EPIDEMIOLOGY OF GENITAL HERPES SIMPLEX VIRUS INFECTIONGenital HSV infection is estimated to occur in approximately I% of pregnant women some time during gestation." Intrauterine transmission of HSV may result in congenital infection, an uncommon but well-documented consequence of genital HSV infection during pregnancy.Intrauterine infection in early pregnancy may result in spontaneous abortion while infection later in gestation does not generally result in termination of the pregnancy but may produce anomalies which are evident at birth including vesicles, skin scarring, microcephaly, hydrocephalus or chorioretinitis. Most episodes of genital herpes in pregnant women are recurrent infections. These may be clinically apparent or asymptomatic recurrences.For women with a history of recurrent genital herpes prior to pregnancy, the mean number of clinically recognised recurrences increases from 0.97 to 1.26 to 1.63 in the first, second, and third trimesters, re~pective1y.l~ Shedding of HSV from the genital tract in the absence of clinically recognised lesions has been well d0~umented.l~ Asymptomatic shedding of virus from pregnant women with a history of recurrent genital herpes has been noted in 0.65% to 3.03% of viral cultures collected some time during gestation.I6 When shedding occurs around the time of delivery, virus may be transmitted to the fetus during the birth process. It has been estimated that from 0.01% to 0.39% of all pregnant women shed HSV at the time of delivery6 and the frequency of shedding increases to 1.3% during the week prior to delivery for women with a history of recurrent genital herpes.16 Fortunately, the duration of shedding appears brief, in the range of 1.5 days.17 Consequently, antepartum viral cultures of the maternal genital tract do not predict the infant's risk of exposure to HSV at the time of delivery,16 such exposure can only be assessed by cultures of the maternal genital tract collected at delivery.The alarmingly high HSV-2 seroprevalence rate and the rising number of cases of symptomatic genital herpes coupled with the high incidence of genital HSV infections in pregnant women and the risk of significant morbidity or mortality in HSV infected neonates combine to make HSV infections one of the most important public health problems in developed countries.
PATHOPHYSIOLOGY OF GENITAL HERPES SIMPLEX VIRUS INFECTIONThe pathophysiology of primary genital herpes is schematically represented in Figure 1. In the susceptible host, primary infection begins when HSV is transmitted to the genital mucosa. The viral glycoprotein, gC, permits attachment (adsorption) of the virus to putative epithelial cell surface receptors, possibly heperan sulphate.I8 Three other viral glycoproteins, gB, gD and gH, facilitate penetration of the virus which occurs by fusion of the viral envelope with the cell plasma membrane.l'~zO Penetration of HSV may be inhibited by cytochalasins suggesting that a change in the cell membrane cytoskeletal structure following virus attachment triggers a microfilament activi...
