Download Common Viral Infections: Influenzaviruses and Herpesviruses

Common Viral Infections:
Influenzaviruses and Herpesviruses
Tintinalli: Chapter 143
Dave Piatt
Influenza A & B
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Antigenic drift
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Minor mutations of the H or N molecule
Antigenicity changes with mutations
Causes annual epidemics (usually type A)
Antigenic shift
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New virus produced by genetic reassortment within a
host infected by two different influenzaviruses
Population lacks immunity against new virus
Causes major flu pandemics (such as in 1918)
Influenza
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Epidemiology
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Occurs Nov. thru April in the U.S.
Occurs year-round in the tropics
Spread via droplets produced during cough
Incubation period is 2 days
Viral shedding (contagiousness) starts 24
hours before onset of symptoms
Influenza
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Clinical features (onset is usually rapid)
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Fever (38.6o – 39.8o) for 2-4 days
Chills/rigor
Headache
Myalgias
Malaise
Cough
Rhinorrhea
Sore throat
Elderly often do not have classic symptoms and
may have only fever, malaise, confusion, and
congestion
Influenza
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Diagnosis
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Clinical diagnosis during outbreak has an
accuracy of about 85%
Rapid antigen tests
Decrease empirical antibiotics
 Sensitivity 57-81%
 Specificity 93-100%
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Influenza
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Complications
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Pneumonitis
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Secondary Pneumonia
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Flu symptoms progressing to cough and dyspnea
Hypoxia
Bilateral infiltrates on CXR similar to ARDS
Supportive treatment
Occurs 1-2 weeks after flu
Treat with broad spectrum antibiotics and pulmonary support
COPD, Reye syndrome (with aspirin use), croup,
myocarditis are also complications
Influenza
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Treatment
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Amantadine and rimantadine (100 mg BID X 5 days)
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Approved for type A only; not active against type B
If started within 48 hours of onset of symptoms, it can
reduce duration of symptoms by 1-2 days
Avoid in pregnancy
Approved for children over 1 year of age
Oseltamivir and zanamivir (Tamiflu and Relenza)
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Active against types A & B
Reduces duration of symptoms by 1 day if started within 48
hours of onset of symptoms
Influenza
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Prophylaxis
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Annual formulation contains 2 strains of type A and 1
strain of type B
70-90% effective in those under age 65
Recommended for all persons over age 65, residents
of chronic care facilities, patients with chronic
cardiopulmonary disease, diabetes, metabolic
disease, or renal disease; immunosuppressed patients,
and healthcare workers
Safe for pregnant/lactating women
Anti-influenza medicines are 75-90% effective in
preventing influenza if given as a 6-8 week course
during peak flu season
Herpesviruses
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Dwell in host as a lifelong latent infection
May cause clinical disease at a time distant from
the primary infection
Some are carcinogenic
Varicella-zoster virus (VZV) is spread via
aerosolized particles and close contact
Herpes simplex virus (HSV) and Epstein-Barr
virus (EBV) transmission occurs during
asymptomatic shedding
Herpes Simplex 1 & 2
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Epidemiology
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Transmitted via infected secretions on
mucous membranes or open skin
HSV-2 is primarily transmitted sexually
Herpes Simplex 1 & 2
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Oral HSV
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Primarily HSV-1, but can be HSV-2
Primary lesion lasts 1-2 weeks
Lesions recur in 60-90% of infected people
Recurrences triggered by local trauma, illness, or
stress
Treatment: acyclovir 400 mg PO 5 times/day (topical
acyclovir is ineffective)
Prophylaxis: oral acyclovir reduces outbreaks by
50-75% in those with frequent/severe outbreaks
Herpes Simplex 1 & 2
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Genital HSV
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Majority caused by HSV-2
Covered in chapter 141 (STDs)
Ocular HSV
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Usually HSV-1
Ulcerative keratitis is most common manifestation.
