HSV1by Merrilyn Reeves, CPM

Herpes is a very large family of viruses.  These are “nerve loving” viruses and include HSV-1, HSV-2, varicella, cytomegalovirus, Epstein Barr virus, and many others.  Genital herpes (HSV-2) is the most prevalent sexually transmitted disease among women today, with nearly a million new cases each year.  About 26% of women have antibodies to HSV-2, with 88% being unaware that they are infected.  HSV-2 is associated with a very low rate of HSV-1 acquisition.

HSV-2 is almost entirely genital (about 95%).  Following exposure, the initial outbreak appears after an incubation period of 7-10 days, but may occur much later.  The initial infection is usually the most severe, followed by 4-6 milder outbreaks during the first year.  Classic presentation includes painful vesicles and ulcers, but abrasions, fissures, itching, and flu-like symptoms may also be seen.  Occasionally the infection may be asymptomatic. Viral shedding takes place from lesions, during which transmission of the disease may take place.  However, transmission may also occur during interlesional periods.  In one study of HSV-2 seropositive women, the virus was found in the genital area on 25% of days with no genital lesion.  Transmission to the newborn may result in serious complications including but not limited to seizures, blindness, and death.

In contrast, 70% of the population have antibodies to HSV-1, with infection taking place around 1-3 years of age.  One third of these develop cold sores and one half are asymptomatic.  Viral shedding takes place when a cold sore is present and a few days before its appearance, but may also occur during asymptomatic periods to a lesser extent than HSV-2.  HSV-1 outbreaks are of shorter duration than HSV-2.  The average is one recurrence during the first year following infection and rarely thereafter.  HSV-1 usually affects the mouth and lips, but comprises an increasing proportion of genital herpes among young people today.  HSV-1 is not likely to reactivate at term and is not likely to cause neonatal herpes. Women with HSV-1 are also at risk for HSV-2 infection.

HSV infection is incurable and significantly impacts physical, psychological and social health, increases risk of HIV infection and may be transmitted to the newborn.  Individuals are at high risk for HSV if they became sexually active at a young age, have other STD’s, have multiple sex partners, sex with HSV infected individuals (especially those with open lesions), or sex with individuals engaging in other high risk behavior.

TESTING

Appropriate treatment depends on accurate diagnosis.  As many as 75% of primary genital HSV infections are missed by either the individual or her health care provider.  Additionally, 20% of cases clinically diagnosed as herpes were actually not herpes.  Clinical assessment of herpes should be confirmed with laboratory testing.  Currently, consideration is being given to testing all pregnant women for herpes.

The polymerase chain reaction (PCR) test is the test of choice for testing lesions and herpes-related infections of the central nervous system.  PCR is 1.5-4 times more sensitive than a viral culture.  A seropositive response may occur as early as 3 weeks following HSV infection, but may take as long as 16 weeks.  False positives are rare.  However, a negative test does not rule out herpes in an individual at high risk for having an STD.  A repeat test in 3-6 months is appropriate.

HerpeSelect ELISA, HerpeSelect Immunoblot, and Captia ELISA are type-specific serologic tests (TSST) based on antibody response to glycoprotein G-2 for HSV-2 and G-1 for HSV-1.  Type-specific testing may be done for HSV-1 or HSV-2 or for both viruses.  Determining the specific HSV virus causing the infection results in a more accurate diagnosis than a clinical assessment based on symptoms and sexual history.  This is important because the prognosis of the two diseases is very different and likewise, the implications for the newborn.

IgM antibody tests cannot be used to differentiate new infections from recurrent ones because IgM tests are not type-specific.  Also, each episode of viral reactivation produces new IgM and IgG.

TREATMENT AND IMPLICATIONS FOR PREGNANCY

Current treatment of HSV uses antiviral drugs acyclovir, famcyclovir, or valacyclovir.  Because these drugs interrupt viral synthesis, they must be used when the virus is actively replicating.  Oral drug therapy should be used during the initial outbreak of genital herpes to decrease lesions, shedding, and other symptoms.  Acetominophen or ibuprofen may be used for pain relief, and warm baths may also be helpful.

Following the initial outbreak, the disease may be managed with either episodic or suppressive therapy.  Episodic therapy is most effective if the drug is begun at the early sign or the beginning of the outbreak, reducing the duration, lesions, pain, and shedding.  Suppressive therapy is used daily and will prevent about 80% of recurrent outbreaks and much viral shedding from the genital area, reducing transmission of the disease.

A woman with an HSV-1 or HSV-2 seropositive partner should be tested to assess her status.  If she does not already have herpes, she is at risk for acquiring the disease during pregnancy.  Condom use will decrease but not eliminate transmission.  Her partner should consider suppressive therapy to decrease the possibility of transmission to her.

A woman experiencing the initial outbreak of HSV-2 before pregnancy or during the first half of pregnancy has a low risk of transmitting the disease to her baby.  However, she should be made aware that she will have viral shedding with and without symptoms and she should inform her partner of her infection.  Risk of acquiring the herpes in the third trimester of pregnancy results in 40-50% risk of infection in the newborn.  The mother will be more likely to be shedding the virus and will not have had time to develop or pass antibodies on to her baby.

Current protocols require Cesarean section for women experiencing active lesions or prodromal symptoms during labor, in order to reduce transmission of herpes to the newborn.  However, up to 70% of neonatal herpes is acquired through mothers who shed asymptomatically near or during labor.  Prophylactic treatment with valacyclovir from 36 weeks of pregnancy to labor results in a reduced number of women with active HSV at the time of birth and a reduced number of C-sections.  To minimize exposure of the newborn to the virus, artificial rupture of membranes, use of scalp electrodes, vacuum extractors, and forceps should be avoided in HSV positive birthing women.

Thanks go to Dr. Gary Richwald, MD, for his very informative talk and many articles on this subject included in the conference workbook at the Idaho Perinatal Project conference in Boise in February 2006.  The above info was gleaned from these sources.

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