Genital herpes: neurologic complications

Marylou V Solbrig MD (Dr. Solbrig of the University of Manitoba has no relevant financial relationships to disclose.)
John E Greenlee MD, editor. (

Dr. Greenlee of the University of Utah School of Medicine received consulting fees from Wheeler Trigg O'Donnell LLP.

Originally released June 27, 1995; last updated June 17, 2019; expires June 17, 2022


The author reviews the neurologic complications of genital herpes and herpes simplex virus type 2 (HSV-2) infections in adults and neonates and summarizes the recommendations for acute and suppressive treatments from the International Herpes Management Forum (IHMF). Illustrative cases of HSV-2 lumbosacral radiculomyelitis in an immunocompromised patient and HSV-2 meningoencephalitis in a child are presented. In this update, the changing epidemiology of genital herpes with the growing proportion of HSV-1 and rare cases of varicella zoster virus infection is presented, along with an expanded discussion of herpes simplex virus in CNS autoimmune disorders and lessons from neonatal herpes generalizable to clinical and research approaches to Zika virus congenital infections.

Key points


• HSV-1 and HSV-2 are prevalent viruses with the capacity to establish lifelong infections and episodic reactivation. As all herpesviruses, HSV-2 performs 2 distinct genetic programs, lytic replication, and latency, to produce primary and recurrent infections.


• The clinical presentation of HSV-2 infection of the CNS in adults is mainly meningitis, but encephalitis, myelitis, and lumbosacral radiculitis occur.


• In immunocompetent adults, about 10% of cases of herpes simplex encephalitis are caused by HSV-2, with the rest due to type 1.


• Recurring lymphocytic meningitis is most often a reactivation of HSV-2.


• HSV-2 infection is common. Currently HSV-2 seroprevalence is 17% in the United States (Xu et al 2006). Annual crude incidence rate of HSV-2 CNS disease is 0.26 per 100,000 in Denmark (Omland et al 2008) and of HSV-2 meningitis is 0.37 per 100,000 in Finland (Kupila et al 2006). When a pathogen is detected, HSV-2 is one of the leading causes of aseptic meningitis in adults.


• Within the past few years, HSV-1 has become the most common cause of genital herpes, shifting the cause of neonatal herpes to HSV-1 in many parts of the world. Estimates of 60% to 78% of new genital herpes cases in the United States are attributed to HSV-1 (Ayoub et al 2019). Ever-increasing HSV-1 genital disease contributes to the enduring HSV-1 disease burden in the United States.

Historical note and terminology

“Throughout nature, infection without disease is the rule rather than the exception” (Dubos 1980) is a statement appropriate to certain primary, latent, and recurrent herpetic syndromes. The term "herpes" was first used in ancient Greece for migratory (creeping or crawling) skin lesions. The ancient Greek historian Herodotus labeled mouth and lip ulcers during fever "herpes febrilis" (Mettler 1947; Whitley and Schlitt 1991). Shakespeare referred to recurrent herpes simplex virus labial lesions in Romeo and Juliet (Wildy 1973). In the 1700s, the French royal court physician introduced genital herpes infections in the medical literature (Astruc 1736).

Transmissibility was established by passage of material from human lip and genital lesions to cornea or abraded skin of rabbits. CNS transmission was demonstrated when Goodpasture showed that material from herpes labialis lesions inoculated onto scarified rabbit cornea produced encephalitis (Goodpasture 1925). Herpes simplex virus was isolated from a case of encephalitis in 1941 (Smith et al 1941), and 2 antigenic types of herpes simplex virus (HSV) were recognized in 1968 (Nahmias and Dowdle 1968). Viral typing distinguished herpes simplex virus type 1 (HSV-1), which is mainly responsible for infections “above the belt,” from herpes simplex virus type 2 (HSV-2), which is primarily responsible for infections “below the belt,” although later studies have shown either virus can infect the mouth, genital tract, or brain.

At present, 8 herpesviruses are known causes of human disease. They are herpes simplex virus types 1 and 2, varicella-zoster virus, cytomegalovirus, human herpesvirus-6 and -7, Epstein-Barr virus, and Kaposi sarcoma virus (human herpesvirus-8). HSV-2 causes a lifelong genital viral infection characterized by high rates of clinical and subclinical reactivation in genital mucosa and risk of sexual transmission. Although HSV-2-associated syndromes such as meningitis may have been under-recognized in the past, now widespread use of polymerase chain reaction amplification of herpes simplex virus DNA has expanded recognized spectrum of HSV-2-related infections of the CNS. Advances in laboratory detection, together with epidemiologic and pathogenesis studies, have enhanced understanding of acquisition of infection, natural history of disease, and strategies for prevention.

Now, lessons learned from congenital and neonatal herpesvirus infections can guide investigation of Zika virus (ZIKV) infection in the newborn and developing infant, particularly in the importance for prospective cohort studies. Other significant issues that generalize from herpes are the contribution of asymptomatic male to female transmission resulting in congenital infection, and whether asymptomatic neonatal infection or long-term subclinical CNS replication occurs (Boppana et al 2017). The latter, subclinical herpes simplex virus replication, has been inferred from resultant improved neurologic outcome noted in patients receiving 6 months acyclovir suppressive therapy beyond treatment of newborn infection (Boppana et al 2017).

The role of sexual transmission for Zika virus congenital disease is not clear. Zika virus RNA has been detected in the female genital tract, and it has also been found in more women than men. Possibly, sexual transmission adds to mosquito-borne transmission, an important hypothesis if, similar to HSV-2, virus reaches the fetal compartment from adjacent contiguous tissues by transplacental transfer rather than hematogenous spread (Coyne and Lazer 2016).

The latter issue, subclinical herpes simplex virus replication, has been inferred from resultant improved neurologic outcome noted in patients receiving 6 months acyclovir suppressive therapy beyond treatment of newborn infection (Boppana et al 2017). The natural history of Zika may or may not include asymptomatic congenital infection. Persistent infection has been documented by serial Zika virus rRT-PCR positive CSF samples from a congenital Zika syndrome case 17 months after birth (Brito et al 2018). The potential for chronic infection reaffirms a need for a flavivirus-specific antiviral. Just as in herpes simplex virus, suppressive therapy would be important to the individual and to public health.

The content you are trying to view is available only to logged in, current MedLink Neurology subscribers.

If you are a subscriber, please log in.

If you are a former subscriber or have registered before, please log in first and then click select a Service Plan or contact Subscriber Services. Site license users, click the Site License Acces link on the Homepage at an authorized computer.

If you have never registered before, click Learn More about MedLink Neurology  or view available Service Plans.

Find out how you can join MedLink Neurology