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Christopher D Paddock - One of the best experts on this subject based on the ideXlab platform.
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established population of the Gulf Coast tick amblyomma maculatum acari ixodidae infected with rickettsia parkeri rickettsiales rickettsiaceae in connecticut
2021Co-Authors: Goudarz Molaei, Eliza A H Little, Noelle Khalil, Bryan N Ayres, William L Nicholson, Christopher D PaddockAbstract:We identified an established population of the Gulf Coast tick (Amblyomma maculatum Koch) infected with Rickettsia parkeri in Connecticut, representing the northernmost range limit of this medically relevant tick species. Our finding highlights the importance of tick surveillance and public health challenges posed by geographic expansion of tick vectors and their pathogens.
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VECTOR-BORNE DISEASES, SURVEILLANCE, PREVENTION The Evolving Medical and Veterinary Importance of the Gulf Coast tick (Acari: Ixodidae)
2016Co-Authors: Christopher D Paddock, Jerome Goddard, J. Med, Entomol DoiAbstract:ABSTRACT Amblyomma maculatum Koch (the Gulf Coast tick) is a three-host, ixodid tick that is dis-tributed throughout much of the southeastern and south-central United States, as well as several coun-tries throughout Central and South America. A considerable amount of scientific literature followed the original description of A. maculatum in 1844; nonetheless, the Gulf Coast tick was not recognized as a vector of any known pathogen of animals or humans for>150 years. It is now identified as the principal vector of Hepatozoon americanum, the agent responsible for American canine hepatozoonosis, and Rick-ettsia parkeri, the cause of an emerging, eschar-associated spotted fever group rickettsiosis identified throughout much of the Western Hemisphere. Coincident with these discoveries has been recognition that the geographical distribution of A. maculatum in the United States is far more extensive than de-scribed 70 yr ago, supporting the idea that range and abundance of certain tick species, particularly those with diverse host preferences, are not fixed in time or space, and may change over relatively short inter-vals. Renewed interest in the Gulf Coast tick reinforces the notion that the perceived importance of a particular tick species to human or animal health can be relatively fluid, and may shift dramatically with changes in the distribution and abundance of the arthropod, its vertebrate hosts, or the microbial agents that transit among these organisms
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the evolving medical and veterinary importance of the Gulf Coast tick acari ixodidae
2015Co-Authors: Christopher D Paddock, Jerome GoddardAbstract:Amblyomma maculatum Koch (the Gulf Coast tick) is a three-host, ixodid tick that is distributed throughout much of the southeastern and south-central United States, as well as several countries throughout Central and South America. A considerable amount of scientific literature followed the original description of A. maculatum in 1844; nonetheless, the Gulf Coast tick was not recognized as a vector of any known pathogen of animals or humans for >150 years. It is now identified as the principal vector of Hepatozoon americanum, the agent responsible for American canine hepatozoonosis, and Rickettsia parkeri, the cause of an emerging, eschar-associated spotted fever group rickettsiosis identified throughout much of the Western Hemisphere. Coincident with these discoveries has been recognition that the geographical distribution of A. maculatum in the United States is far more extensive than described 70 yr ago, supporting the idea that range and abundance of certain tick species, particularly those with diverse host preferences, are not fixed in time or space, and may change over relatively short intervals. Renewed interest in the Gulf Coast tick reinforces the notion that the perceived importance of a particular tick species to human or animal health can be relatively fluid, and may shift dramatically with changes in the distribution and abundance of the arthropod, its vertebrate hosts, or the microbial agents that transit among these organisms.
