Herpes simplex virus 1 (HSV1)

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This virus is known to cause oral herpes/mouth herpes when cold sores appear on the face, lips and in the mouth.

The virus

Herpes simplex virus type 1 belongs to the alpha herpesvirus group. HSV possesses an internal core with a linear double-stranded DNA. The capsid of herpes viruses consists of 162 consumers. The virus is wrapped in a lipid envelope with viral glycoproteins on the surface. Its molecular weight is approximately 100×106 units and diameter of approximately 160 nm.

Epidemiology

HSV1 infection is acquired more often and earlier than HSV-2. It was estimated that more than 90% of  adults have antibodies to HSV-1 by 50. Prevalence of antibody to HSV-1 increases with age and correlates with the individual’s socioeconomic status.  

Transmission

HSV-1 is transmitted by oral-to-oral contact and exposure to infected saliva and mucous. The spread of HSV-1 infection from oral secretions to other skin areas is a possible hazard to some professionals such as dentists. Wrestlers are also at risk of the HSV-1 infection almost anywhere in the body.

Symptoms

The average incubation period of HSV-1 is 4 days with a range from 2 to 12 days.

Primary HSV-1 infection typically manifests with gingivostomatitis and pharyngitis. Such symptoms are usually seen in young children between 1 and 3 years of age and rarely in young adults. When the lesions appear a person experiences fever which lasts from 2 to 7 days, sore throat malaise, itching, burning sensations, myalgia, inability to eat, irritability, cervical adenopathy, and mucosal edema. Tingling and pain may precede the occurrence of sores.When the pharynx is affected the ulcers or exudative lesions are observed the  posterior pharynx, tonsils, or both.

Vesicular rash which looks like small blisters is distributed on the hard and soft palate, the tongue, the gingiva, and around the lips. These lesions, also known as fever blisters or cold sores  tend to rupture, leaving gray-white ulcers. The disease lasts from 3 up to 21 days.

The virus may be found in oral secretions from 7 to 10 days as well as in the stool.

Typically HSV-1 reactivates as herpes labialis. As the HSV-1 recurrence occurs the pain, burning, tingling or itching sensations precede the development of the orofacial lesions. Within 24-48 hours afterwards the painful vesicles appear, typically on the border of the lip. From 3 to 4 days later the vesicles crust and after 8-10 days the lesions disappear.

HSV-1 and Varicella zoster virus are are considered to cause Bell’s palsy – flaccid paralysis of the mandible.

Despite the common thought that herpes genitalis is caused only by HSV-2, it may also be caused be the primary HSV-1 infection.

HSV-1 infection of the finger is known as herpetic whitlow. It occurs when the broken skin of the hand is exposed to the virus. An infected finger swells and becomes reddish acutely, it becomes tender and painful. Vesicles or pustular lesions are detected on the fingertip.

See also: Herpes Zoster

Herpes gladiatorum

Herpes gladiatorum (mat herpes) is common for wrestlers and other sportsmen involved in high-contact sports. This type of HSV 1 infection develops due to the traumas of the mucosa and the skin as the virus penetrates through the injured epithelium. It may affect almost every part of the body.

Herpes HSV1 test

Diagnosis

The diagnosis is made based upon clinical features and laboratory tests such as DNA or PCR tests and virus cultures.

Treatment

Acyclovir, valacyclovir, and famciclovir are commonly used for the treatment of herpes labialis. Acyclovir is administered orally at a dosage of 400 mg five times per day for 5 days. Valacyclovir may be used at a dosage of 2 g twice daily for 1 day with 12 hours in between the two doses. Acyclovir may be used topically, although the effectiveness of topical administration is doubtful.