Ringworm

Definition

Ringworm is a fungal infection of the skin. Despite it’s name it is not actually caused by parasitic worms but by different species of fungi (a specific type of organism). Although ringworm is a common name for this disease, the proper medical term is Tinea (the Latin word of a gnawing worm) or dermatophytosis (the term comes from the word dermatophyte- a parasitic fungus on the skin). Medical stuff can use the term ringworm because often (but not always), a reddish, ring-shaped lesion is seen on the affected skin. These infections can occur in people and some species of animals like cats, dogs, sheep or cattle. They represent a very common problem amongst the world population – according to some estimates, up to 20% of people will be affected at least once in their lifetime.

Ringworms can infect different body parts: the head, trunk, arms, the groin area, the beard area or feet. It is a very infective disease which can spread easily between people, by touching animals or infected items. The fungi which cause this type of disease love moisture, so warm, moist areas of the body are more susceptible to them.   Classic clinical findings of a ringworm infection include a reddish ring with a lighter center, scaling and sometimes even blistering of the skin. The skin lesion can be single or multiple, itching can be a feature or not. Sometimes the fungal disease gets complicated by a bacterial infection. If the ringworm infection is mild and short lived, over-the-counter lotions, powders and creams will usually suffice and the problem will go away in a couple of weeks (usually about four). If the infection gets worse, deeper, if it keeps coming back or if it is located on the scalp, an appointment with the doctor must be scheduled and oral antifungal drugs prescribed.
What does ringworm look like

Classification

Ringworm infections are usually classified by the part of the body where the infection is taking place. The most common are listed below:

Ringworm pictures

Another condition with the same name is Tinea versicolor (also called pityriasis versicolor) which, despite its name, is not a classic ringworm infection because it’s not caused by dermatophytes but by a yeast named Malassezia furfur.

In most cases, the ringworm infection is confined to the upper part of the skin (called epidermis). Sometimes the pathogens can invade the more deeply lying parts of the skin (the dermis) – this is called a Majocchi’s granuloma.

The classification can also be made according to the host preferences the fungi have:

  • Humans (anthropophilic species): anthropophilic species are adapted to humans and can be transferred by direct human – human contact or by infected skin particles (retained in clothes, combs, towels). Because these species are specific to humans the immune response they trigger is usually mild.
  • Animals (zoophilic species): zoophilic species get transmitted by direct contact with the infected animal or by coming into contact with animal hair. Common sources of infection are cats, dogs, rabbits, guinea pigs, horses, cattle, birds or other animals. Favored sites of infection are exposed skin parts like the beard, hands, face and scalp. Zoophilic fungi have adopted to the animal host so the infection in them can be somehow silent. In humans these organisms can produce an intense inflammation.
  • Soil (geophilic species): the geophilic species usually infect people that work with soil. Sometimes, however, animals can carry them as vectors. The infection with this kind of fungi usually results in an intense inflammatory response in humans.

Epidemiology

All the time we are surrounded by a vast number of fungi, but not all of them are harmful to our health. There is about 1.5 million known species of fungi worldwide. Nowadays, there are about forty recognized species of dermatophytes, but most of the infections are caused by three of them: Epidermophyton, Trichophyton and Microsporum. These organisms have a specific feature – they can metabolize and survive upon nonviable keratin (a structural protein of the skin, resistant to other pathogens). Because of this unique behavior they tend to infect the places where there is a lot of keratin- the skin, hair follicles and the nails.

fungi picture

Age: ringworm can affect people of all ages but there are certain specifics to the age of onset- children, for example, usually get scalp infections, young and older patents present with intertriginous rashes (the place where two skin areas touch each other) and the incidence of nail infections correlates greatly with age (up to 50% of 75 year old individuals is supposed to be affected). In general, however, the differences in the incidence between age groups is belived to reflect the rates of exposure, clothing and the immunity decline in older people.

