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Herpes viruses - Human Herpes Viruses Latent Viruses...

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Unformatted text preview: Human Herpes Viruses Latent Viruses Introduction Herpes Viruses are a leading cause of human viral diseases, second only to influenza and cold viruses. Are capable of causing overt disease or remaining silent for many years only to be reactivated. Name Herpes comes from the Latin herpes which, in turn, comes from the Greek word herpein which means to creep. There are 25 families in the Classification Herpeotoviridae but only 6 of them infect man with any regularity. Herpes Simplex virus Type 1 (HSV1) Herpes Simplex virus Type 2 (HSV2) Epstein Barr virus (EBV) Cytomegalovirus (CMV) Varicella Zoster virus (VZV) Human Herpes virus 6 Human Herpes virus 8 Herpes Simplex Virus (HSV) These are very large viruses and their genome encodes at least 80 proteins. Half are not directly involved in the virus structure. Almost any human cell type can be affected by HSV. HSV1 and 2 infections are lifelong. The virus is found in the lesions on the Epidemiology skin but can be present in body fluids including saliva and vaginal secretions. As a result of poor hygiene in underdeveloped countries, HSV1 antibodies are found in more than 90% of children. Epidemiology 2 HSV2 is normally spread sexually and is found in the anus, rectum and upper alimentary tract as well as the genital area. An infant can be infected at birth by a genitally infected mother. The infant can also be infected in utero if the mother's infection spreads. Because of the infant's underdeveloped immune system, the resulting infection can be very severe and sometimes be deadly. Oral Herpes Cold sores Disease caused by Herpes Simplex Viruses Herpetic gingiovostomatitis, the infection, often initially on the lips spreads to all parts of the mouth and pharynx. Disease caused by Herpes Simplex Viruses Eczema Herpeticum This is found in children with active eczema. The virus can spread to other organs such as the liver and adrenals. Disease caused by Herpes Simplex Viruses Genital Herpes Is usually the result of HSV2. Primary infection is often asymptomatic but many painful lesions can be developed on the shaft of the penis and vulva, vagina, cervix and perianal region of women. Genital Herpes Genital Herpes In both sexes, the urethra can be involved. Genital Herpes infections can be accompanied by a variety of symptoms including fever, myalgia, glandular inflammation of the groin area (inguinal). Some patients have only infrequent recurrences but others experience recurrences as often as every 1421 days. Diagnosis of HSV Infections Cells may be obtained from the base of the lesion (called a Tzank smear) and histochemistry performed. These can be seen in the smears as multinucleated giant cells and contain Cowdry type A inclusion bodies. Diagnosis of HSV Infections Diagnosis of HSV Infections The cells can also be stained with specific antibodies in an immunofluorescence test. It can also be detected by viral DNA by in situ hybridization. Typespecific antibodies can distinguish between HSV1 and HSV2. Treatment Acyclovir A Safe and extremely welltolerated drug. More than 35 million patients have been consistent and reassuring. Some authorities have proposed making acyclovir available as a nonprescription drug. Adverse effects, usually mild, include nausea, vomiting, rash and headache. Treatment Valacyclovir New antiviral agent Is the 1valine ester prodrug of acyclovir. It has an oral bioavailability three to five times greater than that of acyclovir. Several large trials have shown that it is safe and well tolerated. Treatment Famciclovir Another new antiviral medication Is the oral form of penciclovir, a purine analog similar to acyclovir. Oral bioavailability is 77% and the drug is quickly converted to its active form. Famciclovir's intracellular halflife is 10 times longer than acyclovir's. Dosing less frequently than twice daily is not recommended. ...
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