Publications by authors named "Backus L"

We conducted surveillance of mammals to investigate their associations with argasid ticks and tick-borne pathogens. During 2021, a total of 20 wild carnivores and 57 lagomorphs were sampled, and 39 argasid ticks belonging to two species were collected. All mammals and ticks were tested by molecular assays to detect Borrelia and Rickettsia infections.

View Article and Find Full Text PDF
Article Synopsis
  • Rocky Mountain spotted fever (RMSF) is a serious tick-borne disease that has become widespread in western North America, especially along the US-Mexico border.
  • The brown dog tick plays a crucial role in transmitting RMSF between dogs and humans, and the disease's spread now shows epidemic patterns rather than sporadic occurrences.
  • A new metapopulation model was developed to analyze RMSF dynamics, revealing that a significant delay occurs between pathogen introduction and epidemic transmission, with large dog populations being key to maintaining and spreading the disease.
View Article and Find Full Text PDF
Article Synopsis
  • 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.
View Article and Find Full Text PDF
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.
View Article and Find Full Text PDF
Article Synopsis
  • A two-decade epidemic of Rocky Mountain spotted fever (RMSF) in northern Mexico reached Tijuana in 2021, affecting marginalized areas with poor infrastructure.
  • Dogs, the primary hosts for the tick that carries RMSF, were found in 76% of homes, with a significant number of them roaming freely, contributing to the spread of ticks among neighbors.
  • The study revealed a high seroprevalence of rickettsial antibodies in dogs, indicating a risk to both canine and human populations, emphasizing the need for improved disease monitoring and management strategies.
View Article and Find Full Text PDF

Rocky Mountain spotted fever (RMSF), caused by the bacterium Rickettsia rickettsii, is a re-emerging tick-borne zoonosis in North America, with hundreds of human fatalities in multiple outbreaks in northern Mexico and the southwestern US in the past few decades. Free-roaming dogs are key because they are reservoirs for the pathogen and the main hosts of the brown dog tick (Rhipicephalus sanguineus), which vectors RMSF in this region. Because coyotes (Canis latrans) can be infected with R.

View Article and Find Full Text PDF

Lagomorphs-principally rabbits and hares-have been implicated as hosts for vectors and reservoirs for pathogens associated with multiple rickettsial diseases. Western North America is home to diverse rickettsial pathogens which circulate among multiple wild and domestic hosts and tick and flea vectors. The purpose of this study was to assess lagomorphs and their ectoparasites in 2 locations in northern Baja California, Mexico, for exposure to and infection with rickettsial organisms.

View Article and Find Full Text PDF

Objective: To assess exposure to and infection with 3 pathogens (Rickettsia rickettsii, Anaplasma platys, and Ehrlichia canis) vectored by brown dog ticks (Rhipicephalus sanguineus) in sheltered dogs at the western US-Mexico border.

Animals: 239 dogs in shelters in San Diego and Imperial counties, US, and Mexicali and Tijuana, Mexico.

Procedures: Each dog had blood drawn and basic demographic data collected.

View Article and Find Full Text PDF

Importance: To our knowledge, there have been no clinical trials of ultra-high-dose-rate radiotherapy delivered at more than 40 Gy/sec, known as FLASH therapy, nor first-in-human use of proton FLASH.

Objectives: To assess the clinical workflow feasibility and treatment-related toxic effects of FLASH and pain relief at the treatment sites.

Design, Setting, And Participants: In the FAST-01 nonrandomized trial, participants treated at Cincinnati Children's/UC Health Proton Therapy Center underwent palliative FLASH radiotherapy to extremity bone metastases.

View Article and Find Full Text PDF

Ixodes (Ixodes) mojavensis, n. sp. (Acari: Ixodidae), is described from all parasitic stages collected from the endangered vole Microtus californicus scirpensis Bailey, 1900 (Rodentia: Cricetidae), Mus musculus L.

View Article and Find Full Text PDF

Invasive tick species and the pathogens they transmit pose increasing threats to human and animal health around the world. Little attention has been paid to the characteristics enabling tick species to invade. Here we analyze examples of tick invasion events in North America to identify factors that facilitated the invasion.

View Article and Find Full Text PDF

Drivers of patterns of ectoparasitism in rodents in patchy Mojave Desert wetlands were investigated. A total of 1,571 ectoparasites in Mesostigmata, Trombidiformes, Siphonaptera and Ixodida were collected from 341 rodents (Microtus californicus scirpensis, Mus musculus, Reithrodontomys megalotis, Peromyscus eremicus, and Neotoma lepida) at eleven marshes. Trombiculids accounted for 82.

