ENVENOMATION Flashcards
(159 cards)
1
Q
Snakebite envonoming is a …… disease
A
Neglected tropical disease
2
Q
Snakebite envenomation is a ————- medical emergency
A
Life threatening
3
Q
Which regions of the world experience snakebites the most
A
Tropical and Subtropical
4
Q
Vast majority of deaths due to snakebites occur in ………
A
Sub Saharan Africa and south east Asia
5
Q
Country with the highest snakebite mortality
A
India
6
Q
Why do children suffer more severe effects from snakebites than adults
A
Due to their smaller body mass
7
Q
Why do children suffer more severe effects from snakebites than adults
A
Due to their smaller body mass
8
Q
Epidemiology of snakebites
A
Males are bitten more than females
Agricultural workers and children are most affected
Elderly are at a greater risk of mortality
9
Q
Number of snake species considered venomous
A
600 out of the 3500 species
10
Q
Classification of snakes to their suborder
A
Class Reptilian
Order Squamata
Suborder Serpentes
11
Q
Venomous snakes are in ——- families
A
Five
12
Q
Largest and second largest venomous snake families
A
Viperidae and Elapidae
13
Q
Five families of venomous snakes
A
Colubridae
Atractaspididae
Elapidae
Viperdae- Viperinae
Crotalidae
14
Q
Examples of Colubridae
A
Boomslang
Bird snake
15
Q
Examples of atractaspididae
A
Burrowing asps
16
Q
Examples of elapidae
A
Cobras, kraits, coral snakes , mambas, death adder, tiger snake, most Australian snakes
17
Q
Examples of Hydrophiidae
A
Hydrophiidae are in the family Elapidae
Examples are Sea snakes and Sea kraits
18
Q
Examples of Viperinae ( True/Pitless vipers)
A
Vipers
Adders
Asps
19
Q
Examples of Crotalidae or pit vipers
A
Rattlesnakes
Bushmaster
Copperhead
20
Q
Types of snake fangs
A
fangless (aglyphous),
rear-fanged (opisthoglyphous),
front fanged and fixed maxilla (proteroglyphous),
Front fanged and mobile maxilla (solenoglyphous)
21
Q
Anatomical classifications of snakes based on fangs
A
Colubridae- Opisthoglyphous
Elapidae- Proteroglyphous
Viperidae- Solenoglyphous
Atractaspididae- All types of fangs
22
Q
Which family of snakes contain species capable of spraying their venom
A
Elapidae
23
Q
Two examples of cobras
A
Common cobra- Naja naja
King cobra- Ophiophagus hannah
24
Q
Examples of kraits
A
Common krait: Bangarus caeruleus
Banded krait: Bangarus fasciatus
25
Most venomous snake based on the murine LD50
Western or Inland taipan from the family Elapidae
26
Examples of true cobras (Najas)
Common cobra - Naja naja
Black necked spitting cobra- Naja nigricollis
Egyptian cobra- Naja heje
27
Key identification feature of the common cobra
Well marked hood
Monocellate or Binocellate spectacle mark
28
Key identification feature of the common krait
Paired white bands
29
Two examples of mambas
Green mamba - Dendroaspis angusticeps
Black mamba - Dendroaspis polyplepis
30
Features of pit vipers
Pit between eye and nostril
Flat triangular shaped head
Vertical pupils
Curved fangs
31
Examples of true or pitless vipers
Russell’s Viper - Daboia russelii
African saw scaled viper or carpet viper - Echis ocellatus
African puff adder - Bitis arietans
32
Examples of pit vipers /Crotalidae
Rattlesnakes
Cottonmouth or Water moccasin
Copperhead
Bushmaster
33
Key identification feature of the Russell’s viper
Black edged almond or chain shaped marks on the back
34
Examples of rattlesnakes
Sidewinder
Diamondback
35
Key venomous snakes in Ghana
West African saw scaled / carpet viper - Echis ocellatus
Puff adders- Bitis arietans
Black necked spitting cobra- Naja nigricolis
Senegales cobra - Naja senegalensis
Western green mamba -Dendroaspis viridis
36
Identification features of venous and nonvenomous snakes
Venomous
Triangular head or arrowhead head
Elliptical pupil
Fangs
Single row of subcaudal anal plates
Harmless
Oval head or egg shaped head
Round pupil
Double row of subcaudal anal plates
37
Difference between poison and venom
Venom must be injected into the body by mechanical means however poisons must be ingested inhaled or absorbed
Venoms are generally nontoxic if swallowed
38
Functions of snake venom
Prey immobilization
Assist in or start the digestive process
Self defense
39
Causes of difference in snake venom composition
Geographical distribution
Seasons of the year
Age or ontogenic variation
40
Two main classes of snake venoms
Proteins and Peptides
Non enzyme and Enzymes
Non proteinaceous components
41
Effect of 3FTX neurotoxin
Selective inhibition of nAchR
42
Effect of 3FTX cardiotoxin
Membrane perturbation by electrostatic and hydrophobic interactions with the cell membranes
43
Effect of Disintegrin peptide components
Inhibit platelet aggregation
.
