Herpes Simplex Virus

HSV-1 and -2; DNA viruses; persistently infecting regional ganglion. Incubation period: initial infection 2 - 7 days.

Epidemiology. Infection with HSV is one of the most common viral infections. Based on reports on antibody titers, three quarters of adults were estimated to be positive for HSV-1, the virus of oral (or labial) herpes, and one quarter was found positive for the genital herpes HSV-2. But strict division between oral and genital herpes virus does not seem reasonable because HSV-1 antibodies are found in the genital area as well in almost 50% of women suffering from genital herpes, as shown by a Swedish study. Thus, a British report found a lower prevalence of antibodies for HSV-1 in 10% of peripubertal girls, which may put them at an increased risk of subsequent genital infection.

As expected, a much higher seroprevalence of HSV-2 is found in risk groups, with up to 80% in female sex workers in Germany.

Symptoms, Diseases, Sequelae. Fifty percent of all genital herpes infections occur asymptomatically. Atypical symptoms are found in 20%, with these cases not being recognized as herpes infection. Only 30% of all genital herpes-infected people unambiguously show clinical symptoms.

The initial genital infection with HSV is characterized by painful groups of small vesicles and ulcers that are localized on both sides of the external genitalia. These spreading viral lesions may last for several weeks. Genital HSV infections in more than 60% of the cases are accompanied by fever, headache, malaise and myalgia. The initial infection is followed in nearly 85% of the cases by at least one recurrence. Recurrent infections usually occur less intensively and do not last as long as the initial one. Subclinical HSV infections may contribute to spreading the disease even by condom-protected sexual intercourse.

Hence, for adolescents both proper treatment and adequate knowledge about the high infectivity of HSV are very important. During the initial infection, virus excretion takes place for 12 - 15 days, during recurrences excretion lasts 3 - 5 days.

Sequelae of HSV infection may include aseptic meningitis, encephalitis, hepatitis and pneumonitis.

Diagnosis. The best means of identifying genital herpes pathogens are cell cultures, antigen detections and DNA methods. Reliable results for the different diagnostic methods are obtained only by using specimens from florid vesicles. Specimens from already dried-up erosions are far less useful.

Based on the gold standard, both HSV-1 and HSV-2 can be easily cultured. The type of virus determination is obtained by differentially specific fluorescent tests, with sensitivities of about 95%.

Other methods such as direct antigen tests or molecular biologic DNA methods are somewhat less sensitive than cultures. But these methods are suitable for the diagnosis of asymptomatic infections.