Rickettsia aeschlimannii sp. nov., a New Spotted Fever Group Rickettsia Associated with Hyalomma marginatum Ticks

Abstract

We formally propose the name Rickettsia aeschlimannii sp. nov. for a new spotted fever group (SFG) rickettsia, strain MCMT, isolated from Hyalumma marginatum marginatum ticks collected in Morocco. This organism shows a typical rickettsial morphology when analyzed by electron microscopy. After characterization by serotyping, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western immunoblotting, PCR-restriction fragment length polymorphism (RFLP), pulsed-field gel electrophoresis, and 16s rDNA sequencing, this organism was found to be different from all of the recognized SFG rickettsiae. Identical PCR-FWLP profiles have, however, been found in H. marginatum marginatum from Portugal and H. marginatum rujipes from Zimbabwe, which suggests that the distribution of this rickettsia reaches from the Mediterranean to southern Africa.Although the first descriptions of Mediterranean spotted fever and its ecology were made in northern Africa (13) and one of the reference strains of Rickettsia conorii is called the Moroccan strain, there have been few recent reports about the ecology and epidemiology of rickettsioses in this area (31). In early studies, all three African spotted fever group (SFG) rickettsioses, Mediterranean spotted fever, South African tick bite fever, and Kenyan tick typhus (25), were attributed to infection with R. conorii. The recognized vectors were dog ticks: Rhipicephalus sanguineus in the Mediterranean area (11) and Rhipicephalus simus or Haemaphysalis leachi in the eastern and southern regions of Africa (22,27). When other tick species were found to be infected with rickettsia-like organisms (RLO), they were considered to be "secondary" vectors of R. conorii (21). More recently, however, it has been shown that other SFG rickettsiae occur throughout Africa and that several tick species carry rickettsiae different from R. conorii (7,41).The presence of RLO in Hyalomma ticks of Morocco and Sudan was first reported in the 1950s (21). RLO have been detected by PCR and direct immunofluorescence in H. impeltatum, H. dromedari, and H. anatolicum in Egypt; however, they have not been identified (30). During a large-scale field survey in Zimbabwe, hemolymph tests showed that 11% of Hyalomma marginatum rufipes ticks were infected with RLO (7). Although isolation attempts were unsuccessful, PCR-restriction fragment length polymorphism (RFLP) analysis showed that these ticks contained SFG rickettsiae genotypically similar to a strain (PoTiR8) isolated from H. marginatum marginaturn ticks from Portugal (2). Strain PoTiR8 has, however, not been further characterized.In Morocco, H. marginatum marginaturn is one of the most widely distributed tick species, possibly representing up to 42% of the tick burden of cattle (3, 32). Although in its juvenile stages it usually bites birds, under particular circumstances it may also infest humans (23). We present here the first description of an SFG rickettsial strain (MC16T) isolated from Moroccan H. marginaturn marginaturn. This isolate was compared to the recogn...

Update on tick-borne bacterial diseases in Europe

“…and then characterized as a new rickettsia in 1997 (Beati et al, 1997). Later, R. aeschlimannii was detected in ticks from Croatia, Spain, Corsica, Portugal, Italy, Greece and Russia Santos-Silva et al, 2006b;Shpynov et al, 2009;Mura et al, 2008;Pundapolic et al, 2002).…”

Rickettsia felis: molecular characterization of a new member of the spotted fever group.

“…3a). (Beati et al, 1992(Beati et al, , 1997. Although effective, the serotyping methods are cumbersome and based on limited epitopes that are determined by small portions of the genome.…”

Tick- and flea-borne rickettsial emerging zoonoses

“…Between 1984 and 2004, nine more species or subspecies of tick-borne spotted fever rickettsiae were identified as emerging pathogens throughout the world, including, R. japonica in Japan [6,46,65,71,72,[82][83][84]146]; "R. conorii caspia" in Astrakhan [35,38,39,143], Africa [47] and Kosovo [48]; R. africae in sub-Saharan Africa and the West Indies [62,63]; R. honei in the Flinders Island, offshore of Australia [9,57,140,141], the Island of Tasmania, Australia [153], Thailand [73], and possibly in the USA [13]; R. slovaca in Europe [29,74,101,122]; "R. sibirica mongolotimonae" in China [157], Europe [44,118] and Africa [106,113]; R. heilongjiangensis in China [42,49]; R. aeschlimannii in Africa [11,112,121] and Europe [43]; and finally R. parkeri in the USA [104]. R. helvetica is also suspected to be a human pathogen in Europe [45] and Asia [46,61,107], but this needs c...…”