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Gual-Gonzalez L, Self SCW, Meyer M, Cantillo-Barraza O, Torres ME, Nolan MS. Human spotted fever group Rickettsia seroprevalence and associated epidemiologic factors among diverse, marginalized populations in South Carolina. Ticks Tick Borne Dis 2024; 15:102288. [PMID: 38071922 DOI: 10.1016/j.ttbdis.2023.102288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 11/21/2023] [Accepted: 11/27/2023] [Indexed: 02/12/2024]
Abstract
Illness caused by spotted fever group Rickettsia (SFGR) is increasing nationally, with affluent, white residents most likely to be diagnosed. The common under-representativeness of marginalized populations in research studies and these vulnerable populations' health inequities make veritable epidemiologic risk factor profiling challenging, which inhibits equitable public health intervention. The current study leveraged 749 banked sera and associated surveys from a cross-sectional minority-represented COVID-19 study to perform an SFGR seroprevalence investigation. SFGR titers (1:64, 1:128, 1:256, 1:512, and 1:1024) were measured using commercially available indirect fluorescent antibody slides-SFGR positive cases were defined as titers ≥1:128. Multivariable logistic regression and Getis-Ord-Gi* hotspot analyses were used to identify seropositivity-associated factors and determine seropositive clusters. Among a mostly minority and lower socioeconomic population, a 3.4 % SFGR seropositivity was noted at the ≥1:128 titer level. Male gender (Odds Ratio (OR): 3.20; adjusted Odds Ratio (aOR)s: 3.73), age (aOR: 1.05), any frequency of tick bite (OR: 2.29), and spending time working outdoors (OR: 5.05) were associated with SFGR IgG seropositivity. Moreover, the geospatial analysis showed clusters of seropositivity in areas where previous case reports occurred, suggesting potential endemic foci.
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Affiliation(s)
- Lídia Gual-Gonzalez
- Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, 915 Greene St, Room 327A, Columbia, SC 29201, USA
| | - Stella C W Self
- Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, 915 Greene St, Room 327A, Columbia, SC 29201, USA
| | - Madeleine Meyer
- Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, 915 Greene St, Room 327A, Columbia, SC 29201, USA; Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC 29201, USA
| | - Omar Cantillo-Barraza
- Grupo Biología y Control Enfermedades Infecciosas, Universidad de Antioquia, Medellín 050010, Colombia
| | - Myriam E Torres
- Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, 915 Greene St, Room 327A, Columbia, SC 29201, USA
| | - Melissa S Nolan
- Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, 915 Greene St, Room 327A, Columbia, SC 29201, USA.
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Sit B, Lamason RL. Pathogenic Rickettsia spp. as emerging models for bacterial biology. J Bacteriol 2024; 206:e0040423. [PMID: 38315013 PMCID: PMC10883807 DOI: 10.1128/jb.00404-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024] Open
Abstract
Our understanding of free-living bacterial models like Escherichia coli far outpaces that of obligate intracellular bacteria, which cannot be cultured axenically. All obligate intracellular bacteria are host-associated, and many cause serious human diseases. Their constant exposure to the distinct biochemical niche of the host has driven the evolution of numerous specialized bacteriological and genetic adaptations, as well as innovative molecular mechanisms of infection. Here, we review the history and use of pathogenic Rickettsia species, which cause an array of vector-borne vascular illnesses, as model systems to probe microbial biology. Although many challenges remain in our studies of these organisms, the rich pathogenic and biological diversity of Rickettsia spp. constitutes a unique backdrop to investigate how microbes survive and thrive in host and vector cells. We take a bacterial-focused perspective and highlight emerging insights that relate to new host-pathogen interactions, bacterial physiology, and evolution. The transformation of Rickettsia spp. from pathogens to models demonstrates how recalcitrant microbes may be leveraged in the lab to tap unmined bacterial diversity for new discoveries. Rickettsia spp. hold great promise as model systems not only to understand other obligate intracellular pathogens but also to discover new biology across and beyond bacteria.
