Last data update: May 28, 2024. (Total: 46864 publications since 2009)
Records 1-4 (of 4 Records) |
Query Trace: Durden T[original query] |
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Ticks and tick-borne microbes identified through passive and active surveillance in Alaska
Hahn MB , Hojgaard A , Disler G , George W , Droghini A , Schlaht R , Durden LA , Coburn S , Gerlach R , Eisen RJ . J Med Entomol 2023 60 (5) 1099-1107 Rapid environmental change in Alaska and other regions of the Arctic and sub-Arctic has raised concerns about increasing human exposure to ticks and the pathogens they carry. We tested a sample of ticks collected through a combination of passive and active surveillance from humans, domestic animals, and wildlife hosts in Alaska for a panel of the most common tick-borne pathogens in the contiguous United States to characterize the diversity of microbes present in this region. We tested 189 pooled tick samples collected in 2019-2020 for Borrelia spp., Anaplasma spp., Ehrlichia spp., and Babesia spp. using a multiplex PCR amplicon sequencing assay. We found established populations of Ixodes angustus Neumann (Acari: Ixodidae), Ixodes uriae White (Acari: Ixodidae), and Haemaphysalis leporispalustris Packard (Acari: Ixodidae) in Alaska, with I. angustus found on a variety of hosts including domestic companion animals (dogs and cats), small wild mammals, and humans. Ixodes angustus were active from April through October with peaks in adult and nymphal activity observed in summer months (mainly July). Although no known human pathogens were detected, Babesia microti-like parasites and candidatus Ehrlichia khabarensis were identified in ticks and small mammals. The only human pathogen detected (B. burgdorferi s.s.) was found in a tick associated with a dog that had recently traveled to New York, where Lyme disease is endemic. This study highlights the value of a combined passive and active tick surveillance system to detect introduced tick species and pathogens and to assess which tick species and microbes are locally established. |
Detection of Rickettsia asembonensis in Fleas (Siphonaptera: Pulicidae, Ceratophyllidae) Collected in Five Counties in Georgia, United States.
Eremeeva ME , Capps D , McBride CL , Williams-Newkirk AJ , Dasch GA , Salzer JS , Beati L , Durden LA . J Med Entomol 2020 57 (4) 1246-1253 We conducted a molecular survey of Rickettsia in fleas collected from opossums, road-killed and live-trapped in peridomestic and rural settings, state parks, and from pet cats and dogs in Georgia, United States during 1992-2014. The cat flea, Ctenocephalides felis (Bouche) was the predominant species collected from cats and among the archival specimens from opossums found in peridomestic settings. Polygenis gwyni (Fox) was more prevalent on opossums and a single cotton rat trapped in sylvatic settings. Trapped animals were infested infrequently with the squirrel flea, Orchopeas howardi (Baker) and C. felis. TaqMan assays targeting the BioB gene of Rickettsia felis and the OmpB gene of Rickettsia typhi were used to test 291 flea DNAs for Rickettsia. A subset of 53 C. felis collected from a cat in 2011 was tested in 18 pools which were all bioB TaqMan positive (34% minimum infection prevalence). Of 238 fleas tested individually, 140 (58.8%, 95% confidence interval [CI]: 52.5-64.9%) DNAs were bioB positive. Detection of bioB was more prevalent in individual C. felis (91%) compared to P. gwyni (13.4%). Twenty-one (7.2%) were ompB TaqMan positive, including 18 C. felis (9.5%) and 3 P. gwyni (3.2%). Most of these fleas were also positive with bioB TaqMan; however, sequencing of gltA amplicons detected only DNA of Rickettsia asembonensis. Furthermore, only the R. asembonensis genotype was identified based on NlaIV restriction analysis of a larger ompB fragment. These findings contribute to understanding the diversity of Rickettsia associated with fleas in Georgia and emphasize the need for development of more specific molecular tools for detection and field research on rickettsial pathogens. |
The Amblyomma maculatum Koch, 1844 (Acari: Ixodidae) group of ticks: phenotypic plasticity or incipient speciation?
