Biology Reference
In-Depth Information
4.4.3
Hydrodynastes gigas
4.4.3.1 Background of an Aberrant Case
Of the three species of
Hydrodynastes
14
(false-water cobras,
H. gigas
; Plate 4.26A
and B),
H. bicinctus
(Hermann's water snake, or double-banded false-water cobra;
two subspecies,
H. b. bicinctus
and
H. b. schultzi
), and the recently described
H. melanogigas
(Franco et al., 2007), only
H. gigas
has figured in any documented
cases of bites (
Table 4.1
). Three of the four reported cases featured only puncture
wounds/lacerations, pain, edema, mild bleeding, and other minor local manifes-
tations (
Table 4.1
; Plate 4.26E). One aberrant case, published as a brief abstract,
describes mild local effects (minor swelling) that occurred shortly after the victim
(an 18-year-old male pet shop worker who was maintaining the snake) received a
protracted bite (
1.5 min) on the left wrist. Due to the mild local edema, the vic-
tim ingested two diphenhydramine tablets. He had received several previous bites
(presumably from this same species, or specimen) without any notable effect. The
insignificant effects from this protracted bite were followed approximately 9 h later
by expanding edema and reportedly serious systemic effects [dysarthria, “muscle
paralysis,” and “unsteady gait” (“causing him to fall
…
”); Manning et al., 1999;
Table 4.1
]. He presented at an emergency room; noted were ECG changes consist-
ing of premature atrial complexes (PACs) and a mild tachycardia of 105 bpm. The
tachycardia resolved in 2 h, and all laboratory testing (including coagulation panels)
remained unremarkable. The patient was observed overnight with his arm elevated/
immobilized, and he was treated with ceftriaxone. The local symptoms persisted
overnight, and the patient was discharged with a prescription for cephalexin. The
patient later reported that the edema subsided after 5 days, but the “muscle pain and
weakness” lasted for 2 months. The authors of this brief report concluded that “This
is the first case reported of
H. gigas
envenomation causing significant local swelling,
pain, muscle paralysis, and arrhythmias” (Manning et al., 1999).
Although not reviewed here, an anecdotal case published in an obscure amateur jour-
nal asserted that a
H. gigas
bite resulted in a “permanently disfigured arm” (Stevens,
2000). The multiple problems with these anecdotal reports are delineated in Section
4.5. As an example, many claims in such reports cannot be considered as evidence of
sequelae assigned to the bite of any species, as there is no formal medical evaluation of
the victim communicated by a qualified physician included in the account.
4.4.3.2 Overview of the Duvernoy's Gland and Associated Dentition
of
H. gigas
Specimens of
H. gigas
exhibit several enlarged deeply grooved posterior maxillary teeth
with a broad depression spanning most of the width of the teeth at the edge of the buccal
mucosum (Plate 4.26C and D). In contrast, Fry et al. (2008) described the posterior
14
The taxonomy of
Hydrodynastes
is argumentatively unsettled as some authors assign the genus to the
family Dipsadidae, subfamily Xenodontinae, while others consider this premature.
