Molluscum contagiosum

Notification requirement for molluscum contagiosum

Notification is not required.

Primary school and children’s services centres exclusion for molluscum contagiosum

Exclusion is not required.

Infectious agent of molluscum contagiosum

Molluscipoxvirus is a member of the pox virus (Poxviridae) family.

Identification of molluscum contagiosum

Clinical features

Molluscum contagiosum is a viral disease of the skin that produces firm, smooth, spherical, pearly white papules with a central dimple. Most papules are 2–5 mm in diameter, although papules may coalesce to form larger lesions.

Lesions in adults are more common on the lower abdomen, genitalia and inner thighs. In children, lesions are more common on the face, trunk and limbs. Lesions may disseminate more widely in patients with HIV infection.

Molluscum contagiosum usually resolves within 6 months, but may persist for a few years in a minority of cases. Lesions may resolve spontaneously or possibly as a result of inflammatory responses secondary to bacterial infection or trauma.

Diagnosis

The virus has not yet been cultivated. Diagnosis is usually made clinically, but can be confirmed by microscopy (the core of the lesion is expressed onto a slide and then stained), by histology or by visualisation of the vesicle fluid by electron microscopy.

Incubation period of molluscipoxvirus

The incubation period is unknown. Clinical reports suggest a range from 7 days to 6 months.

Public health significance and occurrence of molluscum contagiosum

Molluscum contagiosum infection occurs worldwide. Surveys in other countries suggest that peak incidence occurs during childhood. A serosurvey in New South Wales in 1998 showed an overall seroprevalence of 23 per cent and increasing positivity according to age. The seropositivity rate increased from less than 10 per cent in those under 5 years of age to approximately 20 per cent by age 10.

Lesions typically resolve without complication, although occasionally they leave a scar. Molluscum contagiosum may be more severe and more persistent in immunosuppressed patients and particularly in patients with HIV/AIDS.

Reservoir for molluscipoxvirus

Humans.

Mode of transmission of molluscipoxvirus

Molluscum contagiosum is transmitted by direct contact, fomites or sexual contact. Autoinoculation through scratching is also suspected.

Period of communicability of molluscum contagiosum

The period of communicability is unknown but probably as long as the lesions persist.

Susceptibility and resistance to molluscum contagiosum

People of any age may be affected, although infection is more common in children. Infection is more common and more severe in the immunosuppressed.

It is unknown whether previous infection confers any protection against subsequent exposures.

Control measures for molluscum contagiosum

Preventive measures

Avoid close contact with the lesions of affected people. Avoid sharing baths and spas with people with lesions, and do not share face or bath towels.

Control of case

Isolation of the case is not required. Infected children should either avoid contact sports or ensure that lesions are adequately covered during play. No school or childcare exclusion is required.

Transmission through warm water is only very rarely observed. The risk of transmission through public swimming pool contact is low, and exclusion is rarely if ever necessary. When swimming, the case should be advised to cover all lumps with waterproof dressings and not to share towels, pool equipment or toys.

Many treatments cited in the literature have the destruction of the lesions as their common goal, but there is minimal evidence to support them. Watchful waiting may still be the best option for many patients. Generally, treatment is considered for those adolescents and adults with sexually transmitted disease and those who are immunocompromised. If treatment is required, options include curettage, cryotherapy, cantharidin and phodophyllotoxin, or squeezing the lump and removing the core.

Control of contacts

Not required.

Control of environment

Not required.

Outbreak measures for molluscum contagiosum

Consider suspending direct contact and sporting activities.