Presence of antibodies to Crimean Congo haemorrhagic fever virus in sheep in Tunisia, North Africa.

Crimean-Congo haemorrhagic fever (CCHF) is an emerging tick-borne disease causing severe and fatal haemorrhagic syndrome in humans. Hyalomma spp. ticks are the primary vectors and sheep are important CCHF virus (CCHFV)-amplifying hosts. In this study, blood samples and ticks collected in October 2019 from 270 sheep from 15 farms across Tunisia constituted the main research material. Moreover, the sera of the same animals taken at different periods between 2018 and 2019 were also used to obtain comparative results. To investigate the presence of anti-CCHFV antibodies in sheep, all sera were tested using ELISA. Reactive sera were further characterised by a virus neutralisation test (VNT). Overall, one out of the 270 tested sheep was both ELISA- and strongly VNT-positive to CCHFV. Another two sheep were borderline ELISA-positive but did not exhibit neutralising antibodies. Ninety-one ticks were collected from all sampled sheep, of which 34 (37.4%) belonged to Hyalomma spp. This is the first report of anti-CCHFV antibodies in sheep from Tunisia. Both the results of this study and the recent CCHFV detection in ticks collected from camels in southern Tunisia indicate that further studies are needed to determine the competent tick vector in the country and to characterise the epidemiological cycle of CCHFV.

Phenology and phylogeny of Hyalomma spp. ticks infesting one-humped camels (Camelus dromedarius) in the Tunisian Saharan bioclimatic zone.

In this study, we report the results of a survey of Hyalomma ticks infesting one-humped camels in southern Tunisia. Examinations were conducted every second or third month on 406 camels in Tataouine district from April 2018 to October 2019. A total of 1902 ticks belonging to the genus Hyalomma were collected. The ticks were identified as adult H. impeltatum (41.1%; n = 782), H. dromedarii (32.9%; n = 626), H. excavatum (25.9%; n = 493), and H. marginatum for a single specimen. Although the camels were infested by ticks throughout the year, the highest overall infestation prevalence was observed in April 2018 (p < 0.01). The overall infestation intensity varied between 2.7 and 7.4 ticks/animal. There were no statistically significant differences in tick infestation prevalence based on age categories of the camels, and the overall infestation prevalence was between 82.7% and 97.4%. Female camels were significantly more infested with ticks (88.3%) than males (65.5%) (p < 0.01). The infestation prevalence of camels varied significantly according to the region where sampling took place (p < 0.01), but no correlations were found with abiotic factors. The preferred attachment sites for adult Hyalomma ticks were the sternum (38.3%; n = 729/1902), around the anus (36.2%; n = 689/1902), udder (18.4%; n = 350/1902), and inner thigh (6.9%; n = 132/1902). Morphological classification of ticks was corroborated by sequencing the cytochrome c oxidase I (Cox1) and 16S rDNA genes, and these sequences were also used to infer phylogenetic relationships. A single H. dromedarii seemed to be a natural hybrid with H. rufipes. More attention should be devoted by the veterinary services to the infestation of camels by ticks.

TITLE: Phénologie et phylogénie des tiques Hyalomma spp. infestant les dromadaires (Camelus dromedarius) dans la zone bioclimatique saharienne tunisienne. ABSTRACT: Dans cette étude, les résultats d'une enquête concernant les tiques Hyalomma infestant les dromadaires dans le sud de la Tunisie sont présentés. Des examens ont été menés tous les deux ou trois mois sur 406 dromadaires dans le district de Tataouine entre avril 2018 et octobre 2019. Au total, 1902 tiques appartenant au genre Hyalomma ont été collectées. Les tiques adultes ont été identifiées comme H. impeltatum (41,1 % ; n = 782), H. dromedarii (32,9 % ; n = 626), H. excavatum (25,9 % ; n = 493) et un seul spécimen de H. marginatum. Bien que les dromadaires aient été infestés par les tiques tout au long de l'année, la prévalence globale d'infestation la plus élevée a été observée en avril 2018 (p < 0,01). L'intensité globale d'infestation variait entre 2,7 et 7,4 tiques/animal. Il n'y avait pas de différence statistiquement significative de l'infestation par les tiques en fonction des catégories d'âge des dromadaires, et la prévalence globale d'infestation se situait entre 82,7 et 97,4 %. Les dromadaires femelles étaient significativement plus infestés par les tiques (88,3 %) que les mâles (65,5 %) (p < 0,01). La prévalence d'infestation variait significativement en fonction des régions (p < 0.01) mais il n'y avait pas de corrélation avec les facteurs abiotiques. Les sites de fixation préférés des tiques Hyalomma adultes étaient le sternum (38,3 % ; n = 729/1902), autour de l'anus (36,2 % ; n = 689/1902), la mamelle (18,4 % ; n = 350/1902) et la face interne de la cuisse (6,9 % ; n = 132/1902). La classification morphologique a été corroborée par le séquençage des gènes de l'ADNr du cytochrome c oxydase I (Cox1) et du 16S, et ces séquences ont également été utilisées pour déduire les relations phylogénétiques. Un seul spécimen de H. dromedarii semblait être un hybride naturel avec H. rufipes. Une plus grande attention doit être accordée par les services vétérinaires quant à l'infestation des dromadaires par les tiques.

Epidemiological investigation of Crimean-Congo haemorrhagic fever virus infection among the one-humped camels (Camelus dromedarius) in southern Tunisia.

Crimean-Congo haemorrhagic fever is a viral tick-borne zoonotic disease caused by a Nairovirus, Crimean-Congo haemorrhagic fever virus (CCHFV). The present survey aimed to determine the exposure of one-humped camels (Camelus dromedarius) from southern Tunisia to CCHFV. A total of 273 sera from extensively reared camels were collected from Tataouine district, Tunisia, and tested by CCHFV-specific enzyme linked immunosorbent assays. By combining the results of three serological tests, the overall seroprevalence of CCHFV was estimated as 89.7% (245/273). No viral RNA was detected from camel sera using quantitative real-time PCR (RT-qPCR). A total of 165 ticks were collected from camels and tested with RT-qPCR, and only one Hyalomma impeltatum tick was positive for virus RNA.