View Article and Find Full Text PDF

We examined tick communities on wild felid hosts in three ecoregions of Mexico. We collected 186 ticks of 7 species from 10 pumas (Puma concolor) and 9 jaguars (Panthera onca). Tick community composition varied across the ecoregions, and across host species within each region.

View Article and Find Full Text PDF

Achieving global elimination of hepatitis C virus requires a substantial scale-up of testing. Point-of-care HCV viral load assays are available as an alternative to laboratory-based assays to promote access in hard to reach or marginalized populations. The diagnostic performance and lower limit of detection are important attributes of these new assays for both diagnosis and test of cure.

View Article and Find Full Text PDF

Background: We examined whether key sociodemographic and clinical risk factors for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection and mortality changed over time in a population-based cohort study.

Methods And Findings: In a cohort of 9,127,673 persons enrolled in the United States Veterans Affairs (VA) healthcare system, we evaluated the independent associations of sociodemographic and clinical characteristics with SARS-CoV-2 infection (n = 216,046), SARS-CoV-2-related mortality (n = 10,230), and case fatality at monthly intervals between February 1, 2020 and March 31, 2021. VA enrollees had a mean age of 61 years (SD 17.

View Article and Find Full Text PDF

Importance: A strategy that prioritizes individuals for SARS-CoV-2 vaccination according to their risk of SARS-CoV-2-related mortality would help minimize deaths during vaccine rollout.

Objective: To develop a model that estimates the risk of SARS-CoV-2-related mortality among all enrollees of the US Department of Veterans Affairs (VA) health care system.

Design, Setting, And Participants: This prognostic study used data from 7 635 064 individuals enrolled in the VA health care system as of May 21, 2020, to develop and internally validate a logistic regression model (COVIDVax) that predicted SARS-CoV-2-related death (n = 2422) during the observation period (May 21 to November 2, 2020) using baseline characteristics known to be associated with SARS-CoV-2-related mortality, extracted from the VA electronic health records (EHRs).

View Article and Find Full Text PDF

Rhipicephalus sanguineus is a species complex of ticks that vector disease worldwide. Feeding primarily on dogs, members of the complex also feed incidentally on humans, potentially transmitting disease agents such as Rickettsia rickettsii, Rickettsia conorii, and Ehrlichia species. There are two genetic Rh.

View Article and Find Full Text PDF

Sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX) provides a needed hepatitis C virus (HCV) antiviral option for direct-acting antiviral (DAA)-experienced patients. We evaluated the effectiveness of SOF/VEL/VOX for 12 weeks in DAA-experienced patients with genotype 1-4 treated in clinical practice. In this observational cohort analysis from the Veterans Affairs' Clinical Case Registry, 573 DAA-experienced patients initiating SOF/VEL/VOX were included: 490 genotype 1, 20 genotype 2, 51 genotype 3 and 12 genotype 4.

View Article and Find Full Text PDF

Although West Nile virus (WNV) infects many avian species, the prevalence and impact of WNV in hummingbirds (Family Trochilidae) have not been described. We focused on hummingbird mortality and WNV infection using data from the state of California's Dead Bird Surveillance Program for the years 2005-17. The overall prevalence of WNV in tested carcasses was 10.

View Article and Find Full Text PDF

Background & Aim: Understanding the real-world effectiveness of all-oral hepatitis C virus (HCV) regimens informs treatment decisions. We evaluated the effectiveness of daclatasvir + sofosbuvir ± ribavirin (DCV + SOF ± RBV) and velpatasvir/sofosbuvir (VEL/SOF) ± RBV in patients with genotype 2 and genotype 3 infection treated in routine practice.

Methods: This observational analysis was carried out in an intent-to-treat cohort of patients with HCV genotype 2 and genotype 3.

View Article and Find Full Text PDF

In direct acting antiviral (DAA)-treated HCV genotype 1, the sustained virologic response rate with the ∆G/∆G genotype of IFNL4 rs368234815 (86.8%) was significantly lower than with ∆G/TT (95.9%, P = 0.

View Article and Find Full Text PDF

The Department of Veterans Affairs (VA) has made significant progress in treating hepatitis C virus, experiencing more than a 75% reduction in veterans remaining to be treated since the availability of oral direct-acting antivirals. Hepatitis C Innovation Teams use lean process improvement and system redesign, resulting in practice models that address gaps in care. The key to success is creative improvements in veteran access to providers, including expanded use of nonphysician providers, video telehealth, and electronic technologies.

View Article and Find Full Text PDF

Introduction: It is important to monitor the use of optometric services by Veterans and consider the implications for other optometric and vision rehabilitation services. We did not find public health reports documenting the recent utilization of Veterans Health Administration (VHA) optometric eye exam services.

Methods: A cross-sectional study design was used in this secondary data analysis report.

View Article and Find Full Text PDF