| Herpes Simplex Virus | | Counselor, The herpes simplex viruses (HSV) comprise 2 distinct types of DNA viruses, HSV-1 and HSV-2. HSV-1 causes oral lesions in approximately 80% of cases and genital lesions in 20% of cases. The reverse is true for HSV-2, which causes genital lesions in 80% and oral lesions in 20%. About 80% of the general adult population has serologic infection with HSV-1 with only about 30% of these individuals having clinically significant outbreaks. Approximately 20% of the adult population in the United States is seropositive for HSV-2. It has been estimated that the indirect and direct costs of incident HSV genital infection in the United States are presently approximately $1.8 billion and expected to be greater than $2.7 billion by the year 2015. Herpes viruses cause a wide range of diseases, including the following: Gingivostomatitis, Keratoconjunctivitis, Encephalitis, Genital disease, and Newborn infection. We value all your comments, so, if you have a suggestion for a newsletter subject but haven't submitted it yet, or if you have already submitted one but think of another, please take a minute to let us know by clicking on your "Reply" button and dropping us a note. To learn more about AMFS, Inc., the organization run by Physicians and Attorneys that provides medical experts and case review services nationwide, and has produced the following informational newsletter to aid you in understanding complex medical issues, please click here - www.amfs.com. |
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| Primary versus Latent and Recurrent Infection: Primary infections usually are mild and in many cases asymptomatic. Patients who are immunocompromised may develop severe infections involving multiple organ systems. Immunocompetent individuals also may have severe primary infections. After the patient begins to produce antibodies, the infection becomes latent in the sensory ganglia. HSV-1 infection remains latent in the trigeminal ganglia, and HSV-2 in the sacral ganglia. The viruses become reactivated secondary to certain stimuli, including fever, physical or emotional stress, ultraviolet light exposure, and axonal injury. Recurrent infections tend to be less severe because of existing cellular and humoral immunity from prior exposures. Infection by HSV requires a break in the skin's barrier; intact skin is resistant to the virus. |
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| Pathophysiology: HSV-1 infections are spread via respiratory droplets or direct exposure to infected saliva. HSV-2 usually is transmitted via genital contact. The contact must involve mucous membranes or open or damaged skin. Herpes viruses cause cytolytic infections; therefore, pathologic changes are due to cell necrosis as well as inflammatory changes. Fluid accumulates between the dermis and the epidermal skin layers and causes vesicle formation. The fluid then is absorbed, scabs are formed, and healing is completed without evidence of scarring. Shallow ulcers form after the vesicles rupture on mucous membranes. The virus travels from the site of infection in the skin or mucosa to the sensory dorsal root and remains latent until a recurrent outbreak. Outbreaks are usually due to some sort of stress including ultraviolet radiation, trauma, emotional or psychological stress, or immunosuppression. |
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| | Frequency: Approximately 80% of adults have antibodies to HSV-1, whereas antibodies to HSV-2 are found in approximately 20% of the population. The incidence of genital herpes has been estimated to be 500,000-1,000,000 cases per year with a prevalence of 40-60 million affected individuals. In sexually transmitted disease (STD) clinics, HSV-2 seropositivity approaches 40-50%. Herpes encephalitis develops in 1 per 250,000-500,000 patients per year. Neonatal HSV develops in 1 per 2,000-10,000 live births per year. The risk of maternal transmission is increased if vaginal delivery occurs during the mother's primary infection. Approximately 90% of HIV- positive individuals are seropositive for HSV-1, and about 77% of HIV-positive individuals are seropositive for HSV-2. Recurrences may be frequent; 38% of the population with genital herpes have more than 6 recurrences per year; 20% have more than 10 recurrences per year. |
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| | Mortality/Morbidity: Most cases of herpetic infection are limited to patient irritation and discomfort. Infection occasionally may become life threatening. Patients who are immunocompromised are at increased risk of developing severe HSV infections. HSV-1 is a common cause of fatal encephalitis in the US. Mortality rate for encephalitis is 60-80%. Fewer than 10% of patients are left without significant neurologic sequelae. Keratoconjunctivitis may be caused by HSV-1. It is second only to trauma as a cause of corneal blindness in the US. |
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| | History: Symptoms are chronological in nature. First, the prodrome occurs, and lesions then appear along with constitutional signs and symptoms. The lesions coalesce, and tender bilateral lymphadenopathy develops. Lesions usually heal over the next several weeks. Lesions usually are vesicular or ulcerative on an erythematous base and are very painful. Many primary infections are asymptomatic. However, when primary infections are symptomatic, they are usually more severe than recurrent infections. Recurrent lesions are common. |
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| | Physical: Physical examination findings vary depending on location of the lesions. Lesions usually are vesicular or ulcerative on an erythematous base and are very painful. Lesions coalesce and then heal over the next several weeks. Tender bilateral lymphadenopathy occurs with the lesions. Herpetic whitlow or paronychia on the fingers are a common finding. Oropharyngeal disease, gingivostomatitis (herpes labialis on the lips), submandibular lymphadenopathy, keratoconjunctivitis and fever are often present. Signs of herpes encephalitis include: psychiatric symptoms, confusion, seizures, and meningeal signs. |
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| | Lab Studies: The standard study used to be scrapings from suspected lesions (Tzanck smear) for multinucleated giant cells.. This was found not to be a very reliable screening test, with a sensitivity reported around 65%, and it also does not differentiate between the type of HSV present. More sensitive than a Tzanck smear is a viral culture from skin vesicles. Other sensitive tests include: Monoclonal antibody testing, PCR (polymerase chain reaction) and Serology. CSF (cerebrospinal fluid) can also be examined for lymphocytic pleocytosis. |
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| | Treatment: Antiviral drugs with activity against viral DNA synthesis have been effective against HSV infections. These drugs inhibit virus replication and may suppress clinical manifestations but are not a cure for the disease. Since HSV remains latent in sensory ganglia, the rates of relapse are similar in treated and untreated patients. Acyclovir (Zovirax) provides initial, recurrent, and suppressive therapy for genital HSV. It is effective for mucocutaneous HSV in an immunocompromised host as well as HSV encephalitis. Little evidence supports the routine use of acyclovir for primary oral-labial HSV. Oral acyclovir has been shown to be effective in suppressing herpes labialis in patients with immunocompromise who frequently have recurrent infections. One study reported that oral acyclovir reduced duration of pain by 36% and time to loss of crust by 27%. Begin use during the prodromal period. Famciclovir (Famvir) and valacyclovir (Valtrex) are used for recurrent episodes of genital HSV. Herpes simplex keratoconjunctivitis is treated with topical 1% trifluridine (Viroptic). |
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| | Deterrence and Prevention: Patients should abstain from sex when lesions are present. Condoms should always be used because of the potential for asymptomatic viral shedding. Health care personnel should always wear gloves to prevent paronychia and herpetic nail whitlow. |
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| | Medical/Legal Concerns: The following is a list of concerns: Failure to identify active lesions at the time of labor and to perform cesarean section to decrease risk of transmission to the neonate; failure to refer all contacts of patients with genital HSV-2 for follow- up; failure to test, treat, and arrange counseling for associated STDs; failure to treat disseminated disease aggressively in immunocompromised patients; failure to diagnose herpetic keratoconjunctivitis in a patient who presents with a red eye; failure to suspect and diagnose meningitis or encephalitis; performing an incision and drainage of herpetic whitlow. This is contraindicated. |
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