1. Dr Lynne Hepplestone BVSc
The pathophysiology of Honey Bee sting envenomation - and the effect on the body
Dr Lynne Hepplestone BVSc

2. (Journal Allergy Clin Immunol 2017;140:335-48.)
The pathophysiology of anaphylaxis Laurent L. Reber, PhD, Joseph D. Hernandez, MD, PhD, and Stephen J. Galli, MDc (Paris, France, and Stanford,California).
Abstract: Anaphylaxis is a severe systemic hypersensitivity reaction that is rapid in onset; characterized by life-threatening airway,breathing, and/or circulatory problems; and usually associated with skin and mucosal changes. Because it can be triggered in some persons by minute amounts of antigen (eg, certain foods or single insect stings), anaphylaxis can be considered the most aberrant example of an imbalance between the cost and benefit of an immune response. This review will describe current understanding of the immunopathogenesis and pathophysiology of anaphylaxis, focusing on the roles of IgE and IgG antibodies,immune effector cells, and mediators thought to contribute to examples of the disorder. Evidence from studies of anaphylaxis in human subjects will be discussed, as well as insights gained from analyses of animal models, including mice genetically deficient in the antibodies, antibody receptors, effector cells, or mediators implicated in anaphylaxis and mice that have been ‘‘humanized’’ for some of these elements. We also review possible host factors that might influence the occurrence or severity of anaphylaxis. Finally, we will speculate about anaphylaxis from an evolutionary perspective and argue that, in the context of severe envenomation by arthropods or reptiles, anaphylaxis might even provide a survival advantage.
(Journal Allergy Clin Immunol 2017;140: )

3. Case Report Bee Sting Envenomation Sudhansu Sekhar Sethi, Manoj Kumar Jena
Abstract: Among the invertebrates, insects, particularly hymenoptera, most commonly cause anaphylaxis. In stinging bees, wasps and ants, the ovipositor of female has been modified into a stinger. Honey bees leave behind their barbed stinger in the victim’s body and eventually die by evisceration. Bee sting in most of the situations is potentially serious, the severity and duration of reaction varies from one person to another depending on location and number of bee stings received. The spectrum of bee sting disease ranges from local reaction to death. Stings from bees usually cause a transient local reaction which may last for several days and generally resolves without treatment. Occasionally death may occur mostly due to anaphylactic shock. Non anaphylactic causes of death are mainly due to multi organ failure. Honey bee sting is responsible for large number of casualty in tropical and subtropical countries
(J Indian Acad Forensic Med. April-June 2015, Vol. 37, No. 2)

4. Scientific classification of the East African lowland Honey Bee (Linnaeus)
Kingdom Animalia
Phylum Arthropoda
Class Insecta
Family Apidae
Order Hymenoptra
Genus Apis
Species A.mellifera
Subspecies A.mellifera scutellata, A.mellifera capensis
RSA has Only One specie of Honey Bee (A. mellifera) which has 2 subspecies
They have ** the same venom **
The variations in risks when stung lie with the host-that’s-stung, not with the bee nor its’ venom

5. Our African Honey Bee?
The East African lowland honey bee sting is no more venomous than a single European bee sting,
though East African lowland honey bees respond more quickly when disturbed than do European honey bees.
They send out three to four times as many workers in response to a threat.
They will also pursue an intruder for a greater distance from the hive.

7. All the components Bee sting – the antigen (venom)
(antigenic stimulation)
Antibodies (IgE)
Effector cells (Mast cells, Basophils, Platelets)
Mediators (Histamines H1, H2)
(Inflammatory mediators)

8. Type 1 hypersensitivity reaction (Gell and Coombs system)
Antigen-bound IgE
Attaches to a (Fc) receptor on a Mast cell
The mast cell degranulates
Downstream signaling of cellular responses
Cascade of physiological changes
= reaction to a bee sting

9. Type 1 hypersensitivity reactions (Gell and Coombs)
Examples:
Honey bee stings
Venomous Snake bite
Vaccine reactions
Food sensitivities (eg. Nut allergy)

10. What is an antigen?
An external stimuli introduced to the body, evoking an immune response by the body
Honey Bee venom

11. What is antigenic stimulation?
The body’s physiological response to the antigen
How the body changes in response to being stung
Antigenic stimulation causes a cascade effect on cells

12. The Antigen – a bee sting

13. What happens to the bee?
The honey bee’s barbed sting cannot be withdrawn once it has penetrated the skin.
The bee’s only means of escape is to tear away part of its abdomen leaving behind the sting with its venom sac attached.
The muscles of the sting apparatus continue to pulsate after the bee has flown away, driving the sting deeper into the skin and injecting more venom.

