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Emergency And Acute Medicine – Herpes Simplex
Definition And Overview
Herpes simplex is a viral disease characterized by recurrent, painful vesicular lesions involving mucocutaneous surfaces. Commonly affected sites include the lips, oral cavity, genitalia, rectum, hands, and eyes. Infection occurs in two phases: a primary phase during which the virus establishes latency within sensory nerve ganglia, and a secondary phase marked by recurrent reactivation at the same anatomic site. The incubation period is approximately four days after exposure. Viral shedding lasts about 7–10 days in primary infection (up to 23 days) and 3–4 days during recurrences. Neonatal infection may occur in utero, intrapartum (most commonly), or postnatally, with an incidence of approximately 1 in 3,500 births annually in the United States. Transmission is human-to-human, and 60–90% of the population is infected with herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2). Infection is more common in Black populations than White populations under 40 years of age, and females are affected more frequently than males.
Etiology And Virology
HSV-1 and HSV-2 are DNA viruses belonging to the Herpesviridae family. Transmission occurs through contact with infected secretions via mucous membranes or abraded skin, as well as through respiratory droplets. Recurrent asymptomatic mucosal shedding can transmit infection. HSV-1 most commonly causes oral infections, while HSV-2 more frequently causes genital disease, though either virus may infect oral or genital mucosa. Recurrence rates vary depending on viral type and anatomic location; HSV-2 genital infections recur more frequently than HSV-1 genital infections, and HSV-1 oral infections recur more often than genital HSV-1 infections.
Clinical Manifestations
Many primary infections are subclinical and detected only by serologic evidence of antibodies. Symptomatic disease typically presents with grouped 1–2 mm vesicles on an erythematous base, containing clear or cloudy fluid or appearing pustular.
Orofacial Disease
Primary orofacial infection often manifests as gingivostomatitis or pharyngitis with ulcerative lesions of the gingiva and mucosa. Associated symptoms include fever, malaise, irritability, headache, myalgias, and cervical lymphadenopathy. Symptoms may last two to four weeks and usually heal without scarring. Pain may limit oral intake, increasing the risk of dehydration.
Recurrent disease typically involves the lips, especially the vermilion border, and is often preceded by a prodrome of tingling, itching, burning, or throbbing. Triggers include sunlight, stress, heat, trauma, and immunosuppression. Lesions progress from erythema to vesicle, ulcer, crusting, and healing. Transmission can occur even without visible lesions.
Cutaneous Disease
Herpetic whitlow involves infection of the fingers, most commonly caused by HSV-2, and presents with vesicles on the pulp or lateral finger. It may occur from autoinoculation or occupational exposure and can last three to four weeks.
Traumatic herpes may develop after cosmetic, surgical, dental procedures, sun exposure, or burns.
Herpes gladiatorum is a cutaneous infection seen in athletes, particularly wrestlers, affecting the face, chest, and hands.
Eczema herpeticum is a disseminated HSV infection occurring in patients with atopic dermatitis, often associated with fever, headache, fatigue, and risk of secondary bacterial infection.
Ocular Disease
HSV is the most common cause of corneal blindness in developed countries. Infection may result from direct inoculation or spread from facial lesions. Symptoms include eye pain, photophobia, blurry vision, conjunctivitis, chemosis, and periauricular lymphadenopathy. Dendritic corneal lesions are seen on fluorescein examination. Vesicles on the tip of the nose (Hutchinson sign) suggest involvement of the nasociliary nerve and increased risk of ocular disease.
Central Nervous System Involvement
HSV encephalitis is the most common cause of severe sporadic encephalitis in the Western world, usually due to HSV-1 reactivation. Patients may present with altered mental status, seizures, focal neurologic deficits, or coma, with or without a history of mucocutaneous herpes.
Special Populations
In neonates, up to 60–80% of infected infants are born to mothers without known genital herpes. Vesicular lesions may be absent initially. Primary maternal genital infection carries the highest risk of neonatal transmission.
In children, primary infection often occurs early in life, with gingivostomatitis being the most common presentation in those under five years of age.
In pregnancy, suppressive antiviral therapy near term may reduce recurrence and viral shedding.
Diagnostic Evaluation
Diagnosis is often clinical based on history and examination. Definitive testing is indicated in severe disease, immunocompromised patients, suspected abuse, ocular involvement, or CNS disease. PCR testing of vesicular fluid is the most sensitive and specific diagnostic method. Viral culture, fluorescent antibody detection, and Tzanck smear may also be used.
Ocular disease requires fluorescein examination, and CNS disease requires lumbar puncture with CSF PCR, along with neuroimaging.
Differential Diagnosis
Conditions to consider include bacterial pharyngitis, Stevens–Johnson syndrome, herpes zoster, varicella, impetigo, syphilis, contact dermatitis, conjunctivitis, corneal abrasion, glaucoma, and other causes of encephalitis.
Emergency Management
Supportive care with hydration and analgesia is sufficient for mild primary infections in immunocompetent patients. Antiviral therapy is indicated for severe primary disease, recurrent infections with significant symptoms, immunocompromised patients, ocular disease, neonatal infection, and encephalitis. Incision and drainage of herpetic lesions should be avoided. Ocular involvement requires urgent ophthalmology consultation, and corticosteroids should not be used.
Pharmacologic Therapy
First-line treatment includes acyclovir, valacyclovir, or famciclovir. Acyclovir is preferred in children and severe disease. Encephalitis requires high-dose IV acyclovir for 14–21 days. Long-term suppressive therapy may be used for frequent recurrences. Antiviral dosing should be adjusted in renal impairment.
Disposition And Follow-Up
Hospital admission is required for encephalitis, neonatal infection, disseminated disease, severe dehydration, immunocompromised patients, and significant ocular involvement. Uncomplicated localized disease may be managed on an outpatient basis. Patients should be counseled on transmission risk, avoidance of contact with lesions, and indications for suppressive therapy.
Clinical Pearls And Pitfalls
Failure to recognize HSV encephalitis or ocular herpes can result in significant morbidity. Transmission may occur without visible lesions. Patients should be warned about autoinoculation and spread to others, especially during outbreaks. Avoid topical or systemic steroids unless specifically indicated and supervised.
Definition And Overview
Herpes simplex is a viral disease characterized by recurrent, painful vesicular lesions involving mucocutaneous surfaces. Commonly affected sites include the lips, oral cavity, genitalia, rectum, hands, and eyes. Infection occurs in two phases: a primary phase during which the virus establishes latency within sensory nerve ganglia, and a secondary phase marked by recurrent reactivation at the same anatomic site. The incubation period is approximately four days after exposure. Viral shedding lasts about 7–10 days in primary infection (up to 23 days) and 3–4 days during recurrences. Neonatal infection may occur in utero, intrapartum (most commonly), or postnatally, with an incidence of approximately 1 in 3,500 births annually in the United States. Transmission is human-to-human, and 60–90% of the population is infected with herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2). Infection is more common in Black populations than White populations under 40 years of age, and females are affected more frequently than males.
Etiology And Virology
HSV-1 and HSV-2 are DNA viruses belonging to the Herpesviridae family. Transmission occurs through contact with infected secretions via mucous membranes or abraded skin, as well as through respiratory droplets. Recurrent asymptomatic mucosal shedding can transmit infection. HSV-1 most commonly causes oral infections, while HSV-2 more frequently causes genital disease, though either virus may infect oral or genital mucosa. Recurrence rates vary depending on viral type and anatomic location; HSV-2 genital infections recur more frequently than HSV-1 genital infections, and HSV-1 oral infections recur more often than genital HSV-1 infections.
Clinical Manifestations
Many primary infections are subclinical and detected only by serologic evidence of antibodies. Symptomatic disease typically presents with grouped 1–2 mm vesicles on an erythematous base, containing clear or cloudy fluid or appearing pustular.
Orofacial Disease
Primary orofacial infection often manifests as gingivostomatitis or pharyngitis with ulcerative lesions of the gingiva and mucosa. Associated symptoms include fever, malaise, irritability, headache, myalgias, and cervical lymphadenopathy. Symptoms may last two to four weeks and usually heal without scarring. Pain may limit oral intake, increasing the risk of dehydration.
