Allergic dermatitis caused by Culicoides in Texel sheep in the state of Pará, Brazil

Abstract

Clinical and epidemiological data were obtained during monthly visits to the farm. Skin biopsies were performed for histopathological examinations, and insects were captured with Centers for Disease Control and Prevention (CDC) traps and live-bait entomological vacuum devices. The property housed a herd of both genders, with 45 Santa Inês sheep of different ages and 72 Texel adults. Of the 72 Texel sheep, 56 were affected. Of these, 24 exhibited alopecia, erythema, edema, and crust in the ears, on top of the head, and less often, around the eyes. In addition to the lesions described above, 14 animals exhibited hyperpigmentation of the ears and/or around the eyes and crust in the nose. Another 18 animals exhibited chronic lesions characterized by deformed and thickened ears, alopecia with hyperpigmentation, and in most cases, secondary bacterial infections with abscesses and/or myiasis. Some of these animals had lost part of their ears. Histologically, the lesions were characterized as orthokeratotic hyperkeratosis, acanthosis, vacuolization, and necrosis of epidermal cells. An inflammatory infiltrate was present in the dermis, which was composed mainly of eosinophils and macrophages, some lymphocytes and mast cells, and few neutrophils, in addition to edema and collagen deposition. The Santa Inês sheep were not affected. Among the captured insects, 294 specimens of Culicoides (Hoffmania) plaumanni Spinelli, 57 specimens of C. (Hoffmania) insignis Lutz, and 27 specimens of other Culicoides species were identified. We conclude that C. plaumanni, C. insignis, and possibly other Culicoides species are involved in the etiology of allergic dermatitis in Texel sheep in the state of Pará. Santa Inês sheep in the same region and under the same conditions were not affected, which suggests lower susceptibility of these animals.

Allergic Dermatitis in Pêga Breed Donkeys (Equus asinus) Caused by Culicoides Bites in the Amazon Biome, Pará, Brazil

“…The clinical signs such as restlessness, intense itching, and biting of skin lesions exhibited by the donkeys were similar to those found in donkeys in Israel [33]. Similar clinical findings have been reported in horses [11,34,35], mules [10], and sheep [7,9,11,36]. The injuries found in the distal region of the limbs were the most noticeable during clinical examination, as these wounds were caused by self-mutilation due to itching.…”

“…Allergic dermatitis has been diagnosed in Santa Inês and Texel sheep breeds across various municipalities in Pará, with varying prevalence [7,9]. According to Martins et al [32], constant water accumulation in lakes, streams, and pastures promotes the multiplication of these insects.…”

“…Additionally, weight loss, ocular discharge, and in some cases, keratitis with corneal opacity have been observed. These conditions can lead to mutilation, infection, and secondary myiasis owing to skin lesions [5][6][7][8][9][10][11].…”

Intradermaler und serologischer Allergietest zur Abklärung einer Insektenstich-Hypersensitivität bei einem Dahomey-Ochsen

“…Der Zeitpunkt des Auftretens war das Frühjahr der zweiten Weidesaison des Rindes, was der aktiven Periode von Culicoides nach Sensibilisierung im ersten Lebensjahr entspricht. In unserem Fall waren die histopathologischen Befunde ähnlich derer, die bei Pferden und Schafen mit IBH beobachtet wurden: eine gemischte perivaskuläre bis diffuse Dermatitis mit eosinophilen Granulozyten und Mastzellen 4 5 9 . Im IDAT wurden beide Reaktionen als positiv für Culicoides eingestuft, während nur ein positives Ergebnis für Culex gefunden wurde.…”

“…Klinisch zeigen Pferde einen starken Juckreiz mit einer ventral oder dorsal verteilten papulo-krustösen Dermatitis [3]. Bei Schafen ist sie durch Exkoriation, Lichenifikation und Krustenbildung hauptsächlich an der ventralen Körperoberfläche [4] und am Kopf gekennzeichnet [5]. Rinder zeigen als Überempfindlichkeitsreaktion auf Culicoides spp.…”