14. Reaction to sting depends on
The amount of venom injected = toxic load, lethal dose (LD50)
State of (un)health of the victims’ immune system
Absence and presence of underlying sensitivity, diseases
Site of sting

15. Major Constituents of Bee Venom and their activities
Peptides:
Mellitin (haemolysis, cytolysis)
Apamin (neurotoxic, blocks cellular potassium channels)
MCD peptides (=mast cell degranulation) releases histamines and causes allergic reactions

16. Major Constituents of Bee Venom and their activities
Enzymes:
Phospholipase A (blocks cell membrane function, inhibits blood clotting, drops blood pressure)
Hyaluronidase (faciitates the spread of the inflammation)
Acid phosphatase (contributes to the allergic reaction)
Protease (causes tissue necrosis, cellular death)

17. Major Constituents of Bee Venom and their activities
Amines:
Histamine (allergic hypersensitivity and inflammation)
Dopamine (affects blood pressure )
Norepinephrine (affects blood pressure and heart function)

18. What happens to the body when stung by a bee?

19. The body’s response
When stung by a bee, the body engages in a sequence of
DOWNSTREAM SIGNALING EVENTS
with a
CASCADE OF EFFECTS
A sequence of cellular responses to antigenic stimulation

22. Outcomes affected by.. Genetic diversity Immune status
Underlying, pre-existing allergies pre-dispose to a more-serious response to bee-stings

23. Components

24. Antibodies - IgE IgA IgE IgG IgM
IgE the immunoglobulin associated with bee sting reactions
Much higher IgE levels are found / present
** in patients with allergic diseases **
The anti-IgE antibody “omalizumab” can decrease the risks of anaphylaxis

25. Effector cells Mast cells
Mast cells are viewed as key players in IgE-dependent allergies and anaphylaxis
Increased tryptase levels have been detected during acute anaphylaxis in humans
There is a high occurrence of anaphylaxis in patients with high numbers of Mast cells in the body

26. Inflammatory mediators
Histamines
4 known histamine receptors
H1 ( & some H2) in anaphylactic bee stings
Understand the use of anti-histamines (cream, tablets) in mild cases

27. Inflammatory mediators
Some mediators contribute to late consequences of anaphylactic reactions
Delayed reactions (many hours later)

28. Different expressions
There can be
MILD,
MODERATE, or
SEVERE body reactions, that can be
IMMEDIATE,
DELAYED, or
Bi-PHASIC

29. Mild to Moderate Urticaria Red, itchy Swelling, puffiness Spreads…
Eyelids swell closed…
Runny nose
Nauseous

30. Severe reactions Can be from a single sting,
Certainly with Mass envenomation
Anaphylaxis ( = hypersensitivity allergic reaction)
Adrenaline (EpiPen) is the only known effective control of acute hypersensitivity reaction

31. Severe reactions
Mass envenomation occurs with greater than 500 honey bee stings.
This is not an allergic response, it is an anaphylactic response related to a large amount of venom received by the victim.
The dose of sting bee that was calculated to kill (LD50) is
*19 stings per kilogram of body weight*

32. Ring and Messmer grading scale for anaphylactic reactions

33. Downstream signaling and the consequent cascade of effects

34. Bi-phasic & Delayed reactions
A minority of patients exhibit biphasic allergic reactions,
in which signs and symptoms of anaphylaxis recur hours after the early phase of the reaction has waned,
and in some patients late-phase reactions occur without initial hypotension or airway obstruction.

35. Delayed reactions “In addition to mast cells and basophils,
macrophages, neutrophils, and perhaps other leukocytes and platelets, also might produce a diverse array of inflammatory mediators during anaphylaxis,
and have the potential to contribute to reactions that might be difficult to treat, protracted in nature,
or biphasic.”