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rickettsia parkeri and candidatus rickettsia andeanae in Gulf Coast ticks mississippi usa
2012Co-Authors: Flavia A G Ferrari, Christopher D Paddock, Jerome Goddard, Andrea S VarelastokesAbstract:To the Editor: Rickettsia parkeri, a spotted fever group Rickettsia (SFGR) bacterium, is transmitted by Amblyomma maculatum, the Gulf Coast tick (1). The prevalence of R. parkeri in Gulf Coast ticks has been reported as <42% in the United States, which is higher than reported rates of R. rickettsii (the cause of Rocky Mountain spotted fever) in Dermacentor species ticks. Misdiagnosis among SFGR infections is not uncommon, and R. parkeri rickettsiosis can cause symptoms similar to those for mild Rocky Mountain spotted fever (1). We evaluated infection rates of R. parkeri and Candidatus Rickettsia andeanae, a recently identified but incompletely characterized SFGR, in Gulf Coast ticks in Mississippi, USA. During May–September 2008–2010, we collected adult Gulf Coast ticks from vegetation at 10 sites in Mississippi. We extracted genomic DNA from the ticks using the illustra tissue and cells genomicPrep Mini Spin Kit (GE Healthcare Life Sciences, Piscataway, NJ, USA). We tested amplifiable tick DNA by PCR of the tick mitochondrial 16S rRNA gene (2). We tested for molecular evidence of any SFGR species by nested PCR of rompA (rickettsial outer membrane protein A gene) (1). Samples positive for SFGR were subsequently tested by using species-specific rompA PCR for R. parkeri (3) and Candidatus R. andeanae (4). All PCRs included 1) a positive control of DNA from cultured R. parkeri– (Tate’s Hell strain) or Candidatus R. andeanae–infected Gulf Coast ticks and 2) a negative control of water (nontemplate). PCR products were purified by using Montage PCR Centrifugal Filter Devices (Millipore, Bedford, MA, USA) and sequenced by using Eurofins MWG Operon (Huntsville, AL, USA). We generated consensus sequences using ClustalW2 (http://www.ebi.ac.uk/Tools/msa/clustalw2/) alignment and identified the sequences using GenBank BLAST searches (www.ebi.ac.uk/Tools/clustalw2/). Proportions of ticks infected with SFGR, by region and year, were compared separately by using Fisher exact test followed by pairwise comparisons with a Bonferroni adjustment (PROC FREQ, SAS for Windows, V9.2; SAS Institute, Cary, NC, USA). For all analyses, p<0.05 was considered significant. An index of co-infection was calculated by using the formula IC = ([O – E]/N) × 100, in which IC is index of co-infection, O is number of co-infections, E is expected occurrence of co-infection caused by chance alone, and N is total number of ticks infected by either or both Rickettsia species. A χ2 test was used to determine statistical significance (5). A total of 707 adult Gulf Coast ticks were collected during the 3 years (350 in 2008, 194 in 2009, and 163 in 2010). Tick mitochondrial 16S rRNA gene was detected in 698 (98.7%), of which 128 (18.3%) were positive for SFGR DNA, comprising 106 (15.2%) positive only for R. parkeri, 10 (1.4%) positive only for Candidatus R. andeanae, and 12 (1.7%) co-infected with R. parkeri and Candidatus R. andeanae (Table). Positive test results from 22 ticks singly or co-infected with Candidatus R. andeanae were confirmed by sequencing. Table PCR results for adult Rickettsia parkeri– and Candidatus Rickettsia andeanae–infected Gulf Coast ticks (Amblyomma maculatum) collected from 10 sites in Mississippi, USA, 2008–2010* Most (94.6%) ticks were from northern (n = 260) and southern (n = 409) Mississippi (Technical Appendix Figure). No significant difference in the number of R. parkeri–infected ticks between northern and southern Mississippi was observed (p = 0.13) (Table). However, significantly more ticks were singly infected with Candidatus R. andeanae in southern sites than in northern sites (p = 0.03). The infection rate for co-infected ticks in southern sites was higher than that in northern sites (p = 0.06). Among the 3 collection years for northern and southern sites, only the prevalence of R. parkeri in singly infected ticks differed significantly (p = 0.01) (data not shown); the infection rate was significantly greater during 2010 than during 2009 (p = 0.003, α/3 = 0.02). The overall index of co-infection with R. parkeri and Candidatus R. andeanae was 6.5, statistically higher than expected by chance alone (Table) (p<0.0001). The overall prevalence of infection with SFGR species in Gulf Coast ticks sampled was 18.3%; 15.2% of ticks were singly infected with R. parkeri, and 1.7% were infected with R. parkeri and Candidatus R. andeanae. As reported, the frequency of R. parkeri in Gulf Coast ticks is generally high, ranging from ≈10% to 40% (3,4,6–8). We found approximately 1 R. parkeri-infected Gulf Coast tick for every 6 ticks tested, suggesting that infected Gulf Coast ticks are commonly encountered in Mississippi. Because Gulf Coast ticks are among the most common human-biting ticks in Mississippi (9), awareness of R. parkeri rickettsiosis should be increased in this state. We identified Candidatus R. andeanae in ≈3% of Gulf Coast ticks in Mississippi; this frequency is similar to those reported in other studies of Gulf Coast ticks in the southern United States (4,6). Our finding of co-infected Gulf Coast ticks is at a frequency significantly higher than expected from chance alone. The biologic role of co-infections of Gulf Coast ticks with R. parkeri and Candidatus R. andeanae remains to be determined. Technical Appendix: Distribution of Gulf Coast ticks and cases of rickettsiosis. Click here to view.(117K, pdf)
