The incidence of dermatophytoses is becoming increasingly common in developed economies [18, 22, 23] but, in several African countries, this incidence is very high [5, 24–26]. In Cape Verde, despite the clinical empyrical awareness of the same tendency towards a high incidence of dermatophytoses, especially among school-age children in rural areas, there are no reports on dermatophytoses and on which species are more frequent. To our knowledge, this is the first report on dermatophytoses and implicated species ever carried out in Cape Verde. This study was conducted in school-age children, and, at the three elementary schools (total of 249 students in the afternoon shift), 134 children were first selected presenting suspicious signs of dermatophytosis. Among these, only 60 children were clinically considered has having esions compatible with dermatophytoses, and were selected for this study. Of the 60 suspected cases, it was possible to confirme dermatophyte infections in 19 of these children, with a point prevalence of 7.63%, a value lower than that described by several other studies . In the clinical examination of the students, several clinical signs and symptoms were observed, mainly non-inflammatory conditions, scales, and spots similar to seborrheic dermatitis, desquamation of the gray spot, kerion, crust, pustules, hair breakage and loss, nail destruction, and itching in most cases. Dermatophytoses are usually reddish inflammatory lesions, centrifugal, with scaling and occasionally blistering on the edge between the lesion and healthy skin . However, similar lesions can be caused by other organisms, making the clinical diagnosis merely presumptive [27–30]. Most of the selected children, with suspicious dermatophytoses, although with average habits of the daily shower (Table 1), had inadequate hygiene after activities in which could be exposed to fungi such as walking long distances to school, agricultural or animal husbandry activities, usually in their barefoot. Children with such a lifestyle were previously described as having an higher susceptibility of getting dermatophytoses [3, 31]. We also report insufficient health-seeking practices, since even if they attended to a family practitioner and an antifungal was prescribed, there is no monitoring and follow-up of the outcome of the infection/lesion; some were under topical treatment with ethnomedical products (results not shown).
Two different identification methodologies were used, the morphological classical identification of dermatophytes and molecular biology, by ITS-5.8S rDNA sequencing, and several fungal species were isolated and identified out of the lesions. Based on the observation of macroscopic and microscopic features, three species were identified, T. soudanense, T. violaceum, and T. rubrum. However, re-identification using molecular biology, showed only one T. rubrum, with the remaining isolates confirmed to be T. soudanense after sequencing of the ITS region and comparison to the NCBI database. T. soudanense and T. violaceum were considered synonyms by some authors . Recent insights, using MALDI-TOF MS, recognized these as different species of the T. rubrum complex [33, 34]. Moreover, a recent phylogenomic approach revealed ITS sequencing as appropriate to distinguish between the three main species of the T. rubrum complex, T. soudanense, T. violaceum, and T. rubrum . Besides these dermatophytes, we were initially misled by the appearance of the clinican presentation of the lesions and of the macroscopic characteristics of the agar cultures, resembling dermatophytes, but identified as Aureobasidium pullulans, Chaetomium convolutum, and Arthrinium marii, saprophytic and human opportunistic fungi. [36–38]. These results reinforce that dermatophytoses agents cannot be accurately diagnosed based solely on clinical manifestations and on morphological characteristics, with molecular biology techniques assuming an important role in increasing the accuracy, especially in species or strains that do not present typical morphological characteristics, as reported by others [21, 30].
T. soudanense is an anthropophilic dermatophyte endemic in Africa , primarily responsible for tinea capitis and tinea corporis, in children, and more rarely in adults. It is also sporadically isolated in countries with cultural, social, or economic relations with endemic areas, across Europe and North America [22, 23]. A high prevalence of T. soudanense has been reported as a result of growing racial mixing linked to migratory movements, particularly among African immigrants, which confirms the endemic nature of this agent in Africa. Although the number of subjects involved in this study was small, the prevalence of T. soudanense corroborates data from several other studies reporting that T. soudanense, is the most prevalent species of Trichophyton in Central and Western regions of Africa. However, we note that these studies were focused on cases of tinea capitis [24, 39–43], whereas we report T. soudanense as the infecting agent in skin, nails, and scalp.
Considering the non-inflammatory nature of most of the lesions observed and the context of these children's lifestyle, family history, and sociodemographic issues, a presumptive diagnosis of infection by anthropophilic dermatophyte species was raised. However, taking into account some cases of inflammatory lesions, the child's lifestyle consisting of activities exposing them to contact with the ground and animals, it was expected to have a high prevalence of geophilic and zoophilic species. This trend of the switch between zoophylic and anthropophilic dermatophytes was reported by others in India . It is well established that people with dermatophytoses are at risk of spreading the infection to others by direct or indirect contact through shared surfaces and equipment and that the persistence within the same physical environment may represent opportunities for reinfection and disease spread [44, 45]. T. soudanense, has a high epidemiological rate of inter-human transmission. In this study, the sources of infection were unknown. However, most patients from the same school had direct contact with each other, suggesting the contagious nature of these infections. This emphasizes the importance of carrying out periodic epidemiological studies and molecular typing that would allow answering the question of the origin of the isolated strains.
An epidemiological study with accurate identification of dermatophytes is essential for the efficient management of this public health problem [5, 46], because it may 1) help local health providers to differentiate between dermatophytic and non-dermatophytic superficial infections; 2) identify the potential sources of infection by comparing the intra-specific variation; 3) to draw strategies to prevent transmission; 4) to implement the appropriate antifungal therapies [47–49] and 5) to help public health authorities to draw an epidemiological map (i.e., which dermatophyte species are found in the population’s understudy).
Due to the lack of reports or studies on dermatophytes in Cape Verde, it is not known whether the isolated strains were endemic or imported. However, as all the participants were nationals, with no contact with immigrants, it is legitimate to conclude that the dermatophytes species found in this study are endemic. It was left to elucidate whether, in each school, the infections were caused by a single strain that persisted in the population and was transmitted between students or by different strains. Molecular typing of strains could indicate these important epidemiological issues [50–52].
Although our study is limited by its small size, it is a clinical and public health asset in Cape Verde, providing complementary information to the available epidimiological data on the prevalence of dermatophytes infection in Africa, more specifically in an archipelago. Future studies need to be carried out to assess the incidence and trends of change at the national level.