STD Awareness: Cytomegalovirus and Molluscum Contagiosum

Most sexually transmitted diseases (STDs) are caused by microorganisms – lifeforms that are too small to be seen without a microscope. Many STDs, however, are caused by viruses, which technically aren’t even alive. Rather, viruses are pieces of genetic information that are stored in protein capsules. When these capsules come into contact with a host cell, the genetic information is able to enter the cell and hijack its machinery so that the host cell manufactures copies of the virus, as well as potentially harmful viral proteins. Many well-known STDs, such as herpes and HIV/AIDS, are caused by viruses, but this month we will focus on two lesser-known viral STDs, cytomegalovirus and molluscum contagiosum. Your local Planned Parenthood health center, as well as other clinics, health departments, and private health-care providers, can help you get a diagnosis and treatment for these STDs.

Cytomegalovirus leaves granules inside its host cells called inclusion bodies, pictured here. Photograph from the CDC’s Public Health Image Library.

Cytomegalovirus leaves granules inside its host cells called inclusion bodies, pictured here. Image: Public Health Image Library, CDC


The bad news is that most people are infected with cytomegalovirus (CMV) at some point in their lives. About 80 percent of the U.S. population is estimated to be carriers, about 4 in 10 Americans are infected with CMV before puberty (usually through contact with saliva), and adults can be reinfected through sexual activity. The good news is that among healthy adults, a CMV infection usually does not have any symptoms, though if they do they could seem like a mild case of mono. Being reinfected with the virus later in life also carries with it only a small risk for symptoms in healthy adults.

And back to the bad news: While an infection with cytomegalovirus usually does not have symptoms, if someone is infected while pregnant it can harm the fetus. About 1 in 100 U.S. babies is infected with CMV, but usually doesn’t show symptoms. Every year in the United States, around 5,500 babies are born with symptomatic cytomegalic inclusion disease (CID). Symptoms of CID vary, but the most severe include mental retardation and hearing loss. If the mother was already infected before conception, there is a 2 percent chance the virus will be transmitted to the fetus; however, if the infection occurs during pregnancy, this risk jumps into the 40 to 50 percent range.

More bad news: In someone with a compromised immune system, a latent CMV infection can be reactivated, which can cause fatal or near-fatal pneumonia as well as other problems. For example, an eye infection called cytomegalovirus retinitis, which can lead to blindness, is common among AIDS patients. Such conditions can be treated with antiviral drugs.

The virus can be shed in bodily fluids, including urine, cervical and vaginal secretions, saliva, semen, blood, and breast milk. Contact with such fluids increases the risk for transmission; such contact can be facilitated by breastfeeding, kissing, and most sexual activities (vaginal, anal, and oral sex), as well as sharing intravenous drug equipment. It can also be transmitted by blood transfusions or other tissue transplants, but here the risk can be minimized by screening the donated tissues.

Cytomegalovirus is a member of the Herpesviridae family, along with the viruses that cause herpes, chickenpox, shingles, and infectious mononucleosis. When the virus infects a host cell, it leaves granules called inclusion bodies that can be seen under a microscope when stained with certain chemicals. The virus enters a latent state in white blood cells, in which they replicate very slowly while evading the immune system.

Sexually active people can reduce their risk for contracting CMV by using latex barriers such as condoms and dental dams; however, the virus can still be transmitted nonsexually. A blood test can determine whether you carry CMV. It cannot be cured, but in most people it doesn’t cause symptoms. When symptoms do appear, they can be treated with medications. It poses the biggest risk to immunocompromised people and to fetuses whose mothers have been infected during pregnancy. More information can be found at Planned Parenthood’s website.

Two forms of the molluscum contagiousum virus, which contains DNA inside of a viral particle called a virion. Image: Dr. James Nakano, Public Health Image Library, CDC

Molluscum Contagiosum

Another STD caused by a virus is molluscum contagiosum, which is caused by the molluscum contagiosum virus. This virus is a member of the viral family Poxviridae. The virus particles are large, relatively complex, and shaped like bricks. Molluscum contagiosum causes a “wartlike” skin lesion. Each year, there are hundreds of thousands of molluscum contagiosum infections diagnosed. Symptoms can appear within three months and include small round wartlike growths with an indentation in the middle. There are usually no further symptoms in healthy people, but those with compromised immune systems might experience more serious problems.

Molluscum contagiosum can be transmitted sexually or nonsexually, through close, skin-to-skin contact. Most adults get it through sexual contact — vaginal, anal, or oral sex — but it can also be spread through other close contact as well as by sharing clothing or towels. Contact with the wartlike skin growths increases risk, so while it is always best to use latex barriers such as condoms or dental dams, such devices don’t adequately reduce risk unless they cover up all of the growths. The best course of action is to avoid contact with these growths altogether, until they are removed or have cleared up.

Molluscum contagiosum can be diagnosed by a health-care provider, who will examine the skin lesions, perhaps by taking a scraping and giving it a closer look under a microscope. The warts can be treated just like other warts are treated — with chemicals, with an electric current, by freezing them, or with a prescription topical medication. If left untreated, the warts usually clear up within a couple of years, but their presence does increase the risk of transmission to someone else or to another part of your body. More information can be found at Planned Parenthood’s website.

Click here to check out other installments of our monthly STD Awareness series!