition. Although the Babesia natural history and seroprevalence in donors have been well described, gaps in knowledge relevant to transfusion remain. Study design and methods Mice were infected with dilutions of parasitized blood to address the minimal infectious dose and the kinetics of parasitemia by quantitative polymerase chain reaction (qPCR) and of antibodies by enzyme immunoassay. Results In immunocompetent DBA/2 mice infected with 100 parasitized RBCs (pRBCs) and in immunodeficient NSG mice infected with 63 pRBCs, parasitemia was detectable in five of five mice each. Peak parasitemia up to 2 × 107 pRBCs/mL at 2 to 3 weeks or 5 × 108 pRBCs/mL at 6 weeks was observed for DBA/2 and NSG mice, respectively. Protracted fluctuating parasitemia was observed for 8 months in DBA/2 mice, whereas NSG mice exhibited a high-plateau parasitemia. Antibody titers continued to increase until 6 to 18 weeks in DBA/2 mice and remained high through 6 months. This study also investigated the analytical performance of Babesia assays that detect parasite DNA or RNA using a blinded panel. A Babesia assay targeting parasite RNA was approximately 10-fold more sensitive compared to qPCR targeting DNA. Conclusion The mice in this study were highly susceptible to Babesia infection using as few as 1 to 2 log pRBCs and maintained chronic parasitemia. If the infectious dose in human transfusion recipients is comparably low, a highly sensitive assay targeting parasite RNA may safeguard the blood supply, particularly before antibody detection.
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age associated decline in resistance to Babesia microti is genetically determined
The Journal of Infectious Diseases, 2004Co-Authors: Edouard Vannier, Andrew Spielman, Sam R. Telford, Ingo Borggraefe, Sanjay Menon, Timothy Brauns, Jeffrey A Gelfand, Henry H WortisAbstract:Background Although infection by the protozoan Babesia microti is rarely symptomatic in immunocompetent young people, healthy individuals aged >50 years may experience life-threatening disease. To determine the basis for this age relationship, we developed a mouse model of babesiosis using a novel clinical isolate of B. microti. Methods Mice were infected at 2, 6, 12, or 18 months. Parasitemia was monitored on Giemsa-stained blood smears or by flow cytometry. Results In DBA/2 mice, early and persistent parasitemias increased with age at infection. BALB/c and C57BL/6 mice were resistant, regardless of age, which indicates that allelic variation determines resistance to B. microti. Unlike immunocompetent mice, SCID mice, which retain an innate immune system but lack the lymphocytes needed for adaptive immunity, developed high and persistent levels of parasitemia that were markedly reduced by transfer of naive BALB/c or DBA/2 splenocytes. BALB/c cells reduced the persistent parasitemia to a greater extent than did age-matched DBA/2 cells. Of importance, there was an age-associated loss of protection by cells of both strains. Conclusion The resistance to B. microti infection conferred by the adaptive immune system is genetically determined and associated with age. We postulate that there are age-related differences in the expression of alleles critical for adaptive immunity to B. microti.
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case control study of canine infection by a newly recognised Babesia microti like piroplasm
Preventive Veterinary Medicine, 2003Co-Authors: F J Guitian, A T Camacho, Sam R. TelfordAbstract:We did a case-control study to identify risk factors for prevalent infection of dogs by a newly recognised Babesia microti-like piroplasm. Clinical manifestations and haematology of infected dogs also were described. Forty-three laboratory-based cases and 86 individually matched controls were studied. Information on clinical signs and on risk factors was collected by a questionnaire and telephone interviews. Haematology was carried out for all the dogs. Variables were screened in a bivariable conditional logistic regression and checked for colinearity. The final multivariable model was selected by backward stepwise elimination. The odds of a case having ticks when examined at the clinic was 4 times that of a control and the odds of a case being a hunting or a house-guarding dog were, respectively, 24.2 and 2.7 times those of a control. The most consistently reported clinical signs were weakness (79%), tachycardia (43%) and haemoglobinuria (42%). Mean red-blood-cell count, haemoglobin concentration, platelet count, and mean platelet volume of infected dogs were lower than the reference values and those of non-infected dogs-but leukocyte count, mean corpuscular volume and red-blood-cell distribution width were higher.
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what is Babesia microti
Parasitology, 2003Co-Authors: Heidi K Goethert, Sam R. TelfordAbstract:Babesia microti (Apicomplexa: Piroplasmida) has historically been considered a common parasite of Holarctic rodents. However, human babesiosis due to this species has generally been limited to the northeastern seaboard of the United States and Minnesota and Wisconsin. The absence of reports of B. microti babesiosis from sites where the agent is enzootic, such as in western Europe, remains unexplained. Previous work focusing on the 18S rDNA demonstrates little sequence diversity among samples from allopatric host populations across a wide geographical area. It may be that genetic diversity is underestimated due to sample size or the gene analysed. Accordingly, we collected blood or spleen samples from American or Eurasian animals with parasites that were morphologically consistent with B. microti, amplified the 18S rDNA and beta-tubulin gene, and conducted phylogenetic analysis. Surprisingly, what was considered to be 'B. microti' by microscopy appears to be a diverse species complex. We identify 3 distinct clades within this complex, including parasites from non-rodent hosts. Rodent parasites comprise 2 clades, one representing zoonotic isolates, and the other apparently maintained in microtine rodents, and therefore their morphological detection within animals from a site does not necessarily imply a risk to public health.
