Q J Med 2001; 94:551–559

Coagulopathy following lethal and non-lethal
envenoming of humans by the South American rattl...
552                                              I.S. Sano-Martins et al.

through direct action of crotamine. This featu...
Envenoming by C. durissus                                      553

systemic envenoming by C. durissus (e.g. ptosis,     ...
554                                                     I.S. Sano-Martins et al.

ptosis, and 10/19 (53%) suffered from m...
Envenoming by C. durissus                                       555

Table 2 Haematological variables in patients on admi...
556                                              I.S. Sano-Martins et al.

Figure 2. Plasma concentration of (a) fibrin...
Envenoming by C. durissus                                       557

Discussion                                          ...
558                                                 I.S. Sano-Martins et al.

one (4.2%) of our 24 patients having signs ...
Envenoming by C. durissus                                                  559

21. Cupo P, Azevedo-Marques MM, Hering SE....
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Snake Bite Oxford Journal


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Snake Bite Oxford Journal

  1. 1. Q J Med 2001; 94:551–559 Coagulopathy following lethal and non-lethal envenoming of humans by the South American rattlesnake (Crotalus durissus) in Brazil I.S. SANO-MARTINS, S.C. TOMY, D. CAMPOLINA 1 , M.B. DIAS 1 , S.C.B. DE CASTRO, M.C.C. DE SOUSA- E-SILVA, C.F.S. AMARAL 2 , N.A. REZENDE 2 , A.S. KAMIGUTI 3 , D.A. WARRELL 4 and R.D.G. THEAKSTON 5 From the Laboratorio de Fisiopatologia, Instituto Butantan, Sao Paulo, Brazil, ´ ˜ 1 Hospital Joao XXIII, Minas Gerais, Belo Horizonte, Brazil, 2Departamento de Medicina ˜ Interna, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil, 3University Department of Haematology, Royal Liverpool Hospital, Liverpool, UK, 4Centre for Tropical Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford, UK and 5 Liverpool School of Tropical Medicine, Liverpool, UK Received 16 May 2001 and in revised form 3 August 2001 Summary The South American tropical rattlesnake (Crotalus attributed to venom-induced haemostatic dis- durissus subspp) is responsible for ;10% of bites turbances. However, envenoming by C. durissus is from venomous snakes in Brazil. We studied frequently associated with haemostatic disorders, 24 victims of bites by this species over 3 years, which are probably attributable mainly to the in south-eastern Brazil, particularly investigating action of the thrombin-like enzyme, with possible haemostatic alterations. Thirteen patients were additional effects secondary to the powerful defined as moderately envenomed and 11 as myotoxic activity of the venom. severe. There were two deaths, which were not Introduction The Crotalus durissus complex, comprising the in combination with crotamine exerts a neurotoxic South American tropical rattlesnakes, is responsible effect on peripheral nerves10 and a myonecrotic for approximately 10% of cases of envenoming by effect on muscle.11 The crotamine content of snakes in Brazil; the majority of these are caused C. durissus venoms varies between different popu- by the cascavel, Crotalus durissus terrificus. The lations of snakes in Brazil and Argentina. Crotamine venom of this species possesses neurotoxic,1 was absent from populations in north and eastern myotoxic2 and thrombin-like activities.3 Brazil, present in north-western Sao Paulo State ˜ The principal toxins present in the venom include and adjacent areas of Parana and Minas Gerais, and ´ crotoxin,4 crotamine,5 convulxin,6 a thrombin-like in Ceara there were mixed populations, some ´ enzyme7 and gyroxin.8,9 The high toxicity of secreting crotamine and some not.12 An intriguing the whole venom is attributable to crotoxin, a possible clinical correlation with the presence of phospholipase A2 complex, which is the principal crotamine is the ‘broken neck’ sign resulting from component of the venom.4 Experimentally, crotoxin paralysis of the cervical flexor muscles, possibly Address correspondence to Dr Ida S. Sano-Martins, Instituto Butantan, Laboratorio de Fisiopatologia, Av. Vital Brazil, ´ 1500, 05503 900, Sao Paulo (SP), Brazil. e-mail: lusiada@uol.com.br ˜ ß Association of Physicians 2001
