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Clinic

 

Bitis arietans

Studies

Nigeria
Warrell et al. 1975: 10 B. arietans bites; identification: morphological (8/10) or immunological with ELISA (Greenwood et al. 1974) (2/10).
Classification:

  • Local envenoming 10/10
  1. Extent of the swelling (grade 1–6; scale of Warrell et al. 1974):
    Grade 1: 2/10
    Grade 2: 1/10
    Grade 3: 1/10
    Grade 5: 4/10
    Grade 6: 2/10 
  2. Intensity of the swelling (according to the method of Reid et al. 1963c): difference in circumference between the bitten extremity and the healthy extremity up to 28%.
  • Systemic envenoming 4/10
    Criteria: spontaneous bleeding with thrombopaenia, hypotension, bradycardia.


South Africa
Visser and Chapman 1978: 9 B. arietans bites that ended fatally.

Case reports

Visser and Chapman 1978: 2 cases (South Africa).
Pugh and Theakston 1987a: 3 cases (Nigeria; identification: immunological with ELISA).
Phillips et al. 1973
Theakston and Wyatt 1985
Seedat et al. 1974: 2 cases (South Africa).

Signs & symptoms

Autopharmacological effects

Vomiting 2/10 (Warrell et al. 1975).
Arterial hypotension 3/10 (Warrell et al. 1975). Arterial hypotension caused by increased vascular permeability and vasodilatation, among other factors (Osman and Gumaa 1974, Schaeffer et al. 1985).

All 9 fatal cases described by Visser and Chapman (1978) were in a state of hypovolaemic shock.

Local effects

Local pain 10/10 within 10 min after the bite (Warrell et al. 1975).
Local swelling 10/10 within 20 min after the bite, at the latest after 1–2 days, swelling disappeared after 5 days–3 weeks (Warrell et al. 1975).
Local blistering 5/10; necrosis 3/10, 17 h, 48 h and 7 days after the bite, respectively (Warrell et al. 1975).
Ecchymosis (on the bitten extremity) 2/10 (Warrell et al. 1975).
Thrombosis of the popliteal artery 1/10 (Warrell et al. 1975).

Haemostatic effects

Spontaneous systemic bleeding 3/10: gingival bleeding (1/3) 4 h after the bite, epistaxis (2/3) days after the bite (Warrell et al. 1975).

Cardiac effects

Hypotension, bradycardia: among other factors direct myocardial effect of the venom? (Warrell et al. 1975).

Renal effects

Acute kidney failure 1/10: among other factors direct nephrotoxic effect? (Warrell et al. 1975).

Acute kidney failure 2/2 (Seedat et al. 1974).

Morbidity

Extensive tissue defects and chronic ulceration of neglected wounds (necrosis) (Warrell et al. 1975).

Case fatality rate

2/10 (Warrell et al. 1975). Principal causes of death acute and prolonged hypotensive state without significant blood loss, blood loss as well as complications of necroses (Warrell et al. 1975).

All 9 fatal cases described by Visser and Chapman (1978) were in a state of hypovolaemic shock.

Laboratory and physical investigations

1. Haemostasis
Type of haemostatic defect
Haemorrhagic activity (Mebs and Panholzer 1982); platelet-activating effect (→ thrombocytopaenia) (Phillips et al. 1973); coagulation-activating/fibrinolytic effects probably not very marked in humans (Warrell et al. 1975).


Haemostatic parameters


Overview haemostasis
 
A
+
 
                                     
 
H CT (FSP) Tc PT aPTT TT I FSP D II V VIII X XIII PC ATIII PI tPA α2AP
   
B
 
 
C
       
B
                     
 

Essential

bed-side

tests

Tests for full clinical assessment Tests for research purposes
H haemorhagic effects
+ definite evidence in
human envenoming
CT full blood clotting test
(FSP)  FSP rapid test
Tc platlets
PT prothrombin time
aPTT partial thromboplastin time
TT thrombin time
I fibrinogen
FSP  fibrinogen split products
D D-dimer
II, V, VII, X, XIII
  clotting factors
PC protein C
ATIII antithrombin III
PI plasminogen
tPA tissue plasmin activator
α2AP α2-antiplasmin
 
In this overview, the deviations from normal
are recorded for those haemostasis para-
meters only, for which good evidence is
documented in the literature.

 

A

Haemorrhagic activity: the venom contains a haemorrhagic component that contributes to the risk of bleeding (Warrell et al. 1975, Mebs and Panholzer 1982).

B

CT: normal clotting time 9/9. Investigations in individual patients revealed that clotting factors were not decreased and FSP were not raised (Warrell et al. 1975).

C

Platelets: thrombocytopaenia 3/10: 27,000, 68,000, 100,000/µl 2–4 h after the bite (Warrell et al. 1975).


2. Leucocytes
Neutrophilic leucocytosis 5/10 (Warrell et al. 1975).


3. Haemoglobin
Anaemia 3/10 (possible causes: microangiopathic haemolysis, epistaxis, blood loss in the bitten extremity) (Warrell et al. 1975).


4. ELISA

(Greenwood et al. 1974)

5. Renal biopsy
Proliferative glomerulonephritis 2/2 (Seedat et al. 1974).

Treatment (symptomatic)

  1. Acute and prolonged hypotensive state without blood loss: intravenous fluids (Warrell et al. 1975).
  2. Blood loss affecting the circulation: blood transfusion (Warrell et al. 1975).
  3. Pain: codeine phosphate (Warrell et al. 1975).

Treatment (specific)

Antivenoms
Behringwerke (Bitis, Echis, Naja);
Fitz-Simons (Bitis, Hemachatus, Naja);
SAIMR (Bitis, Dendroaspis, Hemachatus).

Studies
No controlled studies available.


Indications for administration of venom
Signs of systemic envenoming: spontaneous bleeding, thrombocytopaenia, hypotension, bradycardia (Warrell et al. 1975).

Signs of local envenoming: local swelling extending over more than half of an extremity (Warrell et al. 1975).


Dose
80 ml or more of a specific antivenom (Warrell et al. 1975).

Efficacy

  1. With regard to the development of necroses: 4 patients with extensive swelling (whole extremity) and blistering, who received antivenom early on, did not develop necroses (Warrell et al. 1975).
  2. With regard to symptoms of shock: antivenom was effective against hypotension and bradycardia if the intravascular volume was restored at the same time (Warrell et al. 1975).