The epidemiology and clinical presentation of herpes virus infections.

The chief characters of infection by the human herpes viruses are considered with particular reference to herpes simplex viruses, types 1 and 2. Infection with type 1 virus is acquired very early in life though infrequently as a true congenital transmission of virus. Primary infections result from direct contact usually with infected saliva or skin vesicles. Kerato-conjunctivitis, when primary, may be severe yet superficial in extent. Vulvo-vaginitis, often acquired in adults as a result of type 2 infection by sexual transmission, can give extensive but superficial ulceration and discharge. Recurrent infections located on the dermatome with the same nerve supply as that of the organ affected primarily occur throughout life and at relatively short intervals. Sensory nerve ganglia harbour the virus particles as latent infection and when reactivation occurs virus spreads along nerve fibres to the skin. The most serious infections occur as disseminated disease with liver involvement in the neonatal period, in infants suffering from malnutrition or those undergoing immunosuppression for malignancies. Eczematous children are then at particular risk from spreading haemorrhagic skin lesions (Kaposi's eruption). Herpes encephalitis, commoner in adults than children, is an insidious severe disease with mortality related to the depth of coma. Antiviral therapy though successful may lead to chronic neurological sequelae. The success of antiviral therapy in herpes partly turns on the ability to bring the drug into close contact with the infected tissues. Latent virus is relatively unaffected by acyclovir and thus far recurrences have continued to occur.