39. Risks? Frequent exposure
Elevated risk of anaphylaxis (underlying allergies, medications, diseases)
Prior sting reactions

40. Risks? Frequent exposure: Beekeepers, their families, and neighbours
Foresters, gardeners, emergency personnel, farmers, construction workers, labourers
Outdoor activity

41. Risks? Elevated risk of anaphylaxis:
Age (over 40), asthmatic, heart disease
Physical, mental, emotional Stress (lowers Ig’s)
Chronic medications (beta-blockers incl. eye- drops, ACE-inhibitors, possibly some NSAID pain meds)
Skin or Systemic Mast Cell growths (MCT’s)

42. Risks? Stress lowers the body’s immune system,
which then impedes the body’s ability to respond appropriately to antigenic stimulation
Eg. stressed then getting ‘flu (=susceptible)
Scientists know that mental, emotional, physical health develops the corresponding healthy immune system
Proven when measuring Immunoglobulin levels with blood tests

43. Risks? Site of the sting (where on the body)
Number of stings (how many)
Prior history of (multiple) incidences of being stung
And prior sting reactions, even if not severe, have been found to be an independent risk factor for later, severe, anaphylaxis

44. What to do?
Work in pairs / have an assistant / let someone know you are working with bees
Be prepared!
Have a plan!
Multiple stings? Seek medical help
Firstline –EPINEPHRINE (EpiPen)
The rest is small stuff, supportive, non-emergency

45. What to do? Dress safely and protectively. Suit up properly.
Preparation

46. Can anaphylaxis be beneficial?
“Given that snake (or arthropod) envenomation in the field can result in systemic distribution of the venom, one could argue that systemic IgE-dependent mast cell activation in this setting could both produce the clinical picture of anaphylaxis and also result in the systemic release of mediators (ie. mast cell proteases) that can degrade toxic components of the venom.
In such settings anaphylaxis could be beneficial if it prevents death by envenomation and the unfortunate subject also survives the anaphylaxis.”

47. Bee venom therapy?
“Although we do not know whether human IgE also can enhance resistance to venoms
(and we imagine that we would have some trouble enlisting volunteers for such a study),
it is tempting to speculate that anaphylaxis induced by small amounts of venom (eg, a single or wasp bee sting) represents only the most extreme and maladaptive end of a spectrum of acquired IgE-mediated immune responses to venom that includes, at the other end of the spectrum, appropriately regulated immune responses that can enhance resistance to such venoms.”

48. Ring and Messmer grading scale for anaphylactic reactions

49. Gr 1 Skin reactions only Itching Flushing, redness
Urticaria (lumps and bumps!)
Angioedema (swelling!)

50. Gr 2 Same as Gr 1… plus Abdomen – Nausea and cramps
Respiratory – Rhinorrhea, hoarseness
Respiratory cont. – Dyspnoea (difficulty breathing)
Cardiovascular - Tachycardia(rise ≥20/min)
Hypotension (≥20 mmHg drop in SBP)
Arrhythmia

51. Gr 3 Including Gr 1 and Gr 2…plus Abdominally – Vomiting, defecation
Respiratory – Laryngeal oedema
Respiratory - Bronchospasm
Cardiovasular – Cyanosis
Clinical shock

52. Gr 4
Respiratory arrest
Circulatory arrest
Cardiovascular arrest

53. What happens to dogs? (Urban scenario)
Firstly, keep in mind that They Cannot Escape from their walled-in, fenced, gated, enviroment
Single stings are seldom problematic
Most often on the lips from bees on a plant (usually lavendar bushes!)
Urticaria, swollen faces
The problem is Multiple stings from swarming bees = lethal dose / high toxic load

54. What happens to dogs? (Urban scenario)
Either swarms fly through overhead, or bees are agitated from disturbances
Dogs hyperexcitable, noisy, distressed, terrified, and cannot escape a confined space
intensified in heat, smells / scent
Bees find their scent and behaviour threatening
Critical, Life-threatening, Emergency situation requiring urgent veterinary intervention
intense cascade of cellular changes
high toxic/venom load on a smaller body mass / surface area

55. Thank you
the end of the beginning of learning More
Hamba kahle

61. Predictors of severe systemic anaphylactic reactions in patients with Hymenoptera venom allergy: importance of baseline serum tryptase-a study of the European Academy of Allergology and Clinical Immunology Interest Group on Insect Venom Hypersensitivity.
Ruëff F, Przybilla B, Biló MB, Müller U, Scheipl F, Aberer W, Birnbaum J, Bodzenta-Lukaszyk A, Bonifazi F, Bucher C, Campi P, Darsow U, Egger C, Haeberli G, Hawranek T, Körner M, Kucharewicz I, Küchenhoff H, Lang R, Quercia O, Reider N, Severino M, Sticherling M, Sturm GJ, Wüthrich B.
J Allergy Clin Immunol Nov;124(5):

62. DISSEMINATED INTRAVASCULAR COAGULATION (DIC): A coagulopathy
that occurs as a secondary complication to many different
disorders. Key features are microthrombi leading to tissue hypoxia
and infarction, as well as hemorrhages caused by depletion of
coagulation factors and platelets and activation of fibrinolysis. Trauma,
sepsis, and malignancy are common triggers.

