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An. Bras. Dermatol. vol.80 no.3 Rio de Janeiro May/June 2005
Tinea capitis micro-epidemic by Microsporum canis in a day care center of Vitória - Espírito Santo (Brazil)*
Thaiz Gava Rigoni GürtlerI; Lucia Martins DinizII; Larissa NicchioIII
IPost-graduated by the Dermatology
Service of Emescam - Santa Casa de Misericórdia de Vitória; Dermatology
specialist at Sociedade Brasileira de Dermatologia (SBD)
IIAssistant Professor of Post Graduation Service in Dermatology of EMESCAM (ES)
IIIPost-graduated by the Dermatology Service of EMESCAM (ES)
Tinea capitis of the scalp is an infection of the skin and hair of this area caused by the dermatophytes of the Microsporum and Trichophyton genus. It preferentially attacks pre-school and school children due to their greater contact with infection sources. The authors report a micro-epidemic of Tinea capitis of the scalp in 11 children of a day care center of Vitória (ES), between two and six years of age, 61% of masculine sex. They presented rounded, scaly lesions with tonsured hair, large and unique in the frontal, occipital and parietal regions. In two cases the scalp was diffusely attacked. The direct mycology showed parasitism of the ectothrix type, and 45.5% of the cultures were positive for Microsporum canis, justified by the history of contact between some children of the day care center and stray dogs of the district.
Keywords: Mycoses; Microsporum; Tinea capitis
Tinea of the scalp or Tinea capitis is a skin and hair infection of the scalp caused by dermatophytes of the genu Microsporum and Trychophyton. It is surface mycosis of universal distribution with predilection for tropical and sub-tropical regions, constituting a public health problem in some countries.1
The prevalence of the dermatophytes is variable in the diverse regions of the world and within the same country due to factors such as climate, socio-economical and hygienic conditions of the population, urbanization, immunological system of the host, fungal characteristics and therapeutic actions.1-3 Tinea capitis caused by the Microsporum canis is most frequent in the North of Africa, Europe, Asia and Brazil (South, São Paulo, Rio de Janeiro, Espírito Santo and Goiânia Regions) and the Trichophyton tonsurans in the United States of America, Caribbean, Central America, Australia and Brazil (North and Northeast regions, DF and Paraná).2-7
It most frequently affects children below 10 years of age, pre-school and school range and rarely in post-menopause and immune-compromised women.3,8
The scalp tineas are exogenous infections having man as source of contagion (anthropophilic fungi such as the Trichophyton tonsurans), aanimals (zoophilic fungi, such as the Microsporum canis) and, more rarely the soil (geophilic fungi such as the Microsporum gypseum).1,2,9 Zoophilic dermatophytes determine lesions in the exposed areas of the body (scalp, arms, hands and feet) by direct contact with domestic animals (dogs and cats) or with their hair deposited in the house environment.10,11 The Microsporum canis normally determine tegumentar lesions in the dogs but the cats can be healthy carriers or present small lesions.11 The inter-human transmission of the Microsporum canis is extremely rare.8
Clinically, according to the length of the hair, tinea of the scalp can be classified into:
a) Microsporic tonsuring;
b) Trichophyton type tonsuring;
c) Kerion Celsi type;
d) Tinea favosa.12,13
The direct mycology of the hair shows the type of parasitism of the fungus: ectothrix, endothrix or mixed. The culture in Sabouraud medium with Actidione permits the macroscopic and microscopic characterization of the genus and species of the infecting fungi of the hair.12,13
The therapy of scalp tinea must be done with systemic anti-fungicides such as Griseofulvin, Cetoconazole, Itraconazole, Fluconazole, Terbinafine, and associated topical anti-fungal shampoos of selenium sulfate 2,5%, or Ketoconazole, Imidazoles (Clotrimazole, Econazole, Miconazole, etc.), Allylamines and Ciclopirox olamine.12
15 children from a public day care center of the district of Jesus de Nazareth were sent to the district health center, being that 11 cases had scalp lesions and four on the skin. The day care center is situated on a Hill, the population of which presents low socio-economical conditions.
Eleven children were aged between two and six year and three months ago presented scalp lesions, scaly tonsuring area type; nine patients (81.8%) with large and single areas and two (18.2%) had minor and more diffuse lesions, diagnosed as microsporic tonsuring scalp tinea (Figures 1 e 2). The other four patients presented ring-like lesions with Erythematosus, vesi-crustaceous borders located on the arm and thorax on three of them and on the glabrous skin of one, diagnosed as body tinea.
Of the 11 patients with scalp lesions, eight (61%) were of female sex and all black or pardo.
The frequency of the location of the scalp lesions varied, four cases (36.4%) being in the frontal region, three (27.3%) in the occipital, two (18.2%) on the parietal and two (18.2%) diffuse throughout the scalp.
The direct mycological examination showed parasitism of the Ectothrix type in the hair of the 11 patients (Figure 3), and five patients in the cultures of Sabouraud medium with Actidione (45.5%) the growth of a flat, reverse filamental colony of white coloration and reverse of yellow-gold, was observed, characteristics of Microsporum canis (Figure 4). The cultures of the other six patients were negative. The micro-morphology of the colonies revealed the presence of hyaline filaments, divided, ramifying and macro-conidia fusiforms, with pointed ends, thick walls, spiny, with more than six internal cells (Figure 5). The direct examination of the scales of the patients with body tinea revealed filaments of dematophytes and there was growth of Microsporum canis in three cases and in one of them the culture was negative.
