Update on Tick-Borne Rickettsioses around the World: a Geographic Approach

Abstract

SUMMARY Tick-borne rickettsioses are caused by obligate intracellular bacteria belonging to the spotted fever group of the genus Rickettsia . These zoonoses are among the oldest known vector-borne diseases. However, in the past 25 years, the scope and importance of the recognized tick-associated rickettsial pathogens have increased dramatically, making this complex of diseases an ideal paradigm for the understanding of emerging and reemerging infections. Several species of tick-borne rickettsiae that were considered nonpathogenic for decades are now associated with human infections, and novel Rickettsia species of undetermined pathogenicity continue to be detected in or isolated from ticks around the world. This remarkable expansion of information has been driven largely by the use of molecular techniques that have facilitated the identification of novel and previously recognized rickettsiae in ticks. New approaches, such as swabbing of eschars to obtain material to be tested by PCR, have emerged in recent years and have played a role in describing emerging tick-borne rickettsioses. Here, we present the current knowledge on tick-borne rickettsiae and rickettsioses using a geographic approach toward the epidemiology of these diseases.

Importance of Common Wall Lizards in the Transmission Dynamics of Tick-Borne Pathogens in the Northern Apennine Mountains, Italy

“…De Sousa et al [7] hypothesise that lizards may also be reservoirs of R. monacensis, the agent of spotted fever rickettsioses [38]. As reported in previous studies in Spain and Portugal, R. monacensis was the dominant rickettsia species in lizard ticks and infected attached I. ricinus larvae and nymphs [7,21].…”

Molecular Identification of Pathogenic Bacteria in Eschars from Acute Febrile Patients, Senegal

“…18 In the case of Rocky Mountain spotted fever, eschars are reported to be very rare; however, eschars are typical in most other spotted fevers. Eschars represent skin lesions with extensive, contiguous infection by Rickettsia spp.…”

“…It is generally thought that the development of a localized defensive reaction is a good prognostic factor, and spotted fevers that generally induce multiple eschars in patients (for example, African tick bite fever) are milder than spotted fevers that are rarely accompanied by eschars (Rocky Mountain spotted fever). 18 Infection by R. felis in Africa was described initially by two independent teams working in Senegal and Kenya. These works identified a novel healthcare problem in Africa: acute R. felis-induced fever that mimics malaria.…”

Check list of parasites and bacteria recorded from pangolins (Manis sp.)

“…Similarly there were reports of Amblyomma latum ticks from Python; Amblyomma exornatum ticks from monitor lizards; Rhipicephalus simus ticks from dogs (Navajas et al 2010;Reeves et al 2006;Parola et al 2013). Guglielmone et al (2014) reported ten species of ticks found in pangolins also occur in different animal hosts (classified up to family level) including mammals, birds and reptiles.…”