Biology Reference
In-Depth Information
Both rabbit- and goat-derived antivenoms were clinically effective, and none of
the patients developed antivenom reactions. Available data suggest that one ampoule
of either goat- or rabbit-derived antivenom should be sufficient to treat most serious
envenomations by
R. tigrinus
. In the setting of a life-threatening envenomation from
this species, procurement of two ampoules is recommended. However, this antive-
nom is in short supply and difficult to obtain.
Treatment of
R. subminiatus
Envenoming
Although there is no commercial antivenom against
R. subminiatus
venom, Kawamura
et al. (1988) reported that 0.1 mL of anti-
R. tigrinus
rabbit-derived antivenom neutral-
ized 46. 2 μg (10.8 MLD) of
R. subminiatus
venom. This suggests that anti-
R. tigrinus
antivenom can provide paraspecific protection against
R. subminiatus
envenomation.
To date, no documented case of
R. subminiatus
envenomation has been man-
aged with
R. tigrinus
antivenom. Some cases have resolved without any specific
treatment (Hoffmann et al., 1992), while others have been managed with support-
ive measures consisting of infusions of fibrinogen, low-dose heparin (this is strongly
discouraged; see later) and exchange blood transfusion (Zotz et al., 1991) or com-
prehensive replacement therapy (i.e., repeated infusions of packed red blood cells
(PRBCs), fresh frozen plasma (FFP)/cryoprecipitate, fibrinogen
platelets; Cable
et al., 1984; Mather et al., 1978). In a recent case of
R. subminiatus
envenoming
in the Netherlands, the patient's severe bleeding diathesis had resolved spontane-
ously by the time
R. tigrinus
antivenom had arrived from the Japan Snake Institute
(DAW, personal communication). Another recent case of a European victim bitten in
Thailand while handling a wild-caught
R. subminiatus
was managed without antive-
nom (DAW, personal communication).
In the case reported by Zotz et al. (1991), repeated exchange blood transfusion,
fibrinogen, and low-dose heparin resulted in intermittent cessation of bleeding. The
bleeding recurred between treatments, and the course of this hemorrhagic diathesis
continued for about 10 days. Hemostatic parameters remained abnormal for over 1
month (Zotz et al., 1991). With replacement therapy, a patient envenomed by a
R. sub-
miniatus
had undetectable fibrinogen for 1 week after the bite (Cable et al., 1984). The
patient's bleeding ceased, but similar to that reported by Zotz et al. (1991) did not have
normal hemostatic parameters for 2 weeks after discharge (Cable et al., 1984).
Serious cases of
R. subminiatus
envenomation should be treated in the same way
as recommended for
R. tigrinus
. As noted when considering
R. tigrinus
envenom-
ation, procurement of antivenom is the primary issue complicating optimal manage-
ment of envenomation by these snakes.
Polyvalent Antivenoms Should
Not
Be Used for Treating Colubrid Bites
A substantial number of colubrid bites from species of unknown medical importance
have been inappropriately treated with polyvalent antivenoms (
Table 4.1
; Section
4.5.1.1). This has been most commonly documented in bites from South American
species, particularly
Philodryas
spp. (
Table 4.1
; Sections 4.1.1 and 4.5.1.1), and
South Asian species (Ariaratnam et al., 2009; Viravan et al., 1992).
