Molluscum Contagiosum

What is molluscum contagiosum?

Molluscum contagiosum is a viral infection of the skin. It is caused by a DNA poxvirus called the Molluscum contagiosum virus or MCV. This common viral disease has a higher incidence in children, sexually active adults, and those who are immunodeficient. The virus commonly spreads through skin-to-skin contact. This includes sexual contact or touching or scratching the bumps and then touching the skin. Handling objects that have the virus on them, such as a towel, can also result in infection. The virus can spread from one part of the body to another or to other people such as among children at day care or school. Molluscum is contagious until the bumps are gone, which, if untreated, may take up to 6 months or longer to resolve.

How does molluscum contagiosum develop?

Molluscum lesions are flesh-colored, dome-shaped, and pearly in appearance. They are often 1–5 millimeters in diameter, with a dimpled center. They are generally not painful, but they may itch or become irritated. Picking or scratching the bumps may lead to further infection or scarring. They may occasionally be complicated by secondary bacterial infections. In some cases the dimpled section may bleed once or twice.

Once the virus containing head of the lesion has been destroyed, the infection is gone. The central waxy core contains the virus. In a process called autoinoculation, the virus may spread to neighboring skin areas. Children are particularly susceptible to auto-inoculation, and may have widespread clusters of lesions.

Individual molluscum lesions may go away on their own and are reported as lasting generally from 6 to 8 weeks to 2 or 3 months. However via autoinoculation, the disease may propagate and so an outbreak generally lasts longer with durations reported with a range of durations from 6 months to 5 years.

What causes molluscum contagiosum?

Molluscum contagiosum is not like herpes viruses, which can remain dormant in the body for long periods and then reappear. Thus, when treatment has resulted in elimination of all bumps, the infection has been effectively cured and will not reappear unless the patient is reinfected. In practice, it may not be easy to see all of the molluscum bumps. Even though they appear to be gone, there may be some that were overlooked. If this is the case, one may develop new bumps by autoinoculation, despite their apparent absence.

How is molluscum contagiosum treated?

Treatments for Molluscum contagiosum include cryosurgery, in which liquid nitrogen is used to freeze and destroy lesions. Application of liquid nitrogen may cause burning or stinging at the treated site, which may persist for a few minutes after the treatment. Scarring or loss of color can complicate both these treatments. With liquid nitrogen, a blister may form at the treatment site, but it will slough off in two to four weeks. Cantharidin is a chemical found naturally in many members of the beetle family Meloidae, which causes epidermal blistering. It is not painful on application, and is often preferred by some when treating small children. It should probably not be used near the eyes or in uncooperative children, as the chemical is caustic if scratched and rubbed on the eyes. It is usually applied with a wooden applicator like the sharp end of a wooden cotton bud. It may be left on for 1-8 houts and may be occluded or left uncoverd. Doctors will occasionally prescribe imiquimod. Imiquimod is a form of immunotherapy that triggers the immune system to fight the virus causing the skin growth. Imiquimod is applied 3 times per week, left on the skin for 6 to 10 hours, and washed off. A cure may take from 4 to 16 weeks. There is no permanent immunity to the virus, and it is possible to become infected again upon exposure to an infected person.

Advantage of treatment is to hasten the resolution of the virus. This limits the size of the "pox" scar. If left untreated, molluscum growth can reach sizes as large as a pea or a marble. Spontaneous resolution of large lesions can occur, but may leave scarring. As many treatment options are available, prognosis for minimal scarring is best if treatment is initiated while lesions are small.


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