Geographical distribution of the dermatophytes: a review

Superficial Dermatophytosis across the World's Populations: Potential Benefits from Nanocarrier-Based Therapies and Rising Challenges

The most prevalent infection in the world is dermatophytosis, which is a major issue with high recurrence and can affect the entire body including the skin, hair, and nails. The major goal of this Review is to acquire knowledge about cutting-edge approaches for treating dermatophytosis efficiently by adding antifungals to formulations based on nanocarriers in order to overcome the shortcomings of standard treatment methods. Updates on nanosystems and research developments on animal and clinical investigations are also presented. Along with the currently licensed formulations, the investigation also emphasizes novel therapies and existing therapeutic alternatives that can be used to control dermatophytosis. The Review also summarizes recent developments on the prevalence, management approaches, and disadvantages of standard dosage types. There are a number of therapeutic strategies for the treatment of dermatophytosis that have good clinical cure rates but also drawbacks such as antifungal drug resistance and unfavorable side effects. To improve therapeutic activity and get around the drawbacks of the traditional therapy approaches for dermatophytosis, efforts have been described in recent years to combine several antifungal drugs into new carriers. These formulations have been successful in providing improved antifungal activity, longer drug retention, improved effectiveness, higher skin penetration, and sustained drug release.

Phenotypic and Genotypic Identification of Dermatophytes from Mexico and Central American Countries

Dermatophytes are fungi included in the genera Trichophyton, Microsporum, Epidermophyton, Nannizzia, Paraphyton, Lophophyton, and Arthroderma. Molecular techniques have contributed to faster and more precise identification, allowing significant advances in phylogenetic studies. This work aimed to identify clinical isolates of dermatophytes through phenotypic (macro- and micromorphology and conidia size) and genotypic methods (sequences of ITS regions, genes of β tubulin (BT2), and elongation factor α (Tef-1α)) and determine the phylogenetic relationships between isolates. Ninety-four dermatophyte isolates from Costa Rica, Guatemala, Honduras, Mexico, and the Dominican Republic were studied. The isolates presented macro- and micromorphology and conidia size described for the genera Trichophyton, Microsporum, and Epidermophyton. Genotypic analysis classified the isolates into the genera Trichophyton (63.8%), Nannizzia (25.5%), Arthroderma (9.6%), and Epidermophyton (1.1%). The most frequent species were T. rubrum (26 isolates, 27.6%), T. interdigitale (26 isolates, 27.6%), and N. incurvata (11 isolates, 11.7%), N. gypsea and A. otae (nine isolates, 9.6%), among others. The genotypic methods clarified the taxonomic status of closely related species. For instance, the ITS and BT2 markers of T. rubrum/T. violaceum did not differ but the Tef-1α gene did. On the other hand, the three markers differed in T. equinum/T. tonsurans. Therefore, the ITS, BT2, and Tef-1α genes are useful for typing in phylogenetic analyses of dermatophytes, with Tef-1α being the most informative locus. It should be noted that isolate MM-474 was identified as T. tonsurans when using ITS and Tef-1α, but when using BT2, it was identified as T. rubrum. On the other hand, no significant difference was found when comparing the methods for constructing phylogenies, as the topologies were similar.

Current Topics in Dermatophyte Classification and Clinical Diagnosis

Dermatophytes are highly infectious fungi that cause superficial infections in keratinized tissues in humans and animals. This group of fungi is defined by their ability to digest keratin and encompasses a wide range of species. Classification of many of these species has recently changed due to genetic analysis, potentially affecting clinical diagnosis and disease management. In this review, we discuss dermatophyte classification including name changes for medically important species, current and potential diagnostic techniques for detecting dermatophytes, and an in-depth review of Microsporum canis, a prevalent zoonotic dermatophyte. Fungal culture is still considered the “gold standard” for diagnosing dermatophytosis; however, modern molecular assays have overcome the main disadvantages of culture, allowing for tandem use with cultures. Further investigation into novel molecular assays for dermatophytosis is critical, especially for high-density populations where rapid diagnosis is essential for outbreak prevention. A frequently encountered dermatophyte in clinical settings is M. canis, which causes dermatophytosis in humans and cats. M. canis is adapting to its primary host (cats) as one of its mating types (MAT1-2) appears to be going extinct, leading to a loss of sexual reproduction. Investigating M. canis strains around the world can help elucidate the evolutionary trajectory of this fungi.

