Biology Reference
In-Depth Information
Plate 4.86
Bushmaster; surucucu; cuaima; culebra sibucano; mapepire z'ananna;
others (
Lachesis muta
), Peru.
The largest species of crotaline viperid, although average adult
specimens attain total body lengths of approximately 1.60 m, exceptional specimens can reach
3.5 m or more. The lighter-colored Central American species,
L. stenophrys
, is one of only
two front-fanged colubroids (the other is the jararaca,
Bothrops jararaca
) with populations
and/or individuals known to have increasing venom toxicity with age. The non-front-fanged
colubroid, the brown tree snake (
B. irregularis
), is the only other ophidian known to show
increased oral secretion (Duvernoy's secretion) toxicity associated with ontogeny.
Photo copyright to David A. Warrell.
constricted; and bites delivered during prey handling sequester large volumes of low
toxicity secretion in the integument and, to date, the only neurotoxin characterized
from
B. irregularis
secretion is a distinctive, heterodimeric species that has marked
prey specificity for avians and saurians with very low toxicity for mammals.
Therefore, although
B. irregularis
clearly presents a medical risk on Guam, par-
ticularly to infants, the precise etiology of the medical sequelae remains elusive.
There may be uncharacterized postsynaptic neurotoxins in
B. irregularis
secretion
that could be active at the mammalian AchR. However, the evidence for neurotox-
icity in humans is equivocal. Spasticity is not usually observed concomitantly with
hypotonicity in neurologically affected pediatric patients (David Kaufman, personal
verbal communication with SAW, August 2010). Thus, clinical interpretation of the
reported signs is not straightforward and without alternative explanation. Some of
the concerning symptoms observed in the five infants bitten by
B. irregularis
may
have resulted from trauma (i.e., constriction involving the head, neck, and/or thoracic
region, causing airway compromise, as well as repetitive biting that may or may not
have included repeated introduction of Duvernoy's secretion). A well-documented,
efficacious clinical response after provision of an acetylcholinesterase inhibitor such
as neostigmine could clarify whether postsynaptic neurotoxicity contributes to the
syndrome observed in infants bitten by
B. irregularis
(see
Table 4.3
). Also, pro-
teolytic activity detected in
B. irregularis
secretion may play a role in some of the
