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Amanda D Loftis

Publications and source records attributed to Amanda D Loftis.

15 recordsLinked to original sources
PubMed2007

Rickettsial pathogens in the tropical rat mite Ornithonyssus bacoti (Acari: Macronyssidae) from Egyptian rats (Rattus spp.).

We collected and tested 616 tropical rat mites (Ornithonyssus bacoti (Hirst)) from rats (Rattus norvegicus (Berkenhout) and R. rattus (Linnaeus)) throughout 14 governorates in Egypt and tested DNA extracts from pools of these mites for Bartonella spp., Coxiella burnetii, and Rickettsia spp. by PCR amplification and sequencing. Three different mite-associated bacterial agents, including one Bartonella and two Rickettsia spp., were detected in eight pools of mites. Further research could demonstrate the vector potential of mites and pathogenicity of these agents to humans or animals.

Animals↗
PubMed2006

Rickettsial agents in Egyptian ticks collected from domestic animals.

To assess the presence of rickettsial pathogens in ticks from Egypt, we collected ticks from domestic and peridomestic animals between June 2002 and July 2003. DNA extracts from 1019 ticks were tested, using PCR and sequencing, for Anaplasma spp., Bartonella spp., Coxiella burnetii, Ehrlichia spp., and Rickettsia spp. Ticks included: 29 Argas persicus, 10 Hyalomma anatolicum anatolicum, 55 Hyalomma anatolicum excavatum, 174 Hyalomma dromedarii, 2 Hyalomma impeltatum, 3 Hyalomma marginatum rufipes, 55 unidentified nymphal Hyalomma, 625 Rhipicephalus (Boophilus) annulatus, 49 Rhipicephalus sanguineus, and 17 Rhipicephalus turanicus. Ticks were collected predominantly (>80%) from buffalo, cattle, and camels, with smaller numbers from chicken and rabbit sheds, sheep, foxes, a domestic dog, a hedgehog, and a black rat. We detected Anaplasma marginale, Coxiella burnetii, Rickettsia aeschlimannii, and four novel genotypes similar to: "Anaplasma platys," Ehrlichia canis, Ehrlichia spp. reported from Asian ticks, and a Rickettsiales endosymbiont of Ixodes ricinus.

Animals↗
PubMed2006

Borrelia, Coxiella, and Rickettsia in Carios capensis (Acari: Argasidae) from a brown pelican (Pelecanus occidentalis) rookery in South Carolina, USA.

Argasid ticks are vectors of viral and bacterial agents of humans and animals. Carios capensis, a tick of seabirds, infests the nests of brown pelicans, Pelecanus occidentalis, and other ground nesting birds along the coast of South Carolina. This tick is associated with pelican nest abandonment and could pose a threat to humans visiting pelican rookeries if visitors are exposed to ticks harboring infectious agents. We collected ticks from a pelican rookery on Deveaux Bank, South Carolina and screened 64 individual ticks, six pools of larvae, and an egg mass for DNA from Bartonella, Borrelia, Coxiella, and Rickettsia by polymerase chain reaction amplification and sequencing. Ticks harbored DNA from "Borrelia lonestari", a novel Coxiella sp., and three species of Rickettsia, including Rickettsia felis and two undescribed Rickettsia spp. DNA from the Coxiella and two undescribed Rickettsia were detected in unfed larvae that emerged in the laboratory, which implies these agents are transmitted vertically by female ticks. We partially characterize the novel Coxiella by molecular means.

Animals↗
PubMed2006

Serologic evidence for Rickettsia typhi and an ehrlichial agent in Norway rats from Baltimore, Maryland, USA.

We screened serum from 90 Norway rats trapped in East Baltimore, Maryland, USA, from April to November 2005 for antibodies against Rickettsia typhi and Ehrlichia chaffeensis. Six rats had positive titers of > or = 1:64 against R. typhi and did not react with R. akari. In addition, four rats had cross-reactive antibodies with titers of > or = 1:64 against Ehrlichia chaffeensis. Sera from these rats also cross-reacted with Anaplasma phagocytophilum or Ehrlichia muris. Our data indicate that the agent of murine typhus and ehrlichial agents are circulating in the Norway rat population in Baltimore.

Animals↗
PubMed2006

Population survey of Egyptian arthropods for rickettsial agents.