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high rates of rickettsia parkeri infection in Gulf Coast ticks amblyomma maculatum and identification of candidatus rickettsia andeanae from fairfax county virginia
2011Co-Authors: Christen Fornadel, Christopher D Paddock, Xing Zhang, Jorge R. Arias, Joshua Smith, Douglas E. NorrisAbstract:Abstract The Gulf Coast tick, Amblyomma maculatum, is a vector of Rickettsia parkeri, a recently identified human pathogen that causes a disease with clinical symptoms that resemble a mild form of Rocky Mountain spotted fever. Because the prevalence of R. parkeri infection in geographically distinct populations of A. maculatum is not fully understood, A. maculatum specimens collected as part of a tick and pathogen surveillance system in Fairfax County, Virginia, were screened to determine pathogen infection rates. Overall, R. parkeri was found in 41.4% of the A. maculatum that were screened. Additionally, the novel spotted fever group Rickettsia sp., tentatively named “Candidatus Rickettsia andeanae,” was observed for the first time in Virginia.
Jerome Goddard - One of the best experts on this subject based on the ideXlab platform.
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VECTOR-BORNE DISEASES, SURVEILLANCE, PREVENTION The Evolving Medical and Veterinary Importance of the Gulf Coast tick (Acari: Ixodidae)
2016Co-Authors: Christopher D Paddock, Jerome Goddard, J. Med, Entomol DoiAbstract:ABSTRACT Amblyomma maculatum Koch (the Gulf Coast tick) is a three-host, ixodid tick that is dis-tributed throughout much of the southeastern and south-central United States, as well as several coun-tries throughout Central and South America. A considerable amount of scientific literature followed the original description of A. maculatum in 1844; nonetheless, the Gulf Coast tick was not recognized as a vector of any known pathogen of animals or humans for>150 years. It is now identified as the principal vector of Hepatozoon americanum, the agent responsible for American canine hepatozoonosis, and Rick-ettsia parkeri, the cause of an emerging, eschar-associated spotted fever group rickettsiosis identified throughout much of the Western Hemisphere. Coincident with these discoveries has been recognition that the geographical distribution of A. maculatum in the United States is far more extensive than de-scribed 70 yr ago, supporting the idea that range and abundance of certain tick species, particularly those with diverse host preferences, are not fixed in time or space, and may change over relatively short inter-vals. Renewed interest in the Gulf Coast tick reinforces the notion that the perceived importance of a particular tick species to human or animal health can be relatively fluid, and may shift dramatically with changes in the distribution and abundance of the arthropod, its vertebrate hosts, or the microbial agents that transit among these organisms
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the evolving medical and veterinary importance of the Gulf Coast tick acari ixodidae
2015Co-Authors: Christopher D Paddock, Jerome GoddardAbstract:Amblyomma maculatum Koch (the Gulf Coast tick) is a three-host, ixodid tick that is distributed throughout much of the southeastern and south-central United States, as well as several countries throughout Central and South America. A considerable amount of scientific literature followed the original description of A. maculatum in 1844; nonetheless, the Gulf Coast tick was not recognized as a vector of any known pathogen of animals or humans for >150 years. It is now identified as the principal vector of Hepatozoon americanum, the agent responsible for American canine hepatozoonosis, and Rickettsia parkeri, the cause of an emerging, eschar-associated spotted fever group rickettsiosis identified throughout much of the Western Hemisphere. Coincident with these discoveries has been recognition that the geographical distribution of A. maculatum in the United States is far more extensive than described 70 yr ago, supporting the idea that range and abundance of certain tick species, particularly those with diverse host preferences, are not fixed in time or space, and may change over relatively short intervals. Renewed interest in the Gulf Coast tick reinforces the notion that the perceived importance of a particular tick species to human or animal health can be relatively fluid, and may shift dramatically with changes in the distribution and abundance of the arthropod, its vertebrate hosts, or the microbial agents that transit among these organisms.
