Epidemiological Aspects of Tinea Capitis among Children Attending to Koranic Schools in Senegal (Thiés)

1. Introduction

Tinea capitis is a superficial fungal infection of the scalp and one of the most commonly seen dermatophyte infections in children under 12 years of age [1,2]. The main determinants of the disease include low socio-economic conditions, high population densities and poor health practices [3]. In addition, the epidemiology is constantly changing all over the world. These changes have been attributed mainly to the movements of population (migration) and changes in the way of life of populations [4,5]. The spectrum of species responsible for scalp ringworms and their frequency vary from country to country. It is caused by anthropophilic, zoophilic or geophilic depending on whether they are transmitted from one infected human to another, acquired through contact with infected animals or contracted from contaminated soil or fomites, respectively [6]. In Sub-Saharan Africa, Microsporum audouinii and Trichophyton soudanense are predominants [7,8,9]. In Western regions of the world, Trichophyton tonsurans has emerged as predominant cause of tinea capitis [10]. Microsporum canis is the most common cause in central and southern Europe [11]. Trichophyton violaceum is the most common cause in North Africa and Asia [12,13]. Changing trends in the epidemiology of this condition and the emergence of antifungal resistance have been documented and recently reviewed elsewhere [14]. Generally, the diagnosis is based on the clinical aspects of the lesions and the treatment is also administrated without mycological confirmation. The identification of the causal agent allows guiding the appropriate antifungal treatment, which is specific and safe in the pediatric population. In Senegal, tinea capitis is endemic and most of the existing data concern adult and come from hospital with prevalence ranging from 25.7% to 71% [15,16,17]. Date on Tinea capitis among children are scarce. In community area Ndir et al when assessing the epidemiological profile of tinea capitis have noted 3,1% of prevalence in 1994 [19]. The most recent study conducted between 2013 and 2015 found 90% prevalence in 210 children living in koranic school The particularity of Koranic schools where hygiene conditions are precarious and where children often live in promiscuity [20]. Because of the scarcity of data on tinea capitis in children in Senegal, it’s become relevant to conduct furthers studies in order to better understand the epidemiology of the diseases in children and the spectrum of pathogens for better case management. It was in this context we conducted this study aiming at assessing the prevalence of tinea capitis and its related factors in children living in koranic school.

2. Materials and Methods

Study design, area and population

A cross sectional survey was performed from February 2019 to March 2020 in koranic school located in Thiès region which is from 70 km to Dakar. Children were recruited from koranic schools located in the same neighborhood in the region. Students who were at the time of the study at one of the targeted schools were included in the study. Two type of students wre recruited: (i) children who are interned in the koranic school (living during all their studies and (ii) children who attend class daily and return to their home after classes.

Data collection

For each child enrolled in the study, a questionary was administered to collect epidemiological, clinical and biological data. The epidemiological data such as age, gender and living conditions were collected. Age was categorized in tree groups (under 5 years, 5 – 10 years and more than 10 years). Clinical examination was performed in order to collect clinical data (presence of plates, type and border of plates, presence of crusts and squama) and the result of WOOD light. Mycological results were also collected using the same questionary.

Sample collection

For each child included in the study, sample were collected in sterile petri dishes. Specimens were collected at the periphery of the lesion. After sample collection, the petri dishes hermetically sealed in order to avoid contamination. All the material used was sterile.

Mycological diagnosis

Laboratory testing was performed at the laboratory of Parasitology – Mycology of Fann teaching hospital. Direct examination with light microscopy was done using a portion of sample. Before examination 30% of hydroxide potassium was added on a slide in order to digest the keratin and for better isolation of fungal agent. The rest of the sample was cultured in two different media (i) Sabouraud dextrose agar plus Chloramphenicol (0,05%) and Sabouraud dextrose agar plus Chloramphenicol (0,05%) plus Cycloheximide (0,05%). Cultures were incubated at 27°C±2 during four weeks. Sample was negative if any growth of pathogen was not noted after four weeks incubation. In case of positive sample, the idenfication of fungal specie was based on the growth rate, the macroscopic and microscopic aspects of the colony after staining the slide with lactophenol blue.