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Affiliation(s)
- Brandon Sit
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Rebecca L. Lamason
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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Gual-Gonzalez L, Self SCW, Zellars K, Meyer M, Dye-Braumuller KC, Evans CL, Cantillo-Barraza O, Torres MW, Nolan MS. Eco-epidemiology of Rickettsia amblyommatis and Rickettsia parkeri in naturally infected ticks (Acari: Ixodida) from South Carolina. Parasit Vectors 2024; 17:33. [PMID: 38273414 PMCID: PMC10811935 DOI: 10.1186/s13071-023-06099-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Accepted: 12/14/2023] [Indexed: 01/27/2024] Open
Abstract
BACKGROUND Spotted fever group Rickettsia (SFGR) is the largest group of Rickettsia species of clinical and veterinary importance emerging worldwide. Historically, SFGR cases were linked to Rickettsia rickettsii, the causal agent of Rocky Mountain spotted fever; however, recently discovered species Rickettsia parkeri and Rickettsia amblyommatis have been shown to cause a wide range of clinical symptoms. The role of R. amblyommatis in SFGR eco-epidemiology and the possible public health implications remain unknown. METHODS This study evaluated statewide tick surveillance and land-use classification data to define the eco-epidemiological relationships between R. amblyommatis and R. parkeri among questing and feeding ticks collected across South Carolina between 2021 and 2022. Questing ticks from state parks and feeding ticks from animal shelters were evaluated for R. parkeri and R. amblyommatis using reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) on pooled samples. A Bayesian multivariable logistic regression model for pool testing data was used to assess associations between R. parkeri or R. amblyommatis infection and land-use classification variables among questing ticks. The Spearman correlation was used to evaluate the relationship between the two tested pathogens. RESULTS The infection prevalence for R. amblyommatis was 24.8% (23.4-26.3%) among questing ticks, and 39.5% (37.4-42.0%) among feeding ticks; conversely, for R. parkeri it was 19.0% (17.6-20.5%) among questing ticks and 22.4% (20.3-24.5%) among feeding ticks. A negative, refractory correlation was found between the species, with ticks significantly more likely to contain one or the other pathogen, but not both simultaneously. The Bayesian analysis revealed that R. amblyommatis infection was positively associated with deciduous, evergreen, and mixed forests, and negatively associated with hay and pasture fields, and emergent herbaceous wetlands. Rickettsia parkeri infection was positively associated with deciduous, mixed, and evergreen forests, herbaceous vegetation, cultivated cropland, woody wetlands, and emergent herbaceous wetlands, and negatively associated with hay and pasture fields. CONCLUSIONS This is the first study to evaluate the eco-epidemiological factors driving tick pathogenicity in South Carolina. The negative interactions between SFGR species suggest the possible inhibition between the two pathogens tested, which could have important public health implications. Moreover, land-use classification factors revealed environments associated with tick pathogenicity, highlighting the need for tick vector control in these areas.
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Affiliation(s)
- Lídia Gual-Gonzalez
- Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, SC, USA
| | - Stella C W Self
- Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, SC, USA
| | - Kia Zellars
- Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, SC, USA
| | - Madeleine Meyer
- Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, SC, USA
| | | | - Chris L Evans
- Vector-Borne Diseases Laboratory, South Carolina Department of Health and Environmental Control, South Carolina Public Health Laboratory, Columbia, SC, USA
| | - Omar Cantillo-Barraza
- Grupo de Biología y Control de Enfermedades Infecciosas, Universidad de Antioquia, Medellín, Colombia
| | - Myriam W Torres
- Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, SC, USA
| | - Melissa S Nolan
- Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, SC, USA.
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McCarthy ML, Wallace DI. Optimal control of a tick population with a view to control of Rocky Mountain Spotted Fever. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2023; 20:18916-18938. [PMID: 38052583 DOI: 10.3934/mbe.2023837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
In some regions of the Americas, domestic dogs are the host for the tick vector Rhipicephalus sanguineus, and spread the tick-borne pathogen Rickettsia rickettsii, which causes Rocky Mountain Spotted Fever (RMSF) in humans. Interventions are carried out against the vector via dog collars and acaricidal wall treatments. This paper investigates the optimal control of acaricidal wall treatments, using a prior model for populations and disease transmission developed for this particular vector, host, and pathogen. It is modified with a death term during questing stages reflecting the cost of control and level of coverage. In the presence of the control, the percentage of dogs and ticks infected with Ri. rickettsii decreases in a short period and remains suppressed for a longer period, including after treatment is discontinued. Risk of RMSF infection declines by 90% during this time. In the absence of re-application, infected tick and dog populations rebound, indicating the eventual need for repeated treatment.