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rickettsia parkeri and candidatus rickettsia andeanae in Gulf Coast ticks mississippi usa
2012Co-Authors: Flavia A G Ferrari, Christopher D Paddock, Jerome Goddard, Andrea S VarelastokesAbstract:To the Editor: Rickettsia parkeri, a spotted fever group Rickettsia (SFGR) bacterium, is transmitted by Amblyomma maculatum, the Gulf Coast tick (1). The prevalence of R. parkeri in Gulf Coast ticks has been reported as <42% in the United States, which is higher than reported rates of R. rickettsii (the cause of Rocky Mountain spotted fever) in Dermacentor species ticks. Misdiagnosis among SFGR infections is not uncommon, and R. parkeri rickettsiosis can cause symptoms similar to those for mild Rocky Mountain spotted fever (1). We evaluated infection rates of R. parkeri and Candidatus Rickettsia andeanae, a recently identified but incompletely characterized SFGR, in Gulf Coast ticks in Mississippi, USA. During May–September 2008–2010, we collected adult Gulf Coast ticks from vegetation at 10 sites in Mississippi. We extracted genomic DNA from the ticks using the illustra tissue and cells genomicPrep Mini Spin Kit (GE Healthcare Life Sciences, Piscataway, NJ, USA). We tested amplifiable tick DNA by PCR of the tick mitochondrial 16S rRNA gene (2). We tested for molecular evidence of any SFGR species by nested PCR of rompA (rickettsial outer membrane protein A gene) (1). Samples positive for SFGR were subsequently tested by using species-specific rompA PCR for R. parkeri (3) and Candidatus R. andeanae (4). All PCRs included 1) a positive control of DNA from cultured R. parkeri– (Tate’s Hell strain) or Candidatus R. andeanae–infected Gulf Coast ticks and 2) a negative control of water (nontemplate). PCR products were purified by using Montage PCR Centrifugal Filter Devices (Millipore, Bedford, MA, USA) and sequenced by using Eurofins MWG Operon (Huntsville, AL, USA). We generated consensus sequences using ClustalW2 (http://www.ebi.ac.uk/Tools/msa/clustalw2/) alignment and identified the sequences using GenBank BLAST searches (www.ebi.ac.uk/Tools/clustalw2/). Proportions of ticks infected with SFGR, by region and year, were compared separately by using Fisher exact test followed by pairwise comparisons with a Bonferroni adjustment (PROC FREQ, SAS for Windows, V9.2; SAS Institute, Cary, NC, USA). For all analyses, p<0.05 was considered significant. An index of co-infection was calculated by using the formula IC = ([O – E]/N) × 100, in which IC is index of co-infection, O is number of co-infections, E is expected occurrence of co-infection caused by chance alone, and N is total number of ticks infected by either or both Rickettsia species. A χ2 test was used to determine statistical significance (5). A total of 707 adult Gulf Coast ticks were collected during the 3 years (350 in 2008, 194 in 2009, and 163 in 2010). Tick mitochondrial 16S rRNA gene was detected in 698 (98.7%), of which 128 (18.3%) were positive for SFGR DNA, comprising 106 (15.2%) positive only for R. parkeri, 10 (1.4%) positive only for Candidatus R. andeanae, and 12 (1.7%) co-infected with R. parkeri and Candidatus R. andeanae (Table). Positive test results from 22 ticks singly or co-infected with Candidatus R. andeanae were confirmed by sequencing. Table PCR results for adult Rickettsia parkeri– and Candidatus Rickettsia andeanae–infected Gulf Coast ticks (Amblyomma maculatum) collected from 10 sites in Mississippi, USA, 2008–2010* Most (94.6%) ticks were from northern (n = 260) and southern (n = 409) Mississippi (Technical Appendix Figure). No significant difference in the number of R. parkeri–infected ticks between northern and southern Mississippi was observed (p = 0.13) (Table). However, significantly more ticks were singly infected with Candidatus R. andeanae in southern sites than in northern sites (p = 0.03). The infection rate for co-infected ticks in southern sites was higher than that in northern sites (p = 0.06). Among the 3 collection years for northern and southern sites, only the prevalence of R. parkeri in singly infected ticks differed significantly (p = 0.01) (data not shown); the infection rate was significantly greater during 2010 than during 2009 (p = 0.003, α/3 = 0.02). The overall index of co-infection with R. parkeri and Candidatus R. andeanae was 6.5, statistically higher than expected by chance alone (Table) (p<0.0001). The overall prevalence of infection with SFGR species in Gulf Coast ticks sampled was 18.3%; 15.2% of ticks were singly infected with R. parkeri, and 