A TEN-YEAR SURVEY OF Tinea pedis IN THE CENTRAL REGION OF THE RIO GRANDE DO SUL, BRAZIL

Um estudo de dez anos sobre a tinha do pé na região central do Rio Grande do Sul, Brasil

A TEN-YEAR SURVEY OF TINEA PEDIS IN THE CENTRAL REGION OF THE RIO GRANDE DO SUL, BRAZIL

Jorge O. LOPES, Sydney H. ALVES, Cristine R. D. MARI, Loiva T. O. OLIVEIRA, Liliani M. BRUM, Jorge B. WESTPHALEN, Fábio W. FURIAN & Márcia J. ALTERMANN

SUMMARY

Tinea pedis is the most common type of dermatophytosis, but can mimic many cutaneous diseases and tend to be chronic. We present a study of the frequency, epidemiology and clinical aspects of tinea pedis in the central region of Rio Grande do Sul during the period 1988-1997.

KEYWORDS: Tinea pedis; Frequency; Epidemiology; Clinical aspects.

INTRODUCTION

Approximately 10 to 20% of the population is estimated to be infected by a dermatophyte and tinea pedis is the most common type of dermatophytosis, occurring in up to 70% of adults with the infection¹. The term tinea pedis is used to encompass several clinically different infections of the skin of the foot. Dermatophytes infect, invade, and persist in the stratum corneum, increasing skin proliferation, which eventuates in scale and epidermal thickening. Infection of the interdigital spaces and plantar surface is characterized by inflammatory and noninflammatory lesions. The major clinical forms of tinea pedis are: 1) intertriginous; 2) plantar hyperkeratosis and 3) vesiculo-bullous infections². Because the infection can mimic many cutaneous diseases and tend to be chronic, it is important to do diagnosis of tinea pedis as early as possible.

We present a study of the frequency, epidemiology and clinical aspects of tinea pedis in the central region of Rio Grande do Sul, Brazil, during the period 1988-1997.

MATERIALS AND METHODS

During the period 1988-1997 a total of 1,986 cases of dermatophytosis were diagnosed in Laboratório de Pesquisas Micológicas of the Santa Maria University Hospital, from which 909(45.8%) of tinea pedis. Skin scrapings obtained from an unique collection from the lesions were clarified with 30% potassium hydroxide for microscopic examination. From cultural studies the skin scales were inoculated on Sabouraud glucose agar with antibiotics(Mycosel, BBL), and then incubated at 25°C for two weeks.

RESULTS

Of the patients, 476(52.4%) were males and 433(47.6%) females, with a male/female ratio of 1.09/1.0. The age of the patients ranged between nine months and 82 years with a peak prevalence occurring after puberty (Table 1); the onset of the lesion ranged between one week and 40 years. Direct examination was positive in 899 (98.9%) of the patients, negative in 9 (1.0%), and an association dermatophyte and Candida was diagnosed in one patient. Cultures failed to grow in 296 (32.6%) cases; in four patients an association of two dermatophytes in the same lesion was disclosed, then 617 strains were isolated. Trichophyton mentagrophytes (48.3%) was the most frequent dermatophyte isolated from tinea pedis in our study, and predominate in the intertriginous and vesiculo-bullous forms, while T. rubrum predominate in the plantar and association forms (Table 2). The intertriginous form of tinea pedis was seen in 50.4% of the patients (Table 3), and in 20.2% association of clinical forms were observed; in 212(23.3%) patients nails were also infected by a dermatophyte. Intertriginous tinea pedis predominate in males, association of clinical forms was diagnosed equally, and the other predominate in females (Table 3). Seasonal variation in the frequency of diagnosis of tinea pedis was observed, with a preponderance in the autumn (Table 4). Eleven (1.21%) patients presented with dermatophytids of the hands, and two patients were infected by HIV.

