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Tick-borne Rickettsioses around the World: Emerging Diseases Challenging Old Concepts

Unité des Rickettsies, CNRS UMR 6020, IFR 48, Université de la Méditerranée, Faculté de Médecine, 13385 Marseille Cedex 5, France.
Clinical Microbiology Reviews (Impact Factor: 16). 11/2005; 18(4):719-56. DOI: 10.1128/CMR.18.4.719-756.2005
Source: PubMed

ABSTRACT During most of the 20th century, the epidemiology of tick-borne rickettsioses could be summarized as the occurrence of a single pathogenic rickettsia on each continent. An element of this paradigm suggested that the many other characterized and noncharacterized rickettsiae isolated from ticks were not pathogenic to humans. In this context, it was considered that relatively few tick-borne rickettsiae caused human disease. This concept was modified extensively from 1984 through 2005 by the identification of at least 11 additional rickettsial species or subspecies that cause tick-borne rickettsioses around the world. Of these agents, seven were initially isolated from ticks, often years or decades before a definitive association with human disease was established. We present here the tick-borne rickettsioses described through 2005 and focus on the epidemiological circumstances that have played a role in the emergence of the newly recognized diseases.

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    • "Furthermore, from current knowledge of the species, it is impossible to determine their ecoregions (Guglielmone et al. 2014). From the epidemiological point of view, R. sanguineus has a high competence as a vector of pathogens of diseases such as babesiosis and ehrlichiosis in dogs and spotted and boutonneuse fevers in man (Walker et al. 2000; Parola et al. 2005; Otranto et al. 2009; Labruna et al. 2011). Comparative studies between R. sanguineus populations from Brazil (Jaboticabal, State of São Paulo) and Argentina (Rafaela, Province of Santa Fé) showed marked biological, morphological and genetic differences between the strains. "
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    ABSTRACT: Comparative studies between brown dog tick Rhipicephalus sanguineus populations from Brazil (Jaboticabal, São Paulo) and Argentina (Rafaela, Santa Fé) showed significant biological, morphological and genetic differences between them. This work aimed to study, in a comparative way, the acquisition of resistance in domestic dogs to R. sanguineus from Jaboticabal and Rafaela, after successive and controlled infestations. Ticks were kept in a BOD incubator under controlled conditions (27 °C, 80 % relative humidity, 12-h photoperiod). Ten dogs, Dachshund breed, males and females, 6 months old, short- or long-haired, without prior contact with ticks, were used as hosts. They were distributed into two experimental groups composed of five animals each: G1 infested with ten adult couples of R. sanguineus (Jaboticabal) per animal, and G2 infested with ten adult couples of R. sanguineus (Rafaela) per animal. Ticks' biological parameters and titration of antibodies from the dogs' sera by ELISA test were used for comparison between the strains. Results of the biological parameters showed that the dogs did not acquire immunity to either of the R. sanguineus strains after repeated infestations. The ELISA test showed low antibody titers in sera of dogs from G2, in successive infestations, and higher antibody responses post second and third infestations in G1. It also demonstrated cross-reactivity between sera of dogs infested with R. sanguineus (Jaboticabal) and antigens from R. sanguineus (Rafaela) and vice versa. We conclude that Dachshund dogs did not develop resistance against neither Jaboticabal nor Rafaela strains of R. sanguineus.
    Experimental and Applied Acarology 06/2015; 67(1). DOI:10.1007/s10493-015-9936-x · 1.82 Impact Factor
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    • "Recently, the combination of the increased incidence, decline in case fatality, occurrence of multiple spotted fevers, and an increase in winter cases has sparked several questions as to whether a diagnostic error is occurring (e.g., false positives and cross-reactive positives), or if the pathogen is becoming less virulent (Dantas-Torres 2007, Cunha 2008, Raoult and Parola 2008). Diagnostic tests for RMSF are often cross-reactive with other spotted fevers including Rickettsia massiliae Beati & Raoult (Mediterranean spotted fever), Rickettsia akari (Queensland tick typhus), and Rickettsia felis Bouyer et al. (flea-borne spotted fever; Parola et al. 2005, Eremeeva et al. 2006, Raoult and Parola 2008). Additionally, pathogenic Rickettsia parkeri Lackman et al., and the strain Candidatus Rickettsia amblyommii have raised further concerns about the true prevalence of RMSF infections in the United States (Paddock et al. 2004, Paddock 2005, Whitman et al. 2007, Apperson et al. 2008). "
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    ABSTRACT: Rocky Mountain spotted fever (RMSF), caused by the etiological agent Rickettsia rickettsii, is the most severe and frequently reported rickettsial illness in the United States, and is commonly diagnosed throughout the southeast. With the discoveries of Rickettsia parkeri and other spotted fever group rickettsiae (SFGR) in ticks, it remains inconclusive if the cases reported as RMSF are truly caused by R. rickettsii or other SFGR. Arkansas reports one of the highest incidence rates of RMSF in the country; consequently, to identify the rickettsiae in Arkansas, 1,731 ticks, 250 white-tailed deer, and 189 canines were screened by polymerase chain reaction (PCR) for the rickettsial genes gltA, rompB, and ompA. None of the white-tailed deer were positive, while two of the canines (1.1%) and 502 (29.0%) of the ticks were PCR positive. Five different tick species were PCR positive: 244 (37%) Amblyomma americanum L., 130 (38%) Ixodes scapularis Say, 65 (39%) Amblyomma maculatum (Koch), 30 (9%) Rhipicephalus sanguineus Latreille, 7 (4%) Dermacentor variabilis Say, and 26 (44%) unidentified Amblyomma ticks. None of the sequenced products were homologous to R. rickettsii. The most common Rickettsia via rompB amplification was Rickettsia montanensis and nonpathogenic Candidatus Rickettsia amblyommii, whereas with ompA amplification the most common Rickettsia was Ca. R. amblyommii. Many tick specimens collected in northwest Arkansas were PCR positive and these were commonly A. americanum harboring Ca. R. amblyommii, a currently nonpathogenic Rickettsia. Data reported here indicate that pathogenic R. rickettsii was absent from these ticks and suggest by extension that other SFGR are likely the causative agents for Arkansas diagnosed RMSF cases.
    Journal of Medical Entomology 03/2015; 52(3):500-508. DOI:10.1093/jme/tjv027 · 1.82 Impact Factor
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    • "During the last 30 years, the recognized number of distinct and epidemiologically important TBDs globally has increased considerably. Since 1984, for example, over 10 newly recognized spotted fever rickettsioses have been identified (Parola et al. 2005). Moreover, by 1998, there were five recognized tick-borne infections in the United States alone. "
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    ABSTRACT: [ab]Based on an assessment of the available research, this article uses syndemic theory to suggest the role of adverse bio–social interactions in increasing the total disease burden of tick-borne infections in local populations. Given the worldwide distribution of ticks, capacity for coinfection, the anthropogenic role in environmental changes that facilitate tick dissemination and contact, evidence of syndemic interaction in tick-borne diseases, and growing impact of ticks on global health, tick-borne syndemics reveal fundamental ways in which human beings are not simply agents of environmental change but objects of that change as well. [tick-borne diseases, syndemics, changing environment, bio–social, coinfection]This article is protected by copyright. All rights reserved.
    Medical Anthropology Quarterly 10/2014; DOI:10.1111/maq.12163 · 1.30 Impact Factor
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