44
Effect of kurnitz type inhibitors
Inhibition of serine proteases (e.g., plasmin, kallikrein, trypsin).
Interferes with the blood coagulation cascade and fibrinolysis
45
Effect of natriuretic peptide components
Vasodilation
Hypotension
Increase NO production
Cardiprotective action
46
Effect of BPP( Bradykinin potentiating peptides) protein components
Inhibit the function of ACE and raise the level of bradykinin.
Hypotension
47
Effects of Crotamine peptide components
Interacts electrostatically with DNA.
Penetrates membranes via heparan sulphate proteoglycans binding.
48
Effects of safarotoxin
Vasoconstriction via endothelin receptors
49
Effect of waglerin
nAChR antagonist.
50
Effect of CRISPs
Inhibit high K induced contraction
51
Effects of PLA2
Hypotension
Vasorelaxation
Antiatgetogenic activity
52
Effects of 3FTXs
Hopotension
Vasorelaxation
Inhibition of platelet aggregation
53
Effect of fibrinolytic enzymes
Inhibit platelet aggregation
Fibrinolytic activity
54
Which snakes produce neurotoxic venoms
Elapidae- cobras, kraits, coral snake
Hydrophiidae
Small Bitis vipers
Russell’s viper
55
Which snakes produce cytotoxic venoms
Black necked spitting cobra
Bothrops asper
Saw scaled/ Carpet viper
56
Snakes that produce haemotoxic venoms
Viperidae, spitting cobra, certain Colubridae
57
Snakes that produce myotoxic venoms
Hydrophiidae
58
Snakes that can produce venoms with combined toxicities
Spitting cobra
Saw scaled or carpet viper
59
Signs of neurotoxic venoms
Descending muscular paralysis
60
Predominant neurotoxic toxins
PLA2
3FTX
61
Sign of cytotoxic venoms
Swelling at the bite site which can develop into blistering and bruising and hypovolaemic shock
62
Predominant cytotoxic toxins
Hydrolytic enzymes eg: Snake Venom Metalloproteinases (SVMPs)
PLA2s
Non enzymatic cytotoxic 3FTs
63
Signs of myotoxic envenoming
Negligible local swelling
Myalgia
Associated features of neurotoxic venoms and progressive descending paralysis
Rhabdonyolysis and renal failure
64
Examples of myotoxic toxins
Myotoxic single chain peptides (42-44amino acid residues)
Myotoxic PLA2s
65
Signs of haemotoxic venoms
Cardiovascular effects- Hypotension leading to shock
Haemostatic effects- local and systemic hemorrhage
66
What is VICC
Venom-induced consumption coagulopathy (VICC) is a disseminated intravascular coagulation(DIC)-likesyndrome, characterized by low or undetectable levels of fibrinogen, resulting in incoagulable blood
67
Examples of haemotoxic venoms
Snake venom serine proteases
Snake venom metalloproteinases
Bradykinin potentiating peptides
C-type lectins
PLA2
Disintegrins
Factor Va toxin
Factor Xa toxin
Kurnitz type serine protease inhibitors
68
Factors determining risk of the human envenomation by different snakes
Venom toxicity/potency
Size of snake
Effectives of the bite
Innate aggressiveness of snake
Likelihood of human contact
69
Clinical features of snake bites
Increasing Local pain at site
Local swelling that extends oroximall
Tender painful enlargement of regional lumpen nodes
70
Examples of snakes with painless bites
Kraits
Sea snakes
71
Local signs and symptoms at the site of a snake bite
Fung marks *
Local pain
Local bleeding *
Brushing
Lymphangitis *
Lymph node enlargement
Inflammation
Blistering *
Local infection
Abscess formation
Necrosis
72
Systemic signs of snake bites
Malaise
Nausea
Vomiting
Abdominal pain
Weakness
Drowsiness
Prostration
73
Cardiovascular signs of snake bites
Hypotension
Shock , Blurred vision , Syncope, Dizziness, Collapse
Pulmonary edema
Cardiac arrhythmias
Cardiac arrest
74
