Rickettsia massiliae and its public health significance across Palearctic and Oriental regions: a scoping review.

Abstract

Background: Arthropod including ticks, fleas, and lice have been found to be infected with Rickettsia massiliae, a pathogenic member of spotted fever group, causing rickettsiosis. This comprehensive scoping review summarize the known facts about its transmission, diagnostic-methods, phylogenetic position, human-case-reports, preventive-measures, and distribution in Palearctic and Oriental regions.

Methods: Three main steps were followed to compile this study: explanation of objective(s), identification of relevant literature, and retrieval of data determined by inclusion and exclusion criteria. Various databases, including Science Direct, Web of Science, PubMed, Scopus, Cochrane, and Google Scholar were screened for relevant literature. Our objectives were to collect data regarding transmission method(s) of R. massiliae, identification-assay(s), phylogenetic position, clinical-reports globally, and distribution via possible vectors & host animals surviving in Palearctic and Oriental regions. Descriptive analysis has been conducted to plot the frequency graphs of reported numbers in different countries and hosts.

Results: Findings presented that R. massiliae have been found across Palearctic and Oriental regions in 5 tick genera (Rhipicephalus, Hyalomma, Haemaphysalis, Ixodes, Amblyomma, and Dermacentor), 1 of louse (Haematopinus), 1 of sheep ked (Melophagus), and 1 of flea (Archaeopsylla), although their role as a vector(s) is still unknown. Dogs, sheep, cattle, and goats were recorded as epidemiologically important host animals for infected arthropods in 30, 23, 17, and 16 different studies, highlighting their role in its possible transmission. Additionally, Rh. sanguineus sensu lato (s.l) and Rh. turanicus were reported to infest the aforementioned animals, which is also being recognized as potential vector for its transmission. Highest number of R. massiliae reports (10) from different animals and vectors were recorded in China. Italy was recorded with highest (3) clinical cases of humans to-date. Moreover, transmission methods like transovarial via Rh. turanicus and horizontal/artificial-feeding via Rh. sanguineus s.l. and various diagnostic methods for R. massiliae have been documented.

Conclusions: R. massiliae has been widely documented throughout Palearctic and Oriental regions, with human cases reported in about six countries. Rh. sanguineus and Rh. turanicus stands out the potential vectors, while further investigation into the implications of diverse range of arthropods in epidemiology of this bacterium.