Between June 2002 and July 2003, 987 fleas, representing four species, and 1019 ticks, representing one argasid and eight ixodid species, were collected from Egyptian animals. These arthropods were tested for rickettsial agents using polymerase chain reaction. DNAs from Anaplasma and Ehrlichia spp. were detected in 13 ticks. Previously undescribed Bartonella spp. were detected in 21 fleas. Coxiella burnetii was detected in two fleas and 20 ticks. Rickettsia typhi was detected in 27 fleas from 10 cities. Spotted fever group rickettsiae were detected in both fleas and ticks and included Rickettsia aeschlimanii and an unnamed Rickettsia sp.

Anaplasma↗
PubMed2006

Louse-borne bacterial pathogens in lice (Phthiraptera) of rodents and cattle from Egypt.

We collected 1,023 lice, representing 5 species, from rats and domestic cattle throughout 13 governorates in Egypt and tested these lice for Anaplasma marginale, Bartonella spp., Brucella spp., Borrelia recurrentis, Coxiella burnetii, Francisella tularensis, and Rickettsia spp. by PCR amplification and sequencing. Five different louse-borne bacterial agents were detected in lice from rodents or cattle, including "Bartonella rattimassiliensis", "B. phoceensis", and Bartonella sp. near Bartonella tribocorum, Coxiella burnetii, and Rickettsia typhi. More lice from governorates bordering the Mediterranean and Red Seas contained pathogens. Our data indicate that lice of urban and domestic animals harbor pathogenic or potentially pathogenic bacterial agents throughout Egypt.

Animals↗
PubMed2006

Surveillance of Egyptian fleas for agents of public health significance: Anaplasma, Bartonella, Coxiella, Ehrlichia, Rickettsia, and Yersinia pestis.

Serologic surveys in Egypt have documented human and animal exposure to vector-borne bacterial pathogens, but the presence and distribution of these agents in arthropods has not been determined. Between July 2002 and July 2003, fleas were collected from 221 mammals trapped in 17 cities throughout Egypt. A total of 987 fleas were collected, representing four species (Ctenocephalides felis, Echidnophaga gallinacea, Leptopsylla segnis, and Xenopsylla cheopis); 899 of these fleas were X. cheopis from rats (Rattus spp.). Fleas were tested for DNA from Anaplasma spp., Bartonella spp., Coxiella burnetii, Ehrlichia spp., Rickettsia spp., and Yersinia pestis. Rickettsia typhi, the agent of murine typhus, was detected in X. cheopis and L. segnis from rats from nine cities. A spotted-fever group Rickettsia sp. similar to "RF2125" was detected in E. gallinacea, and two unidentified spotted fever group Rickettsia were detected in two X. cheopis. Novel Bartonella genotypes were detected in X. cheopis and L. segnis from three cities. Coxiella burnetii was detected in two fleas. Anaplasma, Ehrlichia, and Y. pestis were not detected.

Animals↗
PubMed2005

Detection of Rickettsia, Borrelia, and Bartonella in Carios kelleyi (Acari: Argasidae).

Carios kelleyi (Colley & Kohls 1941), a tick associated with bats and bat habitats, has been reported to feed on humans, but there is little published data regarding the presence of vector-borne pathogens in these ticks. C. kelleyi nymphs and adults were collected from residential and community buildings in Jackson County, Iowa, and tested by polymerase chain reaction for Rickettsia, Borrelia, Bartonella, Coxiella, and Anaplasma. Rickettsia DNA was detected in 28 of 31 live ticks. Sequences of the 17-kDa and rOmpA genes suggest that this agent is a novel spotted fever group Rickettsia. Transstadial and transovarial transmission of this Rickettsia were demonstrated. The flagellin gene of a Borrelia, closely related to B. turicatae, was detected in one of 31 live ticks. The 16S-23S intergenic spacer region of Bartonella henselae also was detected in one of 31 live ticks. Coxiella or A. phagocytophilum DNA were not detected in these ticks.

Animals↗
PubMed2005

High-throughput molecular testing of ticks using a liquid-handling robot.

To meet the need for high-throughput sample testing, DNA extraction kits based on the 96-well plate format have been developed for use with blood and tissue samples. These methods have not been applied to DNA extractions from ticks. To meet this need, we developed a high-throughput method for DNA extraction and polymerase chain reaction (PCR) testing of tick samples. A liquid-handling robot was used to extract DNA in a 96-well binding column plate with vacuum manifold. The quantity, purity, and quality of DNA recovered from Ixodes scapularis Say, 1821 nymphs with this method were reproducible and comparable with existing manual DNA extraction techniques. The DNA yield from pools of five nymphal ticks averaged 0.432 +/- 0.04 microg (95% CI). The robot also prepared real-time PCR reactions in 96-well plates, directly from the extracted DNA. A modification of the existing P20 tool resulted in accurate pipetting of 1- to 2-microl volumes with a reproducibility of +/- 0.038 microl when dispensing 1.0 microl. By using this process, 96 samples can be extracted and tested while reducing human labor to approximately 30 min.