1.7% were infected with R. parkeri and Candidatus R. andeanae. As reported, the frequency of R. parkeri in Gulf Coast ticks is generally high, ranging from ≈10% to 40% (3,4,6–8). We found approximately 1 R. parkeri-infected Gulf Coast tick for every 6 ticks tested, suggesting that infected Gulf Coast ticks are commonly encountered in Mississippi. Because Gulf Coast ticks are among the most common human-biting ticks in Mississippi (9), awareness of R. parkeri rickettsiosis should be increased in this state. We identified Candidatus R. andeanae in ≈3% of Gulf Coast ticks in Mississippi; this frequency is similar to those reported in other studies of Gulf Coast ticks in the southern United States (4,6). Our finding of co-infected Gulf Coast ticks is at a frequency significantly higher than expected from chance alone. The biologic role of co-infections of Gulf Coast ticks with R. parkeri and Candidatus R. andeanae remains to be determined. Technical Appendix: Distribution of Gulf Coast ticks and cases of rickettsiosis. Click here to view.(117K, pdf)
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isolation of rickettsia parkeri and identification of a novel spotted fever group rickettsia sp from Gulf Coast ticks amblyomma maculatum in the united states
2010Co-Authors: Christopher D Paddock, Jerome Goddard, John W. Sumner, Amanda D. Loftis, Pierreedouard Fournier, Yasmin Elshenawy, Maureen G Metcalfe, Andrea S VarelastokesAbstract:Until recently, Amblyomma maculatum (the Gulf Coast tick) had garnered little attention compared to other species of human-biting ticks in the United States. A. maculatum is now recognized as the principal vector of Rickettsia parkeri, a pathogenic spotted fever group rickettsia (SFGR) that causes an eschar-associated illness in humans that resembles Rocky Mountain spotted fever. A novel SFGR, distinct from other recognized Rickettsia spp., has also been detected recently in A. maculatum specimens collected in several regions of the southeastern United States. In this study, 198 questing adult Gulf Coast ticks were collected at 4 locations in Florida and Mississippi; 28% of these ticks were infected with R. parkeri, and 2% of these were infected with a novel SFGR. Seventeen isolates of R. parkeri from individual specimens of A. maculatum were cultivated in Vero E6 cells; however, all attempts to isolate the novel SFGR were unsuccessful. Partial genetic characterization of the novel SFGR revealed identity with several recently described, incompletely characterized, and noncultivated SFGR, including “Candidatus Rickettsia andeanae” and Rickettsia sp. Argentina detected in several species of Neotropical ticks from Argentina and Peru. These findings suggest that each of these “novel” rickettsiae represent the same species. This study considerably expanded the number of low-passage, A. maculatum-derived isolates of R. parkeri and characterized a second, sympatric Rickettsia sp. found in Gulf Coast ticks.
Wayne L. Hynes - One of the best experts on this subject based on the ideXlab platform.
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Rickettsia parkeri in Gulf Coast Ticks, Southeastern
2016Co-Authors: Chelsea L. Wright, Allen L. Richards, Ju Jiang, Robyn M. Nadolny, Daniel E. Sonenshine, Holly D. Gaff, Wayne L. HynesAbstract:We report evidence that Amblyomma maculatum tick populations are well established in southeastern Virginia. We found that 43.1 % of the adult Gulf Coast ticks collected in the summer of 2010 carried Rickettsia parkeri, suggesting that persons living in or visiting southeastern Virginia are at risk for infection with this pathogen. Rickettsia parkeri is an obligate intracellular bacterium belonging to the spotted fever group of rickettsiae; this organism has recently been found to be pathogenic to humans (1). Infection with R. parkeri can be considered an emerging infectious disease, referred to as R. parkeri rickettsiosis, American Boutonneuse fever, and Tidewater spotted fever. Two confi rmed cases of R. parkeri infections, including the index case in 2002, occurred in southeastern Virginia (1–3). Since then, 20 R. parkeri infections have been reported, mainly from the southern United States (2). In the United States, Amblyomma maculatum (family Ixodidae) ticks, commonly referred to as Gulf Coast ticks, are the only known natural vector of R. parkeri. A. maculatum ticks have been reported fro
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Experimental vertical transmission of Rickettsia parkeri in the Gulf Coast tick, Amblyomma maculatum.
