Several common childhood viral infections cause widespread exanthems (rashes): measles, German measles (rubella), chickenpox (varicella), Pityriasis rosea, Hand foot and mouth disease. Smallpox, a deadly disease hopefully now eradicated by widespread vaccination. Chikungunya fever, dengue and dengue haemorrhagic fever and zika fever (due to arboviruses).Various skin complaints are more common with Human Immunodeficiency Virus (HIV) infections (AIDS)
Localised skin conditions caused by viral infections include: Herpes simplex (cold sores and genital herpes), Herpes zoster (shingles), Herpangina, molluscum contagiosum, viral warts (verrucas, genital warts or condylomas and squamous cell papillomas.
Chickenpox is a highly contagious disease caused by primary infection with the varicella-zoster virus. The name may be derived from the French term for chick pea, chiche pois. Once a person has had the chickenpox infection it is unlikely he or she will get it again as for most people one infection is thought to confer lifelong immunity. Chickenpox is highly contagious and is easily spread from person to person by breathing in airborne respiratory droplets from an infected person's coughing or sneezing or through direct contact with the fluid from the open sores. A person who is not immune to the virus has a 70–80% chance of being infected with the virus if exposed in the early stages of the disease. In children, chickenpox usually begins as an itchy rash of red papules (small bumps) progressing to vesicles (blisters) on the stomach, back and face, and then spreading to other parts of the body. Blisters can also arise inside the mouth. The blisters clear up within one to three weeks but may leave a few scars. Chickenpox can now be prevented by vaccination with live attenuated varicella vaccine. A person with chickenpox is contagious 1-2 days before the rash appears and until all the blisters have formed scabs. This may take between 5-10 days. Persons with chickenpox should remain home. It can take from 10-21 days after contact with an infected person for someone to develop chickenpox. This is how long it takes for the virus to replicate and come out in the characteristic rash in the new host. Tablets are available to treat chicken pox. This hastens recovery.
Pityriasis rosea is a viral rash which lasts about 6–12 weeks. It is characterised by a herald patch followed by similar, smaller oval red patches that are located mainly on the chest and back. It improves spontaneously without treatment. Symptomatic treatment is enough.
Hand foot and mouth disease
Hand foot and mouth disease is a common mild and short-lasting viral infection most often affecting young children; 95% are under 5 years of age. It is characterised by blisters on the hands, feet and in the mouth. The infection may rarely affect adults. Hand foot and mouth disease is very infectious, so several members of the family or a school class may be affected. The infection is passed on by direct contact with nasal and oral secretions or faecal contamination. Specific treatment is not necessary. The blisters should not be ruptured to reduce contagion.
Herpes simplex is a common viral infection that presents with localised blistering. It affects most people on one or more occasions during their lives. Herpes simplex is commonly referred to as cold sores or fever blisters, as recurrences are often triggered by a febrile illness, such as a cold. Type 1 is mainly associated with oral and facial infections. Type 2 is mainly associated with genital and rectal infections (anogenital herpes). However, either virus can affect almost any area of skin or mucous membrane. After the primary episode of infection, HSV resides in a latent state in spinal dorsal root nerves that supply sensation to the skin. During a recurrence, the virus follows the nerves onto the skin or mucous membranes, where it multiplies, causing the clinical lesion. After each attack and lifelong, it enters the resting state. The vesicles tend to be smaller and more closely grouped in recurrent herpes. They usually return to roughly the same site as the primary infection. Mild uncomplicated eruptions of herpes simplex require no treatment. Severe infection may require treatment with an antiviral agent.
Herpes zoster is a localised, blistering and painful rash caused by reactivation of varicella zoster virus (VZV). It is characterised by dermatomal distribution, ie the blisters are confined to the cutaneous distribution of one or two adjacent sensory nerves. Herpes zoster is also called shingles.Anyone that has previously had varicella (chickenpox) may subsequently develop zoster. This can occur in childhood but is much more common in adults, especially the elderly. The first sign of herpes zoster is usually pain, which may be severe, relating to one or more sensory nerves. The pain may be just in one spot or it may spread out. The patient usually feels quite unwell with fever and headache. The lymph nodes draining the affected area are often enlarged and tender. Within one to three days of the onset of pain, a blistering rash appears in the painful area of skin. It starts as a crop of red papules. New lesions continue to appear for several days within the distribution of the affected nerve, each blistering or becoming pustular then crusting over. Post-herpetic neuralgia is defined as persistence or recurrence of pain in the same area, more than a month after the onset of herpes zoster. It becomes increasingly common with age, affecting about a third of patients over 40. It is particularly likely if there is facial infection. Post-herpetic neuralgia may be a continuous burning sensation with increased sensitivity in the affected areas or a spasmodic shooting pain. The overlying skin is often numb or exquisitely sensitive to touch. Sometimes, instead of pain, the neuralgia results in a persistent itch (neuropathic pruritus). Antiviral treatment can reduce pain and the duration of symptoms if started within one to three days after the onset of herpes zoster.
Molluscum contagiosum is a common viral skin infection of childhood that causes localised clusters of epidermal papules called mollusca. Molluscum contagiosum mainly affects infants and young children under the age of 10 years. It is more prevalent in warm climates than cool ones, and in overcrowded environments. Adolescents and adults are less often infected. Molluscum contagiosum presents as clusters of small round papules. The papules range in size from 1 to 6 mm, and may be white, pink or brown. They often have a waxy, shiny look with a small central. Each papule contains white cheesy material. In immune competent hosts, molluscum contagiosum is a relatively harmless. The papules may persist for up to 2 years or longer. In children, about half of cases have cleared by 12 months, and two-thirds by 18 months, with or without treatment. Contact with another infected individual later on can lead to a new crop of mollusca.
Warts are very common non-cancerous growths of the skin caused by infection with human papillomavirus (HPV). More than 100 HPV subtypes are known, giving rise to a variety of presentations. A viral wart on the sole of the foot is also called a verruca, and warty lesions are often described as verrucous. Warts are particularly common in school-aged children, but they may arise at any age. HPV is spread by direct skin-to-skin contact or autoinoculation. This means if a wart is scratched or picked, the viral particles may be spread to another area of skin. The incubation period can be as long as twelve months. Warts have a hard surface. A tiny black dot may be observed in the middle of each scaly spot. Common warts arise most often on the backs of fingers or toes, around the nails—where they can distort nail growth—and on the knees. Plantar warts (verrucas) include tender inwardly growing and painful ‘myrmecia’ on the sole of the foot, and clusters of less painful mosaic warts. Many people don't bother to treat viral warts because treatment can be more uncomfortable and troublesome than the warts—they are hardly ever a serious problem. However, warts may be painful, and they often look ugly so cause embarrassment. To get rid of them, we have to stimulate the body's own immune system to attack the wart virus. Persistence with the treatment and patience is essential! Topical treatment includes wart paints containing salicylic acid or similar compounds, which work by removing the dead surface skin cells. Cryotherapy is normally repeated at one to three week intervals. It is uncomfortable and may result in blistering for several day or weeks. Success is in the order of 70% after 3-4 months of regular freezing. Electrosurgery (curettage & cautery) is used for large warts. Under local anaesthetic, the growth is pared away and the base burned. The wound heals in two weeks or longer; even then 20% of warts can be expected to recur within a few months. This treatment leaves a permanent scar. No treatment is universally effective at eradicating viral warts. In children, even without treatment, 50% of warts disappear within 6 months, and 90% are gone in 2 years. They are more persistent in adults but they clear up eventually.