Abstract
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.
Highlights
Production of one-humped camels, Camelus dromedarius (Mammalia: Camelidae), is the principal economic activity in the far south of Tunisia, dominating all other agricultural activities outside the oasis system
Hyalomma excavatum ticks were distributed between the sternum (40.3%) and the anus (40.5%); 40.6% of H. impeltatum were collected from the sternum and 32% from the anus; 37.2% of H. dromedarii were collected from the anus and 33.8% from the sternum
Given the particular significance of H. dromedarii in this region and its large distribution in other bioclimatic zones in Tunisia and North Africa, we inferred the phylogenetic diversity of this tick species, as well as other Hyalomma species, based on the mitochondrial Cox1 and 16S genes which suggest the presence of gene flow
Summary
Production of one-humped camels, Camelus dromedarius (Mammalia: Camelidae), is the principal economic activity in the far south of Tunisia, dominating all other agricultural activities outside the oasis system. In addition to arthropod infestations, several diseases are known to affect one-humped camels’ health. These include parasitic infestations (trypanosomoses [33], toxoplasmosis [39], coccidioses [16], helminthiases [44]), bacterial infections (brucellosis [23, 53] and Q-fever [7]), and viral infections (Middle East Respiratory Syndrome [56]). Ticks (Acari: Ixodidae) belonging to the genus Hyalomma, such as Hyalomma dromedarii Koch, 1844, Hyalomma impeltatum Schulze & Schlottke, 1930 and Hyalomma excavatum Koch, 1844 are the main species infesting one-humped camels in the extensive production systems of south Tunisia [47]. Where there is cohabitation with other domestic animal species, camels are known to be infested with Rhipicephalus ticks [21, 24, 31, 47, 52]
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