Personal Experience of Daboia siamensis Envenomation

Reports of envenomation induced by Daboia siamensis, a medically important venomous snake in Taiwan, are rare, and species identification might not be definitive. This article reports the complete course of a definite D. siamensis bite. The patient in this report was one of the authors who was bitten on the right palm near the base of the index finger by D. siamensis. The patient experienced local effects, neurological manifestations, and acute kidney injury. The laboratory analysis revealed elevated D-dimer and coagulopathy. The patient was administered 8 vials of antivenom and did not undergo surgical intervention or endotracheal tube intubation, but serum sickness occurred 8 days after antivenom administration. The horse immunoglobulin produced by the Centers for Disease Control, R. O. C. (Taiwan), against D. siamensis was effective and safe in the treatment of the patient. However, the best antivenom administration strategy remains unclear and requires further study.


Introduction
Patients who experience the bite of Daboia siamensis, a medically important venomous snake in Taiwan, are mainly resident in the southern and eastern areas of Taiwan [1] e major symptoms of D. siamensis bites in envenomed patients include local effects, varying degrees of acute kidney injury, incoagulable blood with bleeding tendency, and hemolysis [2,3]. Before the availability of a specific antivenom in Taiwan in August 2008, the bite of D. siamensis species induced more serious kidney injury than that of other Russell's vipers in Southeast Asia [4][5][6]. However, reports on the treatment of patients bitten by D. siamensis remain rare, and species identification might not be definitive. is article reports the complete course of a definite D. siamensis bite in a patient.

Case Report
One of the authors (TS Tsai, a 48-year-old man) was bitten on the right palm near the base of the index finger by D. siamensis (Figure 1) in the Reptile and Amphibian Facility at the National Pingtung University of Science and Technology in Pingtung, Taiwan. e accident might have occurred when the patient's fingers stuck to the skin of the snake when he grasped the neck of the snake to inspect its mouth and nostrils for symptoms and signs of infection. After inspection, the patient attempted to release the snake back into the snake box, and it then turned its head around and bit the patient's hand while he was releasing it. Two fang bite marks, scratches, and bruises were visible on the spot. e patient started to feel numbness and tingling of the ankles and experienced slight difficulty in walking approximately 30 min after the snakebite. e patient visited a local hospital 30 min later and was administered 4 vials of monovalent antivenom for D. siamensis at the emergency department within 1 h of being bitten. However, the swelling and redness had progressed to the wrist ( Figure 2) approximately 9 h after the snakebite. erefore, 4 more vials of antivenom were administered, for a total of 8 vials within 10 h. Blood tests showed acute kidney injury, disseminated intravascular coagulation, and coagulopathy (Table 1). No leukocytosis or anemia was observed, and antibiotics, such as ceftazidime, were prescribed. e patient was admitted after which the right hand showed the most obvious swelling and pain for the first 2-3 days. e swelling and pain even extended to the right elbow. e patients' fingers were almost unable to bend. Ice pillow packing was used to relieve the pain, local heat, and swelling. Fortunately, there were no blisters, hemorrhagic bullae, or finger ischemia. e patient also received two courses of hyperbaric oxygen treatment on days 3 and 4, and the swelling of the hand quickly subsided after that. en, the patient's fingers were able to bend slightly on the third night and were able to bend more than 90°on day 4. During hospitalization, the patient's daily stool was soft or fluid and dark blue-green but not black, whereas the urine color was normal. e patient was discharged from the hospital on day

Discussion
Although early antivenom administration would benefit wound recovery and reduce pain in affected patients [7,8], the optimal antivenom administration strategy for D. siamensis envenomation remains unclear. Compared to a recent study [3], most patients with D. siamensis envenomation were administered 4-6 vials of antivenom. e patient in this case was initially administered 4 vials of antivenom. However, the subsequent redness and swelling continued to worsen, extending over the wrist joint, and therefore, another 4 vials were administered. Compared with previous studies, the overall amount of antivenom administered to this patient was more than the average dose, and there were no blisters or hemorrhagic bullae, and surgical intervention was not required [3].
e weak neurotoxic manifestations observed in this patient were numbness and pain at the ankles, general weakness, and difficulty in walking at the initial stage after the snakebite. Similar to previous studies, ptosis or respiratory failure did not occur [2,3].
e laboratory data showed elevated D-dimer levels and coagulopathy. Acute kidney injury occurred, but the patient rapidly recovered, which could be due to the early antivenom administration [4]. Although the evidence of the benefits was not clear, ancillary treatments such as antibiotics, ice packing, and hyperbaric oxygen were administered to this patient.
Ceftazidime was used in this case because of the high infection rate and susceptibility to pathogens associated with snakebites in Taiwan [9,10]. ere was no severe antivenom reaction in this case; however, allergies occurred 8 days later. e adverse effect might have serum sickness, which mostly occurs 5-10 days after serum injection. A previous study also reported that administering more antivenom has a higher risk of inducing serum sickness [11].

Conclusion
is is a complete and definitive report of a case of D. siamensis snake bite in Taiwan. e horse immunoglobulin produced by the Centers for Disease Control, ROC (Taiwan), against D. siamensis was effective and safe in the treatment of this patient. However, the best antivenom administration strategy remains unclear, and further studies are required to determine an appropriate regimen.

Ethical Approval
is case report was approved by the Chang Gung Medical Foundation Institutional Review Board (IRB No.: 202101554B0).

Conflicts of Interest
e authors declare that they have no conflicts of interest.