Infectious diseases

Herpes simplex virus

Herpes Simplex Virus (HSV) is a common human pathogen found worldwide which produces a wide variety of diseases. It infects neonates, children and adults, and, by the fourth decade, more than 90% of the adult population demonstrates antibodies to HSV. Its transmission can result from direct contact with infected secretions from either a symptomatic or an asymptomatic host.
Herpes Simplex virus has been characterized into 2 distinct serotypes: HSV-1 and HSV-2. HSV-1 is generally associated with infection in the tongue, mouth, lips, pharynx and eyes, whereas HSV-2 is primarily associated with genital and neonate infection.
For chronically ill people (with a weak immune system) and newborns the viral infection can be serious, but rarely fatal. Most infectious are unrecognized and misdiagnosed.

Clinical features: The majority of individuals have no or only minimal symptoms from HSV infection. When signs do occur, they typically appear as a single blister or in a cluster on or around the genitals or the face.
Oral herpes is the most common one, with many people acquiring it during early childhood or adolescence through direct contact (via saliva) with friends or relatives who carry the virus. Most people get genital infections following sexual contact with an infected person with HSV-2.
The most frequent manifestation of primary HSV-1 is pharyngitis and gingivostomatitis but other typical manifestations are conjunctivitis, keratitis, vesicular eruptions of skin, and encephalitis. HSV-2 is the most frequent agent of genital ulcer in the western world and it can produce aseptic meningitis and neonatal herpes infection.

Diagnosis: The herpes simplex virus is usually identifiable by its clinical manifestations or physical appearance. However, laboratory tests are essential for confirming herpes diagnosis.
The most used serological methods are complement fixation reaction and enzyme-linked immunosorbent assay (ELISA). The immune response is stronger in the primary infection than during relapses. The two HSV types share many common epitopes that give rise to strongly cross-reacting antigens. Therefore, it is difficult to achieve the serological differentiation between both types by using crude extracts. Yet, the use of purified viral proteins has led to the development of type-specific assays.
Viral culture tests are very accurate and sensitive if lesions are still in the clear blister stage, but they do not work so well for older ulcerated sores, recurrent lesions or during latency. 

Treatment:
 There is really no treatment that completely removes from the body the infection by HSV. Once the virus enters in the body, it will always remain in an inactive form with occasional relapses. Treatment with antiviral drugs is standard during first episodes and can speed healing significantly. This antiviral medication also helps to shorten and prevent outbreaks during the treatment period. Some cases are relatively mild and may not require treatment.

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