Skin lesions in Aubrac cows strongly associated with fly bites (Haematobia irritans).

BACKGROUND: The horn fly Haematobia irritans is known to cause problems in cattle including weight loss and decreased milk production; cutaneous lesions have not been widely reported and descriptions of the clinical manifestations are quite variable. HYPOTHESIS/OBJECTIVES: This study describes the clinical and histopathological lesions of several Aubrac cows that presented with focal to confluent areas of alopecia, skin scaling and thickening, suspected to be induced by H. irritans bites. ANIMALS: Twenty seven, three- to six-year-old Aubrac cows, kept in mountain pastures in France, that presented with an apparently asymptomatic alopecic dermatosis. METHODS: Samples for skin cytological evaluation, skin scrapings and trichograms were examined; also, skin biopsy specimens from affected animals were used for histopathological examination. RESULTS: Clinical lesions consisted of focal to coalescing, symmetrical areas of hair loss and scaling, located on the back, flanks, and lateral and caudal aspects of the thighs. Histopathological examination revealed perivascular, oedematous, eosinophilic dermatitis with eosinophilic folliculitis and furunculosis. Species identification of several flies captured on the cows revealed H. irritans. The final clinicopathological diagnosis was eosinophilic dermatitis and folliculitis and furunculosis, suspected to be due to H. irritans fly-bite. CONCLUSION AND CLINICAL IMPORTANCE: Fly-bite (H. irritans) dermatitis should be included in the differential diagnosis of alopecic dermatoses in cows.

Exotic pediculosis and hair-loss syndrome in deer (Odocoileus hemionus) populations in California.

Infestation with nonnative, "exotic" lice was first noted in Washington black-tailed deer (Odocoileus hemionus columbianus) in 1994 and has since then spread throughout the western United States. In California, infestation with the exotic louse Damalinia (Cervicola) sp. was first detected in black-tailed deer from northern California in 2004, and, in 2009, the exotic louse species Bovicola tibialis and Linognathus africanus were identified on mule deer (Odocoileus hemionus californicus) in central Sierra Nevada in association with a mortality event. Exotic lice have since been detected in various locations throughout the state. We describe the geographic distribution of these exotic lice within California, using data from 520 live-captured and 9 postmortem-sampled, free-ranging mule deer examined between 2009 and 2014. Data from live-captured deer were used to assess possible associations between louse infestation and host age, host sex, migratory behavior, season, and blood selenium and serum copper concentrations. Damalinia (Cervicola) sp. and B. tibialis lice were distinctively distributed geographically, with D. (Cervicola) sp. infesting herds in northern and central coastal California, B. tibialis occurring in the central coastal mountains and the Sierra Nevada, and L. africanus occurring only sporadically. Younger age classes and low selenium concentrations were significantly associated with exotic louse infestation, whereas no significant relationship was detected with serum copper levels. Our results show that exotic lice are widespread in California, and younger age classes with low blood selenium concentrations are more likely to be infested with lice than older deer.

Tick Bite Alopecia: A Report and Review.

Tick bites can cause a number of local inflammatory reactions, which are often difficult to differentiate from those induced by other arthropod bites or stings. These include erythematous nodular or pustular lesions, erosive plaques, annular lesions of erythema chronicum migrans, and both scarring and nonscarring inflammatory alopecia. We report a case of nonscarring alopecia in a 21-year-old male who reported a recent history of tick bite to the scalp. The biopsy demonstrated a dense pseudolymphomatous inflammatory infiltrate with numerous eosinophils associated with hair follicle miniaturization and an elevated catagen-telogen count. Signs of external rubbing, including lichen simplex chronicus and the "hamburger sign", were also visualized and are indicative of the associated pruritus. To the authors' knowledge, this is the fifth report of nonscarring tick bite alopecia in the literature and the first in an adult patient. This text will review the classic clinical presentation, histologic findings, and proposed mechanism of tick bite alopecia.

Demodex Folliculitis of the Scalp: Clinicopathological Study of an Uncommon Entity.

Demodex is a saprophytic mite in humans commonly present in the pilosebaceous units, which has been implicated as a pathogen in several skin conditions. The clinical presentation and histopathology of Demodex folliculitis of the scalp have been described in only a few case reports. This study was performed to further elucidate the clinicopathological features of this entity. We have studied 333 consecutively submitted scalp biopsies performed for hair loss and alopecia. All specimens were completely step-sectioned. Biopsies with Demodex mites were further studied histopathologically, and the patients' clinical files were reviewed. There were 17 biopsies (5.1%) with Demodex in at least 1 pilosebaceous unit. Based on the clinical presentation, histopathology, and response to therapy, Demodex was considered to be nonpathogenic in 13 cases. The remaining 4 cases were characterized by hair loss, scalp erythema, scales, and pustules. There were 2 or more pilosebaceous units with Demodex along mononuclear and/or neutrophilic infiltrates around and in the involved follicles and occasionally granulomas. All 4 cases responded completely to metronidazole therapy. In conclusion, Demodex is infrequently found in scalp biopsies for hair loss and alopecia, and, in most cases, it does not seem to be pathogenic. Occasionally, however, it is associated with folliculitis characterized by hair loss, erythema, scales, and pustules clinically; neutrophilic and/or mononuclear-cell folliculitis with occasional granulomas histopathologically; and a prompt response to anti-Demodex therapy.

Is seborrhoeic dermatitis associated with a diffuse, low-grade folliculitis and progressive cicatricial alopecia?

An association between adult scalp seborrhoeic dermatitis and cicatricial hair loss has not previously been convincingly established. This study seeks to demonstrate a unique relationship between a clinically identifiable chronic scalp dermatitis-folliculitis with the characteristic histological features of low-grade inflammatory fibrosing alopecia, resulting in a distinctive progressive cicatricial alopecia which we believe is prevalent and hitherto unrecognised, and befits the description of seborrhoeic folliculitis. The clinical, epidemiological and histopathological features of seborrhoeic folliculitis are demonstrated to establish its unique status among the disorders of adult diffuse cicatricial alopecia.