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CASE REPORT Table of Contents   
Year : 2008  |  Volume : 1  |  Issue : 2  |  Page : 70-71
Human demodicidosis

Department of Pathology, JN Medical College, AMU, Aligarh, India

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The role of demodex mites in the pathogenesis of skin disorders in humans is still debated in contrast to their well known role as causative agents of various diseases in veterinary medicine. The authors here take the opportunity to report a case of demodicidosis in a 28-year-old male.

Keywords: Demodicidosis, demodex brevis, demodex folliculorum

How to cite this article:
Hasan M, Siddiqui FA, Naim M. Human demodicidosis. Ann Trop Med Public Health 2008;1:70-1

How to cite this URL:
Hasan M, Siddiqui FA, Naim M. Human demodicidosis. Ann Trop Med Public Health [serial online] 2008 [cited 2021 Jan 24];1:70-1. Available from:

   Introduction Top

Infectious folliculitis has various etiologies, including bacteria, viruses, fungi, and parasites. Demodex mites can normally be found during a skin biopsy, however, at times, it may cause an inflammatory reaction or folliculitis requiring treatment. Accurate morphological recognition of microorganisms carries paramount importance in the implementation of appropriate therapy.

   Case Report Top

A 28-year-old male presented to dermatological out-patient department, Jawaharlal Nehru Medical College and Hospital with a complaint of an itching reddish area on his left cheek for the last 1 month. No associated pain was felt. The patient had consulted a private practitioner but was not responding to treatment and was referred to this hospital.

On general examination, the patient was a middle-aged male of average built and nutrition. His vitals were normal and a systemic examination was not contributory. A local examination revealed an erythematous and papulopustular non tender eruption on his left cheek measuring 3x2 cms. Routine blood analysis and chest X-rays were normal. A serological test for HIV was negative.

The patient was given topical corticosteroids and metronidazole. However, the patient found no relief even after 4 weeks of treatment. A skin biopsy was performed, which revealed demodex mites in the follicular ostia surrounded by a dense lymphocytic infiltrate in the dermis [Figure 1] and [Figure 2]. The patient was diagnosed with a case of demodicidosis and was given topical crotamiton. He showed complete clearing after 4 weeks.

   Discussion Top

Demodicidosis or demodicosis are skin disorders in which increased amounts of demodex mites are seen. Demodicidosis was first reported by Ayres in 1930. [1] Demodex folliculorum and demodex brevis are human ectoparasites belonging to the democidae family of the subclass mites. [2] Demodex is a parasite of the pilosebaceous follicle and the sebaceous gland in the seborrheic regions such as the nose, temporal regions, nasolabial folds, periorbital areas, and less commonly in the upper and medial region of the chest and back. [3] Demodex folliculorum is more commonly localized on the face while demodex brevis is more commonly found on the neck and chest. [4]

The number of demodex mites present in the lesion increases with age. [4] Demodicidosis is exceptionally seen in children less than 5 years of age. Delfos, et al., have stated that the rate of infestation in healthy individuals is age dependent and is almost absent in healthy children. [5] In fact, Forton is of the opinion that colonization of skin by demodex mites usually starts after 10 years of age due to increased sebum production. [4]

The pathogenesis of demodicidosis is still debated. Many authors believe the growth of demodex mites is favoured by the altered immune system, especially in immunodeficient individuals, which eventually causes a skin disorder. However, some authors suspect an unusual hypersensitivity against the mite itself, as histopathological examination reveals a dermal infiltrate of lymphocytes, eosinophils, and typical granulomas predominantly composed of CD4+ T helper lymphocytes, which are often distributed around a Demodex body. [6]

Rosacea of demodicidosis needs to be differentiated from common rosacea. Demodex type rosacea is characterized by dryness, follicular scaling, superficial vesicles, and pustules, while common rosacea is characterized by oily skin, absent follicular scaling, and is more deeply seated. On microscopic examination, a large number of demodex mites are seen in demodicidosis. [7],[8] Another useful feature is the complete resolution of demodicidosis on treatment with crotamiton or lindane, but not by drugs effective against rosacea, such as metronidazole, which have no direct action on demodex mites. [9]

   References Top

1.Ayres S Jr. Pityriasis folliculorum (Demodex). Arch Dermatol Syphilol 1930;21:19-24.  Back to cited text no. 1    
2.Patrizi A, Trestini D, D'Antuono A, Colangeli V. Demodicidosis in a child infected with acquired immunodeficiency virus. Eur J Pediat Dermatol 1999;9:25-8.  Back to cited text no. 2    
3.Rufli T, Mumcuoglu Y. The hair follicle mites Demodex folliculorum and Demodex brevis: Biology and medical importance. Dermatologica 1981;162:1-11.  Back to cited text no. 3    
4.Forton F. Dιmodex et inflammation pιrifolliculaire chez l'homme: Revue et observation de 69 biopsies. Ann Dermatol Venereol 1986;113:1047-58.  Back to cited text no. 4    
5.Delfos NM, Collen AF, Kroon FP. Demodex folliculitis: A skin manifestation of immune reconstitution disease. AIDS 2004;18:701-2.  Back to cited text no. 5    
6.Rufli T, Buchner SA. T-cell subsets in acne rosacea lesions and the possible role of demodex folliculorum. Dermatologica 1984;169:1-5.   Back to cited text no. 6    
7.Bonnar E, Eustache P, Powell FC. The Demodex mite population in rosacea. J Am Acad Dermatol 1993;28:443-8.  Back to cited text no. 7    
8.Purcell SM, Hayes TJ, Dixon SL. Pustular follicutis associated with Demodex folliculorum. J Am Acad Dermatol 1986;15:1159-62.  Back to cited text no. 8    
9.Gamborg Nielsen P. Metronidazole treatment in rosacea. Int J Dermatol 1988;27:1-5.  Back to cited text no. 9    

Correspondence Address:
Mahboob Hasan
C-11 Medical Colony, Aligarh Muslim University, Aligarh 202 002, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1755-6783.50690

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  [Figure 1], [Figure 2]


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