Bleeding and clotting disorders associated with snake bites
Bleeding from recent wounds and partly healed wounds
Spontaneous systemic bleeding
75
Signs of spontaneous systemic bleeding in snakebites
Bleeding from gums
Epixtasis
Haemoptysis
Haematemesis
Rectal bleeding
Meleana
Haematuria
Vaginal bleeding
Bleeding into skin and mucosal
Intracranial hemorrhage
Antepartum haemorrhage
76
Examples of skin bleeding
Purpura
Petechiae
Ecchymoses
77
Signs of neurological snake venoms
Drowsiness
Paraesthesiae
Abnormalities of taste and smell
Heavy eyelids
Progressive descending paralysis
78
Which venoms cause broken neck sign and respiratory or flaccid paralysis
Neurotoxic venoms
79
Signs of skeletal muscle breakdown in snake envenoming
Généralised pain
Stiffness and tenderness of muscles
Lock jaw or trismus
Myoglobinuria
Hyperkalemia
Cardiac arrest
80
Which snakes produce venoms that cause skeletal muscle breakdown
Sea snakes
Russell’s viper
81
Signs or renal failure in snake envenoming
Loi or lower back pain
Haematuria
Haemoglobinuria
Myoglobinuria
Oliguria/Anuria
Uraemia signs and symptoms
82
Examples of snakes that release venoms that cause renal failure
Viperidae
Sea snakes
83
Signs and symptoms of uraemia
Acidotic breathing
Hiccups
Nausea
Pleuritic chest pain
84
Four initial questions in assessing snake bites
Which part of body was bitten
When were you bitten
Where is the snake that but you or what did it look like
How are you feeling now
85
Parameters to be examined
Tooth marks
Local signs
Bleeding
Shock
Neurotoxicity or paralysis
86
Earliest signs of snake envenoming
Local swelling , enlargement and tenderness of regional lymph nodes
87
First site of spontaneous systemic bleeding in snake envenoming
Gums (Gingival sulci)
88
Snake responsible for most deaths in northern Ghana
Echis ocellatus
89
Earliest symptoms of neurotoxity or paralysis in snake envenoming
Blurred vision
Heaviness of the eyelids
Apparent drowsiness
Contracted frontalis muscle
90
Haematological investigations in snake envenoming
FBC
Neutrophil leukocytosis
Thrombocytopenia
20WBCT
PT as INT or activated Partial Thromboplastin Test (aPTT)
91
Which snakes cause thrombocytopenia
Vipers
Colubrids
92
How is 20WBCT performed
Leave 2-5 ml of blood in dried test tube
Failure to clot after 20 minutes implies incoagulable blood
93
Biochemistry investigations in snake envenoming
BUE and Creatinine - renal dysfunction and acid base imbalance
LFT- increased bile
Serum electrolytes : CK, AST - muscle damage
94
Other investigations
Urine examination
Arterial oxygen saturation
ECG
Chest radiography
95
Duration to death for snake bites
Hours for Elapidae bites
Days for Viper bites
96
Contraindicated potentially harmful treatments in snake envenoming
Torniquet
Wash, rub, massage, tamper with bite wound
Suction of bite site
Incision of bite site
Cryotherapy
Electric shock
Excision of bite site
Cauterization
Instillation of chemicals like KMnO4
97
Thé Do it RIGHT mnemonic of snake envenoming first aid
R- Reassure patient
I- Immobilize
GH- Get to Hospital
T - Tell
98
Early Treatment of local pain
Oral paracetamol
Opiates for sever pain
99
Why are NSAIDS avoided in snake envenoming
Avoid NSAIDS due to risk of gastric bleeding in pts with incoagulable blood
100
Early treatment of vomiting
Lay patient in recovery position( on left side), head down to avoid aspiration
IM Chlorpromazine 25-50mg in adults, 1mg/kg in children
OR
IM Prochlorperazine 12.5mg in adults
101
What drug is used for mild sedation in snake envenoming
Diazepam oral 5-10mg stat
102