Prevalence of Tinea Capitis among Children in Osogbo, Nigeria, and the Associated Risk Factors

Tinea capitis is a fungi infection of the scalp that disproportionately affects children in rural and underserved communities in Nigeria. A case-control study was conducted to identify the causative agents and factors that predispose school pupils to tinea capitis in two selected government-owned public primary schools in Osogbo, Southwestern Nigeria. A total of 230 participants were included in the study: 115 cases and 115 controls. Head scrapings were collected from pupils with suspected T. capitis lesions, viewed under Potassium Hydroxide smear microscopy and cultured in Sabouraud's Dextrose Agar (SDA) for characteristic fungal elements. A total of 105 (91%) samples were successfully cultured, of which 56% (59/105) were from male pupils. Tricophyton rubrum (34%), Tricophyton mentagrophyte (31%) and Microsporum canis (18%) were the most prevalent organisms. Other dermatophytes obtained include Microsporum nanuum (3%), Epidermophyton floccusum (6%), Tricophyton verucosum (1%), and Microsporum gypseum (8%). Pupils between the ages of 4 and 7 years had the highest distribution (67%) followed by those between the ages of 8 and 11 years (39%). Playing with animals, the sharing of combs and not bathing with soap were significantly associated with tinea capitis infection (P < 0.05) in each case. This study showed a high prevalence of tinea capitis caused by the identified dermatophytes in the area.

Dermatophytes and dermatophytosis in the eastern and southern parts of Africa

Dermatophytosis is currently a disease of global importance and a public health burden. It is caused by dermatophytes, which attack and grow on dead animal keratin. Dermatophytes belong to three genera, namely, Epidermophyton, Microsporum, and Trichophyton. The predominant clinical forms and causative agents vary from one region of the world to another. Poor socioeconomic status, high population densities, and poor sanitary conditions are some of the factors responsible for the high prevalence of dermatophytosis in many developing countries, which include countries in southern and eastern Africa, the focus of this review. To the best of our knowledge, there is currently no review article on published findings on dermatophytosis in the eastern and southern parts of Africa. This information will be of interest to the medical and research community since the world has become a global village. This review covers published research findings in eastern and southern regions of Africa until this date. The countries covered in the current review include Kenya, Ethiopia, Tanzania, South Africa, Mozambique, Madagascar, Malawi, Rwanda, Burundi, Uganda, Zambia, Zimbabwe, and Botswana. T. violaceum is the most common human etiological agent in all the countries under review with prevalence ranging from 56.7% to 95%, except for Madagascar (M. langeronii, reclassified as M. audouinii), Uganda (M. gypseum) and Malawi (M. audouinii). Tinea capitis was the most clinical type, followed by tinea corporis. Etiological agents of animal dermatophytoses were variable in the countries where they were reported. Major risk factors for dermatophytoses are age, climatic, and socioeconomic factors.