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Affiliation(s)
- Maeve L McCarthy
- Department of Mathematics & Statistics, Murray State University, 203A Industry & Technology, Murray KY 42071, USA
| | - Dorothy I Wallace
- Department of Mathematics, Dartmouth College, 27 N. Main Street, 6188 Kemeny Hall, Hanover, NH 03755-3551, USA
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Marcek J, Foley J, Backus L, Suzan G, López-Pérez AM. POTENTIAL SHARED DISEASE RISK AMONG DOGS AND COYOTES (CANIS LATRANS) EXEMPLIFIED BY THE ECOLOGY OF RICKETTSIOSIS IN A ROCKY MOUNTAIN SPOTTED FEVER-EPIDEMIC REGION IN NORTHERN MEXICO. J Wildl Dis 2023; 59:722-733. [PMID: 37846906 DOI: 10.7589/jwd-d-22-00179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 03/31/2023] [Indexed: 10/18/2023]
Abstract
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. rickettsii and infested with Rh. sanguineus, we hypothesized that space sharing among dogs and coyotes could enhance disease risks. In summer 2021, we captured and sampled 11 coyotes at two sites in Baja California, Mexico, near population centers with human cases of RMSF, and fitted seven individuals with GPS logging collars. We also tested tissue samples, sera, and ectoparasites for DNA of R. rickettsii with PCR and used serology to detect antibodies to R. rickettsii. Finally, we deployed an array of cameras to document dog-coyote interactions. Mean home range size was 40.37 km2. Both GPS and camera data showed considerable home range overlap both between individual coyotes and between coyotes and dogs. Coyotes were active in areas where dogs occur including the domestic interface surrounding human settlements. Although none of our samples were positive for R. rickettsii on PCR, 72.7% (8/11) of the samples were seropositive with titers ≥64. Our data confirm shared space use and risk of shared parasites and disease between coyotes and dogs.
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Affiliation(s)
- Jacob Marcek
- University of California-Davis, School of Veterinary Medicine, Department of Medicine and Epidemiology, 1275 Med Science Dr., Davis, California 95616, USA
| | - Janet Foley
- University of California-Davis, School of Veterinary Medicine, Department of Medicine and Epidemiology, 1275 Med Science Dr., Davis, California 95616, USA
| | - Laura Backus
- University of California-Davis, School of Veterinary Medicine, Department of Medicine and Epidemiology, 1275 Med Science Dr., Davis, California 95616, USA
| | - Gerardo Suzan
- Laboratorio de Ecología de Enfermedades y Una Salud, Departamento de Etología, Fauna Silvestre y Animales de Laboratorio, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Ciudad Universitaria, Av. Universidad no. 3000, Coyoacán 04510 Ciudad de México, Mexico
| | - Andrés M López-Pérez
- University of California-Davis, School of Veterinary Medicine, Department of Medicine and Epidemiology, 1275 Med Science Dr., Davis, California 95616, USA
- Red de Biología y Conservación de Vertebrados, Instituto de Ecología, A.C., Carretera antigua a Coatepec 351, El Haya, Xalapa, Veracruz 91073, Mexico
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Sajib MI, Lamba P, Spitzer ED, Marcos LA. False-Positive Serology for Rocky Mountain Spotted Fever in Long Island, New York, during 2011-2021. Pathogens 2023; 12:pathogens12030503. [PMID: 36986426 PMCID: PMC10057202 DOI: 10.3390/pathogens12030503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 03/14/2023] [Accepted: 03/20/2023] [Indexed: 03/30/2023] Open
Abstract
Cases of rocky mountain spotted fever (RMSF) are increasingly reported every year in Long Island, New York. In clinical practice, an uncommonly high number of referrals with a positive RMSF IgG test result have been seen in our tick-borne disease clinic. The aim of this study is to describe the clinical-epidemiological characteristics and outcomes of hospitalized patients with positive serologies for RMSF in our academic center in Long Island, NY. We found that out of twenty-four patients with a positive serology for RMSF, only one case met the case definition per CDC criteria, two had suspected RMSF, and the other twenty-one did not have a clinical picture consistent with RMSF. A high number of false-positive RMSF serology may be due to other spotted fever rickettsioses in Long Island. Further studies are needed to investigate the presence of another Rickettsia spp. (such as Rickettsia amblyommatis) in this area that may affect humans.
