Ringworm: Symptoms, Causes, Diagnosis & Treatment

Ringworm, also know as dermatophytosis or tinea, is a fungal infection of the skin caused by dermatophytes, a type of fungi that has a strong affinity to skin's keratin. The most affect areas are, thus, those with higher keratin concentration, such as the skin, hair, or nails. 

Ringworm transmission usually occurs through direct contact with contaminated animals, people, objects or soil, but it can also happen through inhalation of keratin fragments that may be suspended in the air. 

This type of infection is more common in people whose occupation encourages direct contact with fungi, such as farmers or athletes, but it is also frequent in people with health conditions that favor fungal proliferation, such as diabetes. 

Ringworm: Symptoms, Causes, Diagnosis & Treatment

Main causes and symptoms

The causes and symptoms of ringworm can vary according to the type of fungal infection:

1. Tinea pedis

Tinea pedis is a type foot ringworm that is popularly known as athlete's foot. It is a common condition in athletes, since they tend to wear closed shoes with sweaty socks for longer, promoting fungi develop. 

The main symptoms of athlete's foot include itchiness in between the toes, flaky skin and whitening in the area, as well as foul smell.

2. Tinea capitis

Tinea capitis is a type of ringworm that affects the scalp and it can be caused by Trichophyton tonsurans or Trichophyton schoenleinii, which cause different symptoms.

Trichophyton tonsurans is characterized by the appearance of small dry plaques of alopecia, i.e., areas where there is no hair. Trichophyton schoenleinii may cause the development of big white plaques on the head, similar to dry crusts.

3. Tinea cruris

Tinea cruris is a type of ringworm that affects the groin area, inner thighs and buttocks. This type of ringworm is also known as glabrous skin mycosis or jock itch, and it can affect other areas that have no hair.

Signs and symptoms of tine cruris normally includes itchiness, redness and skin irritation.

4. Tinea corporis

Tinea corporis is the ringworm of the body that can cause characteristic pink patches with a red border, itchiness and sometimes flaky skin. 

5. Onychia

Onychia is a type of ringworm that affects the nails and it usually causes alteration in the coloring, shape, and thickness of the nails. 

How is ringworm diagnosed

Ringworm diagnosis is based on laboratory tests, as well as the characteristics of the lesions caused by the fungal infection. However, visual assessment of the lesions is not sufficient on its own to confirm the diagnosis, since many signs and symptoms can be confused with other skin diseases. Therefore it is recommended to collect some samples of the affected area (skin, hair, and nails) to be analyzed microscopically.

The classic diagnosis of dermatophytosis happens with two tests: the first is a direct test, in which the samples are observed in a microscope as soon as they arrive at the laboratory. The second is a culture test, in which the collected sample is placed in a suitable environment so that fungi can grow, confirming the diagnosis.

Another complementary test that can be carried out is a Wood's lamp exam, in which a UV light is applied to the affected region in order to verify if fluorescence happens. This is because some fungi react to the presence of UV light, allowing them to be identified more easily.

Treatment options

In most cases, treatment for ringworm is topical, so the doctor may recommend lotions or cremes that have antifungal properties, with ingredients like clotrimazole or miconazole. In case of more extensive lesions or in the case of nail or scalp ringworm, oral antifungal medication may also be necessary.

The best oral medication to treat tringworm are terbinafine and griseofulvin, both of which should only be used under doctor prescription. Griseofulvin should not be used to treat ringworm in children.

Home treatment

There are some plants that can help treat ringworm and relieve itchiness, as they contain antifungal and healing properties. These include sage, cassava, aloe vera, and tea-tree. 

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References

  • BARER, Michael E. et al. Medical Microbiology - A guide to microbial infections: pathogenesis, immunity, laboratory investigation and control. 19 ed. Elsevier, 2018. 579-585.
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