Artemisia sieberi Besser essential oil and treatment of fungal infections

A. sieberi essential oil has been used for treatment of hardly curable infectious ulcers in Middle East Medicine and has been famous due to its wormicide effects. In this review, we evaluated the potency of A. sieberi essential oil in treatment of fungal infections. We searched in PubMed Central, Science direct, Wiley, Springer, SID, and accessible books, reports, thesis. There is a lot of mixed information on chemical compositions of A. sieberi essential oil, but most articles reported α, β-thujones as the main components of essential oils. In vitro studies confirmed the antifungal activity of A. sieberi essential oil against saprophytes fungi, dermatophytes, Malassezia sp. and Candida sp. and these results were confirmed in six clinical studies. The clinical studies confirmed the superiority of A. sieberi essential oil (5%) lotion in improvement of clinical signs of fungal superficial diseases, and mycological laboratory examinations of dermatophytosis and pityriasis versicolor diseases than clotrimazole (1%) topical treatment. The recurrence rate of superficial fungal infections with dermatophytosis and pityriasis versicolor was statistically lower in A. sieberi essential oil (5%) lotion than clotrimazole. There are no adverse effects due to the application of A. sieberi essential oil in clinical studies. Despite, the efficacy of A. sieberi essential oil against Candida sp., there is no clinical study about their related infections. Investigation about the effects of A. sieberi essential oil on fungal virulence factors in order to identifying the exact mechanism of antifungal activity and clinical trials on Candida related diseases are recommended.

The Changing Face of Dermatophytic Infections Worldwide

Dermatophytes evolve along with the geography and socioeconomic conditions. Epidermophyton floccosum, Microsporum audouinii and Trichophyton schoenleinii acted as the major pathogens of superficial fungal diseases 100 years ago, but their frequency decreased dramatically since the middle of the twentieth century and they are limited to some less-developed countries nowadays; meanwhile, frequency of Trichophyton rubrum, Trichophyton interdigitale, Trichophyton tonsurans and Microsporum canis increased gradually, and these fungi have become the major species globally. Some other dermatophytes, i.e., Trichophyton violaceum, Trichophyton verrucosum and Microsporum ferrugineum, are mainly endemic in some parts of Africa, Asia and Europe. At present, T. rubrum is the leading pathogen for skin and nail fungal infections, whereas M. canis, T. tonsurans and T. violaceum present as the predominant dermatophytes involved in tinea capitis. Population mobility, changes in human lifestyle and advents of antifungal drugs will continually drive the dermatophyte evolution in the skin microenvironment. Comprehensive observation is needed to better understand this kind of organisms and prospect the trends of their changes in future.

Dermatophyte and non dermatophyte fungi in Riyadh City, Saudi Arabia

Background

Dermatophytes are a scientific label for a group of three genera (Microsporum, Epidermophyton and Trichophyton) of fungus that causes skin disease in animals and humans. Conventional methods for identification of these fungi are rapid and simple but are not accurate comparing to molecular methods.

Objective

This study aimed to isolate human pathogenic dermatophytes which cause dermatophytosis in Riyadh City, Saudi Arabia and to identify these fungi by using conventional and molecular methods.

Methods

The study was conducted in Medical Complex, Riyadh and King Saud University. Samples of infected skin, hairs and nails were collected from 112 patients. Diagnosis of skin infections, direct microscopic test, isolation and identification of dermatophytes by conventional and molecular methods were carried out.

Results

The results indicated that the tinea capitis infection had the highest prevalence among the patients (22.3%) while Tinea barbae had the lowest. In this study the identified dermatophyte isolates belong to nine species as Trichophyton violaceum, Trichophyton verrucosum, Trichophyton rubrum, Trichophyton mentagrophytes, Trichophyton schoenleinii, Trichophyton concentricum, Microsporum canis, Microsporum audouinii and Epidermophyton floccosum which cause skin infections were isolated during this study. Non dermatophyte isolates included 5 isolates from Aspergillus spp. 4 isolates from Acremonium potronii and 15 isolates from Candida spp. M. canis were the most common species (25% of isolated dermatophytes). Out of the 52 dermatophyte isolates identified by conventional methods, there were 45 isolates identified by the molecular method.

Conclusions

The results concluded that approximately M. canis caused a quarter of dermatophyte cases, tinea capitis infection was prevalent and the molecular method was more accurate than conventional methods.

