Tick-borne encephalitis virus in Ixodes ricinus (Acari: Ixodidae) ticks, Tunisia.

Tick-borne encephalitis virus (TBEV) is the etiologic agent of tick-borne encephalitis (TBE) and transmitted by Ixodes ricinus (Linnaeus, 1758) in Europe. The geographical distribution of I. ricinus in the Palearctic region covers also northern Africa, including northwestern Tunisia. While the eco-epidemiology of TBE in Europe is well documented, no data concerning TBEV from northern Africa are available. We investigated whether TBEV is circulating in Tunisia. A total of 877 adult I. ricinus collected from northwestern Tunisia were examined in pools for the presence of TBEV by nRT-PCR. Viral RNA was detected in one pool of three engorged ticks, yielding a minimum infection rate of 0.11 % (1/877). Phylogenetic analysis showed that the Tunisian TBEV strain belongs to the European lineage. We report for the first time the presence of TBEV in I. ricinus from northern Africa. Therefore, more studies are needed to assess the public health importance of TBEV in northern Africa.

TICKS PARASITIZING THE SPUR-THIGHED TORTOISE (TESTUDO GRAECA) POPULATION OF TUNISIA.

From March to April 2017, a total of 147 free-ranging spur-thighed tortoises (Testudo graeca) was captured in different habitat types of northern Tunisia and examined for tick infestation. A total of 134 was infested, yielding an infestation prevalence of 91.2%. From these tortoises, 1,174 ticks were collected, a subsample (10%, n=120) of which was randomly selected and identified; the remaining ticks were stored at -80 C and examined for zoonotic pathogens. Only adult Hyalomma aegyptium were found among the subsample of ticks collected for spur-thighed tortoise. The prevalence of tick infestation did not vary significantly within the study area but differences in intensity were observed in relation to the size of tortoises and the vegetation coverage. Our results provide strong evidence that adult H. aegyptium is the predominant tick species found on wild spur-thighed tortoises in northern Tunisia, where the species is commonly traded illegally across the Mediterranean Basin. Considering the potential transmission of several zoonotic pathogens by H. aegyptium to humans, we highlight the need to develop a surveillance system to prevent the introduction and the spread of tick-borne pathogens in the Mediterranean Basin.

Ixodes inopinatus and Ixodes ricinus (Acari: Ixodidae) Are Sympatric Ticks in North Africa.

In the present study, we report the sympatric occurrence of Ixodes ricinus (Linnaeus, 1758) and Ixodes inopinatus (Estrada-Peña, Nava, and Petney, 2014) in Tunisia. In total, 173 adult Ixodes ticks were collected from four sites (El Jouza, Tamra, Aïn Soltan, and Jbel Zaghouan) between February and April 2017, a period corresponding to the peak of activity of I. ricinus in North Africa. The morphological characters corresponded to both species; thus, we generated a total of 28 16S rRNA sequences and compared them with previously published data in GenBank. The two species were sympatric in Tamra, Aïn Soltan, and El Jouza, whereas collections in Jbel Zaghouan only yielded I. inopinatus. These results indicate that the two taxa are widespread in the humid area of northern Tunisia. The one tick collected in Jbel Zaghouan suggests that the distribution of at least I. inopinatus might extend to the sub-humid area. More studies are needed to fully comprehend the systematic status of the two taxonomic entities using multiple molecular markers and morphological characters; integrating these two identification methods are a necessary step toward a better understanding of the ecology and epidemiology of tick-borne diseases in Tunisia.

Absence of Crimean-Congo haemorrhagic fever virus in the tick Hyalomma aegyptium parasitizing the spur-thighed tortoise (Testudo graeca) in Tunisia.

Free-ranging spur-thighed tortoises Testudo graeca, captured in different habitat types of Northern Tunisia from March to April 2017, were examined for tick infestation: 134/147 (91%) were infested. The overall infestation intensity and abundance was 8.5 and 7.8, respectively. From these tortoises, 1174 ticks were collected, of which 10% (n = 120) taken from 18 randomly-selected tortoises were identified at the species level; the remaining ticks were examined for the presence of Crimean-Congo haemorrhagic fever virus (CCHFv) by real time RT-PCR. Only adult Hyalomma aegyptium were found, suggesting a high degree of host specificity to tortoises. No CCHFv was detected in ticks. Considering the absence of CCHFv in Hyalomma aegyptium infesting its main host, the spur-thighed tortoise, this tick species is unlikely to play a major role in the epidemiology of CCHF. Therefore, more studies are needed to investigate the circulation of this arbovirus between livestock and other tick species from North Africa.

Characterization of Borrelia lusitaniae isolates collected in Tunisia and Morocco.

Borrelia lusitaniae is a species within the complex Borrelia burgdorferi sensu lato and is infrequently isolated in Europe. In contrast, this species is by far the most predominant in North Africa and in Portugal. In this study, we analyzed the genetic diversity, at several loci, of a large population of isolates from free-living Ixodes ricinus ticks collected in Tunisia and Morocco. We found a moderate diversity of the whole genome by using pulsed-field gel electrophoresis as well as in the ospA gene sequences, compared to a high level of strain homogeneity in the small noncoding ribosomal spacer. In contrast, a high diversity of this locus has been previously reported for Portuguese isolates. We hypothesize that B. lusitaniae strains isolated in North Africa constitute a clone of Portuguese origin.