Introduction

Molluscum Contagiosum (MC), a viral skin infection caused by the Molluscum Contagiosum virus (MCV) belonging to the poxvirus family, is characterised by small, raised, pearl-like bumps on the skin, usually painless, often containing a central dimple. Primarily, it is spread through direct skin-to-skin contact, but can also be transferred by scratching the bumps, swimming in contaminated pools or through contaminated objects like towels or clothing. 

While children are commonly infected due to physical interactions, adults are affected significantly through sexual contact. Globally, MC is prevalent, affecting millions, including children, sexually active adults and immunocompromised individuals. Understanding its sexual transmission is crucial for managing outbreaks effectively, public health and preventive practices.¹

Understanding Molluscum Contagiosum

Causative agent (Molluscum contagiosum virus, MCV) 

MC is caused by the MCV, a member of the poxvirus family. There are several strains of this virus, identified as MCV-1 through MVC-4, with MCV-1 being the most prevalent and MCV-2 commonly associated with sexually transmitted cases.²

Characteristics of the virus 

MCV is a double-stranded DNA virus that primarily infects the epithelial cells of the skin. The virus is highly contagious and can spread through direct contact with infected skin or contaminated objects. It replicates within the cytoplasm of host cells, leading to the formation of lesions which are typically dome-shaped, with a central dimple, and contain a central caseous plug composed of viral and cellular debris.³

Symptoms and clinical presentation

MC presents as small, flesh-coloured papules with a central dimple distinguishing them from other conditions, found mainly on the face, torso, limbs, and genital areas. These lesions are usually painless but can become itchy. They may occur singly but typically occur in clusters, varying in size, ranging from 2 to 5 millimetres in diameter. In immunocompromised individuals, lesions can be more extensive and persistent. Usually non-inflammatory, they do not cause redness or swelling unless scratched or infected.⁴

Modes of Transmission

General transmission (skin-to-skin contact, fomites) 

MC spreads through direct skin-to-skin contact, common among children during play. The virus can also be transmitted via fomites like towels, clothing, and gym equipment that have touched infected skin. Specific high-risk settings include schools, nurseries, and daycare centres where children frequently interact closely and share personal items.⁵

Sexual transmission 

• In adults, the virus is often transmitted through direct skin-to-skin contact during sexual activity. This route is significant among sexually active individuals
• Sexual transmission can occur indirectly through shared personal items such as towels and clothing that have been in contact with infected lesions⁴

Preventive measures such as maintaining personal hygiene, avoiding the sharing of personal items, and practising safe sex can help reduce the spread of the virus.⁶

Risk Factors for Sexual Transmission

Sexual Activity

Sexual activity increases MC transmission risk due to direct skin-to-skin contact. During sexual contact, areas of the skin that may have unnoticed lesions can come into contact with a partner's skin. MCV thrives in warm, moist environments, common in areas of close physical contact during sexual activity, facilitating virus transfer. Estimates suggest that 5-20% of sexually active adults may encounter MC, highlighting its significance as a sexually transmitted infection (STI).

Multiple Sexual Partners

Multiple sexual partners heightens the risk of MCV exposure, thus increasing the infection likelihood. Each new sexual partner introduces potential virus transmission. Those with frequent or unprotected sex with multiple partners face higher infection likelihood and spread.

Immunocompromised Individuals

Individuals with weakened immune systems are more susceptible to contracting and spreading MC due to their reduced ability to fight off infections. This includes people living with HIV/AIDS, those undergoing chemotherapy, or individuals taking immunosuppressive medications for conditions such as organ transplants. MCV can persist longer and cause more extensive lesions in these populations, making them more contagious and harder to treat effectively. In immunocompromised individuals, some studies indicate rates as high as 18-20%.

Poor Hygiene Practices

Inadequate personal hygiene facilitates viral transmission through contaminated objects and direct contact with infected lesions. Lesions can become secondarily infected with poor hygiene, encouraging the spread of the infection, and increasing severity.⁶

Good Hygiene Practises to Prevent MC:

• Wash hands thoroughly, especially after touching lesions or infected skin
• Avoid sharing towels, clothing, razors, and gym equipment
• Regularly clean and disinfect shared surfaces, especially in communal areas like gyms and swimming pools
• Keep MC lesions covered with a clean bandage to prevent spreading the virus and refrain from scratching the lesions to prevent secondary infections

Diagnosis

• MC is typically diagnosed through clinical examination by observing characteristic lesions: central dimpled, small, dome-shaped, and pearly papules
• In cases where clinical diagnosis is uncertain, laboratory tests such as skin biopsies or polymerase chain reaction (PCR) can confirm MCV presence
• It is important to distinguish MC from other STIs like genital warts, herpes simplex virus, and other dermatological conditions for proper treatment and management⁷

Treatment and Management

Self-limiting nature of the infection 

MC is often self-limiting, with lesions typically resolving without treatment within 6 to 9 months in individuals with healthy immune systems. Immune system strength, age, hygiene practices, number and location of lesions, intervention and treatment and reinfection factors could impact length of infection. 

