Influenza
Copyright 2005 Kristy Haugen
Influenza is a respiratory tract infection involving the
upper airways and lungs. Many refer to influenza as the
“flu”. Influenza is highly contagious transmitted by
saliva and airborne droplets expelled by coughing and
sneezing. The incubation is very short ranging from one to
three days. Common symptoms of influenza are fever,
chills, muscle aches and pains, dry cough, nasal
congestion, sore throat, headache, malaise, fatigue,
sneezing, sweating, and irritated eyes.
The influenza virus is an RNA virus that belongs to the
orthomyxoviridae family. Three genera of the influenza
virus currently exist. Each influenza virus is identified
by the antigenic differences in their nucleoprotein and
matrix protein.
The influenza B and C viruses infect only humans.
Populations tend to have more resistance to these two
viruses. This is because influenza B and C only undergo a
type of evolution referred to as antigenic drift. RNA
replication in these viruses is frequently error prone and
leads to many point mutations. These point mutations lead
to very little change in the new viral strain. Influenza B
and C viruses cause relatively mild and limited disease
epidemics. The influenza A virus infects mammals and
birds (avian influenza). This virus is more likely to
cause a pandemic (world wide epidemic). Influenza A is a
recombinant virus, meaning an interchange of gene segments
if two different viruses infect the same cell. This type
of evolution is referred to antigenic shift. Avian and
human strains recombining in pigs in the Far East may
permit the virulent human strains to evolve. Common
antigenic variants include H1N1, and H3N2.
Influenza A can be further classified by the surface
proteins. Sixteen subtypes of the viral surface protein
hemagglutinin (HA or H) currently exist. Nine subtypes of
the viral surface protein neuraminidase (NA or N) exist.
These surface proteins are essential for the virus’ life
cycle.
The flu season reaches a peak prevalence in winter. The
Northern and Southern hemispheres have winter at different
times, meaning that there is actually two flu seasons
annually. Two different vaccinations are made for the
different flu seasons each year. The Northern Hemisphere
flu season peaks in January or February. The Southern
Hemisphere flu season peaks in October.
Influenza vaccines are developed each based off the
predominant strains in the Southern Hemisphere. The
vaccine contains an inactivated (killed) virus. Protection
provided by the vaccine depends on effectiveness of the
strain used to make the vaccine.
Vaccinations typically begin in October. Those that are
susceptible to illness such as the elderly (65 years and
older), young children (under 5 years of age), and
immunocompromised patients are encouraged to be vaccinated.
Young children are likely to get complications from the
flu such as pneumonia, bronchitis, sinus and ear infections.
Anyone who has an allergy to eggs should not be vaccinated.
Allergy to the vaccine is due to small amounts of egg
protein that remain in the vaccine after purification.
This is considered to be a rare side effect. Many complain
of injection site soreness up to two days after
vaccination. This is temporary and should go away.
Typical side effects include fever, malaise, muscle aches
occurring 6-12 hours after vaccination.
There are currently medications used to treat influenza.
Amantadine and rimantadine are medications used to treat
influenza A only. Neuraminidase inhibitors such as Tamiflu
and Relenza block the normal function of the viral surface
protein neuraminidase. These medications can be used to
treat influenza A and B. Resistance to adamantine
derivatives (amantadine, rimantadine) is seen in China,
Hong Kong, Taiwan, and South Korea due to availability in
over-the-counter remedies.
The avian flu naturally infects aquatic birds. However,
pandemics occur when the avian adapted virus infects
porcine (pigs). This virus will then recombine to form a
genetically new virus. The genetically new virus infects
humans that are in close contact with the infected porcine.
The flu is then transmitted from person to person,
beginning an epidemic.
In 1997 the avian flu (H5N1) originating from chickens in
Hong Kong, killed 6 of 18 infected. This strain was not
readily transmissible from human to human. However, this
strain resurfaced in 2004 in Cambodia, Vietnam, and
Thailand. This virus remains avian adapted and cannot be
transmitted from person to person. A vaccine cannot be
made until this virus has recombined into a human adapted
form.
Elderberry extract is a trademarked over-the-counter remedy
to shorten the duration of an influenza episode. This will
not prevent the illness if taken before hand. Only
vaccination can help to prevent influenza infections.
Influence is on the minds of many and rightfully so. The
avian flu will pose a threat to the world's population if
predictions are correct. Maintaining good health is
essential during the flu season. One way to do that is
take a good vitamin supplement.
Kristy Haugen is a mother with a Bachelor in Biology and
Chemistry. She is interest in health issues and informing
the consumer. Are you in need of a vitamin supplement this
flu season. Buy vitamins online at
http://www.vitaminmaniac.com/provitamintext.htm and protect
yourself this flu season
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