Eur. J. Pediat. Dermatol.                                                                                                   Contents vol. 9, 1999
9, 25-8, 1999


Demodicidosis in a child infected with acquired immunodeficiency virus*.

Patrizi A., Trestini D., D’Antuono A., Colangeli V.*
Dipartimento di Medicina Clinica Specialistica e Sperimentale
Sezione di Clinica Dermatologica, *Sezione di Malattie Infettive
Università degli Studi di Bologna

*Presented in the XXIX National Congress of the "Società Italiana di Malattie Infettive" (1997).

Summary Mites such as Demodex folliculorum and Demodex brevis are natural hosts of the human pilo-sebaceous follicle. The spectrum of the skin disorders due to these parasites includes follicular pityriasis, papular and pustular eruptions of the scalp, acne rosacea, some cases of blepharitis, perioral dermatitis, pustular folliculitis and hyperpigmented plaques. The presence of Demodex in the human skin is directly related to the age of the subject. Therefore, it is present in almost all aged people, whereas it is exceptionally found in children aged less than 5-10 years. This is probably due to the different activity of the sebaceous glands at various ages. As a matter of fact, the highest concentration of Demodex is found in the cutaneous areas with more numerous sebaceous glands and more abundant sebum production (naso-labial folds, nose, forehead and perioral region). The Authors report a case of demodicidosis in a 7-year-old child, who was HIV positive since birth, because vertically infected by his drug addict mother. On physical examination, papular and nodular lesions were located on the face, neck, shoulders and "décolleté". Topical metronidazole was responsible for worsening of the clinical features. On the other hand, the latter regressed after treatment with topical crotamitone. The compromission of the immune system favors the growth of Demodex. As a matter of fact, the rare cases of childhood demodicidosis so far reported in the relevant literature prevalently occurred in markedly immunocompromised children, such as children with leukemia undergoing chemotherapy and children infected with the human immunodeficiency virus. Most authors believe that the altered immune system, which is characteristic of the acquired immunodeficiency syndrome, favors the growth of this usually saprophyte agent so that the latter eventually causes a skin disorder. On the other hand, some authors suspect an unusual hypersensitivity against the mite itself.

Key words Demodicidosis, AIDS.

Demodex folliculorum (DF) and Demodex brevis (DB) are the most common human ectoparasites. DF and DB belong to the Democidae family of the subclass mites. DF and DB are cigar-shaped mites. They are very similar, although DF is larger in any maturative stage than DB in the corresponding stage. Their usual homing is the pilosebaceous follicle and the sebaceous gland respectively in the seborrheic regions such as the nose, temporal regions, nasolabial folds, periorbital areas and finally, in lesser amounts, the upper and medial region of the chest and back (16). In males these parasites are more numerous as compared with females. Moreover, DF and DB increase with age, although a recent report of Forton e Seys does not support this view (8). On the other hand, DF and DB are exceptionally shown in children, especially under five years old. In fact, only after the age of ten starts the colonization of the skin by these parasites, due to the increased sebum production (7). The role played by Demodex mites in the pathogenesis of the skin disorder is still debated, in contrast with their well-known importance as causative agents of various diseases in veterinary medicine (7).
Demodicidosis or demodicosis are called the skin disorders in which increased amounts of Demodex mites have been shown and the pathogenetic role of the latter can be hypothesized.
Demodicidoses include pityriasis folliculorum and rosacea-like demodicidosis. Both the disorders were reported by Ayres and Ayres in 1961 (1).
Moreover, the causative role of Demodex mites is strongly suspected in perioral dermatitis, blepharitis and rosacea, mainly in the variant with papular and pustular lesions (7). A normal function of the immune system is probably important in contrasting the proliferation of Demodex mites (7).
Here is reported a case of demodicidosis in a child infected with acquired immunodeficiency virus.