DISCUSSION

Tinea pedis often begins in the web between the fourth and the fifth toes, and progress to involve the webs, subdigital and interdigital surfaces of the toes. Simple scaling infections are caused by dermatophyte invasion of the stratum corneum. In chronic infections of intertriginous spaces, a fissure of the toe webs with soggy macerated white epidermis may be the only clinical sign. These erosive infections are caused by selection and overgrowth of bacteria, with the production of sulfur compounds that leads to inhibition of dermatophytes and accounts for the lower recovery of fungi from the most severe and chronic cases³. Chronic infections may also affect the soles, heels and lateral surfaces of the feet resulting in widespread furfuraceous scaly patches or hyperkeratotic plaques, called moccasin-type infection. Chronic plantar infections are usually caused by T. rubrum and found primarily in patients with an atopic background. Acute or subacute infections in the arch and sides of the feet due to an immune response of delayed hypersensitivity to T. mentagrophytes², are characterized by episodes of intense inflammation with the formation of vesicles, secondarily infected by bacteria and resulting in the formation of oedematous and painful vesicopustules.

The most prevalent species of dermatophyte may vary from one geographic region to another, like wise their frequency in the clinical forms of dermatophytosis. In a previous study in the central region of Rio Grande do Sul⁴, T. mentagrophytes was the most frequent agent of tinea pedis during the period 1970-1979; the same study revealed an increase in frequency of T. rubrum in tinea pedis during 1980-1987. More recently, other study revealed again the prevalence of T. mentagrophytes in tinea pedis in the same region⁵, while in the metropolitan area of Porto Alegre T. rubrum was the predominant agent of tinea pedis⁶.

Peak prevalence of tinea pedis occurs after puberty¹. The occurrence of the infection in children is uncommon, with a frequency of 2.2% in children aged seven to 10 years, to 8.2% in children aged 11 to 14 years⁷. In the present report the youngest patient aged nine months, and presented a pustulous lesion in the dorsum of the foot caused by M. gypseum, and the total of children aged until nine years with tinea pedis accounts 1.8%. The concept of tinea pedis as an infection that affects predominantly males⁸ need a revision: in our study the male/female ratio demonstrate that both were equally affected.

On the contrary of the report of ZAITZ⁸, seasonal variation in the frequency of tinea pedis apparently having relations with the time of diagnosis: in our study it is impossible to particularize when the patient was infected, since the onset of the lesions ranged between one week and 40 years. On the other hand, Rio Grande do Sul have well defined seasons, and at the end of the spring specially young people search for medical care, with the purpose to frequent swimming pools. However, the peak incidence in the autumn, as sure as can be, signify that the patients had been infected during the summer, resulting from the communal use of swimming baths and restroom.

Tinea pedis must be differentiated from allergic conditions, non dermatophyte fungi, Candida or bacterial infections. Difficulty in delivering a sufficient quantity of antifungals to the lower layers of a thick stratum corneum makes therapy of tinea pedis a problem. Infections often require prolonged therapy with topical or systemic agents, but recurrence occurs in up to 70% of patients. Recurrence is caused mainly by the persistence of infective fungal elements on the skin, socks and shoes. Another issue in the incomplete eradication, when patients stop applying topical therapy because their symptoms are alleviated. If untreated, tinea pedis may be complicated by nail infections, serving the nails as a reservoir for relapses and recurrence of tinea pedis¹.

RESUMO

Um estudo de dez anos sobre a tinha do pé na região central do Rio Grande do Sul, Brasil.

A tinha dos pés é a forma mais comum das dermatofitoses, mas pode simular outras doenças da pele e tende a se tornar crônica. Apresentamos um estudo da freqüência, epidemiologia e aspectos clínicos da tinha dos pés na região central do Rio Grande do Sul durante o período 1988-1997.

Laboratório de Pesquisas Micológicas-LAPEMI, Hospital Universitário de Santa Maria, RS, Brasil.

Correspondence to: Jorge O. Lopes, Departamento de Microbiologia e Parasitologia, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brasil. Fax [phone]. E mail [e-mail]

Received: 25 November 1998

Accepted: 20 January 1999

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Publication Dates

• Publication in this collection
  02 July 1999
• Date of issue
  Mar 1999

History

• Accepted
  20 Jan 1999
• Received
  25 Nov 1998