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Gregory A Dasch

Publications and source records attributed to Gregory A Dasch.

At least 19 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

Diagnosis and management of tickborne rickettsial diseases: Rocky Mountain spotted fever, ehrlichioses, and anaplasmosis--United States: a practical guide for physicians and other health-care and public health professionals.

Tickborne rickettsial diseases (TBRD) continue to cause severe illness and death in otherwise healthy adults and children, despite the availability of low cost, effective antimicrobial therapy. The greatest challenge to clinicians is the difficult diagnostic dilemma posed by these infections early in their clinical course, when antibiotic therapy is most effective. Early signs and symptoms of these illnesses are notoriously nonspecific or mimic benign viral illnesses, making diagnosis difficult. In October 2004, CDC's Viral and Rickettsial Zoonoses Branch, in consultation with 11 clinical and academic specialists of Rocky Mountain spotted fever, human granulocytotropic anaplasmosis, and human monocytotropic ehrlichiosis, developed guidelines to address the need for a consolidated source for the diagnosis and management of TBRD. The preparers focused on the practical aspects of epidemiology, clinical assessment, treatment, and laboratory diagnosis of TBRD. This report will assist clinicians and other health-care and public health professionals to 1) recognize epidemiologic features and clinical manifestations of TBRD, 2) develop a differential diagnosis that includes and ranks TBRD, 3) understand that the recommendations for doxycycline are the treatment of choice for both adults and children, 4) understand that early empiric antibiotic therapy can prevent severe morbidity and death, and 5) report suspect or confirmed cases of TBRD to local public health authorities to assist them with control measures and public health education efforts.

Anaplasmosis↗
PubMed2006

Rickettsial agents from parasitic dermanyssoidea (Acari: Mesostigmata).

Mites are often overlooked as vectors of pathogens, but have been shown to harbor and transmit rickettsial agents such as Rickettsia akari and Orientia tsutsugamushi. We screened DNA extracts from 27 mites representing 25 species of dermanyssoids for rickettsial agents such as Anaplasma, Bartonella, Rickettsia, and Wolbachia by PCR amplification and sequencing. DNA from Anaplasma spp., a novel Bartonella sp., Spiroplasma sp., Wolbachia sp., and an unclassified Rickettsiales were detected in mites. These could represent mite-borne bacterial agents, bacterial DNA from blood meals, or novel endosymbionts of mites.

Anaplasma↗
PubMed2006

Isolation and identification of Rickettsia massiliae from Rhipicephalus sanguineus ticks collected in Arizona.

Twenty Rhipicephalus sanguineus ticks collected in eastern Arizona were tested by PCR assay to establish their infection rate with spotted fever group rickettsiae. With a nested PCR assay which detects a fragment of the Rickettsia genus-specific 17-kDa antigen gene (htrA), five ticks (25%) were found to contain rickettsial DNA. One rickettsial isolate was obtained from these ticks by inoculating a suspension of a triturated tick into monolayers of Vero E6 monkey kidney cells and XTC-2 clawed toad cells, and its cell culture and genotypic characteristics were determined. Fragments of the 16S rRNA, GltA, rOmpA, rOmpB, and Sca4 genes had 100%, 100%, 99%, 99%, and 99%, respectively, nucleotide similarity to Rickettsia massiliae strain Bar29, previously isolated from R. sanguineus in Catalonia, Spain (L. Beati et al., J. Clin. Microbiol. 34:2688-2694, 1996). The new isolate, AZT80, does not elicit cytotoxic effects in Vero cells and causes a persistent infection in XTC-2 cells. The AZT80 strain is susceptible to doxycycline but resistant to rifampin and erythromycin. Whether R. massiliae AZT80 is pathogenic or infectious for dogs and humans or can cause seroconversion to spotted fever group antigens in the United States is unknown.

Animals↗
PubMed2006

Prevalence of bacterial agents in Ixodes persulcatus ticks from the Vologda Province of Russia.