Treatment of pain in snake envenoming
Paracetamol oral
Morphine IV/IM/SC
103
Dose for polyvalent anti-snake serum
50-100ml (5-10ampoules)
by IV drip in 0.9%N/S or 5%Dextrose over 2-4 hours
104
Treatment for hypovolaemic shock in snake envenoming
Crystalloids
Colloids
Blood
105
Treatments for defects of hémostasis in snake envenoming
Clotting factors
Fresh frozen plasma
Platelets
106
Treatments for respiratory distress in snake envenoming
Oxygen
Intubate
Ventilate
107
Indication for antivenin in snake envenoming
Presence of symptoms and signs of systemic or severe local manifestations of envenomation
108
Complications of antivenin use
Anaphylaxis
Pyrogenic reactions
Later immune complex disease ( Serum sickness)
109
Storage of liquid antivenin
Stored at 2-8 degrees Celsius and not frozen
110
Animals used in producing antivenins
Horses
Donkeys
Sheep
111
Which has a longer shelf life, lyophiliséd or liquid antivenin
Lyophilised has a longer shelf life but is more expensive
112
Types of antivenom
Monovalent or Monospecific
Polyvalent or Polyspecific
113
Disadvantages of polyvalent antivenin
Larger doses required
Higher risk of adverse reactions
Increased cost of treatment
114
Advantages of polyvalent antivenom
Neutralisons antibodies agains a wider pool of antigens
No need to identity snake that has bitten the patient
115
Disadvantage of monospecific antivenom
Limited cross efficacy, often restricted to snake genus
116
Why do children and adults require same dose of antivenom
Antivenom neutralizes a fixed amount of venom
117
Patients with increase risk of severe actions to antivenom
Atopic history ( severe asthma, hay fever etc)
History of reactions to equine antisera(anti-tetanus serum)
118
Pretreatment for diminishing reaction to antivenom
Subcutaneous adrenaline and IV antihistamine and hydrocortisone
119
Why are tests with diluted antivenom not predictive of anaphylaxis or late serum sickness reactions
Large majority of antivenom reactions are not IgE based Type 1 hypersensitivity reactions but rather due to direct complement activation by aggregates of IgG or its fragments
120
Antivenom is best given IV, why is IM not ideal
Absorption is very slow
121
How is antivenom given
IV injection at a rate of about 5ml/min
Or
Diluted in isotonic fluid and infused over 30-60min
122
Response to antivenom treatment on the various systemic and local effects of snake envenoming
Neurotoxic signs - change slowly after several hours
Cytotoxic - limit further damage but not reverse damage
Cardiovascular effects - respond within 10-20min
Spontaneous bleeding - stops within 15-30 min
Blood coagulability - restored within 6 hours
123
If blood is still incoagulable 6hours after the first dose of antivenom, what should be done
Repeat dose and so on every 6h until blood coaguability is restored
124
Which brand of antivenom is a solution
ASNA Antivenom C and
ASNA Antivenom D
125
Symptoms of early antivenom reactions
Cough
Tachycardia
Itching
Urticaria
Fever
Nausea
Vomiting
Headache
126
Symptoms of systemic anaphylaxis
Hypotension
Bronchospasm
Angioedema
127
Treatment of early antivenom reactions
Adrenaline 0.5-1ml for adults, 0.01mg/kg for children
Followed by IV H1 antagonist
128
Dose for IV H1 antagonists in treating early antivenom reaction
Chlorphenamine - 10mg for adults. 0.2mg/kg for children
Promethazine - 25mg IM in adults
129
Signs of pyrogenic reactions to snake antivenom
Chill
Cutaneous vasoconstriction
Gooseflesh and shivering
Myalgia
Headache
Tachycardia
Fever
Intense vasodilation and hypotension