  2. 2. 552 I.S. Sano-Martins et al. through direct action of crotamine. This feature a massive rise in serum myoglobin and creatine has been reported from various parts of Latin kinase (CK) levels, accompanied by myoglobin- America.13 Convulxin causes convulsions and uria.2,20–23 Pain throughout the whole body, respiratory and circulatory disturbances in mice, possibly explained by rhabdomyolysis, was the dogs, cats and guinea pigs; it also causes in vitro main symptom remembered by one of the first platelet aggregation in the platelet rich plasma of recorded victims of cascavel bite. Father Luis many mammalian species.6 Gyroxin, when injected Rodrigues was bitten near Bahia in north-eastern intravenously, induces episodes of opisthotonos Brazil at Christmas-time in 1560. He suffered and rotation of the animal’s body in the longitudinal terrible symptoms for the next 20 days.24 axis.8,9 These signs are not observed in human In the fatal case described in Londrina, Sao Paulo ˜ victims. A thrombin-like enzyme, first isolated and State there were clinical, electrocardiographic, characterized by Raw et al.,7 is responsible for biochemical and histological features suggestive the coagulant action of the venom. More recently, of venom-induced myocardial damage.25 a comparative study of the biological activities of Blood coagulation disturbances have been the venoms of three different Brazilian subspecies described in about 50% of patients bitten by of C. durissus (C. d. terrificus, C. d. collilineatus C. durissus subspp.26 Amaral et al.27 reported and C. d. cascavella) proved that most of these patients with afibrinogenaemia but without activities were common to all these subspecies.14 thrombocytopenia. Spontaneous bleeding has In most respects, Rosenfeld’s clinical descrip- only been rarely observed in human patients. The tions of envenoming by Crotalus durissus ssp in aim of the present study was therefore to examine Brazil have not been bettered.15 Local symptoms at in detail the haemostatic disorders in patients the site of the bite include pain, paraesthesiae bitten by this species, and to assess the ability such as formication or anaesthesia, but little or no of antivenom to reverse them. swelling and no local necrosis. Rosenfeld denied erythema, but we have observed this (Figure 1), for example in patients 3 and 13 (below). There is a similar lack of effect when the venom is injected Methods subcutaneously, intramuscularly or intradermally in experimental animals.16 This contrasts with bites Patients by many Crotalus species in North and Central Twenty-four patients were admitted to Hospital America, which commonly cause severe local Joao XXIII, Belo Horizonte, Minas Gerais State, ˜ necrosis.17,18 Brazil. There were three females and 21 males, ages Systemic envenoming usually starts with the ranging from 11 to 74 years. All had been bitten by development of symmetrical ptosis, external oph- C. durissus subspecies (of which C. d. terrificus thalmoplegia and facial weakness, resulting in the is the most prevalent subspecies in Minas Gerais) characteristic myopathic/neurotoxic facies. Paresis between January 1993 and November 1995. of the pupils may impair visual accommodation Diagnosis of Crotalus durissus bite was based on (responsible for patients’ complaints of difficulties identification of the snake brought with the with vision), loss of pupillary reflexes and mydriasis. patient (four patients, C. d. terrificus in each case); Rosenfeld regarded mydriasis as a fatal prognostic detection of specific venom antigen in serum sign.15 Rarely, respiratory muscle involvement may (11 patients) or on clinical features considered lead to respiratory failure.19 The venom induces diagnostic at admission (nine patients). All of these generalized rhabdomyolysis, causing myalgias, last nine patients showed characteristic signs of a b Figure 1. Extensive erythema and some swelling 3 h after a bite by Crotalus durissus terrificus in Sao Paulo State. ˜
