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Herpes simplex virus (HSV) causes various clinical syndromes. Anatomic sites infected include skin, lips, oral cavity, eyes, genital tract, and central nervous system (CNS). Systemic involvement may also occur.
Fresh brain tissue is the definitive specimen for detection of HSV from patients with CNS disease. However, because brain biopsy is an invasive procedure, it is infrequently performed for laboratory diagnosis. Similarly, it is difficult to recover HSV from cerebrospinal fluid (CSF) specimens in culture systems, and the serologic diagnosis of HSV CNS disease has not been informative during early onset disease. HSV PCR detection from CSF is a sensitive and specific alternative for detection of disease involving the CNS, as well as oral, genital, ocular, and other sites.
Aiding in the rapid diagnosis of herpes simplex virus (HSV) infections, including qualitative detection of HSV DNA in cerebrospinal fluid and other (non-blood) clinical specimens
Qualitative detection of HSV DNA
This is a qualitative assay; results are reported either as negative or positive for herpes simplex virus (HSV) type 1 or HSV type 2. In a small number of cases (eg, <1%), HSV is detected but this assay may not be able to provide a definitive subtype (HSV-1 versus HSV-2). This is due to mutations in the region of the HSV genome that the PCR probes bind to. When this is observed, the report will go out as "Indeterminate", which means that HSV DNA was detected, but the assay was unable to provide a specific subtype.
Detection of HSV DNA in clinical specimens supports the clinical diagnosis of infection due to the virus.
HSV DNA is not detected in cerebrospinal fluid from patients without central nervous system disease caused by this virus.
A negative result does not eliminate the possibility of herpes simplex virus (HSV) infection. HSV DNA may not be detectable in the early acute stages of the central nervous system disease. In addition, in some cases, after initial detection (positive result), HSV DNA may only be present in cerebrospinal fluid (CSF) for 3 to 4 weeks after initial presentation of symptoms. DNA levels may fall to undetectable with time.
Although the reference range is typically "negative" for this assay, this assay may detect viral shedding in asymptomatic individuals. This may be especially relevant when dermal or genital sites are tested, since intermittent shedding without noticeable lesions has been described.(1) CSF DNA is not expected to contain detectable HSV DNA in patients without related disease. This assay is only to be used for patients with a clinical history and symptoms consistent with HSV infection, and must be interpreted in the context of the clinical picture. This test should not be used to screen asymptomatic patients.
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