Download Human Herpes Viruses

Human Herpes Viruses
Latent Viruses
Introduction
• Herpes Viruses are a leading cause of human
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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.
Classification
• There are 25 families in the
Herpeotoviridae but only 6 of them infect
man with any regularity.
Herpes Simplex virus Type 1 (HSV-1)
Herpes Simplex virus Type 2 (HSV-2)
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.
Epidemiology
• HSV-1 and 2 infections are life-long.
• The virus is found in the lesions on the
skin but can be present in body fluids
including saliva and vaginal secretions.
• As a result of poor hygiene in
underdeveloped countries, HSV-1
antibodies are found in more than 90% of
children.
Epidemiology 2
• HSV-2 is normally spread sexually and is found
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in the anus, rectum and upper alimentary tract
as well as the genital area.
An infant can be infected at birth by a genitallyinfected 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.
Disease caused by Herpes Simplex
Viruses
• Oral Herpes - Cold sores
– 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 HSV-2.
– 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 14-21 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.
• Type-specific antibodies can distinguish
between HSV-1 and HSV-2.
Treatment
• Acyclovir
– A Safe and extremely well-tolerated drug.
– More than 35 million patients have been
consistent and reassuring.
– Some authorities have proposed making
acyclovir available as a non-prescription drug.
– Adverse effects, usually mild, include nausea,
vomiting, rash and headache.
Treatment
• Valacyclovir
– New antiviral agent
– Is the 1-valine 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 half-life is 10 times
longer than acyclovir’s.
– Dosing less frequently than twice daily is not
recommended.