Chart 1 shows in details the clinical characteristics and the results of the examinations of all the patients.
The day care center did not have sand but there was reference to games amongst the children of the day care center and loose dogs on the streets of the district.
The 11 children with scalp tinea were medicated with Griseofulvine in the dosage of 15mg/kg/day and Isoconazol topical solution at night during 45 days, with complete regression of the lesions at the end of the treatment. The patients with body tinea used Isoconazol cream twice per day during 30 days and evolved to total cure of the skin lesions.
Micro-epidemics are defined as epidemic outbreaks in a restricted social context where more than one case of the disease in question is registered.8 The presence of 11 cases of scalp tinea in children frequenting the same day care center therefore characterized a micro-epidemic.
The infected children were between two and six year of age, that is, in the pre-school range, and they presented histories of games with stray dogs in the district, confirming the data of some authors as to the preference for this age range and the contact with animals.6,9,11,14 Brilhante and collaborators refer that contact with domestic animals and games in the sand have little importance in the origin of scalp tinea,4 believing that the predilection for children occurs due to the greater exposure to risk factors such as precarious hygienic habits and agglomerations in day care centers and colleges.3,4
Dogs and cats constitute the principal reservoirs and sources of infection of the Microsporum canis, being that the former present skin lesions and the cats diminutive lesions or they are asymptomatic, representing difficulty in the epidemiological control.11,14 The human infections by zoophilic dermatophytes happen sporadically since these fungi have a low frequency in the environment and are dependent on contact with infected animals.8 The possibility of inter-human transmission of the Microsporum canis is rare,9 however there is this possibility, and it probably occurred between the children of the day care center seeing that the parents denied contact of them with animals.
The male sex was more affected than the female, corroborating some works that show predilection of the scalp tinea for this sex.2,6,9,14
The mechanism of penetration of the dermatophyte in the hair can be explained in the following way: after contact with the scalp of a susceptible individual, the arthrospores form filaments that proliferate until the formation of a mass of filaments in the opening of the hair follicles, which will grow in the direction of the capillary bulb between its external and internal borders. Around the tenth day the filament penetrates the follicle in its medium portion, developing only in the anagenous hairs in a balanced way with the velocity of keratinization of them, thus preventing its elimination.10
The direct mycological examination is fundamental to confirm the suspicious diagnosis of scalp tinea, setting aside the differential diagnoses and favoring therapeutic conduct. The discrepancy between the positive results of the direct examinations of the 11 cases under study (100%) and the cultures for positive fungi in only five of them (45.5%) is admitted, considering the irregular distribution of the fungi in the lesions, the presence of dead or scarce fungal elements, previous treatment of fungi more demanding for development in vitro.3-5 Some children had been submitted to previous treatment with oral Cetoconazole, topical anti-fungicides and household medications, which possibly prejudiced the growth of the fungi in the culture medium.
Trichophyton tonsurans is more prevalent in the United States of America, Caribbean, Central America, Australia and Brazil (North and Northeast regions, Federal District and Paraná). The substitution of the Microsporum canis, previously principal etiological agent of Tinea capitis, by Trichophyton tonsurans in some regions correlates to the changes of social habits, urbanization, the climate, human movement and social-economical aspects such as leisure in clubs, swimming pools and saunas, etc. This fact is worrying given that this agent is anthropophilic and therefore adapted to man and can reach greater relevance from the epidemiological point of view.3
Griseofulvin in the dosage of 15 to 20mg/kg/day during 45 to 90 days has been the therapy of choice for the treatment of scalp tinea due to its efficacy and good tolerance, especially in children, low cost and rare side effects.15
Apart from the medicament treatment, the interruption of the transmission chain must be dealt with, that is, to etiologically diagnose the dermatophytes allowing the general measures of control treatment of the human and animal cases, examination of the parents for research of asymptomatic carriers principally in the cases of infection by Trichophyton tonsurans, cleaning of the environment, hair brushes, combs and caps.12
The scalp tinea of the 11 children and the four patients that presented them on the body were only eliminated after the identification of the etiological agent, treatment of all those infected, orientation as to the care of animals and use of Ketoconazole based shampoos on the possible asymptomatic persons, that is, on the other children of the day care center.
It is also important to remember that the dermatophytes, especially of the scalp, are not diseases of obligatory notification, prejudicing the control and intervention in the risk factors. q
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Thaiz Gava Rigoni Gürtler
Av. Nossa Senhora dos Navegantes, 451
Ed. Petro Tower - conj. 809-811 - Clinica AngioDerm - Bairro Enseada do Sua
29050-335 - Vitória - Espírito Santo
Tel/fax: (27) 2123-1020
Received on July 14, 2003.
Approved by the Consultive Council and accepted for publication on December 08, 2004.
* Work done at Escola de Medicina da Santa Casa de Misericórdia de Vitória - EMESCAM (ES) - Brazil.