The essential factor seems to be oxygenation, or exposure
to oxygen. This decreases as we age beyond childhood, and
is further limited by inactive lifestyles. An article by
Tom Valeo, ęSt. Petersburg Times, published February 25, 2003,
"Onychomycosis (ah-nee-ko-my-KO-sis), or toenail fungus,
starts with subtle discoloration; the toenail turns yellow
or dark brown. In rare cases the nail turns white, gets
powdery and sloughs off. The tip of the nail may thicken
and become a challenge even for the sharpest nail clippers.
Debris, or "toe jam," under the nail might develop an odor."
"Toenails need two things to remain healthy: oxygen and attention."
"As we age, less oxygen makes its way to the feet because the
lungs become less efficient at supplying blood with oxygen
and the heart pumps blood with less force. As a result, the
toenails, at the end of our longest appendages, must make
do with less oxygen."
"Without sufficient oxygen and attention, toenails become
increasingly susceptible to fungus, an unusually stubborn
affliction that almost never clears up on its own. Even
oral antibiotics, the most effective treatment, take weeks
to eradicate the infection. Topical treatments, such as
medicated toenail polish, may take longer."
"Fungus thrives in warm, dark, moist environments and loves
to feast on keratin, the protein that makes up the toenail.
Blood, rich in oxygen and antibodies, fights this invasion
effectively, which is why children, who have robust
circulation in their feet, almost never get fungal toenail
"More than half of adults over 65 have problems, says Joshua
Bernard, a podiatrist and assistant professor of surgery at
the University of South Florida."
"When we get beyond 60 or so, the skin tends to thin out and
atrophy," Bernard said. "The blood supply to the tissues,
including the toenails, tends to decrease, and the body's
immune system loses vigor."
"The first line of defense against toenail problems is the
simplest: Wash your feet vigorously every day with soap and
water. The soapy runoff from a shower is not sufficient."
"Failure to wash the feet vigorously gives fungus an
opportunity to grow, especially when toenails develop
tiny cracks. Stubbing your toe or dropping something on
it can crack the nail, but toenails can suffer "microtrauma"
as Bernard calls it, simply from rubbing against the inside
of tight shoes."
"Bernard recommends other simple precautions:
Change your socks every day.
Wear flip-flops or aqua socks when using a communal shower
at a gym or pool.
Dry your feet thoroughly and apply foot powder.
Allow your shoes to dry completely before wearing them again.
For extra protection, swab the inside of your shoes with
cotton balls soaked in a mild bleach solution."
Trim your toenails straight across but not too short. And do
not round the corners because that may encourage the skin to
swell, leading to an ingrown toenail."
There's more in the original article:
Please do not rate this answer until you are satisfied that
the answer cannot be improved upon by means of a dialog
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Searches done, via Google:
"toenail fungus" "oral antibiotics"
Clarification of Answer by
16 Mar 2003 11:08 PST
Sorry. I assumed that you had read xarqi-ga's comments and
understood that, as he noted, infections are more effectively
addressed in a systemic manner. The antibiotics must be made
to enter the bloodstream in order to be carried to all parts
of the body. Given that the primary reason for a fungal
infection in the toe is poor circulation in that area, this
makes it the worst site for the introduction and dispersal of
the antibiotic, not to mention that, due to the large number
of nerve endings in the toes and feet, it would be exceedingly
painful. For this reason, shots are typically given in less
sensitive parts of the body, with better circulation.
Then there is the matter of maintaining a certain level of
the antibiotic in the bloodstream. This would require
repeated shots, which means repeated (daily) office visits.
This is simply not desirable for the recipient or practitioners
in terms of cost and time (not to mention pain), especially
when, as the page I cited notes:
"...oral antibiotics, the most effective treatment, take weeks
to eradicate the infection"
This implies that injectable antibiotics would take even longer.
The reason that the eradication of this infection takes so long
is, again, due to the poor circulation in the feet and toes
(which is the major contributing factor to the infection in the
first place). If the infection were located in a part of the
body where circulation was good, it would not take so long, as
evidenced by the routine 10-day course of antibiotics when they
are prescribed for, say, an infection in the mouth, which has
better circulation than most parts of the body.
For the reasons above, it is more common to be given a shot
upon first visiting your practitioner, as this allows a
major initial delivery of the antibiotic to enter the
bloodstream. This is then followed by pills taken 3-4 times
a day, to maintain the level of antibiotic in the system.
And, of course, this means fewer expensive visits to the
doctor's office, and fewer painful shots.
I hope that clears things up, but if you need further
clarification, please don't hesitate to ask, before
rating this answer.