Immune mechanisms in human and canine demodicosis: A review

Abstract

| INTRODUC TI ONDemodex mites are presumed to be saprophytic parasites of the mammalian skin, and animals including humans are usually carriers without any clinical signs of demodicosis. 1 The two Demodex species in humans, Demodex folliculorum and D brevis, are found ubiquitously in all human races without gender preference, but rarely in newborn and infrequently in children that suggests the main transmission is via physical contact. 2,3 D folliculorum is primarily found as a cluster in the hair follicle and is the predominant type in the face area, while D brevis possesses more wider distribution on the human body and found in the sebaceous gland. 2,4 In contrast, among the three Demodex species found in dogs, while the habitat of D canis and D injai are hair follicles and sebaceous glands, D cornei inhabits in stratum corneum of epidermis. 5,6 There have also been reports documenting cross-infections between humans and animals; however, the reliability of these rare case reports remains to be verified, due to the polymorphism reported in D canis and D folliculorum. [7][8][9] Clinical manifestations of demodicosis differ between humans and dogs; while it is not life-threatening in former, latter can suffer from fatal consequences. Nevertheless, since there is a close genetic relationship between D folliculorum and D canis, and demodicosis is highly prevalent in certain dog breeds while it is rarely reported in laboratory mice, dog studies are thought to provide valuable insights AbstractDemodex mites are saprophytic parasites of the mammalian skin, mostly found in or near pilosebaceous units of hairy regions. While they can be found in healthy humans and animals without causing any clinical manifestations, they were suggested to create pathogenic symptoms when they appear in high densities under favourable conditions (ie, demodicosis). Nevertheless, their role as the primary causative agent

Demodex and eye disease

“…1,55,62,70,71 Demodicosis can also block the openings of follicles and/or sebaceous gland ducts and lead to epithelial hyperplasia and hyperkeratinisation. 26,66…”

“…46,84,85 Bacillus oleronius, a bacterium isolated from the gut of D. folliculorum, produces antigens capable of provoking an immune response. 26,81,[84][85][86][87] Demodicosis in skin lesions, especially the face, is well documented in dermatology. [88][89][90][91] It is well established that a strong correlation exists between acne rosacea and Demodex, whereby a seven-to eight-fold increased risk of having Demodex in acne rosacea patients exists.…”

“…Other factors that may influence the immune system and hence the predisposition to demodicosis, include emotional stress, poor nutrition, poor sleep, ultraviolet phototherapy, skin tumours and concomitant diseases. 26,70,103…”

“…This contrasts to the veterinary literature, which is rich with species-specific Demodex data. [26][27][28][29][30] Although it is believed there are no cross-infections of Demodex between humans and animals, there have been a few reports of suspected D. canis (from dogs) infecting humans. [31][32][33] Early reports of the occurrence of human Demodex were limited to cadaver examinations, which reported prevalence rates as high as 97 per cent.…”

The Anti-Inflammatory Immune Response in Early Trichinella spiralis Intestinal Infection Depends on Serine Protease Inhibitor–Mediated Alternative Activation of Macrophages

“…elminths are considered to have the ability to regulate the host immune system (1,2). In recent years, the immunoregulation mechanism involved in helminth infection has been preliminarily elucidated (3,4). It has been recognized that excretory/secretory (ES) products are responsible for regulating the immune response through their anti-inflammatory effects (5).…”