Fungal skin infections among prison inmates in Abakaliki, Nigeria

Of 402 prison inmates screened for fungal skin lesions, 79 (19.7%) showed skin lesions, which proved mycologically positive by microscopy and culture. Dermatophytes were responsible for skin lesions in 61 (77.2%) of the inmates, while non-dermatophytes accounted for 18 (22.8%) of the lesions. The dermatophytes recovered were mostly anthropophilic and included Trichophyton rubrum 33 (41.8%); T. mentagrophytes var. interdigitale 3 (3.8%); T. tonsurans 3 (3.8%); T. violaceum 2 (2.5%); Epidermophyton floccosum 10 (12.7%). A zoophilic dermatophyte, Microsporum canis, was recovered from 10 (12.7%) cases. The non-dermatophytes were Candida albicans 15 (19%) and Candida spp. 3 (3.8%). Trichophyton rubrum was the most frequently recovered dermatophyte (41.8%) and caused infections in a variety of sites. The groin was the most common site of infection being infected in 50% of the cases by both the dermatophytes and non-dermatophytes. Younger inmates (17-24 years) recorded the highest prevalence of infection (45.6%). Newer inmates (>2 years) were found to be more infected than older ones.

Selective biodegradation in hair shafts derived from archaeological, forensic and experimental contexts

BACKGROUND

Hair is degraded by the action of both dermatophytic and nondermatophytic microorganisms. The importance of understanding hair sample condition in archaeological and forensic investigation highlights the need for a detailed knowledge of the sequence of degradation in samples that have been either buried or left exposed at the ground surface.

OBJECTIVES

To investigate the sequence of biodegradative change to human terminal scalp hair from archaeological and forensic contexts.

METHODS

Cut modern scalp hair from three individuals with caucasoid-type hair was inoculated with soil microorganisms through soil burial in the field and under laboratory conditions to produce experimentally degraded samples. The degraded hair fibres were subjected to detailed histological examination using a combination of high-resolution light microscopy, transmission electron microscopy and scanning electron microscopy to investigate the nature and sequence of degradative change to hair structural components.

RESULTS/DISCUSSION

Degradation was found to occur first within the least structurally robust components that afford the least resistance to microbial/chemical attack. The sequence of degradation (most to least-reflecting degree of vulnerability) in the hair cuticle was as follows: (1) intercellular delta-layer (cell membrane complex); (2) endocuticle; (3) cell membrane beta-layers; (4) exocuticle; (5) epicuticle; and (6) A-layer. In the hair cortex this was as follows: (I) intercellular delta-layer (cell membrane complex); (II) cell membrane beta-layers; (III) intermacrofibrillar matrix/nuclear remnants; (IV) microfibrils; (V) intermicrofibrillar matrix; and (VI) pigment granules (the hair fibre component that was the least vulnerable to degradation).

CONCLUSIONS

The selective progress of degradation in the hair shaft has been charted and this provides a basis for further histological work in better understanding the condition of hair fibres derived from archaeological or forensic contexts as well as being relevant to investigation of diseased hair, in particular hair infected by dermatophytes and hair weakened by genetic hair shaft abnormalities.

Epidemiology of dermatophyte infection in Auckland, New Zealand

This report describes the epidemiology of culture-proven dermatophyte infection in Auckland, New Zealand. The authors undertook a retrospective review of laboratory data for the period from June 1999 to July 2002. There were 10 004 dermatophyte isolates. The most common isolates were Trichophyton rubrum (69%) and Trichophyton mentagrophytes (19%). Microsporum canis was mainly isolated from children. The prevalence of T. mentagrophytes increased with patient age (P < 0.001). Trichophyton rubrum was most common in those aged between 20 and 59 years. The incidence of culture-proven dermatophyte infection was 2.9/1000 population for the year 2000, and the incidence increased with patient age (P < 0.001). It is concluded that dermatophytes causing superficial mycoses in the Auckland region are essentially similar to Australia and other Western countries, although some new organisms are seen as a result of the migration of people from other countries. The incidence of local dermatophyte infection increases with age.