Race: the reported incidence is lower in adult Afro-American people but Tinea capitis in more common in children of the same race.

Who gets the infection: dermatophytosis usually occurs in healthy people, but immuno compromised individuals (like those with AIDS, cancer or those who are taking certain kinds of drugs) are more likely to develop this disease.

The features of a dermatophyte infection are a combination of the hosts immune response to the offending organisms and the destruction of keratin in the affected site.

Spread:

Tinea is a contagious infection that can be spread from one person to another or by touching an infected animal (like a dog or a cat). Another way of getting sick is by touching infected objects like a comb or other personal care items, towels, clothing, locker room floors, pool surfaces, public transport or theatre seats or pillows. It is also possible to transfer the pathogens from one part of your body to another or to get ill by being exposed to the infected soil (although this is not a very common route of transfer).

Predisposing factors:

Some factors or states predispose to ringworm infections. They include:

  • Prolonged moisture affecting a part of the body: a common place where the infection develops is between skin folds.
  • Atopic diathesis: a predisposition to develop one or more of several allegic diseases.
  • Topical immunosuppresion: prolonged usage of creams with glucocorticoids (a type of anti inflammatory drugs).
  • Immunocompromised patient (cancer patients for example): dermatophyte infections in these patients occur more often and tend to progress deeper in the skin sometimes forming granulomas (an inflammatory tumor or growth composed of granulation tissue)
  • Diabetes, obesity and poor circulation
  • Conective tissue diseases
  • Use of topical corticosteroids and shaving
  • Climate, footwear and lifestyle

Prevention:

Ringworm infection is a easily spreadable disease. Close contact with an infected person, animal or object can all result in serious consequences. Because of that it is very important to take precautions when possible:

  • Avoid walking without shoes in places where it is possible for you to catch fungal infections (locker room, pool areas)
  • Try to wear comfortable footwear so your skin can breathe
  • Take care of your nails: clip them regularly and keep them clean, change your socks every day
  • Keep your skin dry and clean
  • Do not touch animals with visible bald spots because a fungus may be the reason for it. If you do pet animals wash your hands with hot water and soap after.
  • Try not to share personal care items such as combs, towels or pieces of clothing
  • If you suspect someone or something you came into contact with may be infected, wash all possibly contaminated objects with fungicidal soap and hot water.
  • Athletes mush shower after practice and keep their clothes and gear clean.
  • If your child has ringworm infection do not send him to school. Consult a pediatrician and contact the school he/ she is attending.
  • Wash your hair with shampoo regularly (especially after getting a haircut)

Diagnosing ringworms:

Sometimes a ringworm infection is so characteristic that the doctor is able to diagnose it just by examining the affected place. The doctor usually sees a reddish, raised, ring with scales that can be further complicated by a bacterial infection. Other times, however, some specific tests need to be performed:

  • Direct microscopy: scrapings of skin, nail clippings or pieces of hair are colected, treated with potassium hydroxide (KOH) and then examined under a light microscope. This is a easy, inexpensive and highly sensitive way to diagnose dermatophytosis.

 potassium hydroxide (KOH)

  • Wood light (a UV lamp): hair infected with specific fungi from Microsporum spp. emit a green-blue light when illuminated with this lamp.

Wood light (a UV lamp)

  • Fungal cultures: specimens collected from an infected site (usually with a brush) are placed into a fungal culture plate, cultivated and then observed under a microscope after being colored with a set of specific pathology stains. The fungal culture is a test that is more specific than the KOH stain but because it takes up to three weeks to perform it is done just in cases when other diagnostic test were inconclusive.

Agar - Fungal cultures

Treatment:

The treatment of ringworm infections depends on the location and the seriousness of the inflammation. If the infection is mild some over-the-counter powders, lotions and creams will alleviate the symptoms and cure the disease. However, if the disease does not get better in a couple of weeks, if it gets worse or if it’s located on the scalp, the doctor must be consulted.