2015Co-Authors: Chelsea L. Wright, Daniel E. Sonenshine, Wayne L. HynesAbstract:Rickettsia parkeri, an obligate intracellular bacterium, is a member of the spotted fever group of rickettsiae (SFGR), and is transmitted to humans and other animals by invertebrate vectors. In the United States, the primary vector of R. parkeri is the Gulf Coast tick, Amblyomma maculatum Koch. This study investigates the vertical transmission dynamics of R. parkeri within a field-derived, naturally infected colony of A. maculatum. Transovarial and transstadial transmission of the pathogen was observed over three generations, with transovarial transmission efficiency averaging 83.7% and transstadial transmission rates approaching 100%. Fitness costs were determined by comparing reproduction values of the R. parkeri-infected A. maculatum colony to values from a R. parkeri-free colony. No significant reproductive fitness costs to the host ticks were detected in the R. parkeri-infected A. maculatum colony. Significantly fewer engorged F1 nymphs and F2 larvae of the R. parkeri-free colony succeeded in molting, suggesting that there may be some advantage to survival conferred by R. parkeri. The results of this study indicate that R. parkeri is maintained in A. maculatum populations efficiently by transovarial and transstadial transmission without any noticeable effects on tick reproduction or survival.
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Rickettsia parkeri in Gulf Coast ticks, southeastern Virginia, USA.
2011Co-Authors: Chelsea L. Wright, Allen L. Richards, Ju Jiang, Robyn M. Nadolny, Daniel E. Sonenshine, Holly D. Gaff, Wayne L. HynesAbstract:We report evidence that Amblyomma maculatum tick populations are well established in southeastern Virginia. We found that 43.1% of the adult Gulf Coast ticks collected in the summer of 2010 carried Rickettsia parkeri, suggesting that persons living in or visiting southeastern Virginia are at risk for infection with this pathogen.
Andrea S Varelastokes - One of the best experts on this subject based on the ideXlab platform.
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rickettsia parkeri and candidatus rickettsia andeanae in Gulf Coast ticks mississippi usa
2012Co-Authors: Flavia A G Ferrari, Christopher D Paddock, Jerome Goddard, Andrea S VarelastokesAbstract:To the Editor: Rickettsia parkeri, a spotted fever group Rickettsia (SFGR) bacterium, is transmitted by Amblyomma maculatum, the Gulf Coast tick (1). The prevalence of R. parkeri in Gulf Coast ticks has been reported as <42% in the United States, which is higher than reported rates of R. rickettsii (the cause of Rocky Mountain spotted fever) in Dermacentor species ticks. Misdiagnosis among SFGR infections is not uncommon, and R. parkeri rickettsiosis can cause symptoms similar to those for mild Rocky Mountain spotted fever (1). We evaluated infection rates of R. parkeri and Candidatus Rickettsia andeanae, a recently identified but incompletely characterized SFGR, in Gulf Coast ticks in Mississippi, USA. During May–September 2008–2010, we collected adult Gulf Coast ticks from vegetation at 10 sites in Mississippi. We extracted genomic DNA from the ticks using the illustra tissue and cells genomicPrep Mini Spin Kit (GE Healthcare Life Sciences, Piscataway, NJ, USA). We tested amplifiable tick DNA by PCR of the tick mitochondrial 16S rRNA gene (2). We tested for molecular evidence of any SFGR species by nested PCR of rompA (rickettsial outer membrane protein A gene) (1). Samples positive for SFGR were subsequently tested by using species-specific rompA PCR for R. parkeri (3) and Candidatus R. andeanae (4). All PCRs included 1) a positive control of DNA from cultured R. parkeri– (Tate’s Hell strain) or Candidatus R. andeanae–infected Gulf Coast ticks and 2) a negative control of water (nontemplate). PCR products were purified by using Montage PCR Centrifugal Filter Devices (Millipore, Bedford, MA, USA) and sequenced by using Eurofins MWG Operon (Huntsville, AL, USA). We generated consensus sequences using ClustalW2 (http://www.ebi.ac.uk/Tools/msa/clustalw2/) alignment and identified the sequences using GenBank BLAST searches (www.ebi.ac.uk/Tools/clustalw2/). Proportions of ticks infected with SFGR, by region and year, were compared separately by using Fisher exact test followed by pairwise comparisons with a Bonferroni adjustment (PROC FREQ, SAS for Windows, V9.2; SAS Institute, Cary, NC, USA). For all analyses, p<0.05 was considered significant. An index of co-infection was calculated by using the formula IC = ([O – E]/N) × 100, in which IC is index of co-infection, O is number of co-infections, E is expected occurrence of co-infection caused by chance alone, and N is total number of ticks infected by either or both Rickettsia species. A χ2 test