Herpes Simplex
Definition: The Herpes Simplex Virus (HSV) is a virus that causes herpes. Herpes is a common infection that can cause painful ulcers or blisters that may recur over time. The virus will remain dormant throughout a person’s life with the number of outbreaks decreasing with age. Two subtypes can cause infection: Herpes Simplex virus type 1 (HSV-1), and Herpes Simplex virus type 2 (HSV-2).
Etiology: The HSV is a member of the Herpesvirales order of double-stranded DNA viruses. Both HSV subtypes affect the skin and mucous membranes. HSV is transmitted from oral or skin surfaces affected by the virus. Rarely, herpes can be transmitted vertically, causing neonatal herpes.
While HSV-1 is associated with oral and facial infections, HSV-2 is associated with genital and rectal infections. Unique features of HSV include latency and reactivation. Following primary exposure there is a viral invasion of epithelial cells and intracellular replication at the site. HSV then ascends through the periaxonal sheath of sensory nerves to the host sacral ganglia- which acts as a reservoir for future outbreaks. As the virus replicates, it is dormant and can be reactivated by various stimuli.
Epidemiology: As of 2016, the WHO estimates that 3.7 billion people under 50, (67% of the global population) had an HSV-1 infection, causing oral or genital herpes. It is estimated that 491 million people aged 15-49 worldwide were affected by HSV-2-causing genital herpes. Prevalence of HSV infection increases with age. The highest number of new infections is seen in adolescents. Women are affected by HSV-2 twice as often as men due to a more efficient route of sexual transmission.
Signs: HSV infections are characterized by recurrent blisters that can rupture and become painful. Initial presentation can appear as painful genital ulcers, inguinal lymphadenopathy and fever. Areas that can become affected by clustered vesicles are the genitalia, perineum, buttocks, upper thigh, and perianal areas. The vesicles are small, umbilicated, and closely grouped with an erythematous base in recurrent herpes. They may have a zosteriform distribution when affecting the lower chest or lumbar region. In darker skin tones, scarring at the site of recurrent HSV attacks is more prominent and hyperpigmented.
Symptoms: Symptoms may vary between the initial outbreak and subsequent infections. Prodromal symptoms can appear up to 48 hours before an outbreak. These include fever, tender lymph nodes, myalgia, itching and tingling of the skin. Primary HSV-1 often presents as gingivostomatitis in children under 5 years. Primary HSV-2 usually presents as genital herpes following sexual activity.
Differentials: Herpes Zoster, Syphilis, Cytomegalovirus, Chancroid, Hand foot and mouth disease
Diagnosis: HSV diagnosis can be confirmed by culture or PCR of a viral swab taken from fresh vesicles.
Treatment: HSV cannot be cured, so treatment is aimed at decreasing symptoms associated with first or recurrent episodes of herpes. Antiviral medication is commonly given in low daily doses to prevent outbreaks. NSAIDS can be given to help with pain related to sores.
References:
- Cole S. Herpes Simplex Virus: Epidemiology, Diagnosis, and Treatment. Nurs Clin North Am. 2020;55(3):337-345. doi:10.1016/j.cnur.2020.05.004
- World Health Organization. Herpes simplex virus. Who.int. Published April 5, 2023. https://www.who.int/news-room/fact-sheets/detail/herpes-simplex-virus
- Herpes simplex | DermNet NZ. dermnetnz.org. https://dermnetnz.org/topics/herpes-simplex