Agriculture Reference
In-Depth Information
Through self-interest (that is, by protecting their own territory), the nor-
mal fl ora help keep yeast and fungi from getting out of control. This is why a
long run of antibiotic use often results in yeast infections — it compromises
the normal bacteria as well as the pathogenic bacteria.
Over time, constant exposure to organisms in the environment (like bac-
teria, viruses, and worms) results in the development of a degree of resis-
tance, or immunity, to the organisms, especially in mature sheep. When a
bad “bug” has breached the previous defenses, then the immune system kicks
into gear.
White blood cells are always ready to mount a quick attack when an
invader shows up — these cells are the fi rst responders of the immune sys-
tem. They fi ght the invader by mounting an infl ammatory response, which is
why redness, swelling, and heat around a wound happen quickly after injury.
During an illness, the heat of an infl ammatory response presents as fever,
but not all illnesses are accompanied by a steady fever, and fevers sometimes
cycle between normal and elevated temperatures. Cycling is an interesting
phenomenon: the body's temperature rises in an effort to kill multiplying
bugs. The increased temperature reduces the number of bugs, and the body's
temperature goes back down. If any bugs remain, however, they multiply
again until the body responds by cranking up the heat.
In some minor situations, such as a skin abrasion, the white blood cell
response is enough to take care of things, but when an attacking virus or
bacterium has gotten a strong start, the white blood cells may not be able
to squelch it. While the infl ammatory response is going on, the body starts
building antibodies. If the white blood cells are the cavalry, then the anti-
bodies are the army. It takes antibodies a little longer to mobilize, but when
they hit the scene, they come in force. Antibodies can form to attack para-
sites, allergens, pathogens, and even cancer cells.
Antibodies are highly specifi c to the various invaders they fi ght and can
take up to 2 weeks to form. But by using vaccinations, we can preprogram
the antibodies. Through preprogramming, antibodies instantly recognize
an invader and mount a full-blown attack almost immediately. Thus, the
response time is cut from 2 weeks to mere hours, which is almost always fast
enough to quell an invading organism's assault.
Strong, healthy animals have strong, healthy immune systems. Their
bodies take care of almost all potential problems, but occasionally even
antibodies aren't enough to overcome an invading organism. At this point,
medical intervention is needed.