was used to determine statistical significance (5). A total of 707 adult Gulf Coast ticks were collected during the 3 years (350 in 2008, 194 in 2009, and 163 in 2010). Tick mitochondrial 16S rRNA gene was detected in 698 (98.7%), of which 128 (18.3%) were positive for SFGR DNA, comprising 106 (15.2%) positive only for R. parkeri, 10 (1.4%) positive only for Candidatus R. andeanae, and 12 (1.7%) co-infected with R. parkeri and Candidatus R. andeanae (Table). Positive test results from 22 ticks singly or co-infected with Candidatus R. andeanae were confirmed by sequencing. Table PCR results for adult Rickettsia parkeri– and Candidatus Rickettsia andeanae–infected Gulf Coast ticks (Amblyomma maculatum) collected from 10 sites in Mississippi, USA, 2008–2010* Most (94.6%) ticks were from northern (n = 260) and southern (n = 409) Mississippi (Technical Appendix Figure). No significant difference in the number of R. parkeri–infected ticks between northern and southern Mississippi was observed (p = 0.13) (Table). However, significantly more ticks were singly infected with Candidatus R. andeanae in southern sites than in northern sites (p = 0.03). The infection rate for co-infected ticks in southern sites was higher than that in northern sites (p = 0.06). Among the 3 collection years for northern and southern sites, only the prevalence of R. parkeri in singly infected ticks differed significantly (p = 0.01) (data not shown); the infection rate was significantly greater during 2010 than during 2009 (p = 0.003, α/3 = 0.02). The overall index of co-infection with R. parkeri and Candidatus R. andeanae was 6.5, statistically higher than expected by chance alone (Table) (p<0.0001). The overall prevalence of infection with SFGR species in Gulf Coast ticks sampled was 18.3%; 15.2% of ticks were singly infected with R. parkeri, and 1.7% were infected with R. parkeri and Candidatus R. andeanae. As reported, the frequency of R. parkeri in Gulf Coast ticks is generally high, ranging from ≈10% to 40% (3,4,6–8). We found approximately 1 R. parkeri-infected Gulf Coast tick for every 6 ticks tested, suggesting that infected Gulf Coast ticks are commonly encountered in Mississippi. Because Gulf Coast ticks are among the most common human-biting ticks in Mississippi (9), awareness of R. parkeri rickettsiosis should be increased in this state. We identified Candidatus R. andeanae in ≈3% of Gulf Coast ticks in Mississippi; this frequency is similar to those reported in other studies of Gulf Coast ticks in the southern United States (4,6). Our finding of co-infected Gulf Coast ticks is at a frequency significantly higher than expected from chance alone. The biologic role of co-infections of Gulf Coast ticks with R. parkeri and Candidatus R. andeanae remains to be determined. Technical Appendix: Distribution of Gulf Coast ticks and cases of rickettsiosis. Click here to view.(117K, pdf)
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isolation of rickettsia parkeri and identification of a novel spotted fever group rickettsia sp from Gulf Coast ticks amblyomma maculatum in the united states
2010Co-Authors: Christopher D Paddock, Jerome Goddard, John W. Sumner, Amanda D. Loftis, Pierreedouard Fournier, Yasmin Elshenawy, Maureen G Metcalfe, Andrea S VarelastokesAbstract:Until recently, Amblyomma maculatum (the Gulf Coast tick) had garnered little attention compared to other species of human-biting ticks in the United States. A. maculatum is now recognized as the principal vector of Rickettsia parkeri, a pathogenic spotted fever group rickettsia (SFGR) that causes an eschar-associated illness in humans that resembles Rocky Mountain spotted fever. A novel SFGR, distinct from other recognized Rickettsia spp., has also been detected recently in A. maculatum specimens collected in several regions of the southeastern United States. In this study, 198 questing adult Gulf Coast ticks were collected at 4 locations in Florida and Mississippi; 28% of these ticks were infected with R. parkeri, and 2% of these were infected with a novel SFGR. Seventeen isolates of R. parkeri from individual specimens of A. maculatum were cultivated in Vero E6 cells; however, all attempts to isolate the novel SFGR were unsuccessful. Partial genetic characterization of the novel SFGR revealed identity with several recently described, incompletely characterized, and noncultivated SFGR, including “Candidatus Rickettsia andeanae” and Rickettsia sp. Argentina detected in several species of Neotropical ticks from Argentina and Peru. These findings suggest that each of these “novel” rickettsiae represent the same species. This study considerably expanded the number of low-passage, A. maculatum-derived isolates of R. parkeri and characterized a second, sympatric Rickettsia sp. found in Gulf Coast ticks.
