Search Our Scientific Publications & Authors

mSphere 2021 May 5;6(3). Epub 2021 May 5.

Department of Microbiology and Immunology, School of Medicine, University of Maryland Baltimore, Maryland, USA.

Species of (: ) are obligate intracellular parasites of a wide range of eukaryotes, with recognized arthropod-borne human pathogens belonging to the transitional group (TRG), typhus group (TG), and spotted fever group (SFG) rickettsiae. Growing in the host cytosol, rickettsiae pilfer numerous metabolites to make a typical Gram-negative bacterial cell envelope. The O-antigen of rickettsial lipopolysaccharide (LPS) is immunogenic and has been shown to tether the S-layer to the rickettsial surface; however, little is known about the structure and immunogenicity of the lipid A moiety. Read More

S Afr Med J 2021 Mar 31;111(4):307-308. Epub 2021 Mar 31.

Department of Medicine, Faculty of Health Sciences, University of Cape Town, South Africa.

Acute disseminated encephalomyelitis (ADEM) is an immune-mediated acute inflammatory demyelinating disorder, which typically occurs after viral infections or immunisation. We present a case of a man with acute Rickettsia conorii infection whose diagnosis was delayed. He presented with fever, headache, an eschar and an acute paraplegia. Read More

Rev Bras Parasitol Vet 2021 2;30(1):e026220. Epub 2021 Apr 2.

Laboratório de Doenças Parasitárias, Universidade Federal do Vale do São Francisco - UNIVASF, Petrolina, PE, Brasil.

Brazilian spotted fever (BSF) is a common tick-borne disease caused by Rickettsia rickettsii. Horses are the primary hosts of the main vector, Amblyomma sculptum, and are considered efficient sentinels for circulation of Rickettsia. Therefore, the aim of this study was to detect antibodies reactive to R. Read More

Insects 2021 Mar 5;12(3). Epub 2021 Mar 5.

Biodiversity Institute, University of Kansas, Lawrence, KS 66045, USA.

Ticks rank high among arthropod vectors in terms of numbers of infectious agents that they transmit to humans, including Lyme disease, Rocky Mountain spotted fever, Colorado tick fever, human monocytic ehrlichiosis, tularemia, and human granulocytic anaplasmosis. Increasing temperature is suspected to affect tick biting rates and pathogen developmental rates, thereby potentially increasing risk for disease incidence. Tick distributions respond to climate change, but how their geographic ranges will shift in future decades and how those shifts may translate into changes in disease incidence remain unclear. Read More

Emerg Infect Dis 2021 Apr;27(4):1245-1247

We report new cases of Rocky Mountain spotted fever in patients from Kinkantu, Ngäbe-Bugle indigenous comarca, Panama. We isolated Rickettsia rickettsii in cell culture after intraperitoneal inoculation of guinea pigs with tissues from a deceased patient. Our results indicate that Rocky Mountain spotted fever is emerging in this region. Read More

Vector Borne Zoonotic Dis 2021 May 17;21(5):385-387. Epub 2021 Mar 17.

Biology Department, University of Central Oklahoma, Edmond, Oklahoma, USA.

For the past 30 years, the number of people infected with causative agents of ehrlichiosis, Rocky Mountain spotted fever, and spotted fever group rickettiosis (SFGR) has increased in Oklahoma. However, there is a lack of data on pathogen prevalence within urban environments. To assess the prevalence of tick-borne pathogens in different environments, 434 (lone star) ticks were collected from the environment in two parks in Edmond, Oklahoma. Read More

Parasite Immunol 2021 May 15;43(5):e12830. Epub 2021 Apr 15.

Center for Molecular and Cellular Biosciences, School of Biological. Environmental, and Earth Sciences, University of Southern Mississippi, Hattiesburg, MS, USA.

Ticks are haematophagous arthropods with unique molecular mechanisms for digesting host blood meal while acting as vectors for various pathogens of public health significance. The tick's pharmacologically active saliva plays a fundamental role in modulating the host's immune system for several days to weeks, depending on the tick species. The vector tick has also developed sophisticated molecular mechanisms to serve as a competent vector for pathogens, including the spotted fever group (SFG) rickettsiae. Read More

Pathogens 2021 Feb 19;10(2). Epub 2021 Feb 19.

Vector Borne Disease Laboratories, Department of Pathobiological Sciences, LSU School of Veterinary Medicine, Baton Rouge, LA 70803, USA.

are significant sources of tick-borne diseases in humans worldwide. In North America, two species in the spotted fever group of have been conclusively associated with disease of humans: , the causative agent of Rocky Mountain spotted fever, and , the cause of rickettsiosis. Previous work in our lab demonstrated non-endothelial parasitism by another pathogenic SFG species, , within THP-1-derived macrophages, and we have hypothesized that this growth characteristic may be an underappreciated aspect of rickettsial pathogenesis in mammalian hosts. Read More

Transbound Emerg Dis 2021 Mar 5. Epub 2021 Mar 5.

Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, USA.

Over one hundred cases of human rickettsiosis, many fatal, are reported annually across the US-Mexico transboundary region, representing a likely undercount. Although cases are often attributed to Rickettsia rickettsii, the agent of Rocky Mountain spotted fever, multiple other Rickettsia pathogens are present in North America. We conducted multiple-host surveillance of domestic, synanthropic, and sylvatic mammals and their ectoparasites to investigate the ecology of Rickettsia species in this region. Read More

MSMR 2021 Feb;28(2):11-15

This report summarizes data from electronic reports of reportable medical events (RMEs) to examine the incidence of vector-borne infectious diseases among members of the U.S. Armed Forces during a recent 5-year period. Read More

J Med Entomol 2021 Feb 22. Epub 2021 Feb 22.

Department of Veterinary Pathobiology, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK.

Throughout North America, Dermacentor spp. ticks are often found feeding on animals and humans, and are known to transmit pathogens, including the Rocky Mountain spotted fever agent. To better define the identity and distribution of Dermacentor spp. Read More

Vector Borne Zoonotic Dis 2021 Apr 17;21(4):232-241. Epub 2021 Feb 17.

Division of Vector Borne Diseases, Rickettsial Zoonoses Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.

Members of the genus range from nonpathogenic endosymbionts to virulent pathogens such as , the causative agent of Rocky Mountain spotted fever. Many rickettsiae are considered nonpathogenic because they have been isolated from ticks but not vertebrate hosts. We assessed the ability of three presumed endosymbionts: , , and , to infect a guinea pig animal model. Read More

Infect Immun 2021 Mar 17;89(4). Epub 2021 Mar 17.

Rickettsial Zoonoses Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.

, the etiological agent of Rocky Mountain spotted fever (RMSF), a life-threatening tick-borne disease that affects humans and various animal species, has been recognized in medicine and science for more than 100 years. Isolate-dependent differences in virulence of have been documented for many decades; nonetheless, the specific genetic and phenotypic factors responsible for these differences have not been characterized. Using and methods, we identified multiple phenotypic differences among six geographically distinct isolates of , representing isolates from the United States, Costa Rica, and Brazil. Read More

Cutis 2020 Nov;106(5):233-235

Department of Dermatology and Dermatologic Surgery, Medical University of South Carolina, Charleston, USA.

The human flea, Pulex irritans, is an important vector in the transmission of human diseases. This flea has been identified as a vector for the bubonic plague as far back as the 14th century, causing millions of deaths. Pulex irritans also has been identified as a vector for Bartonella bacteria species, which can cause trench fever. Read More

Pediatr Infect Dis J 2020 12;39(12):1080

J Med Entomol 2020 Dec 4. Epub 2020 Dec 4.

Quantitative Disease Ecology and Conservation (QDEC) Lab Group, Department of Geography, University of Florida, Gainesville, FL.

The American dog tick, Dermacentor variabilis (Say) (Acari: Ixodidae), is a vector for several human disease-causing pathogens such as tularemia, Rocky Mountain spotted fever, and the understudied spotted fever group rickettsiae (SFGR) infection caused by Rickettsia montanensis. It is important for public health planning and intervention to understand the distribution of this tick and pathogen encounter risk. Risk is often described in terms of vector distribution, but greatest risk may be concentrated where more vectors are positive for a given pathogen. Read More

Parasit Vectors 2020 Dec 1;13(1):603. Epub 2020 Dec 1.

Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.

Background: Rickettsia rickettsii is a tick-borne obligate intracellular bacterium that causes Rocky Mountain spotted fever, a life-threatening illness. To obtain an insight into the vector-pathogen interactions, we assessed the effects of infection with R. rickettsii on the proteome cells of the tick embryonic cell line BME26. Read More

Rev Bras Parasitol Vet 2020 23;29(4):e015420. Epub 2020 Nov 23.

Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo - USP, São Paulo, SP, Brasil.

The aim of this study was to investigate rickettsial infection in equids, opossums and ticks in the municipality of Monte Mor, a place where a Brazilian spotted fever case occurred in 2005. In addition, characteristics possibly associated with seropositivity in horses were analyzed. Serum samples from horses, mules and opossums (Didelphis albiventris) were subjected to indirect immunofluorescence assay (IFA) against Rickettsia rickettsii. Read More

Am J Trop Med Hyg 2021 01;104(1):184-189

4Department of Medicine and Health Sciences, University of Sonora, Hermosillo, Mexico.

