everything you ever wanted to know about bee stings - but ... · pdf fileeverything you ever...

Everything you ever wanted to know about bee stings - but were too afraid

to ask

Jean-Pierre Scheerlinck

Ouch, what’s next?

Symptoms of allergic reaction

• Mild symptoms• Swelling• Redness• Pain

• Moderate symptoms• Hives (itchy pustules at other

locations)

• Severe symptoms• Difficulties breathing• Shock• Death

Hives

wikimedia.org

Allergic reaction of the skin

• Symptoms not at the site of sting

• Swelling > edema• Redness > vasodilation• Itchy > palm of the hand

• Can last days – weeks

wikimedia.org

The immune system was not designed for allergic

reactions Immune system is there to fight the bad

guys Viruses , parasites, bacteria, fungi and

cancer

We are not designed to fight bee stings!

Key requirement for immune system Discriminate pathogens (non self) vs self

Appropriate response to pathogens

Do it better the second time round

How do you destroy something much larger than you?

Mast cells Specialised “suicide bombers”

Loaded with “explosives”

Triggered when they receive the right signal

Release many potent molecules

These are the ones responsible for allergic reactions to bee stings

Kuby 2003

How the immune system deals with large parasite

Introducing the cast:“Attack by the suicide

bomber” T cells – The masterminds

Tell B cells what to make

B cells – The bomb makers The make antibodies

Antibodies are specific for foreign material (including bee venom)

Mast cells – The suicide bombers Loaded with toxic products

Covered with antibodies made by B cells

Explode when trigger is present

Adapted from slideworld.org and Kuby 2007

The masterminds

The bomb makers

The suicide bombers

T cells – The masterminds

Antigen

MHC II

Dendritic cell

T helper cell

TCR

CD4

CD4 CD4

Th1 Th2 IFN- IL-4

--

Different types of T cells Hold the balance of power

Affects what the B cells make

Who decides what T cells make? Genetic predisposition Amount of venom present Frequency of exposure

B cells make antibodies

Kuby 2007

B cells make antibodies There are different

antibodies for different functions

IgE is the main trigger

Antibodies compete for binding to toxins

Who decides whether IgE is made? T cells – the

masterminds

Janeway 2001

Mast Cell – The suicide bomber

Molecules Released by Activated Mast Cells

Janeway 2001

Action of Mast Cells at Different Sites

Janeway 2001

Histamine

Mellitin

Phospholipase A

Histamine

Why you need several exposures

Bee venom

bee venom IgE

Why is not everyone affected in same way?

Everyone has mast cells

• Mast cell density does not vary much in time and between people

Presence of IgE varies a lot

• Need exposure to bee venom at least 2 x• Different people have different susceptibilities

Presence of IgE varies a lot

• Repeated exposure leads to formation of other classes of antibodies

• This protects the beekeeper who is stung repetitively• This is the basis for desensitization

• Unusual contact with of bee venom can lead to IgE formation • Beekeepers family exposed through clothing can develop IgE

response

Multiple beestings are dangerous even in non-allergic

people Bee venom composition (63 components)

Mellitin (50% of dry weight) destroys blood cells lowers blood pressure induces release of histamine main cause of pain induces release of cortisol (natural steroid)

Phospholipase A (12% of dry weight) enzyme that destroys cells

Histamine (0.9% of dry weight) same as released by the mast cells causes itchy and pain

ivegothives.com

newsimg.bbc.co.uk

Evolution of reaction to sting

i1.cpcache.com

Beginner beekeeper

• IgG response likely to be low > no neutralisation• Bee sting hurts more than just the sting• Wears full protective equipment

Experienced beekeeper

• Could have developed strong IgG response > neutralisation of bee venom

• Bee sting is same as needle prick without effect of toxin

• Often does not wear gloves

High level of IgG protects against allergy

Beginner: Low levels of IgG

Degranulation

Experienced: High levels of IgG

No degranulation

Responses in experienced beekeeper

After many beestings over prolonged period of time

• Immune response develops more IgE > anaphylaxis• Immune response develops more IgG > non-allergic > most likely

outcome

Implications of presence of high level of IgG

• Neutralises bee venom toxins soon after sting• Very little local reaction > working without gloves!• Even if stung many time, beekeeper is unaffected• Regular beestings keeps IgG antibody levels high

Beekeeper retires

• Very few beestings > IgG levels drop• No neutralisation of bee venom• Possibility of IgE response developing > Allergic reaction

PeerJ 2:e338;DOI 10.7717/peerj.338

Removing the stinger without injecting the venom

prbka.co.uk

Anaphylactic shock - treatment

askdoctork.com

What to do? Prevent more stinging Remove stinger to minimise

amount of venom Apply ice to reduce swelling (20

min) Anti-sting medication (“Stingo”) Anti-histamine If anaphylactic Epi-pen >

emergency

Infrequent < 5% of population

Symptoms > Immediate type hypersensitivity Neurological Respiration Heart

If stung 10X or more on face > emergency even if not allergic(unless regular reactionless stings > very high levels of IgG)

Treatment and prevention of allergic responses

Treatment Anti-histamine

Blocks histamine effect on smooth muscle and blood vessels

Epi-pen (Adrenaline/epinephrine ) Increase blood pressure and cardiac output Inhibits mast cell degranulation

Prevention Desensitisation (repeated injection of small doses of venom)

Danger: Do not try this on your own !

IgG up and IgE down > Move from “beginner” to “experienced” beekeeper

Induces tolerance (?)

The end

montybees.org.uk

depi.vic.gov.au

Bee pest and disease training opportunity

Are you: Interested in learning about bee pest and disease?

Committed to completing an online course?

A good communicator willing to share your knowledge?

Apicultural Industry Advisory Committee will fund: Online course from TOCAL college in NSW: “Pests and diseases of honey bees”

Time commitment: 25h

Value: ~$415 reimbursement of online course fee upon: Successful completion of all course requirements

Delivery of 3 communications to other beekeepers including one formal presentation

Additional information: Club needs to nominate 1 person

Managed by B Cooper and J-P Scheerlinck through VAA Melbourne section

Expect more information via club officials