  • Dermatophytosis of the skin ( tinea of the foot, groin): the treatment of choice consists of topical creams, powders or lotions that must be applied to the skin for about two to four weeks. Topical treatment is safe and cost-effective. Some of the most used are Clotrimazole, Mikonazole, Terbinafine and Ketoconazole. After the symptoms resolve the medicine should be used for another seven days.
  • Tinea capitis (ringworm of the scalp): gets usually treated with orally taken anti fungal medications for one to three months. Medications that the doctors prescribe include Griseofulvin, Terbinafine, Itraconasole and Fluconasole.

Dermatophytosis of hair (trichomycosis):

ringworms (also called dermatophytes) are able to infect the skin, nails or hair. When the infection occurs in the hair it causes a condition called dermatophytic trichomycosis which can show in different ways:

  • Tinea barbae: when the infected hair are in the beard area
  • Tinea capitis: when the organisms attack the scalp
  • Dermatophytic folliculitis: an inflammatory process that affects the hair follicles. May also be caused by bacteriae or viruses.
  • Majocchi granuloma: a ringworm infection that has spread to deeper parts of the skin-the dermis.

Dermatophytes Ringoworm

Two types of hair involvement are usually seen with a light microscope- ectothrix (where the fungus is seen on the surface of the hair shaft) and endothrix (where the fungus is seen inside the hair shaft).

References:

Cdc.gov, 2015, People at Risk for Ringworm | Ringworm | Types of Diseases | Fungal Diseases | CDC. [online]. 2015. [Accessed 9 January 2015]. Available from: http://www.cdc.gov/fungal/diseases/ringworm/risk-prevention.html

Fitzpatrick, Thomas B and Wolff, Klaus, 2008, Fitzpatrick’s dermatology in general medicine. New York [u.a.] : McGraw-Hill.

James, William D, Berger, Timothy and Elston, Dirk, 2011, Andrew’s Diseases of the Skin. London : Elsevier Health Sciences.

Medscape.com, 2015, Tinea Capitis: A Review. [online]. 2015. [Accessed 9 January 2015]. Available from: http://www.medscape.com/viewarticle/569799

Melissa Conrad Stöppler, MD, 2015, Ringworm Pictures, Treatment, and Tinea Facts. MedicineNet [online]. 2015. [Accessed 9 January 2015]. Available from: http://www.medicinenet.com/ringworm/article.htm

Merckmanuals.com, 2015, Overview of Dermatophytoses (Ringworm, Tinea): Fungal Skin Infections: Merck Manual Home Edition. [online]. 2015. [Accessed 9 January 2015]. Available from: http://www.merckmanuals.com/home/skin_disorders/fungal_skin_infections/overview_of_dermatophytoses_ringworm_tinea.html

Miljković, Jovan, Borko, Elko and Kansky, Aleksej, 2013, Kožne in spolne bolezni. Maribor : Fakulteta za zdravstvene vede.

Nlm.nih.gov, 2015, Ringworm: MedlinePlus Medical Encyclopedia. [online]. 2015. [Accessed 9 January 2015]. Available from: http://www.nlm.nih.gov/medlineplus/ency/article/001439.htm

Rook, Arthur and Burns, Tony, 2010, Rook’s textbook of dermatology. Chichester, West Sussex, UK : Wiley-Blackwell.

Wikipedia, 2015, Tinea capitis. [online]. 2015. [Accessed 9 January 2015]. Available from: http://en.wikipedia.org/wiki/Tinea_capitis

Wikipedia, 2015, Dermatophytosis. [online]. 2015. [Accessed 9 January 2015]. Available from: http://en.wikipedia.org/wiki/Dermatophytosis

Wolff, Klaus, Johnson, Richard Allen and Fitzpatrick, Thomas B, 2009, Fitzpatrick’s color atlas and synopsis of clinical dermatology. New York : McGraw-Hill Medical.

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