What is molluscum contagiosum?

Pronounced 'mo-LUS-kum kun-tay-jee-OH-sum', molluscum contagiosum, also referred to as molluscipoxvirus (MCV), and commonly known as water warts, is a contagious viral disease caused by the poxvirus that affects the skin. The term 'molluscus' (meaning soft-shelled) is derived from the word "mollis" in Latin which means soft. 

Molluscum contagiosum is a relatively common condtion that is defined by the development of firm, rounded, painless bumps on the skin.

The bumps, also known as lesions or papules, range from the size of a pinhead to an eraser on a pencil, or green pea. When the papules are injured or scratched, the viral infection which causes them can spread to the surrounding skin.

While commonly seen in children between the ages of one and fourteen¹ and young adults, the infection can affect people of all ages and those who suffer from immunosuppression (i.e. a weakened immune system) in particular. 

Types of molluscum contagiosum and how they spread

Viral strains are catagorised into four types (I - IV), although type 3 and 4 are rare. Molluscum contagiosum type 1 (MCV-I) is the most commonly seen type of the infection in children. It may also occur in adults, especially those who participate in contact sports. This type results in lesions (warts) forming anywhere on the skin as a result of direct skin-to-skin contact with an infected person or due to transmission and spreading of the virus in an infected person from one area of the body to another due to scratching or rubbing.

MC type 2 (MCV-II) is considerably rarer than type 1, infections are generally sexually transmitted and as such, are more commonly seen amongst otherwise healthy adolescents and adults. Skin-to skin contact during sexual intercourse  leads to the transmission of the virus which results in the formation of lesions (warts) in the genital areas. In these instances, the condition is regarded as an STI/STD (sexually transmitted infection/disease). 

**MyMed Memo: It is important to note that in instances where children develop lesions in the anal and genital regions, this is due the spreading of the type 1 virus through scratching or rubbing itchy lesions and then touching these areas rather than as a result of sexual contact¹.

While the disease is usually spread through direct personal contact it may also be transmitted through contact with infected objects like washcloths and towels that have been contaminated.

Molluscum contagiosum stages

Image: Stages of molluscum contagiosum

Molluscum contagiosum lesions typically develop in stages. In the initial stages, small, flesh-coloured bumps appear just below the skin's surface, they are often quite difficult to see (first image from the left in the above molluscum contagiousum stages graphic). Following the first few weeks of the infection, lesions begin to enlarge, becoming more defined and clearly visible (image second from the left).

As time passes they continue to grow in size and develop white or yellow heads full of pus, often with a characteristic indentation (third image from the left - the purulent stage). These can be popped, however, you are advised not to do so as this can spread the infection. These lesions will burst on their own, this is the final stage which involves burst pus-filled papules forming red sores (fourth image from the left). These sores can become infected with bacteria if not properly cared for, leading to secondary infections. 

References

^{1. NCBI. December 2013. Epidemiology of molluscum contagiosum in children: a systematic review. Available: https://www.ncbi.nlm.nih.gov/pubmed/24297468 [Accessed 12.08.2017]}