Publications by authors named "Christopher D Paddock"

Rocky Mountain spotted fever (RMSF) is a deadly tick-borne disease caused by the bacterium Rickettsia rickettsii. An ongoing epidemic of RMSF is affecting tribal communities in Arizona, with nearly 500 cases and 28 deaths since 2003. The San Carlos Apache Tribe has been consistently working to prevent RMSF using tick collars on dogs, pesticide treatments around homes, and increasing education for nearly a decade.

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Whipple's disease is rarely diagnosed in Latin America. We describe 2 patients with Tropheryma whipplei infection diagnosed in Mexico during 2019-2021. Diagnoses were confirmed by histopathology, electron microscopy, immunohistochemistry, and DNA amplification and sequencing analysis of the 16S rRNA gene.

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Tickborne infections are challenging to diagnose, particularly among solid organ transplant recipients. We report a US case of donor-derived ehrlichiosis from a living kidney donation that highlights how screening for living donors may miss tickborne infections. Clinicians should consider the epidemiology of the donor when screening donations and evaluating recipients for donor-derived infection.

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A Rocky Mountain spotted fever (RMSF) epidemic has spread through the state of Baja California, Mexico over the last decade and a half, beginning in Mexicali, and subsequently to Tijuana and to Ensenada by 2018. In October of 2022, we surveyed dogs and homes in randomly selected Áreas Geoestadisticas Básicas (AGEBs) with and without reported human cases. Brown dog ticks (Rhipicephalus sanguineus sensu lato) were found on 33.

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RMSF, a tickborne infection caused by Rickettsia rickettsii, produces severe and fatal disease in humans and dogs. Since the beginning of the 21st century, cases have risen dramatically, most notably in Mexico and Brazil, where outbreaks occur in urban centers including cities with populations of > 1,000,000 persons. Reported case fatality rates can exceed 50%.

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Mycoplasma (Class: Mollicutes) contamination in cell cultures is a universal concern for research laboratories. Some estimates report contamination in up to 35% of continuous cell lines. Various commercial antibiotic treatments can successfully decontaminate clean cell lines ; however, decontamination of bacterial cultures remains challenging.

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Pacific Coast tick fever is a recently described zoonotic disease in California caused by a spotted fever group rickettsia, Rickettsia rickettsii subsp. californica (formerly Rickettsia 364D) and transmitted by the Pacific Coast tick, Dermacentor occidentalis. Like many emerging vector-borne diseases, knowledge regarding the transmission cycle, contribution from potential amplifying hosts, and geographic distribution of R.

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  • * Between July 2023 and January 2024, California reported six RMSF cases linked to exposure in Tecate, Mexico, raising concerns as it was previously not identified as a high-risk area, and three of these cases were fatal.
  • * Effective detection of RMSF cases necessitated collaborative efforts among various public health agencies, highlighting the need for increased awareness among healthcare providers to enable quicker diagnoses and treatments on both sides of the U.S.-Mexico border.
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  • Amblyomma maculatum is a significant tick species in the southwestern U.S. and northern Mexico, known for transmitting Rickettsia parkeri, which causes spotted fever.
  • Monthly trapping and mist netting in Cochise County, Arizona revealed a total of 1949 ticks from various small mammals and birds, providing data on the tick's seasonal activity.
  • The research indicated a univoltine life cycle tied to the North American monsoon seasons, with cotton rats having the highest infestation rates, suggesting they are key hosts in grass-dominated environments.
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Rocky Mountain spotted fever (RMSF) is a severe tickborne disease that can reach epidemic proportions in communities with certain social and ecologic risk factors. In some areas, the case-fatality rate of brown dog tick-associated RMSF is up to 50%. Because of the spread of brown dog tick-associated RMSF in the southwestern United States and northern Mexico, the disease has the potential to emerge and become endemic in other communities that have large populations of free-roaming dogs, brown dog ticks, limited resources, and low provider awareness of the disease.

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The etiologic agent of Pacific Coast tick fever, a moderately severe tickborne illness that resembles Rocky Mountain spotted fever (RMSF), was first isolated in 1966 from specimens of Dermacentor occidentalis (the Pacific Coast tick) obtained in California. For several decades, this bacterium was identified ambiguously as the unclassified spotted fever group Rickettsia species 364-D, Rickettsia 364, or Rickettsia philipii. However, none of these epithets satisfied criteria of formal bacterial nomenclature.

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We document a case of Rickettsia parkeri rickettsiosis in a patient in Connecticut, USA, who became ill after a bite from a Gulf Coast tick (Amblyomma maculatum). We used PCR to amplify R. parkeri DNA from the detached tick.