Statistical analysis

After data collection, data were entered in Excel software and the analysis was performed using Stata software version MP 16 software. Descriptive analysis was performed. Quantitative variables were described in terms of means, standard deviation. For descriptive data, a description in terms of frequency with 95% confidence interval was used. Risk factors were assessed by multivariate survey logistic regression models Significance level of different tests was set at 5% two sides.

Ethical considerations

This study was conducted according to the declaration of Helsinki and existing national legal and regulatory requirements. The protocol was reviewed and approved by the institutional review board of the Cheikh Anta Diop university. Approval number 0258/2017/CER/UCAD. Informed consent of parent or legal representative was required prior the participation to the study. To respect the confidentiality, an identification code was given to each participant.

3. Results

General characteristic of study participants

A total of 110 participants were included in this study. The mean of the study participant was 9.4 ±3. Study population was mainly represented by children between 5-10 years old (58.18%). Children under 5 years and those aged over represent 8.18% and 33.64% respectively. The sex ratio was 2,7. Bathing was found in all children with a daily frequency in 53.6%. Soap was used in 98.2% of cases. The notion of shaving with a frequency of more than once a month in 74.5%. The children were lying on the mattresses in 77.3% and on the floor in 22.7%. Approximately 50.6% of the children slept with more than 2 persons per mattresses (Table 1).

Clinical aspect of lesions

Clinically, 35.5% of the children had large plaques and 64.5% had small plaques. The borders of the plaques were irregular in 17 children (15.4%) and clear in 7 children (5.5%). The presence of scales and crust was noted in 20.9% and 63.6% respectively.

Wood lamp examination was positive in 78.2% (86/110) (Table 2).

Prevalence of Tinea capitis and identified fungal species

Mycological examination was positive in 75 children given a prevalence of Tinea capitis of 68.2%. The main species found were Trichophyton soudanense 93.4% and Microsporum audouinii 2.7%. T. mentagrophytes and T. violaceum and the association T. soudanense + M. audouinii were noted in one patient respectively. Parasitism was endothirx in 86.7% and endo-ectothrix in 13.3% of cases (Table 3).

Risk factors associated with the prevalence of tinea capitis

An association between tinea capitis age group, gender and number of children sleeping on mattresses was noted in this study. Children with age over 5 years were more affected. The prevalence increased with age. In the age group 5 - 10 years, the prevalence was 67.2 (OR=1.63, 95% CI [0.38 - 6.74] p=0.49). In children aged more 10 years it was 72.9% (OR=2.16 [0.48 - 9.69] p=0.32). According to gender, prevalence of ringworm of the scalp was higher in male 68.8% (OR=2.21 [0.29 - 16.38] p=0.44) (Table 4).

In children using soap during their bath, scalp tinea prevalence was 67.6% (OR=2.08 (1.39 - 3.12), p= 0.44).

The results from the analysis showed that the frequency of shaving and the type of sleeping and were not correlated with the prevalence of scalp tinea. Prevalence was higher in children who made shaving once a month (71.4%). Regarding the sleeping conditions, prevalence was more important in children sleeping on mattresses (76%) (Table 4).

The type and border of plate were associated with tinea capitis prevalence. In children with large plate, prevalence was 94.8% (OR=16.05 [3.6 - 71.8] p<10-3). Tinea capitis carriage was higher in children with irregular border plate with 76.5% prevalence % (OR=1.5 [0.46 - 5.16] p=0.48). Positive Wood light examination was correlated with the carriage tinea capitis. Prevalence was 76.6% (OR=5.5 [2.09 - 14.5] p=0.001). The presence of squama and crust was not associated with the prevalence of tinea capitis (Table 5).

5. Conclusions

The present study shows that tinea capitis is endemic among children living in Koranic schools in Thiès, Senegal. The main causative fungal agent is T. Soudanense. The socio-economic conditions such as living conditions could play important role in the transmission. Therefore, further epidemiological studies are needed to better describe the distribution of the disease in urban and rural areas. Molecular identification will allow to better spectrum of pathogens in order to avoid diagnostic errors due to the polymorphism of the colonies of certain species.