Tinea corporis is a fungal infection that affects the skin, with an appearance which is especially frequent on arms and legs.
The infection can present itself in a variety of ways. It usually begins as a pruritic, circular or oval, erythematous and scaly plaque which starts enlarging rapidly. After a while, the rash gets the appearance of a ring with raised red edges, and a clearing in the center of the affected area. The classical inflammatory elements, like scales, crusts or vesicles, on the raised edges can be observed, especially on the advancing border [12]. Other classical features include hair loss in the infected spots, with dry and flaky stretches of skin surround them.
There are 4 main methodologies to diagnose tinea corporis. The first one is the microscopic examination of superficial samples taken from the skin after scraping. Although simple, this method might take several days to complete, because of the slow fungal growth rate, and the case negative results is not sufficient to rule out the presence of infections. Therefore, this method must usually be integrated with more specific ones.
The second diagnostic methodology for the tinea corporis diagnosis is the potassium hydroxide examination (KOH). Potassium hydroxide dissolves the keratin of the epidermal tissue, leaving intact the fungal elements such as the branching hyphane, which is deeply embedded among the epithelial cells. The samples for this clinical procedure must be taken on the borders of the tinea ring, where the fungal yield is highest. The method is effective at detecting fungal elements but not very specific.
Fungal culture, instead, is very specific as procedure, and can be used in addition to potassium hydroxide examination to identify the fungal species responsible for the infection. The culture can grow on several substrata. Sabouraud agar contains neopeptone, polypeptone and glucose but no antibiotics, which means it can easily allow fungal overgrowth. Mycosel, instead, is very similar to sabouraud agar, but contains antibiotics too and can prevent complications due to overgrowth and infections by other microorganisms. Dermatophyte test medium (DTM) is ideal for dermatophyte, because apart from nutrient agar it also contains antibacterial and antifungal agents which prevent other microorganisms from growing, thus allowing a great level of specificity. Whatever is the substratum chosen, the growth must be monitored for at least 2 weeks.
If the above mentioned methodologies are inconclusive to identify the presence of dermatophytes, PCR (polymerase chain reaction) can be employed to amplify the fungal DNA and identify the species of fungus concerned by studying its nucleic acid sequence [13].
Tinea corporis appears moderately contagious and very uncomfortable. As children are frequently affected by this infection, they should be educated on preventive measures , such as avoiding tight clothes and not sharing personal items. If there are pets in the house, they should be checked for the presence of tinea, especially when on the body of the animals signs of tinea infection can be seen, such as hair loss in patches and excessive scratching [10].
In any case, the prognosis of tinea corporis is excellent, with the 70 to 100% of the affected individuals which recover easily after treatment with antifungal medications, provided that the immune system is intact [11].
As previously said, the fungi responsible for tinea corporis are called dermatophytes, from the word “dermatos”, which means “skin”, and “phyte” , which means “plant”. In other words, fungi that normally live on the skin [3], where they get nutrients from keratinized materials [4]. They form a group of around 40 anamorphic species, which produce spores in asexual reproductive cycles. They normally occur in pets, and this is why they are frequently transmitted through animal-to-human transmission. Frequent is also the transmission by person-to-person contact [5] or from personal items recently touched by affected individuals. The persons who are commonly affected by this infection are children and athletes.
The risk of getting tinea corporis is increased in various situations, like being in crowded and humid conditions, wearing tight clothes or playing sports which require a great deal of physical contact. Tine corporis also occurs with a high frequency rate when the immune system is particularly weak for previous conditions or distressful events, or after excessive sweating, since sweat creates an ideal environment for fungi proliferation in the folds and grooves of the skin.
Tinea corporis is particularly common in hot and humid climates, with the ideal climatic conditions for fungi proliferation. Among the agents causing this infection, some of them appear to be more frequent than others. For example, Trichophyton rubrum is responsible for 47% of tinea corporis cases worldwide [6] [7], whereas Microspores canis for the 14%. According to a 5-year study conducted in Kuwait, the group of most commonly occurring agents also includes Trichophyton mentagrophytes (39%), Epidermophyton floccosum (6.2%), Trichophyton violaceum (2.4%), and Trichophyton verrucosum (0.4%) [8].
No significant mortality or morbidity has ever been found for tinea corporis, although it’s well known to greatly affect the quality of life. The infection appears to affect females and males in equal measure, even though its frequency increases in women of childbearing age who are often in contact with affected children. Furthermore, tinea corporis interests all age groups, but its prevalence reaches the highest levels in preadolescences and adolescences, who frequently touch animals and objects infected.
Dermatophytes tend to invade the cornified layers of the skin, nail and hair, where they find the perfect conditions for proliferation. After spreading on the superficial layers, dermatophytes then begin to invade the deeper layers through the action of keratinases, proteolytic enzymes which break the disulfide bonds in keratin-containing substrata. In any case, the invasion remains limited to epidermis, because the fungi are blocked and neutralized by the defense mechanisms found in deeper strata, like serum inhibitor factors or polymorphonuclear leukocytes.
The period of incubation usually lasts between 1 to 3 weeks, after which the infection begins to spread following a centrifugal pattern of invasion. The host body fights the invasion through cell-mediated immunity, but certain organisms turn out to be hard to destroy. Particularly famous is the case of Trichophyton rubrum, exceptionally resistant to eradication due to its cell wall which contains mannan, a polymer of mannose that is particularly effective at inhibiting cell-mediated immunity, hindering keratinocytes proliferation and enhancing resistance against skin’s defense systems [9].
The fungi responsible for tinea corporis prefer warm and moist environments, as these are ideal for fungal development and growth. Thus, avoiding warm and moist conditions is paramount in tinea corporis prevention. This means first of all keeping the skin dry and avoiding tight clothing, which foster sweating in the folds and grooves of the skin, where the perfect conditions for fungi growth might occur. Other major preventive measures include frequently washing hands, avoiding sports which require a great deal of physical contact, and averting the handling of infectious objects and the sharing of personal items.
Tinea corporis is a superficial dermatophyte infection which presents itself with inflammatory or noninflammatory lesions. The organisms responsible for its occurrence belong to the genera of trichophyton, microsporum, and epidermophyton, collectively known as dermatophytes, which according to their favorite host or source can be defined as anthropophilic, if they mostly infect humans, zoophile, if they mostly infect animals, and geophile, if they tend to be found in soil. Tinea corporis is also known with various other names, like ringworm [1], tinea circinata [2] or tinea glabrosa [1].
Tinea corporis is a fungal infection that affects the skin, with an appearance which is especially frequent on arms and legs. The organisms responsible for the occurrence of this infection belong to the genera of trichophyton, microsporum, and epidermophyton, collectively called as dermatophytes, which might infect both animals and humans.
Tinea corporis is particular frequent in hot and humid climates, with the ideal climatological conditions for fungi proliferation. The condition begins as a small, red, itchy area of skin which slowly becomes ring-shaped, with a raised, sometimes scaly edge and a clearer center.
The classical treatment for tinea corporis includes the use of topical antifungals in the milder cases and oral medications in the more severe cases. The main measures for preventing tinea corporis are: keeping the skin dry, not wearing tight clothing, frequently washing hands, avoiding sports which require a great deal of physical contact, and averting the handling of infectious objects and the sharing of personal items.