Dermatophytes isolated from patients in University Hospital, Kuala Lumpur, Malaysia

A total of 576 dermatophytes were isolated from patients with a variety of skin infections from January 1993 to May 2000. Ten species of dermatophytes were identified: Epidermophyton floccosum (0.7%), Microsporum audouinii (1.1%), M. canis (3.1%), M. gypseum (0.3%), Trichophyton concentricum (3.5%), T. equinum (0.2%), T. mentagrophytes (36.1%), T. rubrum (53.8%), T. verrucosum (0.2) and T. violaceum (1.0%). The body sites most frequently affected by dermatophytes were the buttocks, nails and trunk. Anthropophilic dermatophytes made up 60.1% of the isolates; the most common species was T. rubrum, T. mentagrophytes and M. canis were the two main zoophilic dermatophytes. T. mentagrophytes was isolated from all body sites except the scalp. M. canis was found to be associated with domestic dogs and was not isolated from ethnic Malays. The only geophilic dermatophyte was M. gypseum, an uncommon dermatophyte associated with tinea pedis.

Etiology of dermatophytoses amongst children in northeastern Nigeria

A survey of dermatophytoses was carried out amongst primary school children in Borno State, Nigeria, during February 1997 to January 1998. A total of 2,193 children aged 4-16 years were screened. Out of these, 154 (7.0%) were proved to be mycologically positive by microscopy, culture or both. Incidence was significantly higher (P <0.05) in young children aged 7-11 years (8.1%) and 4-6 years (6.9%) than in older children aged 12-16 years (3.6%). There was a significant difference in the incidence of dermatophytoses amongst children in urban and rural areas (P <0.05). Tinea capitis was the predominant clinical type followed by tinea corporis. Trichophyton schoenleinii was the most prevalent etiological agent (28.1%), followed by T. verrucosum (20.2%) and Microsporum gallinae (18.4%). Other species recovered included T. mentagrophytes (16.7%), T. tonsurans (10.5%), T. yaoundei (4.4%) and M. gypseum (1.8%).

Tinea faciei due to Microsporum canis abscess formation

Superficial dermatophyte infections are common in children; however, complications are encountered rarely. We describe a child with tinea faciei caused by Microsporum canis, who subsequently developed an abscess. Complete resolution occurred after treatment with oral terbinafine.

Tinea capitis

Tinea capitis is a common dermatophyte infection of the scalp in children. Dermatophytes are classified into three genera; tinea capitis is caused predominantly by Trichophyton or Microsporum species. On the basis of host preference and natural habitat, dermatophytes are also classified as anthropophilic, geophilic and zoophilic. The etiological agents of tinea capitis usually fall in the first and last categories. In North America, tinea capitis is now predominantly due to Trichophyton tonsurans. During the past 100 years the most common North American organism for tinea capitis was initially Microsporum canis followed later by M. audouinii. In other parts of the world the epidemiology varies. Tinea capitis is generally observed in children over the age of 6 years and before puberty, with African Americans being the most affected group. Clinical presentations are seborrheic-like scale, 'black dot' pattern, inflammatory tinea capitis with kerion and tiny pustules in the scalp. The clinical diagnosis should be confirmed by mycological examination. Wood's light examination was of value in diagnosing tinea capitis due to M. canis and M. audouinii; however, it is not helpful in T. tonsurans tinea capitis. Asymptomatic carriers may be a significant reservoir of infection and spread of spores may also involve inanimate objects. Carriers may benefit from shampooing their hair. Treatment of tinea capitis requires an oral antifungal agent. The data from the use of terbinafine, itraconazole and fluconazole are promising and suggest that these agents have an efficacy similar to griseofulvin while shortening the duration of therapy. Both griseofulvin and the newer antimycotics have a favorable adverse-effect profile and are associated with high compliance.

Characteristics of dermatophytoses in Basrah, Iraq

A total of 1199 clinical specimens were collected from 1144 patients clinically diagnosed as cases of superficial cutaneous mycoses in Basrah (Iraq). The collected specimens were examined for the etiologic agents of dermatophytoses by direct microscopy and culture. A total of 237 isolates representing eight species of dermatophytes as a causative agents of skin and nails infections were isolated. Among the tinea infections, tinea corporis and tinea cruris were the most common types of dermatophytoses revealed in this study.

