Revista da Sociedade Brasileira de Medicina Tropical
Rev. Soc. Bras. Med. Trop. vol.30 n.6 Uberaba Nov./Dec. 1997
CASES OF HUMAN ENVENOMING CAUSED BY PHILODRYAS OLFERSII AND PHILODRYAS PATAGONIENSIS (SERPENTES: COLUBRIDAE)
Maria Elisabeth de Araújo e Ana Cristina M.C.A. dos Santos
The present paper reports two cases of
human envenoming by colubrid snakes of Philodryas, considered as not
poisonous, showing evidence of the clinical aspects and the evolution of the
symptoms of envenoming. The similarity of these cases with those caused by
Bothrops suggests a more careful evaluation on the victims considering the
medical treatment to be adopted.
Snakes of the genus Philodryas are considered as not poisonous2. However, only a few cases of human envenoming have been reported in the literature. Those cases are mainly restricted to P. olfersii, which is potentially dangerous to medium-sized vertebrates5. The venom of P. olfersii is highly hemorrhagic, has fibrinogenolytic and edematic activities and does not contain procoagulating enzymes1. It also has a 208% higher proteolytic activity than that of Bothrops jararaca 8.
The low incidence of accidents caused by Philodryas is due to the anatomy of the inoculatory teeth (located in the posterior region of the maxilla) of these serpents and, therefore, the difficulty to inject their venom9, and the non- aggressive behavior of the colubrid snakes1. Nevertheless, 132 cases occurred with P. olfersii, P. patagoniensis and P. aestivus have been reported at the Vital Brazil Hospital, Instituto Butantan, SP7.
Ecchymotic lesions attributed to the action of hemorrhagines9 are very similar to those found in botropic accidents. Due to the non identification of the snake and based on clinic features medical staff usually treat Philodryas victims with envenoming as if they had been bitten by Bothrops, with a specific serum unnecessarily6 7.
The present report intends to present new cases of envenoming caused by Philodryas, as well as to alert about the lack medical criteria in the treatment concerning the administration or not of anti-botropic serum and the difficulty to identify the snake through its bite and its symptoms, suggesting an update in the classification of the snakes with medical interest.
The two cases reported here refer to accidents with adult serpents, P. olfersii and P. patagoniensis, which occurred during the manipulation of these animals at the Department of Poisonous Animals, Instituto Vital Brazil, Niterói, RJ. The patients, both technicians, were females, aged 21 and 35 years.
The accident caused by P. olfersii (Figure 1) occurred on March 4th, 1988, at 2:00 p.m. During a captured by hand, the serpent bit the distal phalanx of the 5th finger of the technician's right hand, where it remained alternating the maxillae for about 15 seconds, thus inoculating its poison.
The bite did not cause immediate pain or bleeding. However, after 15 min, a swelling started in the whole hand, followed by rubefaction, mostly around the bite.
By the technician's initiative, she was administered an anti-tetanus vaccine (20 min after the accident). At 3:00 p.m. the victim was reported at the Emergency Sector of the Antônio Pedro University Hospital. In that occasion, she received an anti-histaminic injection, and temperature, blood pressure and tests of coagulation performed, with normal results. Due to the lack of knowledge about accidents by Philodryas, the medical team suggested the administration of an anti-botropic serum, which was not allowed by the patient.
The edema progressed reaching forearm and right arm, with the formation of two ecchymoses areas, in the internal faces of both. The pulsing of the bitten area aggravated. The wound in the 5th finger suppurated. About 48 hours after the accident, the right axilar lymph node appeared enfarted. Joint articulations partially lost their movements, due to the spreading of the edema, and the arm remained in pain, bothered by weight sensation.
The loss of tactile sensitivity and the edema remained on the limb for approximately 10 days, after which the edema started to diminish. Fifteen days after the accident, arm, forearm and hand appeared normal. Fearing for a possible gangrene region, the medical staff made a daily control and local assepsy during the whole period. The medication used was the anti-histaminic.
The second case with P. patagoniensis (Figure 2) is similar to the one described above. The accident occurred on January 20, 1994, at 10:30, when the technician grabbed the serpent on the floor. The animal turned its head and reached the right fist of the victim, biting it several times, advancing the maxillae until the fangs penetrated the skin, thus poison. A second person was needed to remove the serpent, what was only possible two minutes later. The bite itself did not cause immediate problems. However, the patient complained about a constant itching, that could have been caused by an alergic reaction due to the poison of the snake. After a few minutes a local swelling rapidly develops and speads to the hand and fingers, expanding later to the forearm and arm, and reaching the axilla, 72 hours later. This edema, like in the previous case, remained for 15 days. During that period, arm and hand were hampered and painful, having lost part of their movements. Despite the local signs, the patient did not present systemic symptoms. The medical care was done at the Antônio Pedro University Hospital, 45 min after the accident. Results of the temperature, blood pressure and tests of coagulation were normal. Beyond the anti-tetanus vaccine and the anti-histaminic, antibiotic was given 4 days after the accident. The recovery time was similar to the first case.
The effects of the envenoming caused by P. olfersii and P. patagoniensis observed here are much alike. The biting and inoculation mode, some symptoms presented, the time and evolution of the clinic case and the patient's recovery are similar. However, in the accident caused by P. olfersii, beyond the edema and the enlargement of lymph nodes, the wounds showed suppuration and there was presence of ecchymotics wounds. This must have occurred probably due to the powerful venom of this species as well as to the fragility of the region attained. The symptoms presented in the accidents caused by P. olfersii 4 5 9, P. schotii 4 (= P. patagoniensis) and P. baroni3 are similar to those treated in the present study.
The objection of the Vital Brazil technicians in receiving the anti-botropic serum strengthens the worry of Nishioka and Silveira6, who consider this administration unnecessary, beyond showing the lack of medical preparation on accidents with non-poisonous serpents. This question presents a controversy, on the medical care as well as on the scientific level. Assakura et al.1 state that the hemorragic activity of the venom of P. olfersii was neutralized by the action of the commercial anti-botropic serum and also with that obtained from rabbits with isolated botropic hemorrhagic factor.
Even having the knowledge that only small proportions of the accidents caused by Phylodryas species cause human envenoming, cases like these and the few mentioned in the literature intend to bring some contribution, regarding the harms caused by these non-poisonous serpents, and the therapies applied. At the same time, they suggest a bigger investment on the study of the toxic properties of these serpents, which will allow a more adequate medical attention.
O presente trabalho é um relato de dois
casos de acidentes com colubrídeos (Philodryas olfersii e P.
patagoniensis) considerados não peçonhentos, que destaca as manifestações
clínicas e as suas evoluções. A semelhança de tais acidentes com aqueles
causados por serpentes Bothrops indica a necessidade de uma melhor
avaliação dos pacientes quanto à terapêutica a ser adotada.
We are grateful to the Instituto Vital Brazil, represented by Dr. Aníbal Melgarejo, to Dr. Guiseppe Puorto and Vilma Alves Pereira for his appropriate suggestion, and especially to Dr. Maria José Andrada Serpa, who also checked the medical terms of this paper.
Departamento de Engenharia de Pesca, Centro
de Ciências Agrárias, Universidade Federal do Ceará, Fortaleza, CE e Divisão de
Animais Peçonhentos, Instituto Vital Brazil, Niterói, RJ.
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