Recurrent disease typically involves the lips, especially the vermilion border, and is often preceded by a prodrome of tingling, itching, burning, or throbbing. Triggers include sunlight, stress, heat, trauma, and immunosuppression. Lesions progress from erythema to vesicle, ulcer, crusting, and healing. Transmission can occur even without visible lesions.
Cutaneous Disease
Herpetic whitlow involves infection of the fingers, most commonly caused by HSV-2, and presents with vesicles on the pulp or lateral finger. It may occur from autoinoculation or occupational exposure and can last three to four weeks.
Traumatic herpes may develop after cosmetic, surgical, dental procedures, sun exposure, or burns.
Herpes gladiatorum is a cutaneous infection seen in athletes, particularly wrestlers, affecting the face, chest, and hands.
Eczema herpeticum is a disseminated HSV infection occurring in patients with atopic dermatitis, often associated with fever, headache, fatigue, and risk of secondary bacterial infection.
Ocular Disease
HSV is the most common cause of corneal blindness in developed countries. Infection may result from direct inoculation or spread from facial lesions. Symptoms include eye pain, photophobia, blurry vision, conjunctivitis, chemosis, and periauricular lymphadenopathy. Dendritic corneal lesions are seen on fluorescein examination. Vesicles on the tip of the nose (Hutchinson sign) suggest involvement of the nasociliary nerve and increased risk of ocular disease.
Central Nervous System Involvement
HSV encephalitis is the most common cause of severe sporadic encephalitis in the Western world, usually due to HSV-1 reactivation. Patients may present with altered mental status, seizures, focal neurologic deficits, or coma, with or without a history of mucocutaneous herpes.
Special Populations
In neonates, up to 60–80% of infected infants are born to mothers without known genital herpes. Vesicular lesions may be absent initially. Primary maternal genital infection carries the highest risk of neonatal transmission.
In children, primary infection often occurs early in life, with gingivostomatitis being the most common presentation in those under five years of age.
In pregnancy, suppressive antiviral therapy near term may reduce recurrence and viral shedding.
Diagnostic Evaluation
Diagnosis is often clinical based on history and examination. Definitive testing is indicated in severe disease, immunocompromised patients, suspected abuse, ocular involvement, or CNS disease. PCR testing of vesicular fluid is the most sensitive and specific diagnostic method. Viral culture, fluorescent antibody detection, and Tzanck smear may also be used.
Ocular disease requires fluorescein examination, and CNS disease requires lumbar puncture with CSF PCR, along with neuroimaging.
Differential Diagnosis
Conditions to consider include bacterial pharyngitis, Stevens–Johnson syndrome, herpes zoster, varicella, impetigo, syphilis, contact dermatitis, conjunctivitis, corneal abrasion, glaucoma, and other causes of encephalitis.
Emergency Management
Supportive care with hydration and analgesia is sufficient for mild primary infections in immunocompetent patients. Antiviral therapy is indicated for severe primary disease, recurrent infections with significant symptoms, immunocompromised patients, ocular disease, neonatal infection, and encephalitis. Incision and drainage of herpetic lesions should be avoided. Ocular involvement requires urgent ophthalmology consultation, and corticosteroids should not be used.
Pharmacologic Therapy
First-line treatment includes acyclovir, valacyclovir, or famciclovir. Acyclovir is preferred in children and severe disease. Encephalitis requires high-dose IV acyclovir for 14–21 days. Long-term suppressive therapy may be used for frequent recurrences. Antiviral dosing should be adjusted in renal impairment.
Disposition And Follow-Up
Hospital admission is required for encephalitis, neonatal infection, disseminated disease, severe dehydration, immunocompromised patients, and significant ocular involvement. Uncomplicated localized disease may be managed on an outpatient basis. Patients should be counseled on transmission risk, avoidance of contact with lesions, and indications for suppressive therapy.
Clinical Pearls And Pitfalls
Failure to recognize HSV encephalitis or ocular herpes can result in significant morbidity. Transmission may occur without visible lesions. Patients should be warned about autoinoculation and spread to others, especially during outbreaks. Avoid topical or systemic steroids unless specifically indicated and supervised.
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