Frequency of Trichophyton rubrum in tinea capitis

Trichophyton rubrum has led to unprecedented worldwide suppression of other dermatophytes which had been predominant earlier as a causative agent of superficial dermatomycoses. In tinea capitis on the other hand, several other species of Trichophyton or Microsporum are dominant depending on the region or continent. Tinea capitis caused by T. rubrum is a rare event worldwide. Occasional concentrations may be explained by several cases occurring by chance in one family or community. The relative frequency of this causative agent in tinea capitis in children is under 1%. In adults, however, where tinea capitis occurs very infrequently indeed, the incidence of T. rubrum appears to exceed 10%. Apart from two studies from India, one from Iran, two from Portugal and observations from Germany, which in the first country report of around 30% of all cases published, while the others document some 10% each, there are not only any conspicuous, unequivocal concentrations at all. Increased frequency of T. rubrum in this clinical picture has not been easily recognizable over the last decades due to low absolute case numbers.

Tinea capitis in south Wales--observations in change of causative fungi

We report an observed change in the causative organisms in 45 consecutive cases of tinea capitis seen in the Cardiff area over the last 9 years. Direct microscopy using potassium hydroxide was positive in all but one case, but this was subsequently positive on culture. This retrospective analysis shows that more cases are being seen in our department, and that a higher proportion of cases are due to Trichophyton violaceum whereas previously we would have expected the majority of cases to be due to Microsporum canis. We believe that the change in causative organism that we have identified has important practical and diagnostic implications. Endothrix fungi such as T. violaceum do not fluoresce under Wood's lamp unlike ectothrix fungi such as M. canis, and therefore failure to perform adequate mycological examination of specimens could result in missed diagnoses. We are not aware of this change having been reported from other UK centres. The finding indicates a need for further prospective epidemiological studies to confirm this apparent trend.

Ecology and epidemiology of dermatophyte infections

Our knowledge of ecology and epidemiology of dermatophytes and the factors influencing their transmission has helped us understand better the natural history of dermatophytoses. It seems that the anthropophilic agents of scalp infection are being eradicated in developing nations. The exception is Trichophyton tonsurans-related tinea capitis in North America. Microsporum canis is a prevalent agent of tinea capitis in many regions of the world, and this could be related to close association of humans with their pets. Trichophyton violaceum is endemic in certain parts of Eastern Europe, Africa, Asia, and South America but not in North America. Trichophyton rubrum is the most common cause worldwide of tinea pedis, nail infection, tinea cruris, and tinea corporis. Although the incidence of tinea capitis is declining in developed nations, tinea pedis and onychomycosis are becoming more common. The increased use of athletic shoes both by men and women and communal bathing could be contributing factors. Five or six species account for most dermatophytoses globally.

Dermatophytes and dermatophytoses in the Milan area between 1970 and 1989

Between 1970 and 1989 we examined 13,019 patients with dermatophytoses in the Milan area, Northern Italy. The results obtained during the 1980-89 period were compared with those obtained in the years 1970-79. From the data collected, tinea corporis emerged as the most frequently observed dermatophytosis, followed by tinea pedis and unguium. As far as dermatophytes are concerned, the dermatological pattern is dominated by Microsporum canis and Trichophyton rubrum. Other species, such as Epidermophyton floccosum, T. mentagrophytes, M. gypseum, T. violaceum, T. verrucosum, T. tonsurans and T. schoenleinii, have progressively become less evident. Other mycetes, such as T. megninii, T. soudanense, M. langeroni, T. vanbreuseghemii, M. ferrugineum, sporadically isolated in the 1970-79 period, have disappeared in recent years. An analysis of the distribution and frequency of the dermatophytes according to the cutaneous area affected is reported.

