Molecular detection and characterization of spotted fever group rickettsiae in ticks from Central Italy

Abstract

The aim of this study was to investigate the presence of rickettsial pathogens in ticks from Central Italy. A total of 113 ticks hailed from Latium and Tuscany regions were identified and tested by PCR to detect gltA, ompA, ompB genes of Rickettsia. Positive amplicons were sequenced and identified at species level. Ticks were analyzed individually or in pools. The percentage of positivity for SFG rickettsiae was 12.4%, expressed as minimum infection rate (MIR) assuming that one tick was positive in each positive pool. Rickettsia aeschlimannii was detected in Hyalomma marginatum, Rickettsia monacensis in Ixodes ricinus and Rickettsia massiliae and Rickettsia conorii in Rhipicephalus sanguineus sensu lato. These findings confirm the circulation of pathogenic rickettsiae in Latium and Tuscany regions. To our knowledge this is the first report of R. massiliae in Latium region.

Diversity of Rickettsia in Ticks Collected in Abruzzi and Molise Regions (Central Italy)

“…In our study, R. helvetica was identified exclusively in I. ricinus pools (two) which are the main vector and natural reservoir [1], while R. monacensis was found mainly in I. ricinus pools (35 out of 38), with one positive in D. marginatus, R. sanguineus and Hae. punctata-the latter is similar to the finding of Scarpulla and collaborators [12]. These findings suggest that, even if the circulation in the environment is mainly maintained by I. ricinus, there may be other species implicated in the transmission or R. monacensis as suggested by Madeddu and collaborators [28].…”

“…In our study, eight SFG Rickettsia species have been identified in ticks: R. slovaca, R. monacensis, R. massiliae, R. conorii, R. aeschlimannii, R. helvetica, R. raoultii, and R. felis. The findings on Rickettsia species of our study not completely overlap with the findings of similar studies carried out by Scarpulla and collaborators [12] in Tuscany, Maioli and collaborators [11] in Emilia Romagna, and Chisu and collaborators [26] in Sardinia. R. monacensis the second most representative species in our study was the most frequent species in Tuscany [12], and previously in Emilia Romagna [11], while it was not detected in Sardinia [26].…”

“…The findings on Rickettsia species of our study not completely overlap with the findings of similar studies carried out by Scarpulla and collaborators [12] in Tuscany, Maioli and collaborators [11] in Emilia Romagna, and Chisu and collaborators [26] in Sardinia. R. monacensis the second most representative species in our study was the most frequent species in Tuscany [12], and previously in Emilia Romagna [11], while it was not detected in Sardinia [26]. The reasons for the difference are mainly found in the tick composition of the collection that is affected by the host, and also by the environmental features of the study area, that indirectly affect the Rickettsia species composition.…”

“…Results demonstrated evidence of a high rate of infection (52.2%) for Rickettsia spp in ticks (93 positive pools out of 178). The infection rate was higher than what has been reported in a similar study carried out on 77 pools of three ticks by Ebani and collaborators [20] in Tuscany (20.78%) and higher than what has been reported by Scarpulla and collaborators [12] on 113 ticks collected from host and environment in Latium and Tuscany regions (12.4%) and tested singularly (38), or in a pool of 10 ticks (18). Likewise, our infection rate was higher than what has been recently reported in a study carried out testing free living ticks in a sub urban area in Latium 25.8% where however 255 ticks had been selected randomly out of 518 ticks, and singularly tested [21].…”

“…Israelensis, Rickettsia conorii subsp. Indica, Rickettsia raoulti, Rickettsia helvetica, and Rickettsia hoogstraalii, [1,2,[11][12][13][14].…”