Fungal nail infection

Fungal nail infection – What is fungal nail infection?

Fungal infections can affect skin, hair as well as nails. Nail infections are common especially in susceptible individuals. It leads to discoloured, ugly and misshapen nails that may even become painful.

Usually the condition is treatable with medication but medication may be needed for several weeks, months or even years. (1-5)

Who does fungal nail infection affect?

Fungal nail infections also termed Onychomycosis medically, affect around 3 in 100 people in the United Kingdom at some stage of their lives.

It accounts for approximately half of all nail disorders and one third of skin fungal infections.

In the United States 18.5% persons are affected with the condition and the numbers are on the rise. Toenails are more commonly affected than fingernails.

It is also more commonly seen in people over 55 years of age or those who share communal showers or swimming pools like swimmers and athletes.

Fungal nail infections affect 32% of people between ages 60 and 70, and 48% of the population may be affected by age 70.

Causes of fungal nail infection

Fungal nail infection may occur as an extension or spread from fungal skin infection.

Commonly this occurs from athlete's foot that is a fungal skin infection of the toes. Unless the condition is treated it may spread to the toe nails.

Spread to finger nails occurs due to scratching of the lesions of the foot.

Too much exposure to water for example in cooks and cleaners also leads to a risk of fungal nail infections. In addition damaged or broken nails are susceptible to infections.

Repeated washings may damage the protective skin at the base of the nail. This may allow fungi to enter and cause infections.

Those living in hot and humid climates and those who smoke are also at risk.

Those with chronic health conditions are at risk of fungal nail infections. These include people with:

  • diabetes
  • psoriasis
  • poor circulation
  • a poor immune system (for example, if the patient has AIDS or is on immune suppressing cancer chemotherapy)
  • in general poor state of health

Symptoms of fungal nail infection

Fungal nail infections may affect a single or more than one nail. At first the infection is usually painless. The nail appears thickened with a greenish yellow discoloration.

Commonly, this is all that occurs and it often causes no other symptoms. Sometimes this worsens and white or yellow patches appear over the nail. These are places where the nail has come away from the skin under the nail (the nail bed). Sometimes the whole nail comes away.

The nail becomes soft and crumbles or becomes brittle and breaks away. Skin around the nail is red, itchy and painful. There may be scaly appearance of the skin around the nails.

If left untreated, the infection may eventually destroy the nail and the nail bed, and may become painful.

Diagnosis of fungal nail infection

Diagnosis is usually made clinically but tests may help detect the type of fungi affecting the nail. A nail clipping is sent to the laboratory for microscopic examination.

Treatment of fungal nail infection

Cure rates with currently available anti-fungal agents is around 60 to 80% and the drugs need to be taken over several weeks or months especially for slower growing toe nails.

Many people may choose not to have medication if the infection is mild or causing no symptoms. However, if the symptoms worsen or the person has other chronic health conditions that may worsen the symptoms, treatment is usually advised.

Commonly used anti-fungal agents are oral Terbinafine or Itraconazole tablets. A nail lacquer or nail paint that contains the antifungal drug amorolfine is an alternative for most types of fungi that infect nails.

If other treatments have failed, an option is to have the nail removed by a small operation under local anesthesia. This is combined with treatment with antifungal medications.

Prevention of fungal nail infections

Prevention of nail infections with fungi include keeping the feet cool and dry and avoiding communal baths and walking bare foot at swimming pools, showers and bathrooms.

Causes of fungal nail infections

Fungal nail infections are one of the most common dermatological conditions in the United Kingdom. Nearly 3 in 100 in the UK suffer from fungal nail infections at some point in their lives.

In the UK the prevalence of fungal nail infections is as high as 26.9%. In the United States the prevalence of the condition is 18.5% and is said to be on the rise.

Why is the number of fungal nail infections on the rise?

The rise is due to the rising numbers of people with diabetes and poor immunity. Also since this condition affects the elderly the rise is due to increasing numbers of aging individuals.

Who is affected by fungal nail infections?

Fungal nail infections, also called onychomycosis, are the reason behind half of all nail disorders and one third of skin fungal infections. Toenails are more commonly affected than fingernails. Elderly are more commonly affected than the young.

Fungal nail infections affect 32% of people between ages 60 and 70, and 48% of the population may be affected by age 70. In the young those sharing communal baths and showers like swimmers and athletes or long distance runners are particularly at risk.

Causes and risk factors of fungal nail infections

Causes and risk factors of getting fungal nail infections include (1-5):

  • Those with fungal skin infections. Athlete’s foot is a fungal skin infection of the skin between the toes. This infection left untreated often spreads to toenails.
  • Fungal skin infections are responsible for spread to finger nails due to scratching the lesions and spread of the fungal spores to the finger nails.

Fingernail infection may occur after a toenail infection has become established. This also occurs due to excessive scratching.

  • Damaged and broken nails allow fungi to infect them. Constant nail biting and use of artificial and cosmetic nails may also raise the risk of fungal nail infections.
  • Those who wash hands repeatedly e.g. cleaners, cooks and other occupations where working with water for long durations is necessary are also at risk.

Constant washing may damage the protective skin at the base of the nail. This may allow fungi to enter and infect the nails.

  • Individuals living in hot and humid climates are at an increased risk.
  • Those with chronic health conditions are at risk of fungal nail infections. This includes individuals with:
    • diabetes
    • psoriasis
    • poor blood circulation in the fingers and toes
    • suppressed or poor immune system for example in individuals with AIDS or those on cancer or other chemotherapy
    • those with a generally poor state of health
  • Smokers also have a high risk of fungal nail infections. This could be due to poor blood circulation in fingers and toes due to long term smoking.
  • Age of the person is a risk factor. Adults are nearly 30 times more likely than children to suffer the condition. Fungal nail infections affects 2.6% of children younger than 18 years, but as many as 90% of people older than 70 years.
  • Sometimes the cause of the infection is unknown and perfectly healthy individuals may get fungal nail infections due to contact with other people with the infection.

