Diagnosis and management of tickborne rickettsial diseases : Rocky Mountain spotted fever and other spotted fever group rickettsioses, ehrlichioses, and anaplasmosis \u2014 United States : a practical guide for health care and public health professionals

Tickborne rickettsial diseases continue to cause severe illness and death in otherwise healthy adults and children, despite the availability of low-cost, effective antibacterial therapy. Recognition early in the clinical course is critical because this is the period when antibacterial therapy is most effective. Early signs and symptoms of these illnesses are nonspecific or mimic other illnesses, which can make diagnosis challenging. Previously undescribed tickborne rickettsial diseases continue to be recognized, and since 2004, three additional agents have been described as causes of human disease in the United States: Rickettsia parkeri, Ehrlichia muris-like agent, and Rickettsia species 364D. This report updates the 2006 CDC recommendations on the diagnosis and management of tickborne rickettsial diseases in the United States and includes information on the practical aspects of epidemiology, clinical assessment, treatment, laboratory diagnosis, and prevention of tickborne rickettsial diseases. The CDC Rickettsial Zoonoses Branch, in consultation with external clinical and academic specialists and public health professionals, developed this report to assist health care providers and public health professionals to 1) recognize key epidemiologic features and clinical manifestations of tickborne rickettsial diseases, 2) recognize that doxycycline is the treatment of choice for suspected tickborne rickettsial diseases in adults and children, 3) understand that early empiric antibacterial therapy can prevent severe disease and death, 4) request the appropriate confirmatory diagnostic tests and understand their usefulness and limitations, and 5) report probable and confirmed cases of tickborne rickettsial diseases to public health authorities.Suggested citation for this article: Biggs HM, Behravesh CB, Bradley KK, et al. Diagnosis and Management of Tickborne Rickettsial Diseases: Rocky Mountain Spotted Fever and Other Spotted Fever Group Rickettsioses, Ehrlichioses, and Anaplasmosis \u2014 United States. MMWR Recomm Rep 2016;65(No. RR-2):1\u201344. DOI: http://dx.doi.org/10.15585/mmwr.rr6502a1.rr6502.pdfAppendix A. Selected tickborne rickettsioses outside of the United States -- Appendix B. Diagnostic assays for tickborne rickettsial diseases.Infectious DiseasePrevention and ControlCurrentKristen Nichols Heitman by email 5/16/20165/16/2016PMID: 271721132717211

Tick-borne rickettsial pathogens in naturally infected dogs and dog-associated ticks and their role as sentinels of zoonotic rickettsial diseases in Medellin, Colombia

ABSTRACT: Tick-borne rickettsial pathogens (TBRP) are important causes of infections in both dogs and humans. Dogs play an important role as a biological host for several tick species and can serve as sentinels for rickettsial infections. Our aim was to determine the presence of TBRP in dogs and in dog-associated ticks and their potential risk to human diseases in Medellin, Colombia. DNA for E. canis (16S rRNA and dsb) and A. platys (groEl) was detected in 17.6% (53/300) and 2.6% (8/300) of dogs, respectively. Antibodies against Ehrlichia spp. 82 (27.3%) and Anaplasma spp. 8 (2.6%) were detected in dogs. Antibody reactivity against both agents were found in 16 dogs (5.3%). Eight dogs showed antibody for Rickettsia spp. with titers that suggest 3 of them had a probable exposure to R. parkeri. Rhipicephalus sanguineus s.l. (178/193) was the main tick in dogs, followed by R. microplus (15/193). The minimum infection rates (MIR) in R. sanguineus were 11.8% for E. canis and 3.4% for A. platys. Our results indicate that E. canis and A. platys are the main TBRP infecting dogs and ticks in Medellin, Colombia. Interestingly, we found serological evidence of exposure in dogs for spotted fever group rickettsiae.RESUMEN: Los patógenos rickettsiales transmitidos por garrapatas (TBRP) son causas importantes de infecciones tanto en perros como en humanos. Los perros juegan un papel importante como hospedadores biológicos de varias especies de garrapatas y pueden servir como centinelas para las infecciones por rickettsias. Nuestro objetivo fue determinar la presencia de TBRP en perros y garrapatas asociadas a perros y su riesgo potencial de enfermedades humanas en Medellín, Colombia. Se detectó ADN para E. canis (ARNr 16S y dsb) y A. platys (groEl) en el 17,6% (53/300) y el 2,6% (8/300) de los perros, respectivamente. Anticuerpos contra Ehrlichia spp. 82 (27,3%) y Anaplasma spp. 8 (2,6%) se detectaron en perros. Se encontró reactividad de anticuerpos contra ambos agentes en 16 perros (5,3%). Ocho perros mostraron anticuerpos contra Rickettsia spp. con títulos que sugieren que 3 de ellos tuvieron una probable exposición a R. parkeri. Rhipicephalus sanguineus s.l. (178/193) fue la principal garrapata en perros, seguida por R. microplus (15/193). Las tasas mínimas de infección (MIR) en R. sanguineus fueron 11,8% para E. canis y 3,4% para A. platys. Nuestros resultados indican que E. canis y A. platys son las principales TBRP que infectan a perros y garrapatas en Medellín, Colombia. Curiosamente, encontramos evidencia serológica de exposición en perros a las rickettsias del grupo de fiebre manchada