  3. 3. Envenoming by C. durissus 553 systemic envenoming by C. durissus (e.g. ptosis, Haematological tests myalgia, diplopia or paraesthesia). As none of these signs occur following bites by any other venomous Blood (2.5 ml) was mixed with 25 ml of 10% snake in this region, it is reasonable to include potassium EDTA and 50 ml Crotalus antivenom. these cases in the study. The patients were divided Erythrocytes, leukocytes and platelets were counted into two entirely arbitrary groups—‘severe’ and using an automated cell counter (Coulter T 890). ‘moderate’ envenoming—based on their presenting Differential leukocyte counts were carried out on symptoms and signs. ‘Moderate envenoming’ was blood films stained with panchromatic stain. defined as disturbance of visual accommodation, ptosis or neurotoxic facies,15 mild myalgia, slight Biochemical tests or absent urinary pigment with normal urine Blood was sampled for creatinine, urea and creatine output, and altered or normal coagulation time. kinase (CK, normal values: 10–120 U/L) enzyme ‘Severe envenoming’ was defined by the pres- activity determinations using Labtest kits. Serum ence of obvious neurotoxic signs, intense myalgia myoglobin concentration was measured using the accompanied by pigmented urine with the presence Rapitex-myoglobin kit (Behring). or absence of oliguria/anuria and normal or altered coagulation time.28 Patients who had been treated with antivenom before admission to the hospital Venom antigen levels were excluded from the study. Informed consent to Enzyme-linked immunosorbent assay (ELISA) was participate in the clinical study was obtained from used for detection and measurement of C. durissus the patients or, if young children were involved, venom in admission serum samples according from their parents. The study was approved by the to the technique described by Chavez-Olortegui ´ ´ Ethics Committee of Hospital Joao XXIII. ˜ et al.32 A 96-well Microtitre plate (Hemobag Produtos Cirurgicos) was coated overnight with ´ Blood coagulation 100 ml of a 5 mg/ml solution of anti-C. durissus IgG in carbonate buffer. After blocking and Venous blood was sampled on admission, at 6, 12 washing, 50 ml serum diluted 1 : 2 in dilution and 24 h after the end of antivenom therapy, buffer was added (1 h, room temperature). The and then daily until discharge from hospital. For plates were washed and incubated with peroxidase coagulation and fibrinolysis assays, 9.0 ml blood coupled with anti-C. durissus IgG (1 h, room was mixed with 0.8 ml 16 mM trisodium citrate temperature). The wells were washed, and the containing 0.2 ml Instituto Butantan Crotalus assay was completed and stopped by the addition monospecific antivenom29 to neutralize any venom of 20 ml of a 1 : 20 dilution of sulphuric acid. present in the sample at the time of collection. The A reference curve was obtained using dilutions citrated blood was centrifuged at 2000 g for 15 min of known concentrations (4–500 ng/ml) of crude at 4 8C and the platelet-poor plasma was frozen venom from C. durissus terrificus. The baseline for in 0.5 ml aliquots at À20 8C until tested. Control the assay was established according to the recom- samples, collected from people with no history of mendations of Theakston33 and Ho et al.34 A cut-off snakebite living in the same region as the victims was established by testing sera from 103 controls of were treated as described above. the same socio-economic group as the patients. The Standardized reagents purchased from Diag- mean"SD OD at 492 nm was 0.037"0.016 for nostics Stago (France) were used to measure the whole venom assay. Using the mean plus 2 SD prothrombin time (PT) and the activated partial as the negative cut-off value for the assays, which thromboplastin time (APTT). Levels of coagulation corresponded to a whole venom concentration factors (factors II, VII, VIII, IX, X, XI, XII) were of 20 ng/ml, two of the 103 normal sera were estimated using deficient plasmas, protein C (PC) positive for whole venom, resulting in a specificity (Staclot protein C assay), cross-linked fibrin frag- of 98.1%. ment (D-dimer, DD) using