Information for Hawaii’s Healthcare Providers
CLINICAL SIGNS AND SYMPTOMS OF INFLUENZA
Influenza is characterized by the abrupt onset of fever, myalgia,
headaches, malaise, non-productive cough, sore throat and
rhinitis. Children may experience gastrointestinal symptoms
including nausea and vomiting, as well as otitis media.
Clinical manifestation of influenza may resemble that of other
respiratory viruses including enterovirus, adenovirus, parainfluenza virus,
respiratory syncitial virus, and echovirus.
Laboratory analysis and
careful diagnostic evaluation can distinguish influenza from other
respiratory illnesses including the common cold.
Amongst special populations, including the elderly, the very young, severely
immunocompromised
patients, and those with chronic heart, lung or other
metabolic disease, influenza infection may
develop secondary complications including pneumonia,
febrile seizures, myositis, myocarditis, and
pericarditisis. Infants administered with Aspirin
while infected with influenza may develop Reye’s
syndrome.
|
|
Cold
|
Flu
|
|
Illness
|
Respiratory (breathing) illness caused by viruses.
|
Respiratory (breathing) illness caused by influenza viruses.
|
|
Treatment
|
Treat symptoms. Does not respond to antibiotics.
|
Antiviral flu medicines started in the first 2 days of illness can
reduce the severity and duration of influenza illness.
|
|
Vaccine
|
None.
|
Annual flu shots can reduce your risk of getting the flu.
|
|
Transmission
|
Easily spread from person to person when an infected person touches
someone else or sneezes or coughs.
|
Easily spread from person to person when an infected person sneezes
or coughs.
|
|
Symptoms
|
|
|
|
Fever at or above 100°
F
|
Uncommon in adults or older children.
|
Usual and can last 3 to 4 days.
|
|
Headache
|
Usual.
|
Usual with sudden onset, and can be severe.
|
|
Muscle Aches
|
Mild.
|
Usual, and often severe.
|
|
Tiredness and Exhaustion
|
Mild.
|
Usual with sudden onset, can be severe, and can last 2 or more
weeks.
|
|
Runny Nose
|
Usual.
|
Usual.
|
|
Cough
|
Usual.
|
Usual, and can become severe.
|
|
Chest Discomfort
|
Uncommon.
|
Uncommon.
|
|
Vomiting
|
Uncommon.
|
Uncommon in adults but more likely in very young children.
|
For more information, including recent
publications, treatment recommendation, diagnostic testing, etc. for
influenza, go to CDC’s resources for healthcare professionals.
Transmissibility
Influenza is transmitted via respiratory droplets of infected persons.
The incubation period prior to onset of illness is
typically 2 days.
Patients are infectious at
least a day prior to onset of symptoms, and continue to be
infectious for several days.
In general, the weaker the immune response to the virus, the
longer the patient remains infectious.
Therefore, severely immunocompromised patients shed virus
for the longest duration lasting up to several months, whereas
healthy vaccinated adults mount a strong immune response to the
virus and remain infectious for short periods of time following
onset (approximately 5 days).
LABORATORY
DIAGNOSIS
Several diagnostic tests are available for influenza testing with varying
degrees of sensitivity, specificity, and diagnostic
value.
Rapid Influenza Testing
Commercial rapid influenza diagnostic testing can be used to detect the
presence of influenza within 30 minutes.
The
Clinical Laboratories of Hawaii and Diagnostic Laboratory Services
are commercial laboratories that provide rapid
testing capabilities to all clinicians in Hawaii.
Kaiser Permanente’s and Straub’s laboratories
are available to Kaiser and Straub affiliated
physicians respectively.
Rapid testing offered by these commercial
laboratories can detect both influenza A and B, and
also distinguish between the two.
Other in house rapid testing kits are
available that clinicians can use to detect the
presence of influenza.
Studies conducted by the Hawaii Department of
Health reveal a sensitivity of 63.4%
and specificity of 89.7% for a particular brand of
rapid influenza kits (Positive Predictive Power of
70.7% and Negative Predictive Power of 86.2%).
Rapid testing, because of its short
turnaround time, is a clinically valuable tool for
influenza detection.
For more information on influenza rapid testing, please contact the Hawaii
Department of Health Influenza Surveillance Program at 586-4586 or
visit the CDC’s laboratory diagnosis webpage.
Real-Time Polymerase Chain Reaction (RT-PCR)
RT-PCR is available to Hawaii Physicians through the Hawaii State
Laboratories Divisions.
RT-PCR is a highly accurate test for
influenza
detection, and
has much higher sensitivities and
specificities than rapid influenza testing.
PCR testing can be performed within a
few hours, and can distinguish between
influenza A and B.
In addition, PCR testing can also
distinguish various subtypes of influenza
virus.
Because of its high precision and
short turnaround time, RT-PCR is an
excellent and accurate diagnostic tool for
Hawaii’s healthcare providers.
RT-PCR testing is currently conducted on specimens that meet certain
criteria only.
