Cause of Molluscum Contagiosum
Molluscum contagiosum is caused by the molluscum contagiosum virus (MCV), a poxvirus of the Molluscipox genus within the Poxviridae family. 1, 2
Viral Etiology
- The causative agent is a DNA poxvirus that infects only humans and is limited to the cutis and subcutaneous levels of the skin 3, 4
- With the eradication of smallpox, MCV is now the only member of the poxvirus family that causes substantial disease in humans 5
Transmission Mechanisms
The virus spreads through multiple routes:
- Direct skin-to-skin contact is the primary mode of transmission, which can be non-sexual in children or sexual in adults 1, 3
- Fomites (contaminated objects) serve as vectors, including shared towels, clothing, and equipment 1, 6
- Autoinoculation occurs when patients spread the virus from one body site to another through scratching or touching lesions 1, 3
- Water exposure in communal settings such as swimming pools, hot tubs, and bathtubs facilitates transmission, particularly among children 1, 4
High-Risk Populations
Certain groups are more susceptible to infection:
- Preschool and elementary school-aged children are most commonly affected due to close physical contact in day care and school settings 4, 6
- Sexually active adults acquire infection through intimate contact, with lesions predominantly in the genital region 3, 7
- Immunocompromised individuals, particularly those with HIV, develop more extensive and atypical presentations with prolonged persistence 1, 3
Clinical Implications
- The virus remains infectious throughout the entire course of lesions, which typically persist for 6-12 months but can last up to 4-5 years without treatment 1, 4
- In immunocompromised patients, multiple large lesions with minimal inflammation should prompt consideration of underlying immunodeficiency 1, 2