VAPAGuide - Biomedical database - Terrestrial snakes, Pit vipers - Crotalus spp. (without Crotalus durissus sspp.)

Clinic

Crotalus viridis/oreganus ssp.

Case reports

Dart and Gustafson 1991: 1 C. v. lutosus bite; identification: morphological.
Davidson 1988: 2 C. v. helleri (=C. oreganus helleri) bites; identification: morphological.

Effect of ontogenetic differences in venom composition on the symptoms of envenoming

The venom of juvenile snakes (6–12 months) appears to be significantly more toxic than that of adult snakes and can cause unexpectedly severe envenoming (Fiero et al. 1972, Glenn and Straight 1982, Minton 1967).

Signs & symptoms

Autopharmacological effects

C. viridis helleri (=C. oreganus helleri)

Nausea, vomiting, angioneurotic oedema, loss of consciousness with low, undetectable blood pressure within 25–30 min after the bite (increased capillary permeability with fluid sequestration in the extravascular space) (Davidson 1988).

Local effects

C. viridis helleri (=C. oreganus helleri)
Local pain and swelling with ecchymosis (Davidson 1988).

Haemostatic effects

C. viridis helleri (=C. oreganus helleri)
Gingival bleeding, haematuria (Davidson 1988).

Laboratory and physical investigations

1. Haemostasis
Type of haemostatic defect
C. viridis helleri (=C. oreganus helleri)

Fibrinogen-coagulating ("thrombin-like") activity (Denson et al. 1972).

Haemorrhagic activity (viriditoxin) (Fabiano and Tu 1981).

Venom activity that causes thrombopaenia (Davidson 1988, La Grange and Russell 1970).

Haemostatic parameters

Overview haemostasis

(FSP)

aPTT

FSP

VIII

XIII

ATIII

tPA

α₂AP

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.

aPTT, PT:
C. viridis helleri (=C. oreganus helleri)
Increased (Davidson 1988).

Fibrinogen:
C. viridis helleri (=C. oreganus helleri)
Decreased (Davidson 1988).

Platelets:
C. viridis helleri (=C. oreganus helleri)

46,000/μl after hospitalisation (how many hours after the bite?), 13,000/μl on the 1st day after the bite (1/2). Minimum platelet count 10,000/μl; it took several days for the platelet count to return to normal (1/2) (Davidson 1988).

In a study of 30 patients who had suffered from envenoming due to a North American crotalid, 20 had been bitten by C. viridis helleri. The authors report decreases in platelet counts that were dependent on the amount of venom injected. In patients with moderately severe envenoming, the lowest platelet count occurred 24–48 h after the bite, with a value 70–80% of the normal range; in patients with severe envenoming, the lowest platelet count occurred after 72–96 h and was 30% of the normal range (La Grange and Russell 1970).
C. viridis lutosus
Minimum 40,000/μl 3 h after the bite; platelet count began to increase 24 h after the bite (Dart and Gustafson 1991).

Treatment (symptomatic)

C. viridis helleri (=C. oreganus helleri)

Arterial hypotension: responded well to volume expansion with Ringer's lactate solution and albumin (Davidson 1988).

Treatment (specific)

Crotalidae Polyvalent Immune Fab Antivenom, ovine (immunized with Crotalus adamanteus, Crotalus atrox, Crotaus scutulatus ssp. and Agkistrodon piscivorus) / CroFab™, Savage Laboratories, Melville, New York

see Crotalus sp.