Review of dermatophytoses in Galicia from 1951 to 1987, and comparison with other areas of Spain

We have reviewed all the dermatophytoses diagnosed in Galicia during four consecutive 9-year periods 1951-86 and 1987. From 4571 patients, we isolated 3351 fungal strains belonging, in decreasing order of frequency, to the following dermatophyte species: Microsporum canis (25.5%), Trichophyton rubrum (24.6%), T. mentagrophytes (21.4%), Epidermophyton floccosum (11.8%), M. gypseum (5.2%), T. tonsurans (3.9%), T. verrucosum (3.1%), T. schoenlenii (2.5%), T. violaceum (1.2%), T. mengninii (0.3%), M. audouinii (0.2%), T. equinum (0.1%) and T. soudanense (0.1%). Tinea capitis has diminished in frequency since 1951, though there was been a slight increase since 1978; M. canis has always been the most common agent, and between 1951 and 1959 T. schoenleinii was also very frequent but is no longer found. The frequency of tinea corporis, on the other hand, has experienced a considerable increase. Its most common causal agents in the last few years have been T. mentagrophytes, M. canis and T. rubrum. Until 1977 the most common tinea cruris dermatophyte was E. floccosum, but since then it has been T. rubrum. The commonest tinea pedis dermatophytes have been T. rubrum and T. mentagrophytes. Tinea unguium and tinea barbae have been the most frequent dermatophytoses, and their commonest causal agents T. rubrum and T. mentagrophytes respectively. We have documented the distribution of the various causal agents by location of the lesions, age and source of the patients (private or National Health Service patients), and we have compared the results with those obtained in other regions of Spain.

Immunoregulation of dermatophytosis

Dermatophytoses are superficial infections caused by a group of fungi, the dermatophytes, which invade keratinized tissue of skin, hair, and nails in humans and animals. The importance of normal immune function in resistance to dermatophytoses is substantiated by an increased susceptibility to chronic infection seen in patients with impaired immunological responses. Humoral and cell-mediated immunities are both elicited during the infection. However, specific antibodies to dermatophytes do not seem to play a major role in protective immunity. On the other hand, the development of cell-mediated immunity during the infection is critical in eliciting resistance to the disease. For instance, resolution of the disease in both naturally and experimentally infected humans and animals correlates with the development of delayed-type hypersensitivity (DTH), whereas persistence of infection is frequently accompanied by poor in vitro blastogenic response and absent DTH. Furthermore, in experimentally infected mice, immunity to dermatophyte infection can be achieved by adoptive transfer of lymphoid cells, but not by serum, of infected donors. The present review includes an overview of published work and current research on the cellular events implicated in immunity to dermatophytosis. The role of humoral factors in such immunoregulation is also discussed.

Dermatophytes in Iceland

Prior to 1982, no reliable information was available on prevailing dermatophyte species or infections in Iceland. In 1983-1984 fungal cultures performed on 96 patients revealed that Trichophyton tonsurans was the most common isolate, followed by Trichophyton mentagrophytes and Trichophyton rubrum. There were no cases of tinea capitis and tinea corporis was rare, but the most common sites of infection were the feet and toenails.

Tinea capitis among children of Ethiopian immigrants

The incidence, clinical appearance and causative agent of tinea capitis among children of Ethiopian immigrants, was studied. Out of 124 children examined, 36 had scalp lesions and 32 cases were confirmed as scalp-ringworm on direct microscopy. Culture showed the dermatophyte to be Trichophyton violaceum. The clinical presentation, resembling seborrheic dermatitis, without clinically apparent hair invasion, was atypical.

[Demonstrated significance of fungal flora in sand-boxes]

In order to evaluate the risk of fungal contamination in sand-boxes of the city of Angers' game areas, the authors took 100 samples of sand from different environments: parks, gardens, buildings, nursery schools. They report the presence of a varied and important mycoflora and that the frequency and the distribution are more sensitive to the techniques used to isolate the fungus, as well as to the quality of the sand and to the eco-mesological factors in the four studied areas. The examination of earth samples has allowed the findings of a great number of keratinophilie species. The strains living in the sand do not represent a real danger of infection for the children.