The prevalence of rickettsiae, ehrlichiae, and the rickettsia-like endosymbiont called Montezuma relative to that of Borrelia was determined in questing Ixodes persulcatus (I. persulcatus) ticks collected in 2002-2003 from Vologda Province, Russia. Ehrlichia muris, Anaplasma phagocytophilum, Montezuma, and new spotted fever group rickettsiae were detected by polymerase chain reaction (PCR) for the first time in this area. The rickettsiae were all Candidatus Rickettsia tarasevichiae, the furthest west this organism has been detected. After Borrelia, Montezuma was the agent most frequently detected; it may be present throughout the distribution of I. persulcatus in Russia. Ehrlichiae and rickettsiae frequently share the same tick host with Borrelia burgdorferi sensu lato so cotransmission and mixed infections in vertebrate hosts, including humans, may occur.

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

Molecular typing of novel Rickettsia rickettsii isolates from Arizona.

Seven isolates of Rickettsia rickettsii were obtained from a skin biopsy, two whole-blood specimens, and from Rhipicephalus sanguineus ticks from eastern Arizona. Molecular typing of seven isolates of R. rickettsii and DNA samples from two other Rh. sanguineus ticks infected with R. rickettsii was conducted by PCR and DNA sequencing of rompA and 12 variable-number tandem repeat regions (VNTRs). All DNA specimens from Arizona were identical to each other and to reference human and Dermacentor andersoni isolates of R. rickettsii from Montana in their rOmpA gene sequences and 10 VNTRs. Two of the twelve VNTRs had differences in the number of repeat sequences in isolates from Arizona compared to those from Montana, thus conferring the novelty of the Rh. sanguineus-associated R. rickettsii.

Arizona↗
PubMed2006

A spotted fever group Rickettsia from an exotic tick species, Amblyomma exornatum (Acari: Ixodidae), in a reptile breeding facility in the United States.

Adults and nymphs of Amblyomma exornatum Koch (Acari: Ixodidae), an exotic African tick of monitor lizards, were collected from a Gray's monitor lizard, Varanus olivaceus Hallowell, that died in a reptile facility in Alabama. Nine adult ticks were tested by polymerase chain reaction for rickettsial agents. DNA from a novel spotted fever group Rickettsia was amplified and sequenced from one of the nine ticks. The novel Rickettsia was most similar to "Rickettsia anan," which is associated with Amblyomma from Asia. The detection of a spotted fever group Rickettsia in exotic ticks emphasizes the potential threat posed by the importation and propagation of exotic animals in the United States.

Animals↗
PubMed2006

Prevalence of Ehrlichia, Borrelia, and Rickettsial agents in Amblyomma americanum (Acari: Ixodidae) collected from nine states.

Ambyomma americanum (L.) (Acari: Ixodidae) is an aggressive tick that feeds on humans during all postembryonic life stages. In many regions of the United States, it is the tick most commonly found attached to humans. Public health interest has grown recently, due to the recognition of new human pathogens transmitted by A. americanum and the expanding distribution of the tick. A. americanum is a vector of several bacteria pathogenic to humans. Ehrlichia chaffeensis and Ehrlichia ewingii cause moderate-to-severe febrile illness. "Rickettsia amblyommii," a member of the spotted fever group Rickettsia, also has recently been implicated as a possible human pathogen based on serologic evidence from persons recovering from illness after a tick bite. We have determined the prevalence of infection of Ehrlichia chaffeensis, E. ewingii, "Borrelia lonestari", and R. amblyommii within A. americanum ticks from 29 sites in nine states. Overall infection prevalences were 4.7% for E. chaffeensis (range, 0-27%), 3.5% for E. ewingii (range, 0-18.6%), 2.5% for B. lonestari (range, 0-12.2%), and 41.2% for R. amblyommii (range, 0-84.0%). In addition, 87 ticks (4.3%) were infected with two or more bacteria. This report documents new distribution records for E. ewingii, B. lonestari, and R. amblyommii and underscores the nonhomogeneous distribution of pathogen foci of infection. Additional surveillance throughout the range ofA. americanum is warranted to increase physician and public awareness of the risk of disease to humans from exposure to the agents transmitted by this tick.

Animals↗
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

Inferring the population structure and demographic history of the tick, Amblyomma americanum Linnaeus.

