Philodryas (Serpentes: Dipsadidae) Envenomation, a Neglected Issue in Chile

Abstract

Snakebite envenomation is considered a neglected tropical disease, although it also occurs outside the tropics. In this work, we analyzed the literature on Philodryas species in Chile (Philodryaschamissonis, P.simonsii, and P.tachymenoides) from 1834 to 2019, searching for epidemiological, clinical, and molecular aspects of envenomation. Ninety-one percent of the studies found regarded taxonomy, ecology, and natural history, suggesting that snakebites and venom toxins are a neglected issue in Chile. All snakebite cases reported and toxicological studies concerned the species Philodryaschamissonis. Using 185 distributional records from the literature and museum collections for this species, we show for the first time that the reported snakebite cases correlate with human population density, occurring in the Valparaiso and Metropolitan regions in Central Chile. The reduced number of snakebite cases, which were previously considered as having a low incidence in Chile, may be a consequence of under-reported cases, probably due to the inadequate publication or scarce research on this issue. Absence of information about official pharmacological treatment, post-envenoming sequels, clinical management of particular patient groups (e.g., with non-communicable diseases, pregnant women, and the elderly) was also detected. In conclusion, despite having over 185 years of literature on Chilean snakes, knowledge on the envenomation of Philodryas genus remains scarce, seriously affecting adequate medical handling during an ophidic accident. This review highlights the need to develop deep research in this area and urgent improvements to the management of this disease in Chile.

Keywords: Philodryas; colubrid; opisthoglyphous; snakebite; therapeutics; toxins.

Figure 1

Species of the Philodryas genus recognized for Chile. (A) Philodryas simonsii, referential photography, specimen QCAZR13878, Pontifical Catholic University of Ecuador Collection; (B) Philodryas chamissonis from Maule Region, Chile; (C) Philodryas tachymenoides from Arica and Parinacota Region, Chile. (D) The articles published on snakes in Chile covering taxonomic/geographical distribution (blue line), toxicology/human snakebite reports (red line), and natural history/ecology (green line). Total compiled works: 106. (E) The cumulative total number of reports on ophidism by Philodryas species and the (F) percentage of articles published on Philodryas snakes present in Chile.

Figure 2

Distribution of Philodryas chamissonis and the location of snakebite reports for Chile. (A) P. chamissonis distribution in Chile obtained from the literature and museum records shown in circles. (B) Human population density, inhabitants per square kilometer, in the different regions of Chile (abbreviated denominations according to ISO 3166-2). Reported cases of snakebite accidents in the Valparaíso and the Metropolitan regions are shown in squares.

Figure 3

Predicted 3D structures for P. chamissonis toxins. (A,B) Putative toxins with enzymatic activities and (C–E) putative catalytic activity-lacking toxins with ligand properties. Representations from Urra et al. [29].