For example, specimens that
are collected from
passengers meeting clinical criteria
for influenza at the Honolulu
Airport Quarantine Station,
specimens from hospitalized patients
with Acute Respiratory Distress
Syndrome (ARDS), patients with a
travel history outside the United
States within 10 days preceding
onset of symptoms, specimens that
are identified as part of a
suspected influenza outbreak and
specimens submitted by members of
the Hawaii Sentinel Physician
Program are currently eligible for
RT-PCR analysis.
Results are reported within
24 hours of testing.
Beginning in Fall 2006, the
Department of Health will be
expanding upon its RT-PCR
capabilities and begin using this
technique as the primary method of
influenza detection.
For more information on Hawaii’s RT-PCR capabilities, please contact the
Hawaii Department of Health
Influenza Surveillance
Program at
586-4586.
Viral Culture
Viral culture testing is also conducted by the State Laboratories
Division.
This technique is not
diagnostically useful,
because viral isolates are
typically not detected for
2-3 weeks.
However, viral
culture is considered the
“gold standard” of influenza
detection, and is used by
the Hawaii Department of
Health and the CDC for all
influenza confirmation.
Viral culture
distinguishes between
various subtypes of
influenza A and
distinguishes influenza A
from influenza B.
The State
Laboratories Division sends
several influenza isolates
to the CDC for strain-typing
year round.
For more information on Hawaii’s viral culture capabilities, please
contact the Hawaii
Department of Health
Influenza Surveillance
Program at
586-4586.
Although a flu shot is the best way to prevent the
flu, antiviral
drugs are other
tools that can
be used to help
prevent and
treat
influenza. The
four available
drugs are
amantadine,
rimantadine,
zanamivir and
oseltamivir
|
Comparison
of
Antiviral
Drugs
for
Influenza
Table
|
|
Drug
|
Trade
Name
|
Influenza
Virus
Type
|
Approved
Use
|
Treatment
Age
|
Prevention
Age
|
|
amantadine
|
Symmetrel®
|
A
|
Treatment
and
Prevention
|
>1
year
|
>1
year
|
|
rimantadine
|
Flumadine®
|
A
|
Treatment
and
Prevention
|
Adults
|
>1
year
|
|
zanamivir
|
Relenza®
|
A
and
B
|
Treatment
|
>7
years
|
n/a
|
|
oseltamivir
|
Tamiflu®
|
A
and
B
|
Treatment
and
Prevention
|
>1
year
|
>13
years
|
These drugs can
be
divided
into
two
groups
based
upon
how
they
work.
Amantadine
and
rimantadine
can
be
used
to
treat
and
prevent
influenza A infections. These drugs do not work against
influenza
B
viruses.
The
CDC
released
a
Health
Alert
Notice
on
January
14,
2006
recommending
that
neither
amantadine
nor
rimantadine
be
used
for
treatment
or
prophylaxis
of
influenza
A
for
the
remainder
of
the
2005-06
influenza
season.
The second group of
drugs
includes
zanamivir
and
oseltamivir,
which
can be
used to
treat
influenza
A and B
infections.
Oseltamivir
can also
be used as prophylactically to protect the patient
from
developing
influenza
A or B.
Studies
show
that
treatment
with any
of these
drugs
can
shorten
the time
a person
infected
with
influenza
feels
ill by
approximately
1 day,
if
treatment is started during the first 2 days of
illness.
For more information on the CDC’s current recommendations for treatment of influenza infection, please click here.
Side effects of Antiviral Medications
Amantadine and Rimantadine
Among some healthy adults and children, central nervous system (CNS) side
effects such as anxiety, difficulty concentrating, lightheadedness, and gastrointestinal side effects
like nausea and loss of appetite may occur. CNS side effects are more frequent amongst those taking amantadine than among persons taking rimantadine. In persons with long-term illnesses, more serious side effects, such as delirium, hallucinations, agitation and seizures, can occur.
Side effects are generally not long-lasting.
Zanamivir
This drug is inhaled and can cause side effects, especially in those with asthma or other chronic lung disease. Decreased respiratory function
and
bronchospasm
have
been
reported
with
use
of
zanamivir.
Zanamivir
is
generally
not
recommended
for
use
in
persons
with
underlying
lung
disease
such
as
asthma
and
chronic
obstructive
pulmonary
disease.
Other
side
effects
reported
by
less
than
5%
of
those
who
have
used
this
drug
are
diarrhea,
nausea,
sinusitis,
nasal
infections,
bronchitis,
cough,
headache,
and
dizziness.
Oseltamivir
Gastrointestinal side effects occur most commonly. Nausea and vomiting may
be less severe if oseltamivir is taken with food.
Information about the Flu Vaccine
The Influenza Vaccine Bulletin is published by the CDC.
For
instructions
on
how
to
receive
free
e-mail
subscriptions
to
this
publication,
please click here.
SUBMITTING SPECIMENS TO THE HAWAII DEPARTMENT OF HEALTH
Back to Top
|