A hierarchial population genetic study was conducted on 703 individual Amblyomma americanum from nine populations in Georgia, U.S.A. Populations were sampled from the Coastal Plain, midland Piedmont region, and the upper Piedmont region. Twenty-nine distinct haplotypes were found. A minimum spanning tree was constructed that indicated these haplotypes comprised two lineages, the root of which was distinctly star-like. The majority of the variation found was among ticks within each population, indicating high amounts of gene flow and little genetic differentiation between the three regions. An overall F(ST) value of 0.006 supported the lack of genetic structuring between collection sites in Georgia. Mantel regression analysis revealed no isolation by distance. Signatures of population expansion were detected in the shapes of the mismatch distribution and tests of neutrality. The absence of genetic differentiation combined with the rejection of the null model of isolation by distance may indicate recent range expansion in Georgia or insufficient time to reach an equilibrium where genetic drift may have affected allele frequencies. Alternatively, the high degree of panmixia found within A. americanum in Georgia may be due to bird-mediated dispersal of ticks increasing the genetic similarity between geographically separated populations.

Animals↗
PubMed2006

Bartonella spp. in deer keds, Lipoptena mazamae (Diptera: Hippoboscidae), from Georgia and South Carolina, USA.

Deer keds, Lipoptena mazamae (Diptera: Hippoboscidae), were collected from white-tailed deer (Odocoileus virginianus) and humans in Georgia and South Carolina, USA (1 October 2001-6 January 2005) and screened for the presence of DNA from Bartonella spp. Forty deer keds were screened for Bartonella spp. by polymerase chain reaction using primers specific to the riboflavin synthase gene (ribC) of Bartonella. Bartonella species closely related to Bartonella schoenbuchensis and to the etiologic agent of cat-scratch disease (Bartonella henselae) were detected in 10 keds and one ked, respectively.

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↗
PubMed2006

Isolation of Rickettsia akari from eschars of patients with rickettsialpox.

Rickettsialpox is a cosmopolitan, mite-borne, spotted fever rickettsiosis caused by Rickettsia akari. The disease is characterized by a primary eschar, fever, and a papulovesicular rash. Rickettsialpox was first identified in New York City in 1946 and the preponderance of recognized cases in the United States continues to originate from this large metropolitan center. The most recently isolated U.S. strain of R. akari was obtained more than a half century ago. We describe the culture and initial characterization of five contemporaneous isolates of R. akari obtained from eschar biopsy specimens from New York City patients with rickettsialpox. This work emphasizes the importance and utility of culture-and molecular-based methods for the diagnosis of rickettsialpox and other eschar-associated illnesses.

Adult↗
PubMed2005

Rocky Mountain spotted fever from an unexpected tick vector in Arizona.

BACKGROUND: Rocky Mountain spotted fever is a life-threatening, tick-borne disease caused by Rickettsia rickettsii. This disease is rarely reported in Arizona, and the principal vectors, Dermacentor species ticks, are uncommon in the state. From 2002 through 2004, a focus of Rocky Mountain spotted fever was investigated in rural eastern Arizona. METHODS: We obtained blood and tissue specimens from patients with suspected Rocky Mountain spotted fever and ticks from patients' homesites. Serologic, molecular, immunohistochemical, and culture assays were performed to identify the causative agent. On the basis of specific laboratory criteria, patients were classified as having confirmed or probable Rocky Mountain spotted fever infection. RESULTS: A total of 16 patients with Rocky Mountain spotted fever infection (11 with confirmed and 5 with probable infection) were identified. Of these patients, 13 (81 percent) were children 12 years of age or younger, 15 (94 percent) were hospitalized, and 2 (12 percent) died. Dense populations of Rhipicephalus sanguineus ticks were found on dogs and in the yards of patients' homesites. All patients with confirmed Rocky Mountain spotted fever had contact with tick-infested dogs, and four had a reported history of tick bite preceding the illness. R. rickettsii DNA was detected in nonengorged R. sanguineus ticks collected at one home, and R. rickettsii isolates were cultured from these ticks. CONCLUSIONS: This investigation documents the presence of Rocky Mountain spotted fever in eastern Arizona, with common brown dog ticks (R. sanguineus) implicated as a vector of R. rickettsii. The broad distribution of this common tick raises concern about its potential to transmit R. rickettsii in other settings.

Adolescent↗