Rickettsiosis

Las rickettsiosis son consideradas enfermedades desatendidas, poco reconocidas o confundidas con otras patologías en las áreas tropicales y subtropicales. En Colombia, a pesar de tener identificadas zonas endémicas de rickettsiosis son pocos los estudios realizados sobre la enfermedad y son escasos los trabajos de vigilancia en salud pública. Actualmente se están realizando esfuerzos para entender los mecanismos moleculares patogénicos de las diferentes especies de rickettsia, sin embargo, grandes avances deben realizarse para comprender mejor la epidemiologia y desarrollar métodos de diagnóstico rápidos, sensibles y reproducibles para aquellas zonas donde estas zoonosis aparecen de forma impredecible

Epidemiological characterization of incident cases of Rickettsia infection in rural areas of Urabá region, Colombia

Introduction Most of the studies related to rickettsial infection in Colombia are cross-sectional because of the challenge in conducting prospective studies on infectious disease that may have a difficult diagnosis. Although cross-sectional studies are essential to detect people exposed to rickettsiae, they are not suited to demonstrate the recent circulation of this pathogen in areas at risk of transmission. Objective To characterize the epidemiology of incident cases of Spotted fever group (SFG) rickettsial infection in humans and equines from rural areas of Uraba´ region in Colombia where outbreaks of rickettsiae previously occurred. Materials and methods A prospective study was conducted in the Alto de Mulatos and Las Changas in the Uraba´ region. Serum samples and socio-ecological information were collected from 597 people enrolled in 2015, and a second sample was collected from 273 people a year later. Indirect immune-fluorescence assays for detection of IgG antibody against rickettsiae were done using slides with Rickettsia rickettsii antigens. A titer 128 was considered positive. Incident cases were defined as (i) serological conversion of IgG titers from seronegative to seropositive or (ii) at least a four-fold increase in IgG end point titers in the second sample. Results The cumulative incidence of rickettsial infection was 6.23% (95%CI 3.67–9.78) in humans and 32.31% (21/65) of incident cases in equines. Incident cases were mostly females (82.35%), the median age of cases was 41.02 years (IQR 18.62–54.1), and 29.41% reported tick bites during the study period. Results from multivariate analysis showed that removal of ticks after working outdoors is a protective factor for rickettsial infection (RR 0.26, 95%CI 0.08–0.84) and that a higher incidence of infection occurred in people who reported fever in the last year (RR 4.26, 95%CI 1.15–9.31). Conclusions These results showed recent circulation of SFG rickettsiae in areas where previous lethal outbreaks have been reported, supporting the implementation of preventive measures to halt rickettsial transmission in the studied communities.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Centro de Investigación en Enfermedades Tropicales (CIET

Rickettsia felis, Transmission Mechanisms of an Emerging Flea-borne Rickettsiosis

Rickettsia felis is an emerging insect-borne rickettsial pathogen and the causative agent of flea-borne spotted fever. First described as a human pathogen from the United States in 1991, R. felis is now identified throughout the world and considered a common cause of fever in Africa. The cosmopolitan distribution of this pathogen is credited to the equally widespread occurrence of cat fleas (Ctenocephalides felis), the primary vector and reservoir of R. felis. Additionally, R. felis has been identified in other hematophagous arthropods (including numerous species of fleas, ticks, mosquitoes, and mites). Most transmission cycles of pathogenic Rickettsia include transovarial and transstadial passages in their arthropod hosts as well as transmission to new vectors through the infectious blood of vertebrate amplifying hosts. The continuous molecular detection of R. felis from other blood-feeding vectors supports the notion of infectious transmission cycles; however, naturally infected mammalian blood or tissues have never been shown to be a source of R. felis infection from vertebrate to arthropod host. Here we demonstrate that horizontal transmission of R. felis occurs independent of a rickettsemic vertebrate host. The combination of intraspecific and interspecific cofeeding transmission of R. felis on a vertebrate host, sustained transmission of R. felis between cofeeding cat fleas in an artificial host system, and support by modeling demonstrated cofeeding as an important mechanism of pathogen maintenance and transmission within flea populations. Additionally, our results indicate that not only are R. felis-exposed cat fleas infectious following a brief incubation period, but utilization of a mechanical mechanism may also explain the rapid rate of spread that typifies R. felis flea-borne transmission within experimental and computational models. Elucidation of the R. felis transmission cycle is necessary to further our understanding of this emerging rickettsiosis