Herpetic whitlow

Herpetic whitlow is a viral infection caused by the Herpes simplex virus.

Alternative names

Whitlow. The symptoms of herpetic whitlow are sometimes referred to as 'periungual lesions' or lesions around the ungual (nail) area. However, not all periungual lesions are symptoms of herpetic whitlow.

What is herpetic whitlow?

Herpetic whitlow is a common infection by the Herpes simplex virus, usually of the skin near the nail of the thumb or index finger.

What causes herpetic whitlow?

Herpetic whitlow is contracted through direct contact with the Herpes simplex virus. There are two types of Herpes simplex virus: HSV-1 or herpes one, and HSV-2 or herpes two. Herpetic whitlow is most often caused by HSV-1, the type associated with oral herpes, also called 'cold sores' or “fever blisters'.

Herpetic whitlow is more likely to occur when the skin is vulnerable due to breaks in the skin, such as cuts, sores, or more commonly, a torn cuticle.

In rare cases, herpetic whitlow can be caused by HSV-2, the virus that usually causes genital herpes. HSV-2 may in some cases be passed from mother to child during childbirth, if the mother developed lesions shortly before giving birth.

Who gets herpetic whitlow, and who is at risk?

Some research indicates that Herpes simplex is present in most urbanised people over the age of 20, although not everyone who has the virus in their body will suffer the symptoms of the disease, or spread it. The infection usually occurs when the virus infects an open lesion or vulnerable area, or reasserts itself due to a fragile immune system.

A baby, infant or child who has oral herpes can spread it to their thumbs or fingers by sucking their thumb.

In adults, herpetic whitlow can be spread from a small cut or sore in the mouth, and also through direct contact between infected areas and vulnerable skin. It can also be spread between adults during sex or other close physical contact, especially during the first infection. Recurrences of the infection are less dangerous to others, especially if the symptoms are correctly treated.

An infected person can transmit the virus even if no lesions are visible, but wet, open lesions are highly contagious.

The infection is also common among medical professionals. However, the use of gloves when examining and treating patients usually removes any danger of catching the herpes virus and contracting herpetic whitlow.

People suffering from immunodeficiency disorders, such as AIDS, are more vulnerable to herpetic whitlow and find it more difficult to overcome the symptoms. Recurrences of the disease are also more common.

Symptoms and signs of herpetic whitlow

Infection with the herpes virus does not necessarily result immediately in symptoms of herpetic whitlow. The virus can remain in incubation in the affected area – growing, but undetectable – for between two and 20 days.

Initial symptoms of herpetic whitlow may include:

• a tingling feeling in the affected area
• pain and swelling of a finger
• fever and discomfort (in some cases)

These symptoms are usually followed by:

• sudden pain around the nail
• redness (erythema), swelling and warmth around the nail
• the development of small, barely visible blisters around the nail
• swelling of the lymph glands in nearby areas such as the elbow and armpit (in some cases)

Over the next 7-10 days, the following symptoms are typical:

• swelling, heat, and a burning sensation in the affected digit
• the development of visible, blister-like grouped sacs of opaque fluid called vesicles around the nail and on the tip of the finger

How is herpetic whitlow diagnosed?

The doctor will usually make a diagnosis based on your symptoms.

Doctors will look for other evidence of the herpes infection, such as:

• Gingivostomatitis – an infection of the mouth
• Swelling of the finger, fever, lesions and other typical symptoms
• Previous or current herpes infections

The doctor will also try to determine other risks, if the infection is due to direct contact or venereal transmission.

If there is any doubt as to the nature of the infection, definitive diagnostic testing may be carried out. Tests may include:

• Tzanck test, in which smears are obtained by scraping the base of a burst vesicle. Smears are then stained by the Giemsa method in the laboratory, and viewed under a microscope to determine whether the virus is present.
• Viral culture of the blister fluid is probably the most reliable way of confirming diagnosis, however the patient must wait a day or two for results, so this test is rarely used.
• Serum antibody testing to show a rising titer.
• Polymerase chain reaction (immunologic test) in serious cases.

Possible incorrect diagnosis

Herpetic whitlow is most commonly confused with bacterial infections and felon.

It may also show similar symptoms to those caused by cellulitis, paronychia and deep space infections.

