herpes simplex virus 2

Herpes simplex virus 2 can be divided into two clades: one is globally distributed and the other is mostly limited to sub Saharan Africa.Burrel S, Boutolleau D, Ryu D, Agut H, Merkel K, Leendertz FH, Calvignac-Spencer S (2017) Ancient recombination events between human herpes simplex viruses. Mol Biol Evol {{doi|10.1093/molbev/msx113}}

{{See also|Herpes simplex virus}}

Herpes simplex virus 2 infects humans, most often as genital herpes. In the United States more than one in six people have the virus.{{Cite web|url=https://www.cdc.gov/std/herpes/stdfact-herpes.htm|title=STD Facts - Genital Herpes|date=December 11, 2017|website=www.cdc.gov|language=en-us|access-date=September 22, 2018|quote=Genital herpes is common in the United States. More than one out of every six people aged 14 to 49 years have genital herpes.}} It is primarily a sexually transmitted infection. Herpes simplex virus 2 tends to reside in the sacral ganglia. Herpes simplex virus 2 is periodically shed in the human genital tract, most often asymptomatically. Most sexual transmissions occur during periods of asymptomatic shedding.{{cite journal |vauthors=Schiffer JT, Mayer BT, Fong Y, Swan DA, Wald A | title = Herpes simplex virus-2 transmission probability estimates based on quantity of viral shedding | journal = J R Soc Interface | volume = 11 | issue = 95 | pages = 20140160 | year = 2014 | pmid = 24671939 | doi = 10.1098/rsif.2014.0160 | pmc = 4006256 }} Asymptomatic reactivation means that the virus causes atypical, subtle, or hard-to-notice symptoms that are not identified as an active herpes infection, so acquiring the virus is possible even if no active blisters or sores are present.

In one study, daily genital swab samples found Herpes simplex virus 2 at a median of 12–28% of days among those who have had an outbreak, and 10% of days among those suffering from asymptomatic infection, with many of these episodes occurring without visible outbreak ("subclinical shedding").{{Cite journal |vauthors=Johnston C, Koelle DM, Wald A | title = HSV-2: in pursuit of a vaccine. | journal = J Clin Invest | volume = 121 | issue = 12 | pages = 4600–9 |date=Dec 2011 | doi = 10.1172/JCI57148 | pmid = 22133885 | pmc=3223069}} In another study, 73 subjects were randomized to receive valaciclovir 1 g daily or placebo for 60 days each in a two-way crossover design. A daily swab of the genital area was self-collected for Herpes simplex virus 2 detection by polymerase chain reaction, to compare the effect of valaciclovir versus placebo on asymptomatic viral shedding in immunocompetent, seropositive subjects without a history of symptomatic genital herpes infection. The study found that valaciclovir significantly reduced shedding during subclinical days compared to placebo, showing a 71% reduction; 84% of subjects had no shedding while receiving valaciclovir versus 54% of subjects on placebo. About 88% of patients treated with valaciclovir had no recognized signs or symptoms versus 77% for placebo.{{cite journal |vauthors=Sperling RS, Fife KH, Warren TJ, Dix LP, Brennan CA | title = The effect of daily valacyclovir suppression on herpes simplex virus type 2 viral shedding in HSV-2 seropositive subjects without a history of genital herpes | journal = Sex Transm Dis | volume = 35 | issue = 3 | pages = 286–90 |date=March 2008 | pmid = 18157071 | doi = 10.1097/OLQ.0b013e31815b0132 | doi-access = free }} For Herpes simplex virus 2, subclinical shedding may account for most of the transmission. Studies on discordant partners (one infected, one not) show that the transmission rate is approximately 5 per 10,000 sexual contacts.Effect of Condoms on Reducing the Transmission of Herpes Simplex Virus Type 2 From Men to Women. A Wald, AGM Langenberg, K Link, et al. JAMA. 2001;285(24):3197 Atypical symptoms are often attributed to other causes, such as a yeast infection.{{cite journal |vauthors=Gupta R, Warren T, Wald A | title = Genital herpes | journal = Lancet | volume = 370 | issue = 9605 | pages = 2127–37 | year = 2007 | pmid = 18156035 | doi = 10.1016/S0140-6736(07)61908-4 }}{{cite journal |vauthors=Koelle DM, Corey L | title = Herpes simplex: insights on pathogenesis and possible vaccines | journal = Annual Review of Medicine | volume = 59 | pages = 381–95 | year = 2008 | pmid = 18186706 | doi = 10.1146/annurev.med.59.061606.095540 }}

File:GenitalGerpes.gif|Genital herpes in men. Vesicles, ulcers and crusts on the Penis

• Human alphaherpesvirus 1

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{{Herpesvirales}}

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Category:Alphaherpesvirinae