63. Key words Anaphylaxis, epinephrine Antigens, antibodies, IgE
Effector cells, mast cells, basophils,
Mediators, histamine, cysteinyl leukotrienes,
food allergy, allergies
platelet activating factor,
urticaria

64. death showed that 70% were caused by airway obstruction followed by Anaphylactic shock as most important cause of death. Mass envenomation occurs with greater than 500 honey bee stings. This is not an allergic response but is related to large amount of venom received by the victim. The dose of sting bee that was calculated to kill half of the victim (LD50) is 19 stings per kilogram of body weight. [9] The spectrum of bee sting disease ranges from local reaction to death. [4] The symptoms of most stings are: 1. Normal reaction: e.g. redness, flare, whale; 2. Local reaction: e.g. swelling; superimposed Infection e.g. cellulites’ 3. Toxin reaction: e.g. Venom injection (no sensitivity); 4. Generalized allergic reaction: e.g. sensitivity; 5. Delayed reactions: 1-2 weeks after sting; 6. Psychological reaction: e.g. anxiety present; fatal reaction. [6]

65. . Pathophysiologic changes in anaphylaxis and mediators that have been implicated in these processes
First-line treatment of anaphylaxis consists of rapid administration of epinephrine.
Although there is evidence that the mediators shown in the figure, particularly histamine and CysLTs, contribute to some of the various signs and symptoms of anaphylaxis and antihistamines are routinely administered to patients with anaphylaxis, pharmacologic targeting of such mediators represents second-line treatment and should not be considered an alternative to epinephrine.
Red indicates strong evidence for the importance of that mediator in human subjects in the development of some of the signs and symptoms listed in the adjacent box.

66. Major Constituents of Honey Bee Venom
Peptides –
Melittin Hemolytic and Cytolytic activity
Apamin Neurotoxic activity, block potassium channel
MCD peptides (mast cell degranulation) Include release of histamine and allergic reaction
Enzymes –
Phospholipase A - Block biological function of membrane, inhibit blood coagulation, decrease blood pressure
Hyaluronidase - Cause spread of inflammation
Acid phosphatase - Allergic reaction
Protease - Tissue necrosis
Amines - Histamine Allergic hypersensitivity and inflammation
Dopamine Increase pulse rate
Norepinephrine Increase pulse rate Most of the death

67. Antibodies - IgE
“Although mice can exhibit both IgE- and IgG-dependent anaphylaxis, the existence of IgG-mediated anaphylaxis in human subjects has not been conclusively demonstrated.”

68. Effector cells of anaphylaxis
“Mast cells ordinarily express large numbers of the high-affinity IgE receptor FcεRI. During IgE-dependant immune responses, the antigen-dependant cross-linking of antigen-specific IgE bound to FcεRI induces aggregation of FcεRI, promoting the activation of DOWNSTREAM SIGNALING EVENTS that lead to secretion of several biologically active products thought to be implicated in allergic reactions, such as histamine and various cyteinyl leukotrienes (CysLTs)
The molecular mechanisms of such IgE dependent stimulation of mast cells have been extensively reviewed.There is compelling evidence of activation of mast cells during acute anaphylaxis.”

69. Risks? Risk of frequent exposure Elevated risk of severe anaphylaxis
Beekeepers and their families and neighbors
Other professions, including: persons who sell fruit or baked goods, foresters, gardeners, firefighters, farmers, construction - workers, truck drivers
Intense outdoor activity
Elevated risk of severe anaphylaxis
Prior episode(s) of severe sting anaphylaxis (grade III or IV, or grade II with significant airway obstruction)*1
Age (from about age 40 onward)
Cardiovascular disease
Asthma
Certain drugs including beta-blockers (eye drops as well), ACE inhibitors, perhaps non-steroidal anti-inflammatory drugs
Physical and mental stress
Basal serum tryptase concentration >11.4 μg/L (linked to mastocytosis)
Cutaneous or systemic mastocytosis
*1Prior sting reactions, even if not particularly severe, were found in a recent study (3) to be an independent risk factor for later, severe anaphylaxis