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entomologic and serologic evidence of zoonotic transmission of Babesia microti eastern switzerland
Emerging Infectious Diseases, 2002Co-Authors: Ivo M Foppa, Heidi K Goethert, Andrew Spielman, Lise Gern, Peter J Krause, Brigit Brand, Sam R. TelfordAbstract:We evaluated human risk for infection with Babesia microti at a site in eastern Switzerland where several B. microti–infected nymphal Ixodes ricinus ticks had been found. DNA from pooled nymphal ticks amplified by polymerase chain reaction was highly homologous to published B. microti sequences. More ticks carried Babesial infection in the lower portion of the rectangular 0.7-ha grid than in the upper (11% vs. 0.8%). In addition, we measured seroprevalence of immunoglobulin (Ig) G antibodies against B. microti antigen in nearby residents. Serum from 1.5% of the 396 human residents of the region reacted to B. microti antigen (>1:64), as determined by indirect immunofluorescence assay (IgG). These observations constitute the first report demonstrating B. microti in a human-biting vector, associated with evidence of human exposure to this agent in a European site.
Danielle M Tufts - One of the best experts on this subject based on the ideXlab platform.
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vertical transmission a vector independent transmission pathway of Babesia microti in the natural reservoir host peromyscus leucopus
The Journal of Infectious Diseases, 2021Co-Authors: Danielle M Tufts, Maria A DiukwasserAbstract:BACKGROUND Babesia microti, a malaria-like pathogen, is increasing in mammal and human populations in endemic areas and is unlikely to be the sole result of horizontal pathogen transmission. METHODS Peromyscus leucopus mice, natural reservoir hosts, were infected via Ixodes scapularis nymphs. Infected parental females (n = 6) produced F1 offspring (n = 36) that were screened for B. microti using quantitative PCR. Xenodiagnostic larvae were fed on infected offspring to determine horizontal transmission and pathogen viability. Fifty engorged larvae were screened; the rest were allowed to molt and then screened to determine transstadial transmission. Infected F1 generation offspring were placed in breeding groups, producing 34 F2 offspring and screened for B. microti infection. Chronic infection was monitored in parental females since time of initial vector infection. RESULTS Vertical transmission of B. microti was 74% efficient in offspring born in the first 6 months. Horizontal transmission occurred in larvae (61% prevalence) and molted nymphs (58% prevalence); these nymphs were able to infect susceptible hosts. F2 generation offspring infection prevalence was 38%. Chronic infection persisted for 1 year in some adults. CONCLUSIONS These results demonstrate that vertical transmission is an important nonvector-mediated pathway of B. microti transmission in the natural reservoir host.
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vertical transmission a vector independent transmission pathway of Babesia microti in the natural reservoir host peromyscus leucopus
The Journal of Infectious Diseases, 2020Co-Authors: Danielle M Tufts, Maria A DiukwasserAbstract:BACKGROUND Babesia microti, a malaria-like pathogen, is increasing in mammal and human populations in endemic areas and is unlikely to be the sole result of horizontal pathogen transmission. METHODS Peromyscus leucopus mice, natural reservoir hosts, were infected via Ixodes scapularis nymphs. Infected parental females (n = 6) produced F1 offspring (n = 36) that were screened for B. microti using quantitative PCR. Xenodiagnostic larvae were fed on infected offspring to determine horizontal transmission and pathogen viability. Fifty engorged larvae were screened; the rest were allowed to molt and then screened to determine transstadial transmission. Infected F1 generation offspring were placed in breeding groups, producing 34 F2 offspring and screened for B. microti infection. Chronic infection was monitored in parental females since time of initial vector infection. RESULTS Vertical transmission of B. microti was 74% efficient in offspring born in the first 6 mo. Horizontal transmission occurred in larvae (61% prevalence) and molted nymphs (58% prevalence); these nymphs were able to infect susceptible hosts. F2 generation offspring infection prevalence was 38%. Chronic infection persisted for 1 yr in some adults. CONCLUSIONS These results demonstrate that vertical transmission is an important non-vector mediated pathway of B. microti transmission in the natural reservoir host.
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transplacental transmission of tick borne Babesia microti in its natural host peromyscus leucopus
Parasites & Vectors, 2018Co-Authors: Danielle M Tufts, Maria A DiukwasserAbstract:Babesia microti is an emerging tick-borne pathogen and the causative agent of human babesiosis. Mathematical modeling of the reproductive rate of B. microti indicates that it cannot persist in nature by horizontal tick-host transmission alone. We hypothesized that transplacental transmission in the reservoir population contributes to B. microti persistence and emergence in North American rodent populations. Peromyscus leucopus were collected from Connecticut and Block Island, Rhode Island and analyzed using a highly specific quantitative PCR (qPCR) assay for infection with B. microti. In April, 100% (n = 103) of mice were infected with B. microti. Females exhibited significantly higher parasitemia than their offspring (P < 0.0001) and transplacental transmission was observed in 74.2% of embryos (n = 89). Transplacental transmission of B. microti is thus a viable and potentially important infectious pathway in naturally infected rodent species and should be considered in future theoretical and empirical studies. To our knowledge, this study is the first to report transplacental transmission of B. microti occurring in its natural reservoir host, P. leucopus, in the United States and the only study that provides a quantitative estimate of parasitemia. This vector-independent pathway could contribute to the increased geographic range of B. microti or increase its abundance in endemic areas.