May lead to corneal blindness
Vesicles may be seen on the conjunctiva or lid
Fluorescein stain may show corneal dendritic ulcers
Ophthalmologic consultation is imperative, and
patient may need to be admitted for IV acyclovir
Herpes Simplex 1 & 2
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Encephalitis
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Usually HSV-1
Temporal lobes are the major target and lesions may
be seen on CT and MRI
Presents as headache, fever, and altered mental status
with preceding viral-like illness. Patients may have
olfactory hallucinations
CSF findings: elevated WBCs with mononuclear
predominance
Empirical treatment with IV acyclovir at 10 mg/kg
every 8 hours should be initiated if suspicion exists
If untreated, mortality rate is 70%
Herpes Simplex 1 & 2
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Bell Palsy
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Usually HSV-1
Causes palsy of the peripheral branch of CN VII
Presents as facial hemiplegia or hemiparesis, taste
disturbance, decreased blinking, dry eyes, facial
numbness, and jaw/face pain
Central CN VII lesions spare the forehead but cause
unilateral lower facial weakness. Peripheral lesions
result in forehead paralysis. Attempting to close the
eye on the affected side results in an upward gaze
(Bell phenomenon)
Herpes Simplex 1 & 2
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Bell Palsy
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Examination of the ear, tympanic membrane,
mastoid, and parotid gland should be normal
Bell palsy with otitis media, mastoiditis, or parotitis
is an ENT emergency
Vesicles on the TM or canal is diagnostic of Ramsay
Hunt syndrome
Differential includes stroke, tumor, atypical GuillainBarre, and Lyme disease
Treatment: prednisone 60 mg PO X 5 days with
acyclovir 400 mg 5 times/day for 10 days
Eye care with artificial tears is the most important
therapeutic intervention made by the ED physician
Herpes Simplex 1 & 2
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Herpetic Whitlow
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HSV infection of the finger (usually one digit)
HSV-1 is seen in children who self-inoculate during
an episode of oral herpes and in health care workers
(dentists)
HSV-2 more common if digital/genital contact
Very painful and accompanied by axillary
adenopathy
Vesicles contain necrotic epithelial cells, not pus. If
confused with paronychia and the finger is incised,
delayed healing and secondary infection may occur
Spontaneously heals in 2-3 weeks, may use acyclovir
Herpes Zoster: Chickenpox
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HZV is human herpesvirus 3
Primary infection is chickenpox
Reactivates later as zoster (shingles)
Epidemics occur late winter/early spring
Spread via respiratory droplets
Patients are infectious 48 hours before rash
appears until the vesicles have crusted over
Rash appears 14 days after exposure. The
virus becomes latent in a dorsal root ganglion
Herpes Zoster: Chickenpox
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Clinical features
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Prodrome of 1-2 days of fever, malaise
Clear vesicles on an erythematous base appear on the
face and trunk, then spread centripetally to the
extremities. New lesions will appear and the old
ones will become turbid and scab over. The hallmark
of chickenpox is vesicular lesions in various stages
Complications can include encephalitis, cerebellar
ataxia, pneumonitis, and Reye syndrome
Mortality rate among adults is 15 times higher than in
children
Chickenpox during pregnancy can cause fetal
abnormalities
Herpes Zoster: Chickenpox
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Treatment
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Over age 12
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Neonates of mothers who developed chickenpox 5 days
before delivery or within 48 hours postpartum
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Acyclovir 800 mg PO QID X 5 days started within 24 hours
of onset of rash
Varicella-zoster immune globulin (VZIG) to confer passive
immunity
Patients with varicella encephalitis, pneumonitis, or who
are immunocompromised should be admitted for IV
acyclovir
Varicella vaccine recommended for children over age 1
year. It is a live vaccine and is contraindicated in
immunocompromised patients and in pregnant/lactating
women
Herpes Zoster: Shingles
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Is a reactivation of latent VZV infection
Lifetime incidence of 20%, usually in elderly
Lesions limited to a single dermatome, usually
thoracic or lumbar
Begins as a prodrome of pain for 1-3 days in the
affected area, followed by a maculopapular rash
that progesses to vesicles
Disease course is 2-4 weeks
Disseminated disease can cause pneumonitis,
hepatitis, or meningoencephalitis
Herpes Zoster: Shingles
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Complications:
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Herpes zoster ophthalmicus (HZO)
Involves the ophthalmic branch of CN V
 Vision-threatening
 Hutchinson sign (lesion of tip of nose) may be
seen before ocular involvement
 May also see a dendriform corneal ulcer with
fluorescein staining
 Mandatory ophthalmologic consult
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Herpes Zoster: Shingles
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Complications:
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Ramsay Hunt syndrome
Involves the geniculate ganglion of CN VII
 Presents with facial palsy, unilateral weakness,
loss of taste, and ear canal or TM vesicles
 May also see intraoral lesions
 May be a cause of mental status change in elderly
 Presentation and treatment are similar to Bell
palsy
 Admit immunocompromised patients for IV
acyclovir
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Herpes Zoster: Shingles
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Complications:
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Postherpetic neuralgia
Most common complication
 Occurs in 10-20% of all shingles cases, and in
70% of patients over age 70
 Resolves in 1-2 months
 First-line treatment is systemic analgesics; secondline treatment is amitriptyline or carbamazepine
 Corticosteroids improve quality-of-life in elderly
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Start 21-day taper at 60 mg PO daily
Epstein-Barr Virus:
Infectious Mononucleosis
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Human herpesvirus 4
Spread by close contact, such as kissing
Incubation period of 1-2 months, followed by
prodrome of malaise, fatigue, and fever
Classic symptoms include fever, sore throat
(exudative pharyngitis), lymphadenopathy,
splenomegally, and atypical lymphocytosis.
