HSV-1 has been proposed as a possible cause of Alzheimer's disease.[26][27] In the presence of a certain gene variation (APOE-epsilon4 allele carriers), HSV-1 appears to be particularly damaging to the nervous system and increases one's risk of developing Alzheimer's disease. The virus interacts with the components and receptors of lipoproteins, which may lead to its development.[28][29]
Primary orofacial herpes is readily identified by examination of persons with no previous history of lesions and contact with an individual with known HSV infection. The appearance and distribution of sores is typically presents as multiple, round, superficial oral ulcers, accompanied by acute gingivitis.[39] Adults with atypical presentation are more difficult to diagnose. Prodromal symptoms that occur before the appearance of herpetic lesions help differentiate HSV symptoms from the similar symptoms of other disorders, such as allergic stomatitis. When lesions do not appear inside the mouth, primary orofacial herpes is sometimes mistaken for impetigo, a bacterial infection. Common mouth ulcers (aphthous ulcer) also resemble intraoral herpes, but do not present a vesicular stage.[39]

These herpes viruses enter the body through small cuts, abrasions, or breaks in the skin or mucous membranes. The incubation period for herpes simplex infections is about three to six days. Transmission (spread) of the virus is person to person and more likely to occur if blisters or lesions are present. The majority enter after an uninfected person has direct contact with someone carrying the virus (either with or without noticeable lesions). Simply touching an infected person is often the way children get exposed. Adolescents and adults frequently get exposed by skin contact but may get their first exposure by kissing or sexual contact (oral and/or genital contact), especially for HSV-2. Statistical studies suggest that about 80%-90% of people in the U.S. have been exposed to HSV-1 and about 30% have been exposed to HSV-2. Usually, the contagious period continues until lesions heal. Some people (estimated from 30%-50%) occasionally shed herpes virus while having few or no associated symptoms or signs.
Herpes infection of the genital tract is a sexually transmitted infection (sexually transmitted disease or STD). Like in the mouth area, herpes symptoms and signs include a painful, blistering rash around or on the genital or rectal areas. These lesions open and result in painful sores that can take two to four weeks to heal. The sores can sometimes cause painful urination. Recurrent outbreaks are typical, and the time between outbreaks varies among affected people and even within the same individual. Prior to an outbreak, a tingling, burning, or itching sensation may be present on the area of involved skin.

When a herpes outbreak occurs, you can expect cold sores to take about 10–14 days to heal on average. During this time period, the virus is considered to be active, and you should be very careful to avoid direct contact between a sore and someone else. If after trying the natural remedies for herpes described above you still experience frequent recurrences, talk to your doctor for how to get rid of herpes symptoms. Sometimes immunity is suppressed due to another infection or virus, or even as a side effect of taking some medications, so be sure to rule these causes out.
Herpes is contracted through direct contact with an active lesion or body fluid of an infected person.[31] Herpes transmission occurs between discordant partners; a person with a history of infection (HSV seropositive) can pass the virus to an HSV seronegative person. Herpes simplex virus 2 is typically contracted through direct skin-to-skin contact with an infected individual, but can also be contracted by exposure to infected saliva, semen, vaginal fluid, or the fluid from herpetic blisters.[32] To infect a new individual, HSV travels through tiny breaks in the skin or mucous membranes in the mouth or genital areas. Even microscopic abrasions on mucous membranes are sufficient to allow viral entry.
Oral herpes is also known commonly as cold sores and fever blisters but is different entity from oral canker sores although canker sores may sometimes be associated with HSV infection. Canker sores occur solely inside the mouth. Oral herpes occurs inside and around the mouth. Most of the time HSV-1 causes mouth symptoms and in a minority of cases it may also be responsible for genital symptoms. The opposite is true for HSV-2 – it causes genital symptoms in the majority of cases while only a few cases of HSV-2 infection will result in mouth symptoms. HSV-1 infection may be seen in all ages, including children, but when genital herpes is seen in children, sexual abuse needs to be a consideration.
A 2004 study in the New England Journal of Medicine found that suppressive therapy decreases the risk of HSV-2 transmission from symptomatic, infected partners to uninfected partners by 48%. So β€œthe risk of transmission is significantly reduced, but cannot be eliminated even with suppressive therapy,” Johnston explains, and she stresses that the virus can be passed along even without signs or symptoms.
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