Biology Reference
In-Depth Information
for this snake's bite to be responsible for the observed effects: “a venomous saliva”
and “a minimal time of contact between it and the wound” (Bedry et al., 1998). They
concluded that the “
…
exceptional circumstances of this accident explain a poisoning
by
Coluber viridiflavus
…
raises the question of a real toxicity of snakes described as
nonvenomous as they are fangless” (Bedry et al., 1998).
Assessment of this case is hindered by the brevity of the report and its limited
detailed information. However, the available data raise significant questions regard-
ing the possible assignment of envenomation as the cause of the reported syndrome.
First, although the authors inferred that a sustained bite would be necessary in order
to account for medically significant effects, available information suggests “mini-
mal contact” between the victim and the snake. This argues against a protracted bite
that would raise the likelihood of a secretion volume sufficient to cause the serious
effects as reported. This is particularly noteworthy as it is likely that, similar to mem-
bers of the genus
Coluber
, these snakes do not possess any dentition clearly adapted
for grasping prey or possibly allowing increased entry of associated secretions into
inflicted wounds (see Section 4.1). Such brief contact could be sufficient to cause
a medically significant bite if this species had a highly toxic secretion (i.e., see
R. tigrinus
and
R. subminiatus
; Section 4.3). However, there are no available data
indicating that this species produces such a toxic secretion. Although there are no
specific data regarding the presence of any Duvernoy's glands in this species, similar
colubrine taxa such as
Coluber constrictor
(
Plate 4.80A and B
) have been reported
to contain a “venom gland” associated “venom duct” (Fry et al., 2008). As noted in
Section 4.1, there are no well-documented cases of medically significant bites from
any
Coluber
spp. and numerous bites witnessed or experienced personally by several
of us were insignificant.
It is important to recognize that Bedry et al. (1998) assumed in their report that
the bite did in fact occur. As this critical assumption is based on the comments of
the victim's companions, all who may have been ingesting significant amounts
of alcohol, the specific basis for this case must be considered tentative at best.
Unfortunately, the case report lacks any information regarding examination of the
purported bite site. The most likely cause of the reported presentation is a result of
alcohol intoxication, possibly with somatosensory amplification (Section 4.5.2). The
victim's reported blood level (2.1 g/L or 210 mg/dL) is well over the level predic-
tive of gross intoxication (120-160 mg/dL; Trevor et al., 2008). This level is notable
because behavioral, cognitive, and psychomotor changes can occur at blood alcohol
levels as low as 20-30 mg/dL, a level achieved after ingestion of just one or two stan-
dard drinks (Fauci et al., 2009). The level is also over four times the legal blood alco-
hol limit in France [0.05% (50 mg/dL) for drivers of a noncommercial vehicle (
http://
of these basic calculations suggest that the victim ingested a large volume of alco-
hol and the detected blood alcohol level was metabolically decreased from the time
of the incident, as these levels decrease by approximately 0.01%/40 min (
www.cdc.
higher blood alcohol level. The body weight and habitus of the victim (these details
were not included in the case report) would also be important factors influencing the
degree of intoxication per the ingested volume.
