Fatores associados à incoagulabilidade sangüínea no envenenamento por serpentes do gênero Bothrops

Efficacy of the 20-minute whole blood clotting test (WBCT20) in the diagnosis of coagulation alteration related to snakebites in a Western Brazilian Amazon hospital

Introduction:

The efficacy of 20-minute whole blood clotting (WBCT20) and the Lee-White clotting time (LWCT) tests in diagnosing coagulation alterations from snakebites were compared.

Methods:

We evaluated 89 snakebite cases treated at the Hospital Regional do Juruá em Cruzeiro do Sul, Acre, Brazil.

Results:

WBCT20 results were normal in 33.7% and unclottable in 66.3% of cases, while LWCT results were normal in 23.6% and altered (prolonged or unclottable) in 76.4% of cases, with no significant differences.

Conclusions:

The WBCT20 is important for rapidly diagnosing coagulation alterations from snakebites. Furthermore, it is efficient, inexpensive, and can be deployed in isolated hospitals.

Effects of photobiomodulation therapy on the local experimental envenoming by Bothrops leucurus snake

Bothrops leucurus is the major causative agent of snakebites in Brazil's Northeast. The systemic effects of its venom are effectively neutralized by antivenom therapy, preventing bitten patients' death. However, antivenom fails in neutralizing local effects that include intense pain, edema, bleeding, and myonecrosis. Such effects can lead to irreversible sequels, representing a clinically relevant issue for which there is no current effective treatment. Herein, the effects of photobiomodulation therapy (PBMT) were tested in the local actions induced by B. leucurus venom (BLV) in mice (n = 123 animals in 20 experimental groups). A continuous emission AlGaAs semiconductor diode laser was used in two wavelengths (660 or 780 nm). Mechanical nociceptive thresholds were assessed with the electronic von Frey apparatus. Local edema was determined by measuring the increase in paw thickness. Hemorrhage was quantified by digital measurement of the bleeding area. Myotoxicity was evaluated by serum creatine kinase (CK) activity and histopathological analysis. PBMT promoted anti-hypernociception in BLV-injected mice; irradiation with the 660 nm laser resulted in faster effect onset than the 780 nm laser. Both laser protocols reduced paw edema formation, whether irradiation was performed immediately or half an hour after venom injection. BLV-induced hemorrhage was not altered by PBMT. Laser irradiation delayed, but did not prevent myotoxicity caused by BLV, as shown by a late increase in CK activity and histopathological alterations. PBMT was effective in the control of some of the major local effects of BLV refractory to antivenom. It is a potential complementary therapy that could be used in bothropic envenoming, minimizing the morbidity of these snakebite accidents.

Bites by Tomodon dorsatus (serpentes, dipsadidae): Clinical and epidemiological study of 86 cases

A total of 86 proven cases of Tomodon dorsatus bites admitted to Hospital Vital Brazil (HVB) of Butantan Institute, in São Paulo, Brazil, between 1945 and 2018, were retrospectively analyzed. The cases included were those in which the snake was brought to HVB and was correctly identified. Of the 86 cases of snake bites, it was possible to describe the sex of the snake in 52 cases; 31 (59.6%) snakes were male. Only 52 snakes out of 86 could be studied because of their preservation status. The length of snakes (snout-vent length) ranged from 180 to 770 mm. Of the 86 snakes, 72 could be distinguished as adults (n = 63, 87.5%) or juveniles (n = 9, 12.5%). Most bites occurred in the spring and summer seasons (n = 57, 66.3%) and during warmer periods of the day (n = 61, 72.6%), between 9 a.m. and 3 p.m. The mean (±standard deviation) age of the victims was 26.9 ± 17.2 years, and 60 (69.8%) were men. Approximately 90% of the patients sought medical care within 6 h after the bite. Both upper (n = 45, 52.3%) and lower (n = 37, 43.0%) limbs were the most frequently bitten, particularly the feet and hands (n = 54, 62.8%). The local clinical manifestations were pain (n = 55, 64.0%), transitory bleeding (n = 23, 26.7%), erythema (n = 22, 25.6%), edema (n = 14, 16.3%), paresthesia (n = 9, 10.5%), and ecchymosis (n = 3, 3.5%). Only 10 (11.6%) patients reported non-specific systemic symptoms characterized by transient dizziness or mild headache, and 21 (24.4%) patients showed no evidence of envenomation. A 20 min whole blood clotting test was performed in 31 (36.0%) patients on admission and all of them had coagulable blood. Supportive treatment was offered to 38 (44.2%) patients, namely, antiseptic (n = 20, 23.3%), antihistamines (n = 12, 14.0%), and analgesics (n = 9, 10.5%). Four (4.7%) patients were inappropriately treated with Bothrops antivenom before their admission to HVB. No sequelae or relevant complications were observed in patients, and the prognosis was benign. Therefore, although T. dorsatus bites can cause mild local symptomatology, it is important that health professionals know how to make the correct diagnosis to avoid unnecessary use of antivenom.