O F Strey - One of the best experts on this subject based on the ideXlab platform.
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the Gulf Coast tick a review of the life history ecology distribution and emergence as an arthropod of medical and veterinary importance
2010Co-Authors: Pete D Teel, H R Ketchum, Donald E Mock, Russell E Wright, O F StreyAbstract:The Gulf Coast tick, Amblyomma maculatum Koch (Acari: Ixodidae), is a unique univoltine ectoparasite of seven vertebrate host classes in the Western Hemisphere that is increasingly recognized as a pest of livestock and wildlife, a vector of pathogens to humans and canines, and a putative vector of Ehrlichia ruminantium, the causal agent of heartwater, a fatal foreign animal disease of ruminants resident in the Caribbean. This review assembles current and historical literature encompassing the biology, ecology, and zoogeography of this tick and provides new assessments of changes in cyclical population distribution, habitat associations, host utilization, seasonal phenology, and life history. These assessments are pertinent to the emergence of A. maculatum as a vector of veterinary and medical importance, and its pest management on livestock and other animals.
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mating success of two geographically distinct populations of Gulf Coast ticks amblyomma maculatum koch
2006Co-Authors: H R Ketchum, Pete D Teel, O F Strey, M T LongneckerAbstract:Gulf Coast ticks collected from Refugio Co., TX and Osage Co., KS are reproductively compatible despite differences in genetic haplotypes, geographic separation and seasonal phenologies. Two heifers per mating combination (TX males x TX females, KS males x KS females, TX males x KS females, KS males x TX females) were each infested with 360 pairs of Gulf Coast ticks. Only mean pre-oviposition and mean egg conversion efficiency index for the Texas male-Kansas female mating were significantly different (p<0.05) from other mating treatments. These females began oviposition 1-day later and used 4% less body mass toward egg production when compared to site-specific matings. However, the overall trend in reproductive performance of reciprocal tick matings was slightly lower than that of site-specific matings. There appear to be no pre-zygotic barriers to mating among Gulf Coast ticks from these Texas and Kansas populations.
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feeding predilection of Gulf Coast tick amblyomma maculatum koch nymphs on cattle
2005Co-Authors: H R Ketchum, Pete D Teel, O F Strey, M T LongneckerAbstract:Gulf Coast tick nymphs successfully attached and fed on cattle after being freely released. Six Hereford heifers were each infested with approximately 2000 Gulf Coast tick nymphs, three with a strain originating from Refugio Co., TX, and three with ticks from Osage Co., KS by free release on the head and legs to simulate field acquisition of questing nymphs. Two re-infestations were conducted, the first at 7 days and the second at 28 days. Nymph dispersal was estimated by daily inspection of 22 body areas and removal of engorging ticks from the third to the fifth days post-infestation. Total recovery of engorging Texas nymphs was 3.0, 10.2, and 0% and Kansas nymphs was 21.5, 3.3, and 0% for infestations one, two and three, respectively. Immunological resistance to tick infestation expressed as cellular hypersensitivity was evident against Kansas nymphs in the second infestation and against both tick strains in the third infestation. Ticks removed from the withers, midline, and tail-head areas accounted for 68% of the total nymphs recovered in the first two infestations. Within these areas, nymphs were observed to aggregate in small spots where the hair was less dense or naturally parted and the remainder were found scattered in dense hair.