Animals↗
PubMed2005

Molecular and biological characterization of a novel Coxiella-like agent from Carios capensis.

The genus Coxiella is currently defined by a single monotypic species, Coxiella burnetii. Novel Coxiella spp. have been detected in ticks throughout the world. These bacteria have not been cultured or named, and their evolutionary relationships to C. burnetii are poorly known. A novel Coxiella-like agent was detected by PCR amplification and sequencing of DNA extracted from 64 pelican ticks, Carios capensis, from Devoux Bank, South Carolina, USA. PCR was used to amplify and characterize genes from the new bacterium. Sequences from some metabolic and housekeeping genes shared a 92-98% similarity to C. burnetii, but other genes such as the IS1111 transposon, com1, and 5S and 16S rRNA genes were not amplified by conventional PCR. Transovarial and transtadial transmission and environmental shedding of the agent were detected by PCR.

Animals↗
PubMed2004

Lack of susceptibility of guinea pigs and gerbils to experimental infection with Ehrlichia chaffeensis.

Guinea pigs and Mongolian gerbils were experimentally infected with Ehrlichia chaffeensis (St. Vincent strain, 10 passages in vitro). The infection was monitored by serial blood sampling for PCR and by xenodiagnosis with Amblyomma americanum larvae. Exposure to the pathogen was confirmed using serology. Neither guinea pigs nor gerbils were susceptible to infection with E. chaffeensis, and ticks fed upon these animals did not become infected with the pathogen.

Animals↗
PubMed2004

Evaluation of immunocompetent and immunocompromised mice (Mus musculus) for infection with Ehrlichia chaffeensis and transmission to Amblyomma americanum ticks.

Experiments on the natural history of Ehrlichia chaffeensis, the agent of human monocytic ehrlichiosis (HME), would be facilitated by the availability of a laboratory animal model for transmission to vector ticks. Five strains of mice were evaluated for their susceptibility to infection with E. chaffeensis and transmission competence: C57BL/6 mice, inducible nitric oxide synthase (iNOS) deficient mice, MHC I deficient (beta2m /) mice, MHC II deficient mice (Abb /), and B and T cell deficient (Rag1 /) mice. Mice were inoculated with a low passage isolate of E. chaffeensis, and infection and morbidity were monitored for 57 days. Three xenodiagnostic infestations with A. americanum nymphs were performed 1, 8, and 15 days following inoculation. C57BL/6 mice cleared the organism in less than 17 days, with no indication of morbidity, and mounted a rapid, strong antibody response. Transmission to feeding A. americanum nymphs was seen in 1/30 nymphs fed on C57BL/6 mice immediately after inoculation. In MHC I and iNOS deficient mice, pathogen DNA was detected up to 17 or 24 days, respectively, after inoculation. Persistent infection for the duration of the experiment (57 days) was observed in MHC II deficient mice. However, E. chaffeensis was not detected in ticks fed on iNOS, MHC I, or MHC II deficient mice. Susceptibility to infection was greatest in Rag1 knockout mice, with significant morbidity and mortality within 24 days after inoculation. E. chaffeensis DNA was detected in up to 55% of replete nymphs that fed on Rag1 mice. However, E. chaffeensis was not detected in molted adult ticks from the same cohorts.

Animals↗
PubMed2004

Susceptibility of mice (Mus musculus) to repeated infestation with Amblyomma americanum (Acari: Ixodidae) ticks.

Laboratory mice, Mus musculus (L.), BALB/c strain, were assessed for their ability to develop resistance to repeated infestation by Amblyomma americanum (L.) ticks. Mice were infested five consecutive times with A. americanum nymphs. No decrease in tick viability was seen after five infestations, suggesting that BALB/c mice do not develop immune-mediated resistance to A. americanum. In contrast, tick viability was significantly reduced in the second infestation of a New Zealand White rabbit, a laboratory animal known to develop resistance to A. americanum.

Animals↗
PubMed2003

Quantitative real-time PCR assay for detection of Ehrlichia chaffeensis.

A real-time PCR assay was developed for the detection of Ehrlichia chaffeensis. The assay is species specific and provides quantitative results in the range 10 to 10(10) gene copies. The assay is not inhibited by the presence of tick, human, or mouse DNA and is compatible with high sample throughput. The assay was compared with previously described assays for E. chaffeensis.

Animals↗