Insect Venom Allergy
What is it?
Insect venom
allergy is a harmful reaction to insect stings that occurs
in people who have an abnormally high sensitivity to
insect venom. It is an acquired trait, which is not
present at the first exposure to the venom, but
sensitization can occur after the first or subsequent
exposures. Animals classified as insects usually have
three main body segments (head, thorax and abdomen), six
legs and a pair of sensory antennae. Winged insect species
have two sets of wings, such as mosquitoes, bees, and
wasps. Other biting or stinging insects include fleas,
lice, and ants. Many other related animals that are
frequently mistaken for insects such as ticks, spiders and
mites also bite human beings. They can transmit infectious
diseases or cause poisoning but generally do not cause
allergic reactions. Allergic reactions to the venom of
some stinging insects, such as honey bee, yellow jacket,
hornet, wasp or fire ant can be life threatening.
Who gets it?
Anyone can
experience an allergic reaction to an insect bite or
sting. However, only a small number of people with insect
bite or sting allergies suffer fatal reactions.
What causes
it?
An allergic
reaction occurs when the immune system produces antibodies
and other disease fighting cells in response to an
allergen, in this case the insect venom. The antibodies
release chemicals that actually injure the surrounding
cells and cause the physical symptoms of an allergic
reaction. Certain antibodies release histamines, which
affect the skin, mucous membrane, mucous gland, and smooth
muscle cells. Life-threatening allergic reactions can
occur without any previous symptoms of allergy. In fact,
most people with insect bite or sting allergies do not
experience a severe reaction with their first bite.
Multiple bites or stings increase the risk of an allergic
reaction, but just one bite will cause serious symptoms
for someone who is severely allergic.
What insects
are usually involved?
Most serious
allergic reactions to insect venom are caused by stinging
insects, such as bees, yellow jackets, hornets, wasps and
imported fire ants. As natives of the tropics, fire ants
can live only in the warmer climate of the southern states
and cannot survive in Pennsylvania. They are extremely
aggressive and sting exposed parts of the skin when they
feel threatened. Bites or stings from other insects
usually do not cause allergic reaction.
What are the
symptoms?
Symptoms of
insect venom allergy often begin within 15 to 30 minutes
and arise distant from the site of sting. The first
symptom is often itchiness that can affect all or any part
of the skin, the eyes and the nose. As symptoms progress,
the patient begins to sneeze, cough and wheeze, feel
congested, and develop hives or swelling. These symptoms
may be warning signs of a dangerous condition called
anaphylaxis. Symptoms of anaphylaxis include sudden
anxiety and weakness, difficulty breathing, tightness in
the chest, lightheadedness and palpitation, and loss of
consciousness. Anaphylactic shock can occur within minutes
and result in death. Anaphylaxis is a medical emergency
that needs immediate medical treatment, and any delay may
reduce the chance of survival.
How is it
diagnosed?
Insect venom
allergy is suspected based on a constellation of
suggestive symptoms that follow an insect sting. The
diagnosis is confirmed by performing a skin test with the
venom of specific insects, such as honey bee, yellow
jacket, hornet, wasp or fire ant that may be the culprit
of the allergic reaction.
What is the
treatment?
If you have
been bitten or stung by an insect, carefully remove the
stinger, if it is left behind. Wash the bite/sting area
gently with soap and water. Apply ice to the site of
sting. People who are allergic to insect bites should, of
course, avoid situations in which they are likely to get
stung or bitten. Mild reactions, such as pain, itching,
and swelling, can be treated with an over-the counter
antihistamine, pain reliever and topical corticosteroid
creams. Anaphylactic shock is treated with an injection of
epinephrine, a hormone that stimulates the heart and
relaxes the airways. This may be combined with an
injection of an antihistamine, which counteracts the
histamine produced by the immune cells during an allergic
reaction. Those who are known to have severe insect venom
allergies should carry a self-injection kit, including
antihistamine tablets, for emergency treatment. However,
they should still seek emergency medical care after any
type of reaction to an insect bite or sting.
People who are
severely allergic to the venom of stinging insects, such
as bees, yellow jackets, hornets, wasps or fire ants may,
undergo a desensitization. First, skin testing is
performed by an allergy specialist to determine the type
of insect that responsible for the venom allergy. Then the
patient receives a series of injections of the venom from
the same insect(s). Starting dose is minute but
increasingly larger doses are given until the venom doses
several times larger than a single insect sting can be
tolerated. This type of program must be administered by an
allergy specialist, and it usually takes 20 weekly
injections to eliminate this abnormal and exaggerated
sensitivity. These are followed up with monthly booster
shots and continued for 3 to 5 years to consolidate the
cure.
Self-care tips
There are many
ways you can help prevent insect bites and stings. Don’t
use flowery colognes, soaps, or lotions, or wear brightly
colored clothing, which attract insects. Do not keep open
garbage or food that attract stinging insects when you are
outdoors. Avoid drinking sweet beverages especially from
open cans that have been left unattended and may harbor
insects. Wear light, protective clothing such as long
sleeves top and long pants whenever you will be outside
for longer periods of time. Wear work gloves when you are
gardening. Do not walk barefoot on the grass where insects
are difficult to detect and can be stepped on. If an
insect is near you, move away. Do not swat at the insect,
which may awaken its defensive instincts and trigger
aggressive behavior. Make sure any insect nests around
your home are removed and destroyed.
This information has been designed as a comprehensive and quick reference
guide written by our health care reviewers. The health information written
by our authors is intended to be a supplement to the care provided by your
physician. It is not intended nor implied to be a substitute for
professional medical advice.
|