immunoassay by latex agglutination, a2-antiplasmin (a2-AP) (Stachrom Antiplasmin) and serum fibrin(ogen) degradation products (FnDP/FgDP) using immunoassay (latex Results agglutination). Thrombin-antithrombin antigen (TAT) was determined using an EIA kit system from Clinical observations Behring (Enzygnost-TAT). Factor V was estimated The time between bite and admission to hospital in using the standardized technique of Denson30 the 24 envenomed patients ranged from 2 to 60 h. and fibrinogen levels were measured using the In 13/24 (54%) a tourniquet had been applied, method of Ratnoff and Menzie.31 7/22 (32%) had paraesthesiae, 18/22 (82%) had
  4. 4. 554 I.S. Sano-Martins et al. ptosis, and 10/19 (53%) suffered from myalgia. patients; thrombocytopenia was observed only in Only 1/24 (4%) had respiratory insufficiency on the two fatal cases. admission. The basic information and clinical Twelve hours after antivenom treatment, fibrino- symptoms for each patient are shown in Table 1. gen and FnDP/FgDP levels were within the normal haemostatic range. Fibrinogen levels increased, and this was paralleled by a decrease in FnDP/ Laboratory findings FgDP levels and normalization of DD levels in On admission and before antivenom therapy, 10/22 the plasma. Simultaneous consumption of a2- (45%) patients had a PT-10% and 12/22 (55%) antiplasmin indicated secondary activation of the had a prolonged APTT, with three patients having fibrinolytic system. All these levels had returned totally incoagulable blood (Table 1). Assays of to normal by the time the patient was discharged clotting and fibrinolytic factors showed fibrinogen from hospital (Figure 2). and factor V consumption, consumption of a2-AP As expected, the increased levels of myoglobin and consequent increase of FnDP/FgDP and D-DD in serum, highest on admission, decreased rapidly and the formation of thrombin-antithrombin com- following antivenom therapy (Figure 3a). Serum CK plex in some patients (Table 2). Only 3/5 patients levels were significantly elevated compared with studied had decreased levels of protein C (0%, the normal range (10–120 U/l) from admission to 26%, 49%). 24 h after the start of antivenom (Figure 3b). There were no gross alterations in the haem- However, the differences in CK levels on admission atological picture, although a slight polymorpho- and 12 and 24 h after antivenom were not nuclear leukocytosis was recorded in the majority significant (p)0.05). of cases (Table 2). Interestingly, there was no Admission venom levels were measured in 19/24 alteration in the platelet count in the majority of patients. The mean venom antigen level in the Table 1 Clinical features and relevant laboratory findings on admission in 24 patients envenomed by Crotalus durissus Patient Age Time Dose Paraesthesiae Ptosis Myalgia Tourniquet Classification PT (%) APTT (s) Venom (years) after AV (ml) antigenaemia bite on admission (h) (ng/ml) 1S 39 7 100 À À À q Moderate 64 36 0 2 26 4 200 q q q À Severe -10 ‘ 750 3*a,b,c 15 27 200 ND ND ND À Severe -10 ND 325 4 11 2 100 q q À q Moderate 75 36 162 5S 53 2 150 À q À q Moderate -10 ND 63 6 19 3 100 q q À q Moderate 62 30 172 7 14 9 200 À q À À Severe -10 ‘ 97 8 19 6.5 200 À q q À Severe 45 36 ND 9 27 60 200 À q q À Severe ND 55 ND 10 11 3 200 À q q q Severe 36 34 417 11 13 3 200 À q q À Severe -10 )60 250 12 74 4 100 À q q q Moderate 16.5 35 ND 13*c 50 18 200 ND ND ND q Severe 55 44 ND 14 24 2 100 À À À q Moderate 70 38 0 15 68 7.5 100 À q ND À Moderate 37 )80 0 16 21 5 200 À q q À Severe -5 ‘ 76 17 40 5 200 q q q q Moderate -5 )120 25 18 47 24 100 q q q q Moderate -10 )120 0 19 12 20 100 À q À À Moderate 5 120 0 20 26 7 200 q q ND q Severe -10 )120 95 21 56 5.5 200 q q q q Severe ND )180 0 22S 64 6 100 À À À À Moderate 46 39 0 23S 45 2.5 100 À À À q Moderate 95 29 0 24 24 4 150 À q ND À Moderate 85 32 ND *Fatal case; adeveloped acute renal and respiratory failure; bshowed gingival bleeding on admission; cdeveloped thrombocytopenia; Sdead snake brought with patient to the hospital. ND, not done; AV, Instituto Butantan Crotalus antivenom; PT, prothrombin time; APTT, activated partial thromboplastin time.
