Morphological, Ultrastructural, and Histopathological Characterization of Natural Rhipicephalus annulatus Infestation in Sheep Skin From Kerbala Province, Iraq

Abstract

Ticks constitute most epidemiologically important group of ectoparasites in the veterinary medicine, causing direct host injury and serving as obligate vectors for many pathogenic organisms. The present study was designed for providing an integrated morphological, ultrastructural, and histopathological characterization of Rhipicephalus annulatus that are infesting sheep in Kerbala Province, central Iraq. A total of 540 sheep of both sex with variable ages were examined at several rural localities across the province, including Touyrige region, Al‐Husseiniya area, and Al‐Chemmalya countryside, in period between March and November 2023. Tick samples were collected from various anatomical sites on the body of the host. Adult female ticks of genus Rhipicephalus were recognized morphologically and exposed to both scanning electron microscopy (SEM) and light histological examination. Gross examination of tick attachment positions revealed local swelling and erythema. Histopathological evaluation of infested skin demonstrated marked epidermal hyperkeratosis, acanthosis, epithelial cell degeneration, multifocal dermal necrosis, and a dense mixed inflammatory infiltrate comprising predominantly eosinophils and lymphocytes. The active immunological response is presented by vascular congestion with dilation at the site of attachment. SEM investigation confirms the specialized mouthparts and cuticular surface adaptations of R. annulatus females which enable the mechanical injury and continuous tissue attachment. These findings advance the understanding of host with the ectoparasite connections and underscore the requirement of tick surveillance with control programmed in sheep‐rearing communities in Kerbala Province.