Herpes virus

1. OPTOM FASLU MUHAMMED

2.  Viruses are strictly intracellular parasites,
relying on the host cell for their replication.
 Herpes viruses, which are large-enveloped,
double-stranded DNA viruses. are one of the
most common human infectious agents,
responsible for a wide spectrum of acute
and chronic diseases.

3.  The major members of the group are :
 Herpes simplex viruses (HSV-1 and HSV-2)
 Varicella-zoster virus
 Cytomegalovirus (CMV)
 Epstein-Barr virus.

4.  HSV has 2 antigenic types, each with
numerous antigenic strains.
 Each type has different epidemiologic
patterns of infection.
 Many people with HSV antibodies are
asymptomatic.

5.  The virus can spread within nerves and cause
a latent infection of sensory and autonomic
ganglia.
 Serologic testing and viral culture can assist
in the diagnosis of difficult cases, particularly
CNS infections.

6.  Herpes simplex type 1 is associated with
mucocutaneous superficial infections of the
pharynx, skin, oral cavity, vagina, eye, and
brain.
 Ophthalmic infection most often manifests
as corneal dendritic or stromal disease, but
may present as acute retinal necrosis.

7.  Herpes simplex type 2 is an important sexually
transmitted disease that is associated with
genital infections, aseptic meningitis, and
congenital infection.
 The drug of choice for treating acute
systemic infections is acyclovir.
 Localized disease can be treated with oral
acyclovir.

8.  Topical treatment of skin or mucocutaneous
lesions with acyclovir ointment decreases the
healing time
 Two newer antiviral agents, famciclovir and
valacyclovir, are approved for the treatment
of herpes zoster and herpes simplex.
 HSV is also sensitive to vidarabine.

9.  Varicella-zoster virus (VZV), also sometimes
referred to as herpes zoster, produces infection
in a manner similar to herpes simplex
 Primary infection usually occurs in childhood in the
form of chickenpox (varicella), a generalized
vesicular rash accompanied by mild constitutional
symptoms.

10.  Other neurological syndromes following
herpes zoster involvement include segmental
myelitis,Guillain-Barre syndrome etc..
 The incidence of herpes zoster is 2 to 3 times
higher in patients older than age 60.

11.  Treatment of acute infection in
immunocompromised patients or those with
visceral involvement may include acyclovir,
famciclovir, or valacyclovir.
 Newer drugs being evaluated for resistant
VZV strains or concomitant HIV infection
include sorivudine, brivudine, netivudine,
lobucavir, foscarnet, and cidofovir.

12.  A live attenuated varicella vaccine (Varivax) is
available for prevention of primary disease,
and it appears to also reduce the incidence of
recurrentVZV infection and neuralgia.
 This vaccine is recommended for children,
patients with chronic diseases or leukemia,
and patients receiving immunosuppressive
therapy.

13.  Cytomegalovirus is a ubiquitous human virus.
 Serologic testing is done to diagnosis CMV
infection.

14.  Clinical syndromes with greatest morbidity
include congenitalCMV disease, with a
20% incidence of hearing loss or mental
retardation and a 0.1% incidence of various
other congenital disorders, including
jaundice, hepatosplenomegaly, anemia,
microcephaly, and chorioretinitis.

15.  In immunocompromised patients, CMV
interstitial pneumonia carries a 90% mortality
rate.
 Disseminated spread to the gastrointestinal
tract, CNS, and eye is common in patients with
AIDS.

16.  CMV retinitis and colitis have been
successfully treated with the nucleoside
derivative ganciclovir, which is available for
intravenous, oral, or intravitreal routes
 Intraocular ganciclovir insert is also available
for the treatment of retinitis.

17.  Intravenous foscarnet and cidofovir have also
been effective in the treatment of retinitis.
 Intravitreal cidofovir given at 6-week intervals
was highly effective for treating retinitis.
 Valganciclovir is a well-tolerated, newer oral
agent that is highly effective in the treatment
of CMV infection, including retinitis.

18.  Childhood infections are usually asymptomatic,
with symptomatic disease occurring in young
adults
 Infectious mononucleosis is the usual clinical
disease in most symptomatic adults.
 EBV is epidemiologically associated with Burkitt
lymphoma and nasopharyngeal carcinoma.

19.  Treatment of acute disease is largely
supportive - acyclovir and ganciclovir, which
decrease viral replication in tissue culture.
 No vaccine is currently available against EBV,
but research is ongoing toward developing a
cytotoxicT-cell-based vaccine.