Rocky Mountain spotted fever (RMSF) is a serious disease in northwest Mexico, particularly in low-income communities. This study aimed to evaluate RMSF-related knowledge, attitudes, and practices in an endemic urban area with a high burden of the disease. A cross-sectional study design using a non-probabilistic household survey was conducted with 400 residents in Hermosillo, Mexico. Read More

J Vector Ecol 2020 12;45(2):321-332

Biology Department, Gonzaga University, Spokane, WA, 99258.

Due to climate change-induced alterations of temperature and humidity, the distribution of pathogen-carrying organisms such as ticks may shift. Tick survival is often limited by environmental factors such as dryness, but a predicted hotter and wetter world may allow the expansion of tick ranges. Dermacentor andersoni and D. Read More

Bol Med Hosp Infant Mex 2020 ;77(6):341-342

Departamento de Patología, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City. Mexico.

Health Secur 2021 Jan-Feb;19(1):108-115. Epub 2020 Nov 6.

Oghenekaro Omodior, PhD, is an Assistant Professor, School of Public Health, Indiana University, Bloomington, IN.

The purpose of this study was to identify age group, gender, rural-urban differences, and spatiotemporal clusters of tickborne disease diagnoses in Indiana. We analyzed retrospective surveillance data for Lyme disease, ehrlichiosis, Rocky Mountain spotted fever, typhus/rickettsial diseases, and tularemia diagnosed in Indiana from 2009 to 2016. We used chi-square cross tabulation to test gender, age group, and county classification (rural, rural-mixed, urban) differences in tickborne disease. Read More

Am J Trop Med Hyg 2021 01;104(1):190-197

2Rickettsial Zoonoses Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.

Rocky Mountain spotted fever (RMSF), caused by , is a severe and potentially fatal tick-borne disease. In 2015, Mexico issued a declaration of epidemiologic emergency in response to ongoing outbreaks of RMSF in northern Mexico. Sonora state is one of the most heavily impacted states in Mexico, with historic case fatality rates (CFRs) of 18%. Read More

Rev Bras Parasitol Vet 2020 21;29(4):e014220. Epub 2020 Oct 21.

Pós-graduação em Medicina Veterinária, Clínica e Reprodução Animal, Faculdade de Veterinária, Universidade Federal Fluminense - UFF, Niterói, RJ, Brasil.

Spotted fever group rickettsioses are emerging diseases. In some of these diseases, domestic dogs act as sentinels. Canine serological studies have demonstrated that rickettsial dispersion is concentrated in rural areas, seroprevalence being higher where human rickettsioses are endemic. Read More

Ticks Tick Borne Dis 2020 11 7;11(6):101538. Epub 2020 Aug 7.

Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA. Electronic address:

The guinea pig (Cavia porcellus) has an established track record as an animal model, with its utility in rickettsial research documented as early as the turn of the 20 century. From identifying Rickettsia rickettsii as the agent of Rocky Mountain spotted fever and ticks as the natural transmission route to evaluating protective immunity and treatment for tick-borne rickettsiae, guinea pigs have been essential for advances in our understanding of spotted fever rickettsioses (SFR). Tick feeding on guinea pigs is feasible and results in transmission of tick-borne rickettsiae. Read More

MSMR 2020 Sep;27(9):17-23

Spotted fever rickettsioses (SFR) are emerging in the Atlantic and Central regions of the U.S., though cases have been reported across the contiguous U. Read More

Vnitr Lek 2020 ;66(4):232-235

While investigating patients with gastrointestinal (GI) and/or hepatic symptoms, tickborne diseases are only rarely considered to be the cause. However, the Czech Republic is an endemic region for several of tickborne diseases and, therefore, they should be a part of differential diagnosis of GI symptoms of unknown origin. This article describes GI and hepatic symptoms of several tickborne diseases - Lyme disease, ehrlichiosis, Rocky mountain spotted fever, tularemia, Colorado tick fever, tickborne relapsing fever, Q fever and babesiosis. Read More

Pathogens 2020 Sep 10;9(9). Epub 2020 Sep 10.

Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA.

Rocky Mountain spotted fever (RMSF) is a life-threatening tick-borne disease caused by , which is widely distributed throughout the Americas. Over 4000 cases of RMSF are recorded annually in the United States, while only around 100 cases are reported in Brazil. Conversely, while case fatality rates in the United States oscillate around 5%, in Brazil they can surpass 70%, suggesting that differences in tick vectoring capacity, population sensitivity, and/or variability in virulence of the rickettsial strains may exist. Read More

PLoS One 2020 20;15(8):e0229277. Epub 2020 Aug 20.

Departamento de Ciências da Natureza, Matemática e Educação, Laboratório de Fauna, Universidade Federal de São Carlos, Araras, São Paulo, Brasil.

Human activities are changing landscape structure and function globally, affecting wildlife space use, and ultimately increasing human-wildlife conflicts and zoonotic disease spread. Capybaras (Hydrochoerus hydrochaeris) are linked to conflicts in human-modified landscapes (e.g. Read More