Molluscum contagiosum

Molluscum contagiosum is caused by a poxvirus. Transmission is by direct contact, and can be sexual or non-sexual, the latter including spread by fomites.

Incubation period from clinical reports is 7-days to 6 months (usually 2-6 weeks), experimental inoculation reports 19-50 days. The period of communicability is probably as long as the lesions persist with contact infectivity high.

The lesions occur most often around the pubic area, thighs, buttocks and lower abdomen in adults. Lesions have a pearly edge with an umbilicated centre but may vary in colour from pink to yellow. They are highly infectious, and molluscum can be spread by skin contact. Lesions may be misdiagnosed as genital warts. HIV-infected individuals may develop quite large lesions that may appear as several lesions grouped together and these may not always be in genital or nearby sites (e.g. may appear on face, neck and upper trunk).

The incubation period can vary from days to months.

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Diagnosis is usually made by observation. NAAT is available for difficult diagnoses. Use a fine swab to collect material from the centre of the lesion. Biopsy with H&E staining is diagnostic but rarely necessary.

In immunocompetent patients watchful waiting should be encouraged as lesions usually resolve spontaneously although it may take 6-12 months for all lesions to clear. Treatment may be offered to reduce transmission and to speed up lesion resolution. 

Trauma to the lesion is required by:

• cryotherapy using liquid nitrogen, CO2 snow or N2O cryoprobe (preferred treatment)

• de-roofing the lesions with a sharp stick or needle, and expressing the contents (with care to avoid inoculation of adjacent skin)

• diathermy and curettage.

• Other options include podophyllotoxin 0.5% twice daily for 3 days then rest for 4 days. Repeat up to 4 times. 

The patient should be advised to avoid shaving, waxing, shared towels or bedding. 

Pregnancy

Medicines in pregnancy.

Avoid podophyllotoxin in pregnancy. 

Related links

• Molluscum contagiosum (Healthy WA)

Partners should be offered assessment if they have noticed lesions.

The patient should be advised to return for further treatment if any lesions remain after first treatment. New lesions may occur.

This is not a notifiable disease.

Advise patients not to shave the pubic area as this spreads the infection.

Always offer tests for other STIs.

Lesions are probably communicable for as long as they persist.