Serologic testing for herpes simplex viruses is used to determine if the patient has previously been exposed to these viruses as well as for laboratory differential diagnosis between infection caused by herpes simplex viruses type 1 and 2, especially in patients with subclinical or undiagnosed herpes infection.
Herpesviruses (family Herpesviridae) are globally spread, affecting both humans and animals while there are hundreds of different species. Common to all types of herpes viruses is the high level of infection (60-90% of the population are carriers) and their ability to remain latent in the body for long periods.
Herpes Simplex Virus (HSV) is the pathogen that causes bladder rash (herpes simplex and genital herpes), encephalitis, and generalized infant infection (neonatal herpes). Herpes simplex viruses have a double-stranded DNA (dsDNA) genome and have been classified into two different types, the herpes simplex virus type 1 (HSV-1) and the herpes simplex virus type 2 (HSV-2).
Initial herpes simplex virus type 1 infection occurs in early childhood and is usually transmitted by contact. The entrance gate is usually the oral mucosa (oral type) and the infection is usually manifested as gingivostomatitis. After an incubation period of about 1 week, fluid-filled blisters develop in the mouth or on the face, which may be accompanied by nausea, fever, or difficulty swallowing. Viruses move along the nerve axis to the central nervous system (CNS), where they continue to be latent in the trigeminal ganglion. As with all herpes viruses, the virus remains in the vector host permanently after the primary infection. After a recurrence, the viruses follow the same upstream path, from the CNS to the periphery, where they cause the known vesicular rash (cold sores). Despite the established immunity to the virus, recurrences can occur repeatedly, because the viruses are constantly inside the nerve cells and do not enter the intercellular space, thus staying away from the immune system's defense mechanisms. Possible complications of HSV-1 infection include keratoconjunctivitis and a particularly lethal form of encephalitis.
Initial herpes simplex virus type 2 infection occurs in the urogenital region (genital type) and can occur regardless of the presence of herpes simplex virus infection 1. The disease occurs with self-inflicted lesions or ulcers that can be accompanied by influenza-like symptoms (fever, swollen lymph nodes). The herpes simplex virus type 2 remains latent in the lumbar ganglia or peripheral tissues, where it can cause episodes of active genital herpes. Neurological complications are much rarer and milder than those of herpes simplex virus type 1. On the other hand, infections of newborn infants (neonatal herpes) in cases of maternal genital herpes have a very high mortality rate. The herpes simplex virus type 2 is usually transmitted by sexual intercourse and therefore, this type of infection is not observed before puberty.
The detection of IgM antibodies cannot distinguish the two types of herpes viruses (1 and 2) because of their antigenic similarity. Specific IgG antibodies or detection of the virus by molecular techniques may be helpful.
The presence of IgM antibodies against herpes simplex viruses 1 and 2 is indicative of recent infection either primary or due to reactivation, but without distinction. The negative result does not necessarily preclude primary or secondary, since the sample may have been taken too early during the disease, when the antibodies had not yet reached detectable levels, or too late when IgM antibody titer had dropped below detectable levels.
In pregnant women, the determination of IgM-specific antibodies should not be used as the sole criterion for the diagnosis of herpes simplex infection. The presence of the herpes simplex virus must be demonstrated by molecular methods.
Important Note
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.