Febrile convulsions in children
130
Treatment for pyrogenic reactions to snake antiserum
Reduce temperature by fanning, tepid spongin and antipyretics
IV adrenaline for severe cases with hypotension
131
Symptoms of late reactions ( serum sickness) to snake antivenom
Itching
Urticaria
Lymphadenopathy
Arthralgia
Periarticular swellings
Proteinuria
Neurological symptoms
132
Treatment of serum sickness
Antihistamine Chlorphenamine 2mg/6h adult 0.25mg/kg/day in divided doses for children: 5 days
Prednisolone for severe cases and failure of antihistamines within 24 hours
133
Timelines for the different reactions to snake antivenom
Early and anaphylactic reactions - 3-60min
Pyrogenic reactions - 1-2 hours
Late reactions or serum sickness- 5-24 hours, averagely 7 hours
134
Antibiotic prophylaxis in local envenoming
Amoxicillin/ Clavulanate
135
Treatment of coagulopathy if not reversed by ASV therapy
Fresh frozen plasma
Cryoprecipitate ( Fibrinogen, Factor VIII)
Fresh whole blood
Platelet concentrate
136
Treatment of bulbar paralysis and respiratory failure in snake envenoming
Tracheotomy
Endotracheal intubation
Mechanical ventilation
IV Neostigmine 50-100mcg/kg/4hours infusion
Glycopyrrolate 0.25mg before neostigmine in place of atropine
137
Which snakes cause snake venom ophthalmia
Spitting elapid species
138
Taxonomy of order Hymenoptera
Phylum Arthropoda
Class Insecta
Order Hymenoptera
139
The three families under Hymenoptera
Vespidae ( True Wasps)
Apidea (bees)
Formicidae(Wasps)
140
Subfamily and family of genus solenopsis (fire ants)
Subfamily - Myrmicinae
Family- Formicidae
141
Examples of insects in subfamily aspinae
Honeybees
Bumblebees
142
Genus of honeybees
Genus apis
143
Insects under subfamily Vespinae
Hornet
Yellowjackets
144
Which insects causes most all allergic reactions
Vespids
145
Difference between apids and vespids in relation to stinging
Female apids sting once
Vespids sting multiple times, both males and females
146
Composition of Vespids venoms
Proteins
PLA
Hyaluronidase
Acid Phosphatase
Antigen 5
Peptides
Mast cell degranulating peptide
Kinins
147
Components of Formicids venoms
Proteins
PLA
Hyaluronidase
Unidentified third protein
Alkaloids
Piperidiones
148
Components of Aphid venom
Proteins
PLA
Hyaluronidase
Acid Phosphatase
Peptides
Melittin
Apamin
Mast cell degranulating peptide
149
Effects of melittin
Pain
Destruction of tissues
Basophils and mast cell degranulation
150
Which insect mostly causes local infections from its stings
Yellow jacket
151
Management of airway in anaphylactic reactions due to Hymenoptera
High flow oxygen
152
Treatment of hypotension in anaphylactic reactions due to Hymenoptera
Lactated ringers
153
Treatment of severe shock in anaphylactic reactions due to Hymenoptera
SC epinephrine 0.01mg/kg (0.3mg in adults
IV epinephrine 0.1mg
154
Antihistamines used in anaphylactic reactions due to Hymenoptera
IV diphenhydramine 1mg/kg (50mg in adults )
IV cimetidine 300mg in adults
IV steroids (100-250’mg hydrocortisone or methyl prednisolone)
155
Treatment of wheezing in anaphylactic reactions due to Hymenoptera
Orciprenaline 0.3cc or
Salbutamol 2.5cc in 3cc NS
156
Management of hypotension despite IV fluids in anaphylactic reactions due to Hymenoptera
IV dopamine or Epinephrine drip
157
If sting site of insect is red and swollen but mainly pruritic
Treat with oral antihistamines
158
If sting site is red and swollen but mainly painful
Treat with oral antibiotic
159
If sting site is red and swollen and pruritic and painful
Treat with oral antibiotic and antihistamines
