In the 2008 edition of "Archives of Internal Medicine," internist Christina Cernik, M.D., describes cold sores as painful, itchy, 1- to 2-mm blisters or shallow ulcers that typically develop in clusters that coalesce to produce larger lesions. Cold sores usually develop on the mouth, especially on the border of the lip. However, they also may develop around the mouth; on the chin, cheeks or nose; or inside the mouth on the palate, throat, tongue, gums or lining of the cheeks. Viruses that cause cold sores belong to the herpes family.
Herpes Simplex-1
Most cases of cold sores are caused by the herpes simplex-1 virus, according to University of Washington virologist Lawrence Corey, M.D., in the 2008 edition of "Harrison's Principles of Internal Medicine." Between 50 and 80 percent of adults are infected with the virus, according to Corey. Most people acquire the infection in childhood when they receive kisses from family members or put objects that have been handled by infected people into their mouths. Only about 30 percent of people ever experience symptoms, according to Corey, and those who do typically experience between one and six recurrences each year.
Herpes Simplex-2
The second most common cause of cold sores, according to Corey, is the herpes simplex-2 virus. Herpes simplex-2 usually causes genital herpes; however, it may also cause cold sores when the mouth is the site of inoculation. People may contract the infection by performing oral sex on someone with genital herpes, or they may contract it through direct or indirect oral contact with someone who has cold sores caused by herpes simplex-2. Corey reports that cold sores due to herpes simplex-2 recur one-tenth as frequently as those caused by herpes simplex-1. However, Corey notes, only laboratory tests can definitively distinguish between the two.
Varicella-Zoster
Varicella-zoster, the virus that causes both chicken pox and shingles, is a herpes virus that infects humans. Varicella-zoster produces cold sores; however, the lesions caused by varicella-zoster follow patterns rarely seen with herpes simplex viruses. In the case of chicken pox, according to National Institutes of Health dermatologist Stephen E. Straus in the 2008 edition of "Fitzpatrick's Dermatology in General Medicine," lesions initially develop on the mouth and head but spread quickly to the trunk, legs and arms. These sites are rarely involved in herpes simplex infections. Shingles may exclusively involve the mouth; however, lesions usually develop on just one side of the body, says Straus. In addition, Straus notes that cold sores due to varicella-zoster almost never recur.
References
- "Archives of Internal Medicine"; The Treatment of Herpes Simplex Infections; C. Cernik et al.; 2008
- "Harrison's Principles of Internal Medicine, 23rd Edition"; A.S. Fauci et al.; 2008
- "Fitzpatrick's Dermatology in General Medicine, 7th Edition"; K. Wolff et al.; 2008
