Depending on immunological and
clinical differences two types of herpes simplex viruses can be distinguished.
Type 1(HSV 1):
It is responsible for most nongenital
herpetic infections.
But up to half of new cases of
adult genital herpes are caused by HSV 1.
Type 2(HSV 2):
It is recovered almost exclusively
from the genital tract.
Sexual contact is the main mode of
transmission.
Maternal infection:
HSV 2 infections can be
categorized into 3 types:
-Primary infection: No presence
prior antibodies to HSV 1 or HSV 2.
-Nonprimary first episode: Newly
acquired HSV 2 infection with preexisting HSV 1 cross-reacting antibodies.
-Recurrent infection: Reactivation
of prior HSV 2 infection in the presence of HSV2 2 antibodies.
Primary infection:
-Among newly acquired primary HSV
2 genital infections only one third are symptomatic.
-Incubation period: 3 to 6 days.
-Clinical features: Papular
eruption follows with itching and tingling.
-The eruption then becomes painful
and vesicular with multiple vulvar and perineal lesions that may coalesce.
-Severe inguinal adenopathy may
occur.
-Transient systemic influenza like
symptoms caused by viremia.
-Hepatitis, encephalitis, pneumonia
etc may develop.
-Usually by 2 to 4 weeks all signs
and symptoms of infection will disappear.
-Cervical involvement can occur
but may not cause clinical symptoms.
-Some cases may require
hospitalization.
Nonprimary first infection:
-Previously existing HSV 1
antibody can give partial protection.
-They may present as first
clinical infection but symptoms will be less severe.
-They will have fewer lesions,
less systemic manifestations, less pain, briefer duration of lesion and viral
shedding.
-Sometimes difficult to
distinguish with primary infection.
Recurrent infection:
-In latency period viral particles
recide in nerve ganglia. They can get reactivated.
-It is called recurrent infection
and virus shedding occurs during this.
-The lesions will be fever in
number, less painful and shedding of the virus will be for shorter periods (2
to 5 days).
-Usually recurrence will be at the
same site.
Sub clinical shedding occurs in
around 60% of women with history of genital herpes infection.
Many sexually transmitted cases
occur due to sub clinical shedding. Its effect on pregnancy has yet to be
determined.
Neonatal infection:
-Vertical transmission through
placenta or membranes is rare.
-Usually the fetus will get
infection by contact with virus shed from cervix or lower genital tract during
birth.
Newborn infection presents as:
-Disseminated wit involvement of
major viscera.
-Localized with involvement
confined to central nervous system, eyes, skin, mucosa etc.
-Asymptomatic.
With primary maternal infection
50% risk of neonatal infection is there.
With recurrent infection the risk
decreases to 0 to 5%.
This could be due to smaller viral
load in maternal secretions and transplacentally acquired
antibody, which will decrease the severity and incidence of the disease.
Localized infection will be
usually associated with good outcome.
But disseminated infection, even
when treated with acyclovir or vidarabine can result in around 50% mortality
rate.
In at least half of the survivors
serious ophthalmic and central nervous system damage can occur.
Diagnosis:
-Tissue culture is optimal to
confirm apparent infection and asymptomatic recurrences.
-The tissue should be taken from
lesions before they undergo crusting, then it will give 95% of sensitivity.
-Tzanck smear: cytological
examination after alcohol fixation and papanicolaou staining. It is having 70%
sensitivity.
-Using PCR increases HSV detection
by four to eight fold compared to culture.
Management:
-Antiviral therapy with acyclovir,
fansciclovir and velacyclovir are used to treat first episode of genital herpes
in non pregnant and pregnant women.
-In recurrent infections and to
reduce heterosexual transmission the drugs can be used as suppressive therapy.
-Intense discomfort can treated
with analgesics and topical anesthetics.
-Severe urinary retention may need
catheterization.
-Trails are going on to keep
acyclovir or valacyclovir as suppressive therapy during last month of pregnancy
to prevent recurrence nears term.
-It reduces signs and symptoms of
recurrent infection but does not completely eliminate asymptomatic viral
shedding.
-Cesarean delivery is indicated to
those with active genital lesions or in those with a typical prodrome of an
impending outbreak.
-So if primary or recurrent lesions visualized
near the time of labor cesarean to be done irrespective of the time of rupture
of the membranes.
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