Medical treatments 

Physical removal (cryotherapy, curettage, laser therapy) 

• Cryotherapy: Freezing the lesions with liquid nitrogen is a common and effective method for removing MC lesions. Side effects may include procedural pain, blistering and temporary skin discolouration
• Curettage: This involves scraping the lesions off with a curette, which can provide immediate results but may cause discomfort, bleeding, and the potential for scarring
• Laser Therapy: Using laser treatment to remove lesions is another effective method, particularly for extensive or stubborn cases. Side effects can include pain, redness, and the risk of scarring⁸

Topical treatments (imiquimod, podophyllotoxin) 

• Imiquimod: An immune response modifier applied to the lesions to stimulate the body's immune system to fight the virus.
• Podophyllotoxin: A plant-based treatment that is applied directly to the lesions, causing death to infected cells and lesions to fall off⁹

Preventive measures 

• Safe sex practices - Using condoms and reducing the number of sexual partners can lower the risk of transmitting the virus during sexual activity.
• Personal hygiene - Regular hand washing and keeping the affected areas clean and covered can help prevent the spread of the virus. It is also important to avoid scratching or picking at the lesions.
• Avoiding sharing personal items - Not sharing towels, clothing, and other personal items with others can help prevent the spread of MC. Using separate personal items can minimise the risk of transmission through fomites.

Complications and Long-term Outlook

Secondary infections 

One of the primary complications of MC is bacterial superinfection. This occurs when bacteria infect the skin at the site of lesions, leading to redness, swelling, and pus formation. Managing secondary bacterial infections in MC involves maintaining good hygiene practices, avoiding lesion irritation, and using topical antiseptic treatments as needed to promote healing and reduce the risk of secondary bacterial infections.

Scarring 

Although the lesions of MC usually resolve without leaving scars, aggressive treatments or secondary infections can sometimes result in scarring, usually occurring in around 7% of affected individuals. To prevent scarring, avoid aggressive treatments, promptly manage secondary infections, refrain from scratching lesions, keep the skin hydrated, and protect it from sun exposure.

Psychological impact 

MC lesion presence, particularly in visible or sensitive areas, can lead to psychological distress, embarrassment, and social anxiety, affecting the individual's quality of life. For support dealing with the psychological impact of MC, affected individuals can find resources from online support groups like the Molluscum Contagiosum Support Group on Facebook, counselling services like BetterHelp, and dermatology clinics offering comprehensive care and psychological support alongside medical treatment.

Prognosis

The overall prognosis for MC is good, as the infection is typically self-limiting, resolving within 6 to 12 months without treatment. However, in immunocompromised individuals, the infection can be more persistent and require medical intervention and thus the prognosis could be worse in such individuals.¹⁰

Public Health Implications

Awareness and education 

Raising awareness about MC is crucial for public health. Educational initiatives should inform the public about the infection’s nature, its transmission methods, and prevention strategies. Targeted campaigns in schools, sports facilities, and sexual health clinics can help reduce the spread of the virus.

Screening and preventive strategies 

Implementing screening programs in high-risk populations, such as sexually active adults and immunocompromised individuals, can help identify and manage cases early. Preventive strategies, including promoting safe sex practices, personal hygiene, and avoiding sharing personal items, are essential to control the spread of the virus.

Role of healthcare providers

Healthcare providers play a critical role in MC management and prevention. They should have knowledge of how to diagnose, treat, and educate patients about the infection. Counselling on preventive measures and addressing the psychological impact of the infection are also important aspects of patient care.¹¹

Summary

MC, a viral skin infection caused by the MCV, is characterised by small, dome-shaped, pearly papules. MC is highly contagious and spreads through direct skin-to-skin contact and contaminated objects. While MC is generally self-limiting, it can cause complications such as bacterial infections, scarring, and psychological distress. Understanding both general and sexual transmission routes, along with effective treatment options, is essential for managing the infection.

Importance of awareness and prevention 

Raising awareness about MC is crucial for effective management and prevention. Public health efforts should focus on educating individuals about transmission methods, promoting safe sexual practices, and encouraging good personal hygiene. Awareness campaigns and preventive measures can help reduce infection rates and manage outbreaks more effectively.

Future directions for research and public health efforts

Future research should explore:

• Transmission Mechanisms: A better understanding of how MC spreads can improve prevention strategies
• New Treatments: Development of more effective and less invasive treatment options
• Preventive Measures: Enhancing current preventive strategies and evaluating new ones
• Psychological Impact: Addressing the emotional and social effects of MC on individuals

These areas of focus will help advance both treatment and prevention efforts for MC.