Herpes simplex virus type 1, or HSV-1, and herpes simplex virus type 2, or HSV-2, are virtually identical under a microscope, according to Herpes.com, and both, once contracted, remain in the body for life. Sharing about 50 percent of their DNA, the two types cause similar symptoms. After the initial outbreak, the virus enters a period of latency, meaning that it becomes inactive. Reactivation can occur at any time, though subsequent recurrences tend to be less severe and to last for a shorter period of time than the initial outbreak.
Latency, HSV-1
A major difference between the two viruses is where each type prefers to establish latency. After the initial infection, the virus retreats to the nervous system where it lies dormant, sometimes for years. HSV-1, which is most often transmitted through kissing or the sharing of utensils, according to the University of South Carolina, tends to remain near the trigeminal ganglion, a nerve center near the ears. When it flares, it follows neural pathways the relatively short distance to the face, where it causes an outbreak, generally around the mouth. In approximately 10 percent of cases, when HSV-1 infects the genital area, the virus hibernates in the sacral ganglion at the base of the spine. For unknown reasons, a reactivation of HSV-1 from the sacral ganglion is less likely than from the trigeminal ganglion.
Latency, HSV-2
HSV-2 causes approximately 90 percent of the cases of genital herpes, according to the University of South Carolina. After the initial infection, HSV-2 generally establishes latency in the sacral ganglion at the base of the spine. When it reactivates, it returns to the genital area and causes an outbreak there. While the preferred location of latency of each of the viruses affects future outbreaks, it is important to note that HSV-2 can cause oral herpes just as HSV-1 can cause genital outbreaks.
Ocular Herpes
HSV-1, after establishing latency near the trigeminal ganglia, can reactivate and infect the eyes. When it does, it usually affects just one eye. Ocular herpes can range from mild, when the infection occurs on the cornea--the clear covering of the eye, to the severe, when it infects deep within the eye. Severe ocular herpes can cause vision loss, or even blindness. The National Eye Institute reports that approximately 400,000 Americans have some form of ocular herpes with some 50,000 new and recurring cases being diagnosed each year.
Herpes Whitlow
Both HSV-1 and HSV-2 can infect other areas of the body besides the face, eyes and genitals, according to the University of South Carolina. Herpes whitlow, which can be caused by either HSV-1 or -2, is an outbreak of the hand and/or wrist. It is occurs when a person with a wound, or even a very small cut on the hands, comes into manual contact with either virus type.
Other Outbreaks
Herpes gladiatorum is an infection generally contracted by wrestlers, according to the University of South Carolina. It occurs on the head or neck area, sites where contact is common in wrestling, and is spread through direct contact with skin lesions. HSV encephalitis is a serious febrile disease, which is usually caused by HSV-1, with less than 100 cases reported yearly in the United States. HSV meningitis, most often caused by HSV-2, tends to resolve spontaneously.