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  • * A scientific symposium held from November 8-10, 2023, brought together experts from academia and health authorities to discuss RMSF challenges and potential solutions.
  • * The One Health approach is emphasized as a key strategy to enhance surveillance, diagnosis, and prevention efforts to combat RMSF effectively in Mexico.
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Hard ticks (Acari: Ixodidae) have been historically identified by morphological methods which require highly specialized expertise and more recently by DNA-based molecular assays that involve high costs. Although both approaches provide complementary data for tick identification, each method has limitations which restrict their use on large-scale settings such as regional or national tick surveillance programs. To overcome those obstacles, the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been introduced as a cost-efficient method for the identification of various organisms, as it balances performance, speed, and high data output.

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Article Synopsis
  • * Historically, RMSF has received less attention compared to other diseases, leading to inadequate resources and prevention efforts in endemic areas.
  • * Recognizing RMSF as a neglected tropical disease (NTD) could drive greater public policy interest, improve resource allocation, and enhance prevention efforts, ultimately reducing its impact on affected communities.
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Spotted fever rickettsiosis is rarely observed in solid organ transplant recipients, and all previously reported cases have been associated with tick bite months to years after transplantation. We describe a kidney transplant recipient in North Carolina, USA, who had a moderately severe Rickettsia parkeri infection develop during the immediate posttransplant period.

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Article Synopsis
  • The text discusses five children in Sonora, Mexico who developed Rocky Mountain spotted fever (RMSF) and showed symptoms resembling multisystem inflammatory syndrome.
  • It highlights the importance of recognizing RMSF as a possible diagnosis for patients displaying these symptoms, especially in areas where the disease is common.
  • The aim is to raise awareness among physicians to help prevent serious health issues and fatalities related to rickettsial diseases.
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Leishmaniasis is an important travel-related parasitic infection in the United States. Treatment regimens vary by Leishmania species and require an accurate diagnosis. The sensitivity and specificity of diagnostic methods depend on the type and condition of specimen analyzed.

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  • The brown dog tick, Rhipicephalus sanguineus s.l., is a significant carrier of Rickettsia rickettsii, which causes Rocky Mountain spotted fever, prompting public health measures to control tick infestations around homes and on pets.
  • Current control strategies primarily rely on acaricides, particularly synthetic pyrethroids, but many ticks have developed resistance to these chemicals, complicating prevention efforts.
  • Researchers used advanced sequencing techniques to study genetic variations associated with acaricide resistance in different lineages of the tick, finding a specific genetic mutation tied to resistance that was commonly found in tropical lineage ticks across various locations in the US.
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Article Synopsis
  • - Rocky Mountain spotted fever (RMSF) is a serious, tick-borne disease caused by Rickettsia rickettsii, affecting primarily impoverished communities in the southwestern U.S. and northern Mexico, with high fatality rates linked to poor diagnosis and treatment delays.
  • - The disease is exacerbated by free-roaming dogs and widespread brown dog tick populations, with the U.S. facing a 5%-7% fatality rate while Mexico often exceeds 30%.
  • - One Health professionals are working on prevention and management strategies, including public education, urgent treatment protocols, vaccine research, and new methods to control tick populations and improve management of dog populations.
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The Pacific Coast tick (Dermacentor occidentalis Marx, 1892) is a frequently encountered and commonly reported human-biting tick species that has been recorded from most of California and parts of southwestern Oregon, southcentral Washington, and northwestern Mexico. Although previous investigators have surveyed populations of D. occidentalis for the presence of Rickettsia species across several regions of California, populations of this tick have not been surveyed heretofore for rickettsiae from Baja California, Oregon, or Washington.

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  • The study examines the pathology and tissue involvement of the Monkeypox virus (MPXV) in severely ill or deceased patients, emphasizing its impact on immunocompromised individuals.
  • Researchers analyzed samples from 22 patients, finding extensive viral presence in tissues, including lesions in the digestive tract and lungs, along with various complications like necrosis and bronchopneumonia.
  • The findings highlight the prevalence of coinfections, the severe implications for treatment, and the need for improved biosafety protocols in medical settings dealing with mpox cases.
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Some of the most prevalent arthropod-borne pathogens impacting humans in the United States are transmitted by Ixodes ticks. However, little is known regarding the Rickettsia species that inhabit Ixodes scapularis in the United States. The aim of this study was to screen adult I.

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Article Synopsis
  • Researchers found the DNA of a bacteria similar to Anaplasma bovis in blood samples from 4 patients in the US suspected of having tickborne illnesses.
  • The new agent shows a molecular link to A. bovis-like bacteria found in Dermacentor variabilis ticks from various states.
  • This suggests a possible connection between these patients’ illnesses and ticks carrying this specific bacterium.
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