Case report

A 7-year-old child with symptomatic HIV and HCV infection, which had been vertically transmitted by his drug addict mother, presented with an eruption on the face, neck, shoulders and upper part of the trunk, lasting from 10 days.
The patient had been treated wih zidovudine during the first two years, thereafter with didanosine till the age of six and finally with a protease inhibitor (Indinavir) and an inverse transcriptase (Zalcytabine). The patient was being treated with the last treatment when presented the skin eruption.
The history showed numerous febrile episodes with productive cough treated with antibiotics and sulphonamides during the first three years. From the age of three towards the patient presented with an interval of six months two episodes of interstitial pneumonia, one of which associated with pericardial effusion and numerous episodes of recurrent herpes simplex labialis, one of which with fever. Finally, when aged six years, he presented lung mycobacteriosis treated with alternated clarythromicin and rifampicin.
At the time of the first visit the laboratory examinations showed anemia, leukopenia (2,900/cmm), with reduction of CD4+ lymphocytes (11) and of CD4+/CD8+ ratio (0.05). Moreover, hyposideremia and slightly increased transaminases (GOT 67 U/l, GPT 39 U/l) were shown. The latter were attributable to HCV infection.

   
Fig.1:Erythematous papules of the face, sometimes surmounted by vesicles or vesicles and pustules.   Fig. 2: Worsening of the clinical features after
treatment with topical metronidazole.		   Fig. 3: Demodex folliculorum.

On physical examination, isolated, slightly itchy erythematous papules and papulo-pustules were shown on the face, mainly on the cheeks (Fig. 1), on the nape of the neck and in lesser amounts on the shoulders and "décolleté".
On direct microscopic examination by scotch test according to the technique proposed by Varotti et Al. in 1981 (21), numerous Demodex mites were shown (Fig. 2), thus confirming the clinical hypothesis of demodicidosis.
The treatment with topical 0.75% metronidazole was responsible for a deterioration of the clinical features (Fig. 3), whereas 10% topical crotamitone led to the regression of the skin disorder.

Discussion

Demodicidosis in patients infected with immunodeficiency virus was already reported in the relevant literature, both in adults (2, 3, 4, 6, 3, 13, 19) and in children (4, 5, 9, 10, 17, 18). Particularly, some of the pediatric cases regarded leukemic patients with drug induced immunodepression (5, 9, 10, 17, 18) and two cases regarded children with acquired immunodeficiency syndrome (4, 18).
Most Authors believe that the altered immune system, which is characteristic of the acquired immunodeficiency syndrome, favors the growth of this usually saprophyte agent so that the latter eventually causes a skin disorder. On the other hand, some authors suspect an unusual hypersensitivity against the mite itself. The latter view is based on the pathological findings of demodicidosis showing a dermal infiltrate of lymphocytes and eosinophils and typical granulomas prevalently composed by CD4+ T helper lympho-cytes, which are often distributed around a Demodex body (15). However, a so marked inflammatory reaction mediated by CD4+ T helper lymphocytes can be hardly understood in patients with acquired immunodeficiency syndrome.
Bacterial, viral and mycotic infections as well as infestation with mites of scabies are much more frequently reported (10, 11, 12) in children with AIDS than infestation with Demodex mites.
However, even infestation with Demodex should be considered in subjects with HIV infection, both in the early stage with slight immunocompromission (18) and in the fully developed disease with marked decrease of CD4+ lymphocytes (14), as in our case.
Demodicidosis mainly affects children with diseases causing immunodeficiency. However, 8 immunocompetent children with cutaneous lesions of the face consistent with the diagnosis of demodicidosis have been recently reported in the relevant literature (11).
All these patients responded to a 3-week cycle of topical metronidazole. The treatment with topical metronidazole and erythromicin per mouth is effective in most patients with Demodex infestation.
On the other hand, in our case topical metronidazole was absolutely not effective. Also other Authors (14, 22) successfully treated with topical crotamitone adult patients with HIV infection and demodicidosis, who did not respond to topical metronidazole.



Address to: Dr. Annalisa Patrizi
Dipartimento di Medicina Clinica Specialistica e Sperimentale
Sezione di Clinica Dermatologica
Via Massarenti, 1 - 40138 Bologna (Italy)


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