  5. 5. Envenoming by C. durissus 555 Table 2 Haematological variables in patients on admis- with gingival bleeding, and oedema and redness sion to hospital (before antivenom therapy) following at the site of the bite. He was tachycardic bites by Crotalus durissus (120 bpm) and tachypnoeic (28 breaths/min) with nasal flaring and audible rhonchi. Blood pressure Parameters Patients Controls was 100/60 mmHg. His blood was incoagulable, with a grossly prolonged prothrombin time, fibrino- Mean"SD n Mean"SD n gen 0.023 g/l, platelets 1663109/l, leukocytes Fibrinogen (g/l) 0.60"0.70 17 2.50"0.36 11 12.33109/l (83% polymorphs), CK 96 000 U/l FII (%) 60"22 16 96"13 8 (3.9% CKMB), haemoglobin 115 g/l, haematocrit FV (%) 33"38 13 120"37 4 35%. The venom antigen level was 325 ng/ml. FVII (%) 87"33 16 102"21 11 Urine was strongly positive for blood, haemoglobin FVIII (%) 71"42 17 117"35 15 or myoglobin. Twenty ampoules of Crotalus anti- FIX (%) 75"33 16 98"27 14 venom (Anticrotalico, Instituto Butantan) was given ´ FX (%) 80"39 7 86"21 7 27 h after the bite. Two hours after admission, FXI (%) 95"55 10 140"39 8 the patient’s respiration had become shallow and FXII (%) 88"28 16 112"9 13 he was intubated, transferred to the intensive care FnDP/FgDP (mg/ml) 564"501 15 4"0 11 D-dimer (mg/ml) 37.3"33.5 17 0.5"0 11 unit and mechanically ventilated, but he may have a2-antiplasmin (%) 36"27 15 100"5 3 aspirated at this time. There was radiographic evid- TAT (mg/l) 73.0"25.4 7 5.3"1.3 3 ence of right basal consolidation. There was evid- Platelets3109/l 278"80 17 237"16 20 ence of renal impairment (urea 760 mg/l, creatinine Erythrocytes31012/l 4.8"0.4 15 5.5"1.0* 20 mg/l) and mild metabolic acidosis. Despite Haemoglobin (g/l) 144"15 15 155"25* treatment with intravenous fluids, furosamide and Haematocrit (%) 44"4 15 47"7* dopamine, urine output was only 500 ml in 24 h, Leucocytes3109/l 12.8"6.1 15 7.5"3.5* and the patient became more comatose with neck Neutrophils3109/l 10.6"6.4 15 2.0 –7.5* rigidity and extensor plantar responses. A brain scan Basophils3109/l 0 15 0.02–0.1* showed no evidence of intracranial haemorrhage. Eosinophils3109/l 0.16"0.23 15 0.04 –0.40* At 42 h after the bite, 12 h after antivenom treat- Lymphocytes3109/l 1.5"0.7 15 1.5–4.0* Monocytes3109/l 0.2"0.2 15 0.2–0.8* ment, blood urea had risen to 1450 mg/l, creatinine to 36 mg/l, potassium to 7 mequiv/l and the FnDP/FgDP, fibrin(ogen) degradation products; TAT, leukocyte count to 16.33109/l (77% polymorphs). thrombin-antithrombin III complex. *Data from Dacie The prothrombin ratio had improved to 42%, and Lewis.35 activated partial prothrombin time (APPT) 50/32 seconds. Following initiation of peritoneal dialysis, the patient’s level of consciousness improved. The 11 moderately envenomed patients was 38.4 ng/ml pupils were equal in size and reacted to light. The "20.0 ng/ml (SEM) and in the eight severely platelet count had fallen to 853109/l. Eighty hours envenomed patients it was 251.2 ng/ml"86.9 after the bite, the patient remained oliguric on ng/ml (SEM) (Table 1). The difference between peritoneal dialysis. Diffuse