Lado P , Nava S , Mendoza-Uribe L , Caceres AG , Delgado-de la Mora J , Licona-Enriquez JD , Delgado-de la Mora D , Labruna MB , Durden LA , Allerdice MEJ , Paddock CD , Szabo MPJ , Venzal JM , Guglielmone AA , Beati L . Parasit Vectors 2018 11 (1) 610 BACKGROUND: The goal of this study was to reassess the taxonomic status of A. maculatum, A. triste and A. tigrinum by phylogenetic analysis of five molecular markers [four mitochondrial: 12S rDNA, 16S rDNA, the control region (DL) and cytochrome c oxidase 1 (cox1), and one nuclear: ribosomal intergenic transcribed spacer 2 (ITS2)]. In addition, the phenotypic diversity of adult ticks identified as A. maculatum and A. triste from geographically distinct populations was thoroughly re-examined. RESULTS: Microscopic examination identified four putative morphotypes distinguishable by disjunct geographical ranges, but very scant fixed characters. Analysis of the separated mitochondrial datasets mostly resulted in conflicting tree topologies. Nuclear gene sequences were almost identical throughout the geographical ranges of the two species, suggesting a very recent, almost explosive radiation of the terminal operational taxonomic units. Analysis of concatenated molecular datasets was more informative and indicated that, although genetically very close to the A. maculatum - A. triste lineage, A. tigrinum was a monophyletic separate entity. Within the A. maculatum - A. triste cluster, three main clades were supported. The two morphotypes, corresponding to the western North American and eastern North American populations, consistently grouped in a single monophyletic clade with many shared mitochondrial sequences among ticks of the two areas. Ticks from the two remaining morphotypes, south-eastern South America and Peruvian, corresponded to two distinct clades. CONCLUSIONS: Given the paucity of morphological characters, the minimal genetic distance separating morphotypes, and more importantly the fact that two morphotypes are genetically indistinguishable, our data suggest that A. maculatum and A. triste should be synonymized and that morphological differences merely reflect very recent local adaptation to distinct environments in taxa that might be undergoing the first steps of speciation but have yet to complete lineage sorting. Nonetheless, future investigations using more sensitive nuclear markers and/or crossbreeding experiments might reveal the occurrence of very rapid speciation events in this group of taxa. Tentative node dating revealed that the A. tigrinum and A. maculatum - A. triste clades split about 2 Mya, while the A. maculatum - A.triste cluster radiated no earlier than 700,000 years ago. |
Estimated future HIV prevalence, incidence, and potential infections averted in the United States: a multiple scenario analysis
Hall HI , Green TA , Wolitski RJ , Holtgrave DR , Rhodes P , Lehman JS , Durden T , Fenton KA , Mermin JH . J Acquir Immune Defic Syndr 2010 55 (2) 271-6 OBJECTIVES: To estimate the potential future burden of HIV in the United States under different intervention scenarios. METHODS: We modeled future HIV incidence, prevalence, and infections averted using 2006 estimates of HIV incidence (55,400 new infections per year), prevalence (1,107,000 persons living with HIV), and transmission rate (5.0 per 100 persons living with HIV). We modeled 10-year trends for 3 base-case scenarios (steady incidence, steady transmission rate, declining transmission rate based on the 2000-2006 trend) and 2 intensified HIV intervention scenarios (50% reduction in transmission rate within 10 and 5 years). RESULTS: Base-case scenarios predicted HIV prevalence increases of 24%-38% in 10 years. Reducing the transmission rate by 50% within 10 years reduces incidence by 40%; prevalence increases 20% to an estimated 1,329,000 persons living with HIV. Halving the transmission rate within 5 years reduces incidence by 46%; prevalence increases 13%, to 1,247,000. Although in year 10 incidence is similar regardless of the intervention time frame, more infections are averted when halving the transmission rate within 5 years. CONCLUSIONS: HIV prevalence will likely increase creating additional demands for health care services. These analyses are instructive for setting HIV prevention goals for the nation and assessing potential cost savings of intensified HIV prevention efforts. |
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