Causes of Molluscum Contagiosum
Molluscum contagiosum is caused by the molluscum contagiosum virus (MCV), a double-stranded DNA poxvirus of the Molluscipoxvirus genus in the Poxviridae family 1, 2, 3.
Transmission Mechanisms
The virus spreads through several distinct routes:
Direct Contact Transmission
- Skin-to-skin contact is the primary mode of transmission 2, 3
- In children: non-sexual contact during play, sports (particularly wrestling and judo), and close physical activities 1
- In sexually active adults: transmission occurs through intimate genital contact 3, 4
- Autoinoculation allows spread from one body area to another through scratching or touching lesions 3, 5, 6
Indirect Transmission
- Contaminated fomites serve as vectors, including:
Population-Specific Risk Factors
Children (Primary Affected Group)
- Affects 5% to 11% of children aged 0-16 years 1
- Preschool and elementary school-aged children most commonly affected 5
- Swimming pool attendance strongly linked to childhood infections 4
- Close contact in school settings facilitates transmission 1
Adults
- Predominantly transmitted through sexual contact in immunocompetent adults 3, 4
- Lesions typically confined to genital and adjacent skin areas 4, 7
Immunocompromised Individuals
- HIV-infected patients particularly susceptible to extensive, disseminated disease 8, 9, 8
- Multiple and/or unusually large lesions common in immunosuppressed states 8, 9
- Lesions can affect various body regions rather than remaining localized 4
Clinical Pitfalls
Important caveat: The virus is highly infectious even with brief intimate skin contact 4. Healthcare providers should recognize that:
- Wrestlers and contact sport athletes require pre-competition skin examinations 1
- Immunocompetent patients can develop giant lesions (>1.5 cm), though this is rare 7
- The Koebner phenomenon (pseudo-koebnerization) can create unusual distribution patterns through scratching 6
The infection presents as benign, self-limited viral skin infection with characteristic skin-colored papules developing central umbilication 1, 2, but understanding transmission routes is critical for prevention and outbreak control, particularly in organized sports and institutional settings.