Treating some of these infections, including deep space infections, may involve surgery. Correct diagnosis is essential before ruling out herpetic whitlow and proceeding with other treatments, as surgery carried out on an area infected with herpetic whitlow can spread the virus deeper into the body, causing serious complications.

Can herpetic whitlow be prevented?

The only way to reliably avoid contracting herpetic whitlow is by avoiding contact with the virus. Take the following preventative measures:

• Avoid direct mouth contact, such as kissing, with anyone who has a cold sore or fever blister, usually visible as small blisters or scabs on the skin of the lips, mouth or gums.
• Minimise the risk of indirect spread by thoroughly washing items that have been in contact with others' mouths, preferably in boiling water.
• To avoid catching the virus through necessary direct physical contact with lesions or other affected areas, wear gloves or other protection and ensure that you wash your hands thoroughly after contact.

Many people are already infected with the virus, but are not aware of this. Many never experience symptoms. Some spread of the disease from person to person occurs when lesions or blisters are not obvious, as that is when precautions are often not taken.

If you have had fever blisters in the past, avoid recurrence by:

• Avoiding exposure to triggers (especially sun exposure).
• Keeping your immune system in good shape.
• Not touching oral herpes lesions if you have any.
• Not putting your hands in your mouth.

Also discourage those close to you from making physical contact until the symptoms are completely gone.

How is herpetic whitlow treated?

Treatment relieves symptoms and speeds up their disappearance. However, the virus lies dormant, and less severe recurrences are likely.

HSV infection will probably heal in one to two weeks without treatment; however, treating the affected area decreases the risk of infecting others as well as other areas on your own body, and shortens the cycle of the disease.

Treatment is usually carried out using topical anti-viral (analgesic) treatments containing acyclovir (Zovirax®). Acyclovir taken orally can prevent recurrences if taken when repeat symptoms first appear.

What is the outcome of herpetic whitlow?

As is typical of other herpetic (herpes-related) infections, herpetic whitlow might lie dormant for a while. This is followed by a primary infection, and then a latent period. Subsequent recurrences occur in 20-50% of cases.

After the initial infection, the virus enters the peripheral nervous system (i.e. excluding the brain and spinal cord) where it lies dormant. The first infection is usually the most unpleasant, and results in the most typical symptoms. Recurrences are generally milder and shorter in duration.

If the condition is treated, it will go into remission. Lesions will dry out or burst and crust over, then heal. The pain and swelling will recede fairly quickly, and scarring is uncommon if the area is left alone and allowed to heal. With treatment, the lesions will crust over and heal without scarring faster.

Treatment with acyclovir will shorten the duration of the symptoms in primary infections. It acts by interfering with the DNA replications within the virus.

People who also have compromised immune systems might struggle to heal from herpetic whitlow, and suffer more frequent attacks.

Contraindications (bad reactions) to treatments are rare, but care should be taken with treatment if the patient experiences renal failure, or is pregnant, or if other nephrotoxic drugs (drugs dangerous to the kidneys) are used, especially when treatment is taken orally rather than applied directly to the area.

When to call the doctor

It is wise to consult a doctor before treating for herpetic whitlow, as misdiagnosis can lead to incorrect treatment. The sooner you begin correct treatment, the better.

Call your doctor if:

• Symptoms persist longer than 20 days when treated.
• Symptoms are particularly severe.
• Pus appears in the area.
• You experience any unpleasant reactions to the treatment.
• You have an immunodeficiency disorder, such as AIDS.
• The virus appears to be spreading to other areas, or if fever persists, as this could indicate a deeper and possibly dangerous infection.

Definitions

Felon: an infection of the tip of the finger or thumb, usually as a result of an infected puncture wound. Because of the way the fingers, thumbs and other digits are constructed, abscesses develop in a way that causes them to wrap around the fingertip, causing a great deal of pain as the nerve endings in fingers are very sensitive.

Cellulitis: literally, 'inflammation of the cells', specifically the skin layers and tissues under the nails, resulting in painful swelling due to accumulation of pressurised fluids, heat, and redness of the skin of the affected digit.

Paronychia: a superficial infection next to the nail plate, cured by opening the infected area and draining the pus.

Deep space infection: infection of one or several deep structures of the hand or fingers, including the tendons, blood vessels and muscles. Infection may involve one or more of these structures. A collar button abscess is such an infection when it is located in the web space of the fingers.

(Reviewed by Prof. Don du Toit, University of Stellenbosch)