consolidation developed these levels was statistically significant (p ¼ 0.022). in both lungs, with progressive deterioration in The majority of the severely envenomed patients respiratory and haemodynamic function. He died (6/9, 67%) had an intense coagulopathy (PT-10%) 110 h after the bite. The key features of this on admission, whereas only 4/13 (31%) of the fatal progression were early shock, coagulopathy moderately envenomed patients had evidence of with spontaneous bleeding, renal failure, respiratory severe coagulopathy (PT-10%) on admission failure, rhabdomyolysis and finally, progressive (Table 1). respiratory failure compounded by aspiration pneumonia, adult respiratory distress syndrome and possibly pulmonary haemorrhage. Patient 13 was a 50-year-old man bitten on the Severe coagulopathy in two fatal cases dorsum of the foot. On admission to Hospital Joao ˜ Among the 24 patients, there were two deaths XXIII 15 h after the bite, there was redness and (8.3%). A 15-year-old boy (patient 3) was bitten on swelling at the site of the bite, blurring of vision, the back of the hand and, 8 h later, was admitted bilateral ptosis, diplopia and passage of red urine. to a local hospital, prostrated, sweating, hypo- The blood was incoagulable, with prolonged pro- tensive and in urinary retention. Urethral catheter- thrombin time and APPT and thrombocytopenia ization yielded 1000 ml of cloudy urine. He was (783109/l). Clotting factors V, VIII, VII and X were transferred to Hospital Joao XXIII, arriving 25 h ˜ grossly depleted but with normal levels of factors II, after the bite. He was comatose and dehydrated, IX, XI and XII, indicating disseminated intravascular
  6. 6. 556 I.S. Sano-Martins et al. Figure 2. Plasma concentration of (a) fibrinogen, (b) fibrin/fibrinogen degradation products (FnDP/FgDP), (c) cross-linked fragment D (DD), (d) a2-antiplasmin in patients on admission and following treatment with antivenom. Bars represent the mean"SEM. Numbers over bars ¼ number of patients. Figure 3. Plasma levels of (a) myoglobin and (b) creatine phosphokinase on admission and following antivenom administration in patients bitten by Crotalus durissus. Bars show the mean"SEM. Numbers over bars ¼ number of patients. coagulation. CK was 14 400 U/l (5% CKMB), evidence of renal impairment, falling levels of CK haemoglobin 147 g/l, haematocrit 46%, leukocytes and an increase in platelet count. His vision and 14.83109/l (85% polymorphs). The urine was ptosis improved. On the fourth day of admission strongly positive for blood, haemoglobin or myo- (107 h after the bite), the patient developed visual globin, but there was no evidence of renal impair- and auditory hallucinations with paranoia. There ment. He was treated with 20 ampoules of Crotalus was no biochemical or haemostatic abnormality. antivenom (Anticrotalico, Instituto Butantan) 18 h ´ Ten days after the bite, the patient suffered a fatal after the bite and remained haemodynamically cardiac arrest while taking a bath. Permission for stable, with normal urine output, no biochemical autopsy was not granted by his family.