Organisms that lead to fungal nail infections

Organisms that lead to fungal nail infections include (2, 3):

  • Dermatophytes – this includes Trichophyton rubrum or Trichophyton mentagrophytes that causes over 90% of cases. Of these T. rubrum is responsible for about 70% cases.
  • Epidermophyton spp. and Microsporum spp. are other organisms that may cause fungal nail infections.
  • Around 8% (5 to 17% cases) of total infections is caused by yeast infections like Candida albicans in the UK and Malassezia furfur in tropical countries.
  • Some Non-dermatophyte moulds like Scopulariopsis brevicaulis, Acremonium spp and Fusarium spp. may lead to 3 to 5% of infections.

Symptoms and diagnosis of fungal nail infections

Fungal nail infections, also called onychomycosis, are among the most common nail disorders. With rising prevalence of conditions like diabetes and increasing number of the aged population the numbers of individuals with these infections are also on the rise.

Types of fungal nail infection

Fungal nail infections may be classified according to the part of the nail affected. (1-5) They can be categorised into Distal and lateral subungal onychomycosis (DLSO), superficial white onychomycosis (SWO) and so forth.

Distal and lateral subungual onychomycosis

Distal and lateral subungual onychomycosis is also called DLSO. This is the most common form of onychomycosis. It is caused commonly be dermatophytes and may affect a healthy nail or one already diseased, e.g. by psoriasis.

The most common feature is affliction of the lateral edges or sides of the nail bed initially. The spread occurs over the nail bed leading to yellowish or creamy discoloration of the nails. The white and creamy patches indicate places where the nail has been detached from the nail beds.

The nail also becomes thickened. The nail becomes soft or brittle and crumbles or breaks away. The spread may be limited to one side of the nail or spread sideways to involve the whole nail bed.

The progress of the nail infection usually takes weeks or more slowly over months or years. As time progresses the nail becomes opaque, thickened and cracked, friable and raised from the nail bed.

Skin around the nail becomes inflamed, scaly and shows signs of fungal infections. Toe nails are more commonly affected than finger nails with 80% of cases affecting the feet.

Superficial white onychomycosis

Superficial white onychomycosis is also known as SWO. This is less common form of fungal nail infection. It is caused by T. mentagrophytes.

There is usually a white chalky plaque on the nail and occurs almost exclusively on the toenails. The top of the nails or nail plate is more commonly affected than the nail bed unlike DLSO.

Nail plate may become eroded and even lost. There is a whitish yellow discoloration of the nails and flakes over the nail plate. The nail may become brittle and friable and break off.

Fungal infection of the skin around the nails or elsewhere is less common than seen with DLSO.

Proximal subungual onychomycosis

This is a rarer form of fungal skin infection. It is seen in those with a suppressed immunity like those with HIV infection and AIDS. It is also seen in those with diabetes and those with poor blood supply to fingers and toes.

This is usually caused by dermatophyte infection. The infection begins with a white spot beneath the nail bed that fills up the nail bed completely.

There is concomitant athlete’s foot or fungal foot infection. The nail becomes white especially towards the base of the nail and remains normal at the tips.

Candidal onychomycosis

This may be of three types. Candida paronychia occurs as swelling of the nail bed with pain. There are usually patchy opaque spots that may be discoloured appearing white, yellow, green or black. Sometimes furrows may be seen over the nails.

Most cases are on fingernails usually the middle finger. There may also be a Candida granuloma where there is direct invasion and thickening of the nail plate. It is uncommon and seen with Candida paronychia.

Subungual abscess with DLSO is another form where there is collection of pus in the nail beds.

The third type of infection is Total nail dystrophy that leads to thickening of the entire nail. Those dealing with water exposure and psoriasis are more at risk of this condition. There is complete destruction of the nail.

Secondary bacterial infections

Fungal nail infections may be complicated by superimposed bacterial nail bed or nail infections. This is extremely painful and there may be formation of pus.

In rare cases (especially those with diabetes or the elderly) there may be a risk of cellulitis or bacterial infection under the skin or osteomyelitis or infection of the bone.

Diagnosis of fungal nail infection

Diagnosis of fungal nail infection is usually made clinically. However, only about 20-50% of discoloured nails have a fungal infection confirmed with dermatophyte.

The rest may be due to:

  • eczema
  • damage to nails
  • other conditions like Lichen planus
  • psoriatic nail disease
  • poor foot care
  • bacterial nail infections
  • discoloration of nails due to health conditions like thyroid disease, diabetes etc.
  • drug reactions or side effects e.g. with tetracyclines or quinolone antibiotics (1, 5)

For appropriate diagnosis the affected nail is clipped and sent to the laboratory for microscopic examination. The nail bits are stained with special dyes and under the microscope the organism may be seen.

The specimen can be immersed in a solution of 10 to 30% KOH or NaOH mixed with 5% glycerol before examination.

Results are usually obtained in around 3 to 4 days.

For DLSO cases a scraper like instrument is used to take bits of tissues from under the nails or the nail beds.

For SWO the top of the nail is scraped and sent to the laboratory. Sometimes diagnosis may be confirmed by allowing the fungi on the nail to grow in culture media in the laboratory and examine once the growth is obtained. This usually may take weeks for a confirmed diagnosis.

The nail anatomy under the microscope helps determine other causes of nail discoloration and deformity like psoriasis. (1, 5)