A retrospective study of the characterization of Rickettsia species in ticks collected from humans

Abstract

Rickettsiae (family Rickettsiaceae, order Rickettsiales) are obligate intracellular bacteria transmitted by arthropod vectors. Several Rickettsia species causing vector-borne rickettsioses belong to the spotted fever group (SFG). Traditionally, Rickettsia conorii has been considered as the main etiologic agent of Mediterranean spotted fever. However, the molecular characterization of rickettsiae allowed identifying other species involved in spotted fever in the Mediterranean region. In this study, 42 ticks collected from humans were subjected to morphological identification and molecular characterization of Rickettsia species potentially involved in human rickettsiosis in Sicily. Fourteen ticks positive to at least two Rickettsia spp. molecular markers were used in the study. Identified Rickettsia spp. included R. conorii, found in Rhipicephalus sanguineus sensu lato and Rhipicephalus turanicus, Rickettsia aeschlimannii found in Hyalomma marginatum, Hyalomma lusitanicum, Dermacentor marginatus and Ixodes ricinus, Rickettsia massiliae found in R. turanicus and R. sanguineus s.l., and Rickettsia slovaca found in D. marginatus and R. sanguineus s.l. Our results showed a great variety of zoonotic Rickettsia spp. in ticks collected from humans in Sicily. The Rickettsia spp. reported in this study were identified in previously recognized or new potential tick vectors in Europe, highlighting the risk of infection by different Rickettsia spp. for humans bitten by ticks in Sicily.

What viruses tell us about evolution and immunity: beyond Darwin?

“…Gene reduction was demonstrated in vitro by “Spiegelman's Monster,” where a long coding phage RNA in the presence of an RNA polymerase, free nucleotides, and salts degenerated to a small extremely fast replicating ncRNA after 74 generations, demonstrating that loss of genes for the benefit of fast replication can occur . Rickettsia , mitochondria, and chloroplasts are other examples for loss of genes resulting in an exclusively intracellular lifestyle …”

“…150,151 Rickettsia, mitochondria, and chloroplasts are other examples for loss of genes resulting in an exclusively intracellular lifestyle. 141,142,145 Possibly, viruses gave up their independence for a parasitic lifestyle. In this case, viruses could be our oldest ancestors.…”

“…These events, however, are not as rare as thought and similar uptakes of bacteria into other cells may still happen today. For example, bacteria of the Rickettsia genus lost the ability for autonomous replication and became dependent on the host . Thus, genomes do not only increase in size during evolution, but there are also counteracting forces, loss of genes as exemplified by endosymbionts and Rickettsia .…”

“…For example, bacteria of the Rickettsia genus lost the ability for autonomous replication and became dependent on the host. 145 Thus, genomes do not only increase in size during evolution, but there are also counteracting forces, loss of genes as exemplified by endosymbionts and Rickettsia. This may be an energy-saving measure of symbionts compared to autonomously living species.…”

First Report of the Ticks Haemaphysalis punctata Canestrini et Fanzago, 1878, Haemaphysalis parva (Neumann, 1897) and Dermacentor marginatus (Sulzer, 1776) (Acari, Amblyommidae) from Humans in Lebanon

“…In fact, H. punctata is known from many European, North African, Asian and Mediterranean countries-Palearctic realm (Estrada-Peña 2004; [1,4,5,9,11,13,16,21]. Recently, many studies in the Middle East have reported H. punctata infesting humans; for instance, Turkey [6,16], Palestine, Iraq [8], Iran [14], Sicily [3] and Israel [15]. Although H. punctata occurrence in Lebanon was lately reported by Dabaja et al [7] and on ruminants, its finding on humans (mainly remains) has not been recorded yet from this country.…”