Understanding toxicological implications of accidents with caterpillars Megalopyge lanata and Podalia orsilochus (Lepidoptera: Megalopygidae).

Megalopygids Megalopyge lanata and Podalia orsilochus are common causative agents of accidents in agricultural workers. These accidents are provoked by dermal contact at their larval stage and are characterized by cutaneous reactions, such as burning pain, edema and erythema, typically mild and self-limited. There is very little information about their venoms and their toxicological implications on human health. Thus, we employed proteomic techniques and biological assays to characterize venoms (bristle extracts) from caterpillars of both species collected from Misiones, Argentina. The electrophoretic profiles of both venoms were substantially different, and they presented proteins related to toxicity, such as serinepeptidases, serpins and lectins. P. orsilochus venom exhibited higher caseinolytic activity than M. lanata venom, agreeing with the fact that only P. orsilochus venom hydrolyzed human fibrin(ogen). In addition, the latter shortened the clotting time triggered by calcium. While the venom of M. lanata induced a mild inflammatory lesion in mouse skin, P. orsilochus venom caused prominent necrosis, inflammatory infiltration and hemorrhage at the site of venom injection. On the other hand, P. orsilochus venom was better recognized by Lonomia obliqua antivenom, although many of its proteins could not be cross-reacted, what may explain the difference in the clinical manifestations between accidents by Podalia and those by Lonomia. Altogether, this study provides relevant information about the pathophysiological mechanisms whereby both caterpillars can induce toxicity on human beings, and paves the way for novel discovery of naturally occurring bioactive compounds.

Haematological evaluation of patients bitten by the jararaca, Bothrops jararaca, in Brazil.

Complete blood counts are used frequently by physicians to assess and manage the development of complications of diseases. We studied 100 patients bitten by Bothrops jararaca snakes, and correlated their haematological values with the severity of envenoming and the development of complications. Patients who developed both local and systemic bleeding showed a greater drop in packed cell volume, red blood cell (RBC) count and haemoglobin concentration than those with who did not bleed. No morphological changes in RBCs were seen in blood films. Total white blood cell (WBC) counts were significantly higher in the clinically "more severe" group than in the "less severe" group on admission. Neutrophilic leucocytosis with left shift was present on admission, concurrently with a decrease in eosinophil and lymphocyte counts. These changes tend to become more marked 6h after antivenom therapy, and are greatest in "more severe" envenoming. Thrombocytopenia on admission is positively associated with the development of systemic bleeding and the severity of envenoming. Thrombocytopenia may also be a useful prognostic indicator for the development of local complications, such as necrosis. The intensity of neutrophilia and eosinopenia might be used to follow the progression of necrosis in victims of snake bite.

Clinical picture and laboratorial evaluation in human loxoscelism.

Loxosceles spiders are found globally, especially in South and North America. In Brazil, approximately 10,000 cases of Loxosceles spp. spider bites are reported annually. Herein we analyzed 81 patients diagnosed as either cutaneous or cutaneous-hemolytic loxoscelism, in a geographical area where most accidents are caused by Loxosceles gaucho, and we report their clinical and laboratory data obtained during week 1 and 2 after the bite. Massive hemolysis was noticed in only 2 cases, but high serum bilirubin and LDH levels, suggestive of hemolysis, were noticed in 25 cases on admission. Anemia was not frequent (14.7%), and reticulocytosis was particularly noticed during week 2 (in 56% of patients). High D-dimer levels were suggestive of endothelial cell activation and intravascular thrombin generation, but thrombocytopenia was noticed in only 17.6% of patients in week 1. Acute kidney injury (AKI) only occurred in patients with massive hemolysis. The definitive diagnosis of overt disseminated intravascular coagulation (DIC) could not be established on admission. Fever was associated with the presence of hemolysis (p = 0.03). Altogether, these findings provide evidence that mild hemolysis is frequent in loxoscelism and suggest that AKI is uncommon, exclusively occurring in patients with massive hemolysis.