Local Reactions to Tick Bites

Abstract

A retrospective histological and immunohistochemical study has been carried out in 25 cases of tick bites recorded in our Departments. The samples that included an attached tick showed a cement cone anchoring the mouthparts to the skin and a blood-soaked, spongiform appearance of the superficial dermis, with a mild neutrophilic and eosinophilic infiltration. The vessels displayed a loose multilayered endothelial proliferation, with plump endothelia, permeated with erythrocytes. A few of them were severed, allowing copious blood extravasation. The established lesions included the following: erythema chronicum migrans-like cases, foreign body granulomas-sometimes containing remnants of the mouthparts-cutaneous lymphoid hyperplasia, either of the T-cell or the B-cell type, and tick-bite alopecia. In both the T-cell and B-cell pseudolymphomas, several vessels showed concentric endothelial and perithelial proliferation similar to that seen in the acute lesions. In the tick-bite alopecia, a lymphocytic infiltrate attacked the permanent portion of the hair follicles, whose reaction was a noticeable hyperplasia of the fibrous sheaths, although only a minority of the hairs was destroyed. The observed alterations are specific in the acute lesions and in the alopecia, where they directly arise as a result of the interactions between the host's tissues and the antihemostatic, anti-inflammatory, and immunomodulatory chemicals contained in the tick saliva. In the other lesions, the changes seem less characteristic, although the fragments of mouthparts and the special vascular changes provide a clue to their etiology.

Novel Immunomodulators from Hard Ticks Selectively Reprogramme Human Dendritic Cell Responses

“…Japanin therefore seems to impose a powerful block on this differentiation process. Given the influx of monocytes into the bite site in response to local tissue damage [44], the effect of Japanin on differentiating monocytes may be as important to ticks as its effects on DC, preventing the re-establishment of immune surveillance following initial DC exodus. Further study of the Japanin-treated cells will be required to elucidate whether they truly resemble “arrested” monocytes, or whether they have differentiated along an alternative pathway, but what is clear is that DC differentiation is blocked or greatly altered.…”

Human otoacariasis caused by Amblyomma testudinarium

“…[20] Accordingly, the cases presented in this report provide excellent examples of the 2 scenarios a clinician may encounter during the diagnosis of an unattached tick in the EAC of a patient.…”

Foreign Body Granulomas

“…155 Local reactions to tick bites display a variety of histologic pictures, which are mostly considered nonspecific, and have been reviewed by Castelli and colleagues. 156 In the granulomatous reactions, the finding of recognizable remnants of the mouthparts and the presence of special vascular changes may provide a clue to the etiologic diagnosis (Fig. 15).…”