Herpes whitlow can be caused by infection by HSV-1 or HSV-2. Recurrent oral infection is more common with HSV-1 infections than with HSV-2. HSV-2 is primarily a sexually transmitted infection, but rates of HSV-1 genital infections are increasing. HSV is classified into two types, HSV-1 and HSV-2. The HSV is a double-stranded DNA virus categorised into two types; HSV-1 and HSV-2. Those with both HSV-1 and HSV-2 antibodies are estimated at 13.3% of the population. Worldwide rates of either HSV-1 or HSV-2 are between 60% and 95% in adults. Ocular herpes simplex is usually caused by HSV-1. In viruses such as the herpes simplex virus (HSV-1), primase can form complexes with helicase. The herpes simplex virus HSV-1 has been found in the same areas as amyloid plaques. Many white Americans become sexually active while seronegative for HSV-1. European women are more likely to be HSV-1 seropositive than men. HSV-1 is often acquired orally during childhood. In addition, HSV-1 infection is associated with demyelination of nerves. Changes in the immune system during menstruation may play a role in HSV-1 reactivation.