Bilateral tender cervical adenopathy is universal
Hepatomegally and jaundice is common in adults
EBV: Infectious Mononucleosis
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Palpable splenomegally occurs in ½ of patients,
most prominent during week 2 of the illness
The incidence of splenic rupture is 0.1-0.5% and
is generally at week 2-3 of the illness. Patients
should be instructed to avoid contact sports and
strenuous activity for 4 weeks
Complications of mono include hemolytic
anemia, thrombocytopenia, encephalitis,
meningitis, obstructive tonsillitis, and lymphoma
EBV: Infectious Mononucleosis
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Lab analysis may show elevated WBC with
increased atypical lymphocytes and monocytes
Commercial tests (monospot) are 78-83%
sensitive and 98-100% specific. Patients with
classic EBV symptoms and a negative monospot
should have a repeat monospot in 1 week
Treatment is supportive. If penicillin is given to
treat a suspected strep pharyngitis, 95% of
patients will develop a rash
Cytomegalovirus
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Human herpesvirus 5
Causes a primary illness and then exists in a
latent state in the host until reactivation
Found in milk, saliva, urine, semen, and cervical
secretions
Also transmitted during blood transfusions and
bone marrow and organ transplantations
One of the TORCH agents known to cause
intrauterine infections
Cytomegalovirus
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Infection is usually asymptomatic, but symptoms
can include fever, chills, myalgias, and headache.
Fever may last for 1-5 weeks
May see atypical lymphocytosis, splenomegally,
lymphadenopathy, and increased LFTs
Consider CMV in patients with mono-like
symptoms but who are monospot negative
Cytomegalovirus
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10% of AIDS patients develop CMV
retinitis, which causes floaters or decreased
vision. Fundoscopic exam may show
retinal hemorrhages or exudates. Without
treatment, this will progress to blindness
Treat with IV ganciclovir or foscarnet
Cytomegalovirus
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CMV causes significant morbidity and
mortality in post-transplant patients
Pneumonia is the most common infection
Most common in bone marrow transplant
patients
CMV should be considered for a fever
within 3 months of a transplant
Cytomegalovirus
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Treat CMV with ganciclovir or foscarnet
Ganciclovir is approved for CMV retinitis in
AIDS patients and for CMV prevention in
transplant patients
Foscarnet is used for resistant CMV infections or
for patients unable to take ganciclovir
Neither medication cures patients of CMV, but
they suppress the acute disease process
Questions
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1. Bell palsy involves which cranial nerve?
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A. CN IV
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B. CN V
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C. CN VI
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D. CN VII
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E. CN VIII
2. Which is false regarding influenza?
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A. The vaccine is unsafe in pregnancy
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B. Amantadine is effective against types A and B
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C. Complications of influenza include pneumonia, pneumonitis, and COPD
exacerbation
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D. The vaccine is 70-90% effective
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E. Antigenic drift causes annual epidemics
3. Incision of a herpetic whitlow vesicle will produce pus
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T or F?
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4. Which of the following is false regarding EBV?
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A.
B.
C.
D.
E.
Splenomegally is palpable in 90-100% of all patients with infectious mononucleosis
Bilateral cervical adenopathy is nearly universal
Virus is spread by close contact, such as kissing
Atypical lymphocytosis is a common finding
Treatment is primarily supportive
5. Retinitis in AIDS patients is usually caused by which virus?
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A.
B.
C.
D.
E.
VZV
EBV
CMV
HSV-1
HSV-2
Answers
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1.
2.
3.
4.
5.
D
B
False
A
C