AUTHOR=Belkahia Hanène , Selmi Rachid , Zamiti Sayed , Daaloul-Jedidi Monia , Messadi Lilia , Ben Said Mourad 

TITLE=Zoonotic Rickettsia Species in Small Ruminant Ticks From Tunisia

JOURNAL=Frontiers in Veterinary Science

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2021.676896

DOI=10.3389/fvets.2021.676896

ISSN=2297-1769

ABSTRACT=<p>Tick-borne rickettsioses present a significant public health threat among emerging tick-borne diseases. In Tunisia, little is known about tick-borne <italic>Rickettsia</italic> pathogens. Therefore, the aim of this study was to investigate the presence of <italic>Rickettsia</italic> species in small ruminant ticks from Tunisia. Adult ticks (<italic>n</italic> = 694) were collected from goats and sheep in northern Tunisia. Obtained ticks were identified as <italic>Rhipicephalus turanicus</italic> (<italic>n</italic> = 434) and <italic>Rhipicephalus sanguineus</italic> sensu lato (<italic>n</italic> = 260). Selected ticks (<italic>n</italic> = 666) were screened for the presence of <italic>Rickettsia</italic> spp. by PCR targeting a partial sequence of the <italic>ompB</italic> gene followed by sequence analysis. Rickettsial DNA was detected in 122 (18.3%) tested tick samples. The infection rates in <italic>Rh. turanicus</italic> and <italic>Rh. sanguineus</italic> s.l. ticks were 23.4 and 9.5%, respectively. The overall prevalence of rickettsial DNA was markedly higher in ticks collected from goats (23.2%) compared to those infesting sheep (7.9%). The detection of rickettsial DNA was significantly higher in ticks from the governorate of Beja (39.0%) than those from the governorate of Bizerte (13.9%). Two additional genes, the outer membrane protein A gene (<italic>ompA</italic>) and the citrate synthase gene (<italic>gltA</italic>), were also targeted for further characterization of the detected <italic>Rickettsia</italic> species. Genotyping and phylogenetic analysis based on partial sequences (<italic>n</italic> = 106) of the three different genes revealed that positive ticks are infected with different isolates of two Spotted Fever Group (SFG) <italic>Rickettsia</italic>, namely, <italic>Rickettsia massiliae</italic> and <italic>Rickettsia monacensis</italic>, closely related to those infecting camels and associated ticks from Tunisia, and humans and small ruminant ticks from neighboring countries like Italy, France, and Spain.</p>