Len's Medical Stuff #7: Influenza

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Len Leshin

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Sep 8, 1996, 3:00:00 AM9/8/96
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INFLUENZA

Flu season is typically described as late fall and winter. We're coming up
on the optimal time for vaccine (October), so I thought I'd use this as my
next topic.

The Virus
-------------
The flu has been known since ancient times. The word "influenza" comes from
the Italian astrologers who thought the flu was due to the "influence" of
the heavenly bodies. In fact, it's not very heavenly at all. The worst
epidemic for the most people killed in the shortest time was the Spanish Flu
in 1918-19, killing 27 million people world-wide in just 18 months (by
contrast, World War I had killed 9 million men in 4 years).

The flu virus comes in two main flavors: type A and B. Each winter, one
type usually predominates over the other quite a bit. Type A is usually the
more severe, but there are exceptions.

The virus is notorious for mutating. Usually, these are subtle changes that
only involve the virus' outer coat, which most people's immune system can
effectively handle; but every ten to twenty years a major change occurs,
leaving the population vulnerable to the infection as well as pneumonia,
which quite frequently follows the flu. These subtle mutations are the
reason why we need yearly vaccinations, rather than one vaccine giving
long-term protection.

The flu virus is spread by direct contact, sneezing and coughing, or
articles recently contaminated by direct contact. During an outbreak, the
highest attack rates occur in schools and office buildings. Infected people
are most contagious during the 24 hours BEFORE symptoms occur, but are also
contagious throughout the course of the illness. The incubation period (the
time from when you become exposed to when you get sick) is about 3 days.

The Infection
------------------
Community epidemics can last 4 to 8 weeks, but the peak is usually 2 weeks
after the beginning of the epidemic. The flu is hardest on children, the
elderly, and people with chronic illnesses that already put strain on the
immune system.

Signs and symptoms: sudden fever, chills, an all-over achiness, and burning
of the eyes is common. Some flu varieties affect the respiratory tract
more, causing nasal drainage, cough and sore throat. Other flu varieties
cause more intestinal symptoms, such as nausea and vomiting. The length of
illness is usually 5 to 7 days. Because influenza can quite frequently lead
to pneumonia, a cough and fever for more than 5 days should be investigated
by a physician. Croup can also be associated with the flu in younger
children. Flu is often worse in children with chronic lung or heart diseases.

If you can catch it in the first 24 hours, there is a treatment for type A
flu. The antiviral medications amantadine (Symmetrel) and rimantidine
(Flumadine) are very useful for this purpose. (Digression: There are two
jobs I'd love to have: naming streets and naming drugs.) Amantadine has
gone generic and is cheaper, but has the more frequent side effect of
hallucinations. Amantadine is not recommended in people who have epilepsy.
Both are equally effective at curing the flu, but only if you start it in
the first 24 hours of the illness; both can be used in children over 1 year
of age. Neither is effective against type B flu. If influenza A is
diagnosed in a member of a family, either amantadine or rimantidine may be
given to other household members as a prophylaxis.

Chicken soup (Bubbemycin) is highly recommended for the flu unless vomiting
is present; then, stay away from all soups.

Occasionally, an inflammation of the muscles ("myositis") will develop
several days after the flu. This is especially seen in the calves, and can
last 3 to 4 days. Reyes syndrome, a devastating disease of the liver and
brain, has been associated with the use of aspirin and influenza;
acetaminophen or ibuprofen should be used instead.

The Vaccine
------------------
Each spring, the Center for Disease Control analyzes the recent years'
strains and predicts which strains might hit the US that winter; and they've
been more accurate than not.

Children as young as 6 months of age can get the flu vaccine. If the child
is less than 9 years of age, the first year the child gets the flu vaccine,
the child will need 2 shots, 1 month apart. If the child is 9 years or
older the first year, 1 shot is enough. It takes 10 to 14 days from the
time of vaccination to full immunity. The flu vaccine is estimated to
protect fully 7 out of 10 children who get the vaccine. The other 3 get
milder cases.

Children who are at *high risk* from serious complications from the flu
should get the vaccine every year. This category includes children with the
following diseases or conditions: asthma, bronchopulmonary dysplasia or
other chronic lung diseases; heart diseases; sickle-cell anemia or other
hemoglobinopathies; HIV or other immunosuppressive diseases; diabetes
mellitus; chronic kidney diseases; chronic metabolic diseases; children
getting immunosuppressive drugs; children taking long-term aspirin therapy.

Children and adults who are close contacts of high-risk children should also
be vaccinated. This includes hospital personnel and other health care
workers, and household contacts of high-risk children.

The Center for Disease Control also advocates the vaccine for anyone in whom
getting the flu would result in a major "disruption of routine activities."
I'm trying to figure out if that phrase leaves anyone uncovered. Actually,
I do personally recommend the vaccine for all the children in my practice.

Side effects: the main one is a sore arm from the injection. Infrequent
fevers, achiness and local redness can occur, usually within the 24 hours
after vaccination. (The whole virus vaccine causes more side effects than
the split-virus (subviron) version, so the split virus version is
recommended for children 12 years and younger. Children who get
anaphylactic reactions to eggs (severe hives and difficulty breathing)
should not get the vaccine. The manufacturers of the vaccines suggest not
giving the vaccine to anyone sick with a respiratory illness at the time of
the clinic visit.

The vaccine is usually given about mid-October to November, in time for the
flu season which usually starts about Thanksgiving. The CDC has noted today
(9/9/96) that the first flu cases in the US have just been reported in
Hawaii, so we may have an early season this year; so doctors will probably
be starting immunizing in early october this year.
(And yes, I take the vaccine each year, and no, I can't convince my wife to
take it. She'd rather be sick and let me minister to her. I open a mean
can of chicken soup.)

Questions?

Len Leshin, MD, FAAP
Father of Avi, 2 (DS) and Nathan, 4
lle...@davlin.net
http://ptolemy.eecs.berkeley.edu/~pino/DS/health/index.html

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