Impact of antivenom administration on the evolution of cutaneous lesions in loxoscelism: A prospective observational study.

BACKGROUND: Spiders of the genus Loxosceles are distributed throughout tropical and temperate regions worldwide. Loxosceles spp. bites may evolve to necrosis, with or without intravascular hemolysis. There is no consensus regarding the best treatment to prevent necrosis. The objective of this study was to evaluate the factors associated with the development of necrosis and the impact that antivenom administration has on the evolution of cutaneous loxoscelism. METHODOLOGY/PRINCIPAL FINDINGS: This was a prospective observational study carried out at a referral center for envenoming. Over a 6-year period, we included 146 patients with a presumptive or definitive diagnosis of loxoscelism. Depending on the symptom severity, a polyvalent anti-arachnid antivenom was administered or not-in 74 cases (50.7%) and 72 cases (49.3%), respectively. Cutaneous and systemic manifestations were assessed at admission and weekly thereafter. Adverse reactions to the antivenom were also evaluated. Cutaneous loxoscelism was observed in 141 cases (96.6%), and the spider was identified in 29 (19.9%). The mean time from bite to antivenom administration was 41.6 ± 27.4 h. After discharge, 130 patients (90.9%) were treated with corticosteroids, antihistamines and analgesics being prescribed as needed. The probability of developing necrosis was significantly lower among the patients who were admitted earlier, as well as among those who received antivenom (p = 0.0245). Among the 74 patients receiving antivenom, early and delayed adverse reactions occurred in seven (9.5%) and four (5.4%), respectively. Local infection was observed only in three (2.3%) of the 128 patients for whom that information was available. CONCLUSIONS/SIGNIFICANCE: Necrosis after a Loxosceles sp. bite appears to more common when hospital admission is delayed or when antivenom is not administered. In addition, the administration of a polyvalent anti-arachnid antivenom appears to be safe, with a relatively low rate of adverse reactions.

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.

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 weanalyzed 81 patients diagnosed as either cutaneous or cutaneous-hemolytic loxoscelism, in a geographical area where most accidents are caused by Loxosceles gaucho, and wereport 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 week1. Acute kidney injury (AKI) only occurred in patients with massive hemolysis. The definitive diagnosis of overt disseminated intravascular coagulation (DIC) could not beestablished 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.

Short report: A case of hemolysis resulting from contact with a Lonomia caterpillar in southern Brazil.

Contact with a caterpillar of the genus Lonomia can result in a hemorrhagic syndrome. Lonomia obliqua venom activates prothrombin and factor X and promotes fibrinogenolytic activity. Although crude L. obliqua bristle extract can induce hemolytic activity in human and rat erythrocytes, there have been no reports of hemolysis in the cases of human contact. We report a confirmed human case of Lonomia venom-induced hemolysis.