The changing epidemiology and emerging patterns of dermatophyte species

The anthropophilic agents of tinea capitis are being eradicated from their historic areas in developed and developing nations. The one exception is T. tonsurans in the United States and Canada. In these nations, the infections are increasing among black children, probably because of hair style and hygiene habits. Elsewhere in the world, M. canis has become or is becoming the dominant agent of tinea capitis. Tinea corporis reflects either the dominant agent of tinea capitis or the sphere of T. rubrum. Trichophyton rubrum is the most common agent worldwide of crural and pedal disease and often tinea corporis. The other anthropophilic species, T. mentagrophytes var. interdigitale and E. floccosum, are also firmly established, but as a distant second and third. These five species account for most ringworm worldwide. Other species are of lowlevel infection, are rare, are locally endemic, or--in the case of some anthropophiles--are dying out. The only evidence of active evolution among the dermatophytes is seen in M. canis and T. mentagrophytes. In both, host-specific strains have emerged and will probably separate as species. This probably has happened already in the case of the variety interdigitale of T. mentagrophytes.

A survey of dermatophytes isolated from human patients in the United States from 1979 to 1981 with chronological listings of worldwide incidence of five dermatophytes often isolated in the United States

A survey of dermatophytes isolated from patients seeking medical advice was made from 1979 to 1981 in the United States. The survey included 54 locations with data from 40 cities and 2 states. Correlations of these data with that of the other localities of the world were made to illustrate the dynamic epidemiology of several common dermatophytes. The most often isolated dermatophyte in this survey was Trichophyton rubrum having 53.66% of the total for these three calendar years. In a chronological listing of ringworm infections caused by this organism, many areas of the world have reported similar increased incidence of this pathogen. Trichophyton tonsurans was isolated 27.85% of the total. A dramatic increase of this pathogen as a cause of tinea capitis has been observed in most cities of the United States. It has been isolated in 25 different countries of the world. The percentage of isolation of Trichophyton mentagrophytes was 8.56%. This percentage may not be near the true incidence of infection by this dermatophyte because the infections are mild and respond to treatment without the individual seeking medical advice. Since the 1950s the percentage of isolations of the total has dropped for T. mentagrophytes in the United States. Epidermophyton floccosum accounted for 4.36% of the total. In a few areas of the world it causes over 30% of the total of dermatophytoses. Microsporum canis was isolated 3.72% of the total in the United States. It has recently been reported to be the dominant agent of tinea capitis in several South American countries, Tucson, Arizona and Kuwait. Once the dominant pathogen of tinea capitis in children in the United States, it was replaced by Microsporum audouinii before 1960. Today in the United States, M. audouinii only accounts for 0.30% of the total. It is considered eliminated as a pathogen in England. In this survey, isolated less than 1.0% of the total were Microsporum gypseum. Microsporum ferrugineum , Microsporum nanum , Microsporum fulvum and Trichophyton schoenleinii . Trichophyton meginii and Trichophyton terrestre were reported isolated but no numerical data were available.

[Superficial mycoses in a wooded region of Gabon: results of fungus isolation]

The authors draw up an inventory of the dermatophytes in Gabon (13 species isolated from 593 people in the wet and hot forest). They show the clear prevalence of Microsporum langeroni, Trichophyton soudanense, Trichophyton rubrum, and Epidermophyton floccosum, Trichophyton violaceum also is fairly often isolated. More infrequently, they find T. mentagrophytes, T. mentagrophytes var. interdigitale, T. gourvili, M. canis, M. audouini, T. yaoundei, M. gypseum.

The rise and fall of fluorescent tinea capitis

The epidemiology of tinea capitis has had a remarkable change in the past 20 years. It is important for physicians to realize that most tinea capitis in the United States is caused by Trichophyton tonsurans and that these lesions cannot be diagnosed by the Wood's lamp. Trichophyton tonsurans tinea capitis is frequently misdiagnosed because the lesions mimic such common scalp conditions as dandruff and seborrhea. Further, this organism can cause chronic tinea capitis in women that may become a infectious reservoir for other family members. A negative potassium hydroxide preparation will not rule out infection with T tonsurans and cultures are necessary. Scalp lesions in children should be considered tinea capitis until culturally proved otherwise.