Herpes simplex virus - Cellulitis
Infection is acquired through contact with contaminated saliva or other body fluids during periods of viral shedding. The virus establishes lifelong latency in the dorsal root ganglia. Clinical disease occurs with reactivation (spontaneously or with trauma, UV exposure, fever, or immunosuppression) of the latent virus, which travels from the nerve root to innervated skin regions.
Primary infection denotes the initial inoculation episode, which may be subclinical or cause significant disease, usually in children. Recurrent disease describes reactivation episodes, which occur in 30%-50% of oral HSV and 95% of genital HSV infections. An individual may be co-infected with more than one type of HSV and in more than one location. HSV acquisition at a new site in a previously infected person is designated non-primary, first episode infection.
Ninety percent of adults are antibody positive to HSV-1. HSV-2 prevalence is lower, affecting almost a quarter of the US population. Risk factors for genital herpes infection include multiple sexual partners, being black or Hispanic, lower educational and socioeconomic levels, and being female, a man who has sex with men, or HIV infected.
Symptoms of primary disease are usually more severe than recurrent disease and depend upon the site of inoculation. Herpetic gingivostomatitis (usually HSV-1) presents with fever, malaise, bleeding, painful gums, pain upon eating, and sometimes pharyngitis and foul breath. In primary herpes genitalis, headache, fever, malaise, pain, and dysuria are common. Complications include urinary retention, constipation, and aseptic meningitis. Primary keratoconjunctivitis is associated with pain, eyelid edema, photophobia, and tearing. Localized adenopathy is common with primary infection. Disease occurs 3-7 days after exposure; recovery from a primary episode usually occurs in 2-6 weeks. Disseminated infection and pneumonitis may occur in the immunocompromised. Other complications include bacterial superinfection, radiculoneuropathy, encephalitis, hepatitis, and eczema herpeticum in patients with atopy. Pregnant women with primary HSV infection are at increased risk for severe illness, ie, dissemination and hepatitis, particularly in the third trimester.
Recurrent disease usually lacks constitutional symptoms. Itching, burning, or pain often precedes the skin lesions. Complications include bacterial superinfection, eczema herpeticum, erythema multiforme, Bell palsy, aseptic meningitis, and encephalitis.
HSV infection in HIV-infected patients and other immunodeficiency states with T-cell defects is common and often presents with more severe and chronic disease. Chronic, non-healing, painful ulcers occur, particularly in the perianal region. Others at risk for this include marrow and solid organ transplant patients and patients with lymphoma and leukemia.
Grouped, umbilicated vesicles and a history of recurrent "flares" should alert one to the possibility of this diagnosis over cellulitis.
B00.1 – Herpesviral vesicular dermatitis
88594005 – Herpes simplex
- May cause lymphangitic streaking that could be confused with cellulitis or erysipelas.
- Differentiate from zoster, which also presents with umbilicated vesicles.
- Contact dermatitis
- Molluscum contagiosum
- Dermatitis herpetiformis
- Fixed drug eruption
- Insect bites
- Erythema multiforme minor