All spiders with the exception of
the hackled orb weavers, the
Holarchaeidae and the primitive
Mesothelae are capable of producing
venom. Bearing this in mind, only a
small percentage of species have
venom that poses a threat to people.
Also, many spiders don't have
mouthparts capable of puncturing
human skin. Venom defined is a
"Matter fatal or injurious to life"
with only a few with sufficient
toxicity to be harmful to humans and
require medical attention and only a
few known to produce fatalities.
A spiders venom works on two
fundamental principles, one being a
Neurotoxin that attacks the nervous
system and the other, necrotic that
attacks the tissue around the bite
and in some cases, attacking vital
organs and systems.
Neurotoxic
venom
A Neurotoxin is a toxin that
specifically acts on nerve cells,
normally by interacting with
membrane proteins. Most spiders with
serious bites have a neurotoxin
venom of some sort. The specific
style in which the nervous system is
attacked varies from spider to
spider.
The Widow spiders venom contains
latrotoxins, this causes the release
of neurotransmitter acetylcholine,
that stimulate muscle contractions.
This can affect the body in a few
different ways such as painful
abdominal cramps, interfering with
respiration and causing other
systemic effects.
The Australasian funnel web spider
and the mouse spiders venom works by
opening sodium channels, this causes
excessive neural activity that
interferes with normal bodily
functions.
The Brazilian wandering spiders
venom is a potent neurotoxin that
attacks multiple types of ion
channels, there venoms also contains
a high level of serotonin that makes
a bite from this species very
painful.
Necrotic venom
Necrosis is the premature death
of cells and living tissue. Necrotic
venom is found in the spider family
Sicariidae, this includes the
recluse spiders and the six eyed
sand spiders. Spiders within this
family possess a known dermonecrotic
agent sphingomyelinase D. Some
species with this family are more
venomous than others. A bite from a
spider in the Sicariidae family can
produced symptoms that are minor
localized to very bad dermonecrotic
lesions, up to severe systemic
reactions that include renal failure
and in cereous cases, death. With
the absence of systemic effects, the
bite from a Sicariidae spider can
still be serious, by forming a
necrotising ulcer, this destroys
soft tissue that may take months and
sometimes years to heal but leaving
a deep scare. Damaged tissue may
become gangrenous and eventually
fall away. When first bitten, there
may be no pain but become painful
and itchy in around 2 to 8 hours,
with the wound growing in the worst
cases to 25cm. Pain and other local
effects become worse around 12 to 36
hours after the initial bite, with
necrosis developing over a few days.
As the venom spreads throughout the
body in minutes, serious systemic
effects may occur before this time.
More mild symptoms include fever,
rashes, nausea, vomiting, muscle and
joint pain. More sever symptoms
rarely occur that may include
hemolysis, thrombocytopenia and
disseminated intravascular
coagulation. Weak and feeble
patients, the elderly and children
may be more vulnerable to systemic
loxoscelism.
Treatment
The treatment of a spider bite
depends on the spider its self, most spider bites
are harmless to humans and don't require first aid.
If bitten and experience extreme discomfort and
require treatment, the spider if seen biting you may
need to be identified by an expert, so that they can
determine the species of the spider so the proper
course of treatment can be administered. The best
thing to do is to try and catch the spider, either
alive or in a well preserved condition.
A spider that has
been flattened or left to decay may
not be useful in a definite
identification. The majority of
medical responders are not trained
to identify spiders and very few
hospitals have spider experts on
there staff. In general it is not
possible to identify the type of
spider responsible for a bite by
observing the symptoms, contrary to
media reports.
Unless a spider was seen biting some
one, it can not be assumed it was a
spider that has coursed any
symptoms. Assuming the injury and
side effects are from a spider bite
can lead to misdiagnosis and
mistreatment, leading to potentially
life threatening consequences.
Spiders are the most common source
for false reports. A larger number
of spider bites including ones from
dangerous species, can be painless
and go unnoticed if un observed.
Symptoms from more dangerous species
bites can manifest hours later, and
by this time the spider will be long
gone and identification impossible.
Treating a minor bite should be the
same for any puncture wound, the
wound should be first, encouraged to
bleed to wash out any foreign
debris. A topical antiseptic should
be applied on the chance the bite
may have introduced a virus or
microbe beneath the skin level, were
the antiseptic can penetrate.
Observing the bite for a couple of
days after is important so that if
there are any signs of infection,
medical help can be sought after.
First aid may involve applying an
icepack to control inflammation,
applying aloe Vera is a good idea to
help soothe the pain, if symptoms
are sever, immediate medical care
should be sought after.
If bitten by a widow spider,
Australian venomous funnel web
spider or a Brazilian wandering
spider, immediate medical attention
should be sought after. In a few
cases, bite from these spiders can
develop into medical emergency's.
Also, medical attention should be
sought if there is a severe allergic
reaction.
Necrotic bite
treatment
Unfortunately there is no
established treatment for necrosis.
Routine treatments should include
immobilization and elevation of the
affected limb along with, applying
ice, local wound care and tetanus
prophylaxis. Other therapies have
been tried with varying degrees of
success such as hyperbaric oxygen,
antihistamines, dapsone, dextran,
antibiotics, vasodilators,
glucocorticoids, heparin, electric
shock, nitroglycerin, curettage,
surgical excision and antivenom. All
the therapies have not been subject
to controlled, randomized trials to
conclusively show benefits. Bites
are self limited in almost every
case and will heal without
medical help. Spider
Exterminators - Pest Control
Generally speaking, people do not
like spiders and most
of all, do not want them in their
homes! There are many forms of pest
control and ways to exterminate
spiders. There are
spider exterminators, services,
spider zappers, spider traps, spider
repeller, spider catchers, spider
traps for the removal and
extermination process. Advice is
available on subjects such as pest
controls, pest prevention, spider
catchers, spider exterminators and
how to kill spiders. Some
people would like to eliminate
spiders from there homes completely,
this can be very difficult as an
open window on a summers day will
allow spiders in, even opening your
front door when entering and leaving
will allow pesky spiders in. It is
very easy to get rid of spiders by
catching them yourself. Its best not
to kill spiders as they are very
important in controlling the level
of other insects that are pests. |
