42 research outputs found
Observations on questing activity of adult Gulf Coast ticks, Amblyomma maculatum
Abstract During August of 2008 and 2009, observations were made on the questing heights, behaviors, and spatial distribution of adult Gulf Coast ticks, Amblyomma maculatum, in a plot near Gautier, Jackson County, Mississippi, U.S.A. Ticks were not evenly distributed in the plot, being found mostly on torpedograss and/or wiregrass along and in a small dirt field road. Adult ticks were visually observed questing on three different plants: torpedograss, Panicum repens, wiregrass, Aristida stricta, and Johnsongrass, Sorghum halepense, all but the last of which have small-diameter stems and thin, pointed leaves. Ticks were located at or near the tips of the plants (2-tail binomial probability, p = 0.0074). Observed questing heights ranged from 20-75 cm, with an average of 36 cm. Nine of 15 ticks (60%) seen questing were oriented head upward, while 6 (40%) were headdown. Limited mark-release-recapture observations were made in the study site, using ticks collected from the field road. Of 27 ticks marked and released, 15 were recaptured in three samples spanning a 24-d period. Of these, 5 had moved closer to the dirt road where they were originally captured and 2 farther away
Rickettsia parkeri Rickettsiosis, Argentina
Rickettsia parkeri, a recently identified cause of spotted fever rickettsiosis in the United States, has been found in Amblyomma
triste ticks in several countries of South America, including Argentina, where it is believed to cause disease in humans. We describe the clinical and epidemiologic characteristics of 2 patients in Argentina with confirmed R. parkeri infection and 7 additional patients with suspected R. parkeri rickettsiosis identified at 1 hospital during 2004–2009. The frequency and character of clinical signs and symptoms among these 9 patients closely resembled those described for patients in the United States (presence of an inoculation eschar, maculopapular rash often associated with pustules or vesicles, infrequent gastrointestinal manifestations, and relatively benign clinical course). Many R. parkeri infections in South America are likely to be misdiagnosed as other infectious diseases, including Rocky Mountain spotted fever, dengue, or leptospirosis
Multistate Survey of American Dog Ticks \u3ci\u3e(Dermacentor variabilis)\u3c/i\u3e for \u3ci\u3eRickettsia\u3c/i\u3e Species
Dermacentor variabilis, a common human-biting tick found throughout the eastern half and along the west coast of the United States, is a vector of multiple bacterial pathogens. Historically, D. variabilis has been considered a primary vector of Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever. A total of 883 adult D. variabilis, collected between 2012 and 2017 from various locations in 12 states across the United States, were screened for rickettsial DNA. Tick extracts were evaluated using three real-time PCR assays; an R. rickettsii-specific assay, a Rickettsia bellii-specific assay, and a Rickettsia genus-specific assay. Sequencing of ompA gene amplicons generated using a seminested PCR assay was used to determine the rickettsial species present in positive samples not already identified by species-specific real-time assays. A total of 87 (9.9%) tick extracts contained R. bellii DNA and 203 (23%) contained DNA of other rickettsial species, including 47 (5.3%) with Rickettsia montanensis, 11 (1.2%) with Rickettsia amblyommatis, 2 (0.2%) with Rickettsia rhipicephali, and 3 (0.3%) with Rickettsia parkeri. Only 1 (0.1%) tick extract contained DNA of R. rickettsii. These data support multiple other contemporary studies that indicate infrequent detection of R. rickettsii in D. variabilis in North America
Quantitative Factors Proposed to Influence the Prevalence of Canine Tick-Borne Disease Agents in the United States
The Companion Animal Parasite Council hosted a meeting to identify quantifiable factors that can influence the prevalence of tick-borne disease agents among dogs in North America. This report summarizes the approach used and the factors identified for further analysis with mathematical models of canine exposure to tick-borne pathogens
Aspidoderidae from North America, with the Description of a New Species of \u3ci\u3eAspidodera\u3c/i\u3e (Nematoda: Heterakoidea)
Aspidodera sogandaresi n. sp. (Heterakoidea: Aspidoderidae) from Dasypus novemcinctus Linnaeus, 1758 is herein described. This nematode occurs in armadillos from as far south as the canal zone of Panama, north through central Mexico, and into the southern United States. Previously identified as Aspidodera fasciata (Schneider, 1866), this new species has blunt projections on the lips and lateral expansions at the distal tips of the spicules, whereas A. fasciata has conspicuous digitiform projections on the lips, and a terminal round expansion at the tips of the spicules. Other species of the family present in North America include Aspidodera binansata Railliet and Henry, 1913; Aspidodera vazi Proenc¸a, 1937; and Lauroia trinidadensis Cameron, 1939
Rickettsia parkeri in Amblyomma maculatum Ticks, North Carolina, USA, 2009–2010
We detected Rickettsia parkeri in 20%−33% of Amblyomma maculatum ticks sampled in North Carolina. Results highlight the high frequencies of R. parkeri–infected ticks in the state with the highest annual incidence of Rocky Mountain spotted fever. Epidemiologic studies are needed to definitively link R. parkeri to cases of spotted fever rickettsiosis
Multiplex TaqMan® Quantitative PCR Assays for Host-Tick-Pathogen Studies Using the Guinea Pig-Tick-Rickettsia System
Spotted Fever Rickettsiosis (SFR) is caused by spotted fever group Rickettsia spp. (SFGR), and is associated with symptoms common to other illnesses, making it challenging to diagnose before detecting SFGR-specific antibodies. The guinea pig is a valuable biomedical model for studying Spotted Fever Rickettsiosis (SFR); its immune system is more like the human immune system than that of the murine model, and guinea pigs develop characteristic clinical signs. Thus, we have a compelling interest in developing, expanding, and optimizing tools for use in our guinea pig-Amblyomma-Rickettsia system for understanding host-tick-pathogen interactions. With the design and optimization of the three multiplex TaqMan® qPCR assays described here, we can detect the two SFGR, their respective primary Amblyomma sp. vectors, and the guinea pig model as part of controlled experimental studies using tick-transmission of SFGR to guinea pigs. We developed qPCR assays that reliably detect each specific target down to 10 copies by producing plasmid standards for each assay target, optimizing the individual primer-probe sets, and optimizing the final multiplex reactions in a methodical, stepwise fashion. We anticipate that these assays, currently designed for in vivo studies, will serve as a foundation for optimal SFGR detection in other systems, including fieldwork