PatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
This is a common skin infection caused by a pox virus that affects both children and adults. Transmission is usually by direct skin contact and has occurred in contact sports and by sharing baths, towels and gymnasium equipment. Outbreaks in schools are well recognised.
Molluscum contagiosum is a viral skin infection caused by molluscum contagiosum virus (MCV), a DNA pox virus, specifically a member of the Poxviridae family. There are four distinct subclasses of MCV, with MCV1 being the most common cause of molluscum contagiosum.
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- There are no precise figures but molluscum contagiosum is common. The exact prevalence is uncertain. Many people never seek medical care and it is not a notifiable disease. Studies done often look at selected populations (for example, attendees at genitourinary medicine (GUM) clinics or dermatology outpatient departments).
- A large UK general practice-based survey reported:
- The overall annual incidence of new cases of molluscum contagiosum was 261/100,000.
- The annual incidence of such cases in children aged under 15 years was 1,265/100,000.
- Over 80% of reported cases occurred in children aged under 15 years, with the maximum incidence in pre-school children aged 1-4 years.
- In a general practice population of 10,000 people, about 24 new cases of molluscum contagiosum would present each year.
- It occurs most often in children.
- People who are immunocompromised, in particular from HIV, steroid treatment or lymphoproliferative disorders, are more at risk of molluscum contagiosum. However, the vast majority of infected people have a competent immune system.
- Molluscum contagiosum may occur more often in children with atopic eczema.
- It is usually spread by direct contact, but may be transmitted via contaminated objects such as towels, clothes or toys. In adults it is often spread by sexual contact.
- It is almost exclusively a disease of humans and so there is neither a risk of children infecting pets nor of pets infecting children.
The incubation period is usually between two and seven weeks, but can be anywhere between one week and six months. It is assumed to be infectious as long as there are visible lesions present. Usually it is asymptomatic but there may be tenderness, pruritus and eczema around the lesions. They tend to spread more rapidly in atopic individuals or in skin conditions where the skin barrier is less effective. It is almost invariably confined to the skin but cases affecting the eyelids and conjunctiva have been reported. There is no pyrexia or malaise.
- Firm, smooth, umbilicated papules, usually 2-5 mm in diameter. Lesions bigger than 15 mm have been described in AIDS.
- They may be the colour of skin, white, translucent or slightly yellow.
- They may be single or more typically in clusters of up to 20 lesions but sometimes there are many more.
- In children they are usually on the trunk or extremities. In adults they are often on the lower abdomen, inner thighs or genital region, suggesting sexual transmission. The discovery of this distribution in children is not usually an indication of sexual abuse.
- Although rare, it has been reported on the buccal mucosa.
- In some conditions (for example, sarcoidosis, lymphocytic leukaemia, congenital immunodeficiency, selective immunoglobulin M deficiency, thymoma, prednisolone and methotrexate therapy, AIDS, malignancy, atopic dermatitis), multiple widespread, persistent and disfiguring lesions can occur (especially troublesome on the face but also involving the neck and trunk).
- Any one lesion is likely to persist for about two months.
Note the multiple, red, umbilicated papules as well as some smaller ones of a paler colour.
- Lichen planus.
- Dermatitis herpetiformis.
- Basal cell carcinoma.
- Fibrous papule of the face.
- Cutaneous cryptococcosis - also umbilicated papules, not uncommon on the face, found in conditions with immunosuppression (especially HIV).
- Spitz' naevus.
- Herpes virus infections.
These are not usually required and diagnosis is made on clinical grounds based on the appearance of lesions. In exceptional circumstances when diagnosis is uncertain, excision biopsy can be performed. Laboratory confirmation is obtained by electron microscopy at Public Health England (PHE), previously the Health Protection Agency (HPA) Colindale. Serum antibody checks generally are not well standardised. It is best to discuss available diagnostic options with the local microbiology department. Referral to a GUM clinic may be indicated if it is thought that it may have been transmitted through sexual contact.
- Parents often request treatment for their children and express concern about the infection spreading. However, all techniques are a little painful and the management that is most popular with children is to await spontaneous resolution.
- The disease is usually self-limiting but if there is auto-infection or infection of others, treatment may be required. Each case should be individually assessed.
General self-care advice
- Reassurance. Set realistic expectations. Most cases will clear up spontaneously within 18 months.
- Avoid scratching. This increases the chance of spread within the individual and to others, and increases the risk of infection and of scarring.
- Advise there is no need for exclusion from school, swimming or gym activities.
- Advise not to share towels. There is possibly some value in covering lesions for communal activities such as PE.
- In adults with anogenital lesions, advise the use of condoms.
A Cochrane review found that no single treatment was convincingly effective for molluscum contagiosum. Their report suggests that although many treatment strategies are used, there is not a solid evidence base yet for any of them.
- Cryotherapy with liquid nitrogen.
- Benzoyl peroxide cream. (There is limited evidence of efficacy in the Cochrane review.)
- Sodium nitrate co-applied with salicylic acid. (There is limited evidence of efficacy in the Cochrane review.)
- Potassium hydroxide 5 or 10% topical solutions. (There is no statistical significance to benefit in the Cochrane review. Commercial over-the-counter preparations are available.)
- Iodine preparations.
- Hydrogen peroxide 1% cream.
- Imiquimod 5% cream. (No convincing benefit was found in healthy individuals in the Cochrane review, but this has been used in immunocompromised people.)
- Pulsed dye laser.
- Emollients or mild corticosteroid creams for itch or eczema around lesions.
- Topical antibiotic creams if lesions develop secondary infection.
- This is rarely indicated.
- Refer to an ophthalmologist if the eyes are involved.
- Refer to a sexual health clinic to screen for other sexually transmitted disease if anogenital lesions are present in adults.
- Refer immunosuppressed individuals with extensive lesions.
- Discomfort and irritation.
- Secondary infections.
- Eyelid lesions may be associated with follicular or papillary conjunctivitis.
It is a benign, self-limiting infection with an excellent prognosis. The literature on molluscum contagiosum should be interpreted with care. Much research originates from secondary care on patients with impaired immunity.
Further reading & references
- Molluscum contagiosum; DermNet NZ
- UK national guideline for the management of Genital Molluscum in adults 2014, BASHH (July 2014)
- Pannell RS, Fleming DM, Cross KW; The incidence of molluscum contagiosum, scabies and lichen planus. Epidemiol Infect. 2005 Dec;133(6):985-91.
- Molluscum contagiosum; NICE CKS, September 2012
- Molluscum contagiosum; Public Health England
- van der Wouden JC, van der Sande R, van Suijlekom-Smit LW, et al; Interventions for cutaneous molluscum contagiosum. Cochrane Database Syst Rev. 2009 Oct 7;(4):CD004767.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Richard Draper
Dr Mary Harding
Dr Helen Huins