Genital herpes is a common infection caused by herpes simplex virus type 1 (HSV-1) or herpes simplex virus type 2 (HSV-2). Although life-threatening health consequences of HSV infection after infancy are uncommon, women with genital herpes remain at risk for recurrent symptoms, which can be associated with significant physical and psychosocial distress. These patients also can transmit the disease to their partners and neonates, and have a 2- to 3-fold increased risk of HIV acquisition. In this article, we review the diagnosis and management of genital herpes in pregnant women.
CASE Asymptomatic pregnant patient tests positive for herpes
Sarah is a healthy 32-year-old (G1P0) presenting at 8 weeks’ gestation for her first prenatal visit. She requests HSV testing as she learned that genital herpes is common and it can be transmitted to the baby. You order the HSV-2 IgG assay from your laboratory, which performs the HerpeSelect HSV-2 enzyme immunoassay as the standard test. The test result is positive, with an index value of 2.2 (the manufacturer defines an index value >1.1 as positive). Repeat testing in 4 weeks returns positive results again, with an index value of 2.8.
The patient is distressed at this news. She has no history of genital lesions or symptoms consistent with genital herpes and is worried that her husband has been unfaithful. How would you manage this case?
How prevalent is HSV?
Genital herpes is a chronic viral infection transmitted through close contact with a person who is shedding the virus from genital or oral mucosa. In the United States, the National Health and Nutrition Examination Survey indicated an HSV-2 seroprevalence of 16% among persons aged 14 to 49 in 2005–2010, a decline from 21% in 1988–1991.1 The prevalence among women is twice as high as among men, at 20% versus 11%, respectively. Among those with HSV-2, 87% are not aware that they are infected; they are at risk of infecting their partners, however.1
In the same age group, the prevalence of HSV-1 is 54%.2 The seroprevalence of HSV-1 in adolescents declined from 39% in 1999–2004 to 30% in 2005–2010, resulting in a high number of young people who are seronegative at the time of sexual debut. Concurrently, genital HSV-1 has emerged as a frequent cause of first-episode genital herpes, often associated with oral-genital contact during sexual debut.2,3
When evaluating patients for possible genital herpes provide general educational messages regarding HSV infection and obtain a detailed medical and sexual history to determine the best diagnostic approach.
What are the clinical features of genital HSV infection?
The clinical manifestations of genital herpes vary according to whether the infection is primary, nonprimary first episode, or recurrent.
Primary infection. During primary infection,which occurs 4 to 12 days after sexual exposure and in the absence of pre-existing antibodies to HSV-1 or HSV-2, patients may experience genital and systemic symptoms (FIGURE and TABLE 1). Since this infection usually occurs in otherwise healthy people, for many, this is the most severe disease that they have experienced. However, most patients with primary infection develop mild, atypical, or completely asymptomatic presentation and are not diagnosed at the time of HSV acquisition. Whether primary infection is caused by HSV-1 or HSV-2 cannot be differentiated based on the clinical presentation alone.
Nonprimary first episode infection. In a nonprimary infection, newly acquired infection with HSV-1 or HSV-2 occurs in a person with pre-existing antibodies to the other virus. Almost always, this means new HSV-2 infection in a HSV-1 seropositive person, as prior HSV-2 infection appears to protect against HSV-1 acquisition. In general, the clinical presentation of nonprimary infection is somewhat milder and the rate of complications is lower, but clinically the overlap is great, and antibody tests are needed to define whether the patient has primary or nonprimary infection.4
Recurrent genital herpes infection occurs in most patients with genital herpes. The rate of recurrence is low in patients with genital HSV-1 and often high in patients with genital HSV-2 infection. The median number of recurrences is 1 in the first year of genital HSV-1 infection, and many patients will not have any recurrences following the first year. By contrast, in patients with genital HSV-2 infection, the median number of recurrences is 4, and a high rate of recurrences can continue for many years. Prodromal symptoms (localized irritation, paresthesias, and pruritus) can precede recurrences, which usually present with fewer lesions and last a shorter time than primary infection. Recurrent genital lesions tend to heal in approximately 5 to 10 days in the absence of antiviral treatment, and systemic symptoms are uncommon.5
Asymptomatic viral shedding. After resolution of a primary HSV infection, people shed the virus in the genital tract despite symptom absence. Asymptomatic shedding tends to be more frequent and prolonged with primary genital HSV-2 infection compared with HSV-1 infection.6,7 The frequency of HSV shedding is highest in the first year of infection, and decreases subsequently.8 However, it is likely to persist intermittently for many years. Because the natural history is so strikingly different in genital HSV-1 versus HSV-2, identification of the viral type is important for prognostic information.
The first HSV episode does not necessarily indicate a new or recent infection—in about 25% of persons it represents the first recognized genital herpes episode. Additional serologic and virologic evaluation can be pursued to determine if the first episode represents a new infection.