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Affiliation(s)
- Monirul I Sajib
- Infectious Disease Division, Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA
| | - Pooja Lamba
- Infectious Disease Division, Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA
| | - Eric D Spitzer
- Department of Pathology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Luis A Marcos
- Infectious Disease Division, Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, NY 11794, USA
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Wang HH, Grant WE, Donaldson TG, Teel PD. Modeling Effects of Vertebrate Host Exclosures and Host-Targeted Acaricides on Lone Star Tick ( Amblyomma americanum, L.) Infestations. Pathogens 2022; 11:pathogens11121412. [PMID: 36558745 PMCID: PMC9784951 DOI: 10.3390/pathogens11121412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/18/2022] [Accepted: 11/23/2022] [Indexed: 11/27/2022] Open
Abstract
We used a spatially explicit model to simulate the potential effects of exclosures and acaricides targeted at medium-sized mammalian hosts on the local distribution and abundance of lone star ticks (Amblyomma americanum) within forestlands of the southeastern United States. Both exclosures and acaricides were successful in markedly reducing the densities of all off-host tick life stages inside the treatment areas. Densities dropped to almost zero immediately inside the edges of the exclosures, with noticeably depressed densities extending outward 30 to 60 m from the exclosures, and the simulated exclosures maintained their effectiveness as their sizes were decreased from 4.5 to 2.25 to 0.8 ha. Densities exhibited a smooth gradient across the edges of the acaricide-treated areas, with depressed densities extending ≈100 m outward from the edges, but with perceptible densities extending ≈60 m inward from the edges; thus, the simulated acaricide areas lost their effectiveness as size was decreased to slightly less than one-half the diameter of the activity range of the targeted host. Our simulation results indicated that off-host nymph densities responded to reductions of medium-sized host densities. These results suggest that targeting acaricides at medium-sized hosts may be an effective, and currently under-utilized, method for tick suppression.
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Affiliation(s)
- Hsiao-Hsuan Wang
- Ecological Systems Laboratory, Department of Ecology and Conservation Biology, Texas A&M University, College Station, TX 77843, USA
- Correspondence: ; Tel.: +1-979-845-5702
| | - William E. Grant
- Ecological Systems Laboratory, Department of Ecology and Conservation Biology, Texas A&M University, College Station, TX 77843, USA
| | - Taylor G. Donaldson
- Department of Entomology, Texas A&M AgriLife Research, College Station, TX 77843, USA
| | - Pete D. Teel
- Department of Entomology, Texas A&M AgriLife Research, College Station, TX 77843, USA
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Antibody Prevalence and Risk Factors Associated with Rickettsia spp. in a Pediatric Cohort: SFGR Remains Underdiagnosed and Underreported in El Salvador. Pathogens 2022; 11:pathogens11111241. [DOI: 10.3390/pathogens11111241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 10/24/2022] [Accepted: 10/26/2022] [Indexed: 11/16/2022] Open
Abstract
Spotted fever group rickettsioses (SFGR) are caused by a group of tick-borne pathogens that are increasing in incidence globally. These diseases are typically underreported and undiagnosed in low- and middle-income countries, and thus, have been classified as neglected bacterial pathogens. Countries with high poverty, low human development index score, and limited health infrastructure—like El Salvador in Central America—lack necessary surveillance for SFGR and other tick-borne pathogens. This paucity of baseline SFGR infection prevalence leaves vulnerable populations at risk of misdiagnosis. Further, tick-borne disease burdens in El Salvador are severely limited. To lay the foundation for tick-borne disease epidemiology in El Salvador, our team conducted two different enzyme-linked immunosorbent assays (ELISA) on banked human sera samples from a cohort of approximately 1000 pediatric participants from a high-risk vector-borne disease population. Eleven percent of all tested banked pediatric sera were positive for at least one ELISA assay at the time of enrollment: 10.7% were positive for only IgM antibodies (acute SFGR infection), and 2.5% were positive for IgG antibodies (a past SFGR infection). Older, male, children enrolled during the wet season, with a household history of infectious disease and higher maternal education level had higher odds of SFGR antibodies. Additionally, children from households with domestic poultry birds and previous knowledge of other vector-borne diseases had significantly reduced odds of SFGR antibodies. The large percentage of acute SFGR infections indicates that it continues to remain an underreported and undiagnosed issue in El Salvador and the Central American region. Much is still unknown regarding the complexity of the tick, animal host, and human host ecology transmission cycle of SFGR in El Salvador.
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