  7. 7. Envenoming by C. durissus 557 Discussion involved. Alternatively, the thrombin-like enzyme in C. durissus venom may be different from that In this study, the severity of envenoming correlated present in Bothrops venoms, and act more like with venom antigenaemia and haemostatic abnor- physiological thrombin. The thrombin-like enzyme malities on admission to hospital. The four highest of Bothrops jararaca venom is not capable of venom antigen levels were found in the severely clotting rabbit fibrinogen,37 whereas C. d. terrificus envenomed patients. However, in patient 21, venom clots both human (Minimum Coagu- in whom a negative admission venom level was lant Dose, MCD, 21.5 mg/ml) and rabbit (MCD recorded, it is likely that the blood sample was 33.3 mg/ml) fibrinogen.14 This suggests that the taken before release of the tourniquet. It is pos- thrombin-like component of the major Brazilian sible that only after release of the tourniquet subspecies of C. durissus venom has an action were the clinical signs observed, probably due to similar to physiological thrombin. In C. durissus the release of the venom, previously retained by envenoming, all the changes in the coagulation the tourniquet, into the circulation. system, with the exception of fibrinogen levels, Both the fatal cases recorded here had profound are milder than in Bothrops envenoming, as we haemostatic abnormalities including thrombo- reported previously.38 cytopenia. Among 12 cases of fatal envenoming The venom of C. durissus includes a powerful by C. durissus in the State of Sao Paulo, 10 (83%) ˜ myotoxin which causes rhabdomyolysis in patients2 presented with coagulopathy.36 However, the likely and damages the microvasculature of smooth cause of death in patient 3 in the present study was muscle, especially that of endothelial cells lining respiratory complications of probable respiratory the capillaries and arterioles.22 The changes in muscle weakness that required intubation and vascular smooth muscle may be due directly to mechanical ventilation. Other life-threatening the toxic effect of the venom components or effects of envenoming identified in this study were indirectly to the ischaemia39 described in patients hypotension and shock, rhabdomyolysis, possible envenomed by South American rattlesnakes.26 It myocardial damage (patient 13), renal failure and is possible that endothelial cells thus stimulated spontaneous haemorrhage. may release various constituents that can activ- Alterations of the whole-blood clotting time ate the coagulation system. The generation of have been observed in 48% (104/216) of patients intravascular thrombin in C. durissus envenoming bitten by C. durissus, and incoagulability in 38% could therefore be a consequence of the secondary (86/216).26 Some patients present with no detect- activation of the coagulation system as suggested able fibrinogen.27 In this study, consumption in this study. coagulopathy, characterized principally by the Ontogenic variations in snake venoms may be consumption of fibrinogen, factor V and protein C, important.40 In the genus Bothrops, the venoms of was observed with slight depletion of factors II the young snakes of the majority of species contain and VIII; however, levels of other coagulation larger amounts of both factor II and factor X factors were generally within the normal range. activators than those of adult snakes.41 This results The coagulopathy was accompanied by an increase in relatively more severe haemostatic disorders in levels of FnDP/FgDP and DD, and a significant following envenoming by young snakes.42 In consumption of a2-antiplasmin, indicating a sec- young Crotalus atrox, a direct thrombin-like ondary activation of the endogenous fibrinolytic clotting action on fibrinogen was observed in 2–8- system; this is consistent with evidence that month-old specimens; from 11 months onwards, the venoms of C. d. terrificus, C. d. collilineatus the venoms of the same individual snakes no longer and C. d. cascavella do not have fibrinolytic clotted fibrinogen directly.43 However, these activity in vitro.14 