Definition

Herpetic whitlow is an infection on the skin of your finger caused by the herpes simplex virus (HSV). HSV is also often called the herpes virus.

You get herpetic whitlow through skin to skin contact with another person with active symptoms of the herpes virus (specifically an open, fluid-filled blister), or from contact with another part of your body that has active symptoms (this is called autoinoculation). The virus enters your finger through a break in your skin, for example a cut or torn cuticle. Once inside your finger, the virus invades your skin and the tissue below.

Once you have the herpes virus, it stays in your body. It lives above the nerves in your finger, where it can remain inactive indefinitely. After your initial symptoms of herpetic whitlow have cleared up, you may never have it again. However, it's possible for the inactive virus to be triggered and cause you to have symptoms again.

Symptoms

Symptoms of herpetic whitlow mostly affect your finger or thumb. They include:

1. a burning or tingling sensation (at the start of the infection)
2. swelling and redness
3. itching
4. one or a group of small fluid- or pus-filled blisters that burst and crust
5. pain, which can be severe

Occasionally, you may have a fever and feel generally unwell. You may also get small swellings under your armpits in your lymph nodes.

Symptoms don't always start as soon as you have been exposed to HSV infection. It's common for the virus to remain inactive in your skin for a couple of days or weeks. Once symptoms do start, they usually last between seven and 10 days. After this, your blisters will begin to crust over and heal, and your symptoms will begin to improve.

The symptoms you get when you first have herpetic whitlow are called the primary infection. If you have symptoms again, this is called a recurrent infection. Up to half of people with herpetic whitlow are thought to have recurrent infections. The symptoms of a recurrent infection are normally less severe and don't last as long as the primary infection.

Complications

A common complication of herpetic whitlow is for your affected finger or thumb to become overly sensitive or numb once your symptoms have gone. This can happen as a result of a primary or recurrent infection.

With any HSV infection, there is always a risk that the infection will spread. With herpetic whitlow, it's possible for the infection to spread to your other fingers or to your eyes through rubbing and touching.

For people with a weakened immune system, for example people with HIV/AIDS or taking immunosuppression treatments, HSV infection can be severe and cause serious complications, such as pneumonia. It's important that you see your GP immediately if you have a weakened immune system and start to get symptoms of an HSV infection.

Occasionally, people with atopic eczema may develop a condition called eczema herpeticum after they have been exposed to HSV. This can cause symptoms to appear over much larger areas of skin.

Causes

There are two types of HSV infection that cause herpetic whitlow: HSV-1 and HSV-2. It's thought that six out of 10 herpetic whitlows are caused by HSV-1 and the rest are caused by HSV-2.

In children, herpetic whitlow is usually caused by HSV-1. It happens when a child with oral herpes, for example a cold sore or gingivostomatitis, sucks his or her fingers or thumb. The virus can spread from the mouth or lips to the finger or thumb through a break in the skin, for example, a cut. This is called autoinoculation.

In adults not involved in healthcare activities, it's usually caused by HSV-2 through autoinoculation from genital herpes.

Herpetic whitlow commonly affects healthcare workers who regularly come into contact with people infected with HSV. This is often HSV-1 as a result of contact with people who have oral herpes, for example dentists or GPs.

Diagnosis

Your GP will be able to diagnose a herpetic whitlow. He or she will examine your finger and ask you about your symptoms. In particular, he or she will ask you if you have ever had any similar infections on your fingers, in your mouth, on your lips or around your genitals.

Treatment

Symptoms of herpetic whitlow usually clear up by themselves within three to four weeks. Your GP may give you treatment to relieve your symptoms and help the infection go more quickly.

Medicines

Your GP may prescribe you a medicine called aciclovir (eg Zovirax) to help your symptoms go more quickly or to prevent recurrent infection.

If you are in pain, you can take painkillers that you would normally take for a headache, such as paracetamol or ibuprofen. Always read the patient information leaflet that comes with your medicine.

Prevention

HSV infection is spread by the clear fluid that comes from the blisters on your finger. Once all the blisters have crusted over they are no longer infectious.

To stop the infection spreading, you should try to avoid contact with your blisters. There are several ways in which you can lower your risk of getting or passing on herpetic whitlow, including:

1. trying not to touch the infected area or covering it with a plaster
2. not sharing towels, facecloths, nail brushes or other toiletries that have come into contact with infected fingers
3. try to avoid spreading the virus to other parts of your body, for example, by touching your eyes, putting your fingers in your mouth or rubbing your fingers together
4. keeping your hands clean by thorough, regular washing
5. not holding or touching hands with someone who has active symptoms or if you have active symptoms
6. wear your glasses rather than your contact lenses (if you wear them) - it's possible to contaminate your lenses with the virus and spread it to your eyes.