Biology Reference
In-Depth Information
fast-moving, active snakes feed on a broad variety of prey and exhibit a wide range
in South America (see
Table 4.2
for examples). An uncommon characteristic of some
Uruguayan populations of
P. patagoniensis
(Plate 4.41) is that they are known to par-
ticipate in communal nesting (Vaz-Ferreira et al., 1970).
3
The biology, taxonomy,
and perceived medical risks of this genus have been comprehensively reviewed by
Campbell and Lamar (2004). Campbell and Lamar (2004) also described the hab-
itats of various taxa and illustrated the recognized species. Of 16 genera included
in a broad study of colubrid snakebite in Brazil, Salomão et al. (2003) ascribed 11
symptoms to
Philodryas
spp. bites as noted from records of Hospital Vital Brazil,
Instituto Butantan—more than for any of the other species. Among these
Philodryas
spp. bites, the authors reported a 1.3% incidence of “gum hemorrhage” (Salomão
et al., 2003), implying uncommon antihemostatic systemic effects from these
bites and thereby suggesting “envenoming.” In contrast, Ribeiro et al. (1999), who
reviewed 43 cases of
P. olfersii
(Plate 4.39A and B) bites that presented to Instituto
Butantan between 1982 and 1990, described only local effects. Whole blood clotting
tests performed in 11 cases were unremarkable (Ribeiro et al., 1999). These authors
also cited several unpublished cases characterized by mild-to-moderate local effects
but lacking any systemic manifestations. Two pediatric cases were misdiagnosed
as
Bothrops
spp. envenoming and treated with polyvalent anti-
Bothrops
antivenom
(Ribeiro et al., 1999). Similarly, Nishioka and Silveira (1994) reported a case of mild
local effects (“mild edema and warmth”) in a 5-year-old patient bitten by
P. patag-
oniensis
. The patient was incorrectly diagnosed as having been envenomed by a
Bothrops
spp. and was given polyvalent anti-
Bothrops
antivenom. Salomão et al.
(2003) reported the case of a 17-year-old male admitted to Hospital Vital Brazil with
“all the symptoms of a
Bothrops
envenomation.” The victim described the snake
responsible as a “green snake with a brown head.” When shown a specimen of
P.
olfersii
, he immediately confirmed that it was the snake that had bitten him, and he
was therefore not given antivenom (Salomão et al., 2003). These cases may suggest
that misidentification of
Philodryas
spp. for crotaline species (e.g., some
Bothrops
spp.) could account for some reports of “bleeding gums” and other symptoms/signs
reflecting systemic effects. As described earlier, antivenom may also be given inap-
propriately to patients with moderate local effects from a
Philodryas
spp. bite, as this
may be wrongly ascribed to
Bothrops
spp. envenoming.
Misunderstanding of snakebite management and misinformation about differences
between medical risks posed by front-fanged venomous snakes and “colubrids” con-
tribute to the inappropriate treatment of bitten patients with clinically significant local
effects. Ironically, this may assume greater importance in some hospitals admitting
patients bitten by local species such as
Philodryas
spp. A patient bitten by a verified
P. olfersii
in Recife, Brazil, presented with local pain, moderate edema, erythema, and
mild ecchymoses of the right hand, and was given eight ampoules of anti-
Bothrops
3
Communal nesting is well known among a number of Nearctic, Palearctic, and a few Australian snake
taxa, but is quite rare among Neotropical species. The only South American species known to participate
in this behavior are specific populations of
Dipsas oreas
(Ecuador snail eater; Cadle and Chuna, 1995),
Sibynomorphus mikanii
(Alburquerque and Ferrarezzi, 2004),
Psomophis obtusus
(wide ground snake),
and
P. patagoniensis
(Vaz-Ferreira et al., 1970).