An increase in levels of the age-related differences have not been described thrombin-antithrombin complex was also observed, in envenoming by the South American rattle- indicating the formation of intravascular thrombin. snake,44 and there is no reference in the literature The decrease in fibrinogen levels soon after demonstrating ontogenic differences in coagulant the bite can be explained by the thrombin-like activity of the venoms of either C. d. terrificus or enzyme in the venom. However, the alterations in C. d. collilineatus. the levels of some coagulation factors (II, V, VIII and Venom-induced systemic haemorrhage is rarely protein C) and the formation of DD and thrombin- reported following envenoming by C. durissus antithrombin complex, characteristic of physio- subspecies; slight bleeding at the site of the bite is logical thrombin action, are difficult to explain as usual.45 However, according to Jorge and Ribeiro,26 a direct effect of C. durissus venom, since no activ- about 4.8% (12/249) patients had systemic bleed- ator of factors II or X is present.14 It is possible ing; gingival haemorrhage, epistaxis, and vaginal that another, not yet identified, activator may be bleeding. The figures in our study agree, with only
  8. 8. 558 I.S. Sano-Martins et al. one (4.2%) of our 24 patients having signs of (Crotalus durissus terrificus) envenomation in Brazil. Toxicon 1985; 23:631–6. spontaneous systemic haemorrhage, despite the prevalence of severe coagulopathy. Various 3. Nahas L, Denson KWE, Macfarlane RG. A study of the coagulant action of eight snake venom. Thromb Diath snake venoms possess activators and inhibitors of Haemorrh 1964; 2:355–67. platelets.46 In patients envenomed by Bothrops 4. Slotta KH, Fraenkel-Conrat H. Estudos quımicos sobre ´ species, thrombocytopenia is very common, os venenos ofıdicos. 4. Purificacao e cristalizacao do ´ ¸˜ ¸˜ and is frequently associated with a bleeding veneno da cobra cascavel. Mem Ins Butantan 1938; tendency47 and platelet dysfunction.48 However, 12:505–12. in C. durissus envenoming, thrombocytopenia is 5. Moura-Goncalves J, Vieira A. Estudo sobre veneno de ¸ rarely recorded;27 our results support this observa- serpentes brasileiras. I. Analise eletroforetica. An Acad Bras ´ ´ tion. Although it is well known that convulxin is a Cienc 1950; 22:141–50. ˆ potent platelet-aggregating agent6,49 and that cro- 6. Prado-Franceschi J, Vital Brazil O. Convulxin, a new toxin toxin can also cause platelet aggregation,50 in our from the venom of the South American rattlesnake Crotalus study only two patients developed thrombo- durissus terrificus. Toxicon 1981; 19:875–87. cytopenia. The polymorphic leukocytosis observed 7. Raw I, Rocha MC, Esteves MI, Kamiguti AS. Isolation and characterization of a trombin-like enzyme from the venom in C. durissus envenoming is similar to that seen of Crotalus durissus terrificus. Braz J Med Biol Res after bites by many species of snakes, including 1986; 19:333–8. Bothrops.38 8. Barrio A. Giroxin, a new neurotoxin of Crotalus durissus Following treatment with specific C. d. terrificus terrificus venom. Acta Physiol Latinoamericana 1961; antivenom,29 levels of fibrinogen, FnDP/FgDP, DD, 11:224. a2-antiplasmin and myoglobin rapidly returned to 9. Alexander G, Grothusen J, Zepeda H, Schuartzman RJ. normal. In fact, by 12 h after the start of antivenom, Gyrotoxin, a toxin from the venom of Crotalus durissus almost all laboratory haemostatic variables had terrificus, is a thrombin-like enzyme. Toxicon returned to normal; however as would probably 1988; 26:953–60. be expected, CK values remained elevated for 10. Vital Brasil O. Neurotoxins from the South American over 24 h. We can thus confirm the efficacy rattlesnake venom. J Form Med Ass 1972; 71:394–400. of antivenom treatment, as with envenoming by 11. Gopalakrishnakone P, Hawgood BJ. Morphological changes induced by crotoxin in murine nerve and neuromuscular B. jararaca.38 junction. Toxicon 1984; 22:791–804. Clinically moderate and severe systemic 12. Schenberg S. 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