Hui Wen Fan

Snakebite envenoming from a global perspective: Towards an integrated approach

Snakebite envenoming is a neglected public health challenge of compelling importance in many regions of the world, particularly sub-Saharan Africa, Asia, Latin America and Papua-New Guinea. Addressing the problem of snakebite effectively demands an integrated multifocal approach, targeting complex problems and involving many participants. It must comprise: (a) Acquisition of reliable information on the incidence and mortality attributable to snakebite envenoming, and the number of people left with permanent sequelae. (b) Improvements in production of effective and safe antivenoms, through strategies aimed at strengthening the technological capacity of antivenom manufacturing laboratories. (c) Increasing the capacity of low-income countries to produce specific immunogens(snake venoms) locally, and to perform their own quality control of antivenoms. (d) Commitments from regional producers to manufacture antivenoms for countries where antivenom production is not currently feasible. (e) Implementation of financial initiatives guaranteeing the acquisition of adequate volumes of antivenom at affordable prices in low-income countries. (f) Performance of collaborative studies on the safety and effectiveness of antivenoms assessed preclinically and by properly designed clinical trials. (g) Development of antivenom distribution programmes tailored to the real needs and epidemiological situations of rural areas in each country. (h) Permanent training programmes for health staff, particularly in rural areas where snakebites are frequent.(i) Implementation of programmes to support those people whose snakebites resulted in chronic disabilities. (j) Preventive and educational programmes at the community level, with the active involvement of local organizations and employing modern methods of health promotion. Such an integrated approach, currently being fostered by the Global Snake Bite Initiative of the International Society on Toxinology and by the World Health Organization, will help to alleviate the enormous burden of human suffering inflicted by snakebite envenoming.

A clinical and epidemiological study of Loxosceles spider envenoming in Santa Catarina, Brazil

A clinical and epidemiological study of 267 cases of envenomation by Loxosceles spp. (loxoscelism), notified to Centro de Informações Toxicológicas de Florianópolis (Santa Catarina State, Brazil), was conducted between January 1985 and December 1995. Most of the incidents occurred along the coast of the mid-southern region of the state, during the warmest months. L. laeta and L. intermedia were identified as the causative agents. Cutaneous loxoscelism was clinically diagnosed in 232 (86.9%) patients with local pain (86.5%), oedema (80.5%), hyperaemia (79.8%) and necrosis (56.9%). Cutaneous-visceral loxoscelism was detected in 35 patients (13.1%) with intravascular haemolysis, manifested by jaundice (68.6%), oliguria (45.7%), dark urine (28.6%), haemorrhage (25.7%), anuria (8.6%) and shock (2.9%), besides the cutaneous effects. Specific antivenom was given to 125 patients (46.8%) and only 8 (6.5%) had mild reactions. Acute renal failure was observed in 17 cases (6.4%); 4 patients (1.5%) died, all of whom were children under 14 years old.

Reliability of the simple 20 minute whole blood clotting test (WBCT20) as an indicator of low plasma fibrinogen concentration in patients envenomed by Bothrops snakes

Reliability of the simple 20 minute whole blood clotting test (WBCT20) as an indicator of low plasma fibrinogen concentration in patients envenomed by Bothrops snakes. Toxicon 32, 1045-1050, 1994.--A simple whole blood clotting test (WBCT20) was assessed for its efficacy in determination of severe defibrinogenation in patients envenomed by Bothrops snakes in Brazil. There was a close relationship between the results of the WBCT20 and plasma fibrinogen levels in 69 moderately envenomed patients. The advantage of the WBCT20 over estimation of plasma fibrinogen concentrations in patients is that it is a simpler, faster and more reliable test. It is also of use in assessing the effectiveness of antivenom therapy in relation to the restoration of blood coagulability.

Clinical trial of two antivenoms for the treatment of Bothrops and Lachesis bites in the north eastern Amazon region of Brazil

The efficacies of specific Bothrops atrox-Lachesis and standard Bothrops-Lachesis antivenoms were compared in the north eastern Amazon region of Brazil. The main aim was to investigate whether a specific antivenom raised against the venom of B. atrox, the most important Amazon snake species from a medical point of view, was necessary for the treatment of patients in this region. Seventy-four patients with local and systemic effects of envenoming by Bothrops or Lachesis snakes were randomly allocated to receive either specific (n = 38) or standard (n = 36) antivenoms. In 46 cases (24 in the standard antivenom group, 22 in the other) the snake was identified either by enzyme immunoassay or by examination of the dead snake, as B. atrox in 45, L. muta in one. Patients were similar in all clinical and epidemiological respects before treatment. Results indicated that both antivenoms were equally effective in reversing all signs of envenoming detected both clinically and in the laboratory. Venom-induced haemostatic abnormalities were resolved within 24 h after the start of antivenom therapy in most patients. The extent of local complications, such as local skin necrosis and secondary infection, was similar in both groups. There were no deaths. The incidence of early anaphylactic reactions was 18% and 19%, respectively for specific and standard antivenoms; none was life-threatening. Measurement of serum venom concentrations by enzyme immunoassay (EIA) confirmed that both antivenoms cleared venom antigenaemia effectively. EIA also revealed that one patient had been bitten by Lachesis muta, although the clinical features in this case were not distinctive.

Sequential randomised and double blind trial of promethazine prophylaxis against early anaphylactic reactions to antivenom for bothrops snake bites

Abstract Objective: To investigate the efficacy of the H1 antihistamine promethazine against early anaphylactic reactions to antivenom. Design: sequential randomised, double blind, placebo controlled trial. setting: Public hospital in a venom research institute, São Paulo, brazil. Participants: 101 patients requiring antivenom treatment after being bitten by bothrops snakes. Intervention: Intramuscular injection of promethazine (25 mg for adults and 0.5/kg for children) or placebo given 15-20 min before starting intravenous infusion of antivenom. Main outcome measures: Incidence and severity of anaphylactic reactions occurring within 24 hours after antivenom. Results: Reactions occurred in 12 of 49 patients treated with promethazine (24%) and in 13 of 52 given placebo (25%); most were mild or moderate. Continuous sequential analysis indicated that the study could be interrupted at the 22nd untied pair, without preference for promethazine or placebo. Conclusion: Prophylaxis with promethazine does not prevent early reactions. Patients should be observed carefully during antivenom infusion and the subsequent few hours. Key messages Antivenom therapy may cause early anaphylactic reactions Various drugs are used to prevent reactions, but none have been tested in randomised controlled studies This study showed that promethazine is not better than placebo at preventing early reactions Although most reactions are mild or moderate, trials of other drugs should be done to reduce frequency of anaphylaxis

Stability, distribution and use of antivenoms for snakebite envenomation in Latin America : Report of a workshop

The issues of antivenom stability and distribution, and the training of health staff in the correct use of antivenoms in Latin America were discussed in a workshop held at Instituto Clodomiro Picado, Costa Rica, in September 16-19, 2008, under the auspices of the program CYTED. Participants from public antivenom production laboratories of the region, together with representatives of the Ministries of Health, from Argentina, Paraguay, Brazil, Bolivia, Perú, Ecuador, Colombia, Venezuela, Panamá, Costa Rica and Nicaragua participated in the event. Technical advances in the study of antivenom stability and in the design of novel formulations aimed at generating products of higher stability were presented. In addition, antivenom acquisition and distribution systems in every country were presented and discussed, together with novel tools that could be useful for improving antivenom distribution, such as the software SIGEpi, developed by the Pan American Health Organization. The issue of the cold chain, as well as the most frequent causes of misuse of antivenoms in the region, were also analyzed. Finally, the experiences of training programs for health staff on the correct use of antivenoms in snakebite envenomation treatment in Latin America were presented. It was concluded that, in addition to the fostering of antivenom production and quality control, renewed efforts should be implemented at improving the stability, distribution and correct use of antivenoms in the region.

Hemorrhagic syndrome and Acute renal failure in a pregnant woman after contact with Lonomia caterpillars: a case report

A case of a 37-week pregnant woman who developed a hemorrhagic syndrome and acute renal failure after contact with Lonomia caterpillars is reported. The accident also initiated labour and the patient gave birth to an alive child. Some pathophysiological aspects of the genital bleeding and of the acute renal failure are discussed.

Envenoming by Bothrops jararaca in Brazil: association between venom antigenaemia and severity at admission to hospital

The association between the clinical severity of Bothrops jararaca envenoming at admission and serum venom and plasma fibrinogen concentrations before antivenom administration is reported in 137 patients admitted to Hospital Vital Brazil, Instituto Butantan, São Paulo, Brazil, between 1989 and 1990. Other variables such as age, gender, site of the bite, use of tourniquet and the time interval between the bite and start of antivenom therapy, spontaneous systemic bleeding, and the 20 minute whole blood clotting test (20WBCT) at admission showed no association with either severity or serum venom antigen concentration (SVAC). Mean SVAC in patients with mild envenoming was significantly lower than in the group with moderate envenoming (P = 0.0007). Patients with plasma fibrinogen concentrations > 1.5 g/L had a lower mean SVAC than patients with plasma fibrinogen concentrations < or = 1.5 g/L (P = 0.02). Those admitted with a tourniquet in place had significantly higher plasma fibrinogen concentrations than those without a tourniquet (P = 0.002). A multiple logistic regression model showed independent risk factors for severity: bites at sites other than legs or forearms, SVACs > or = 400 ng/mL, and the use of a tourniquet. Rapid quantification of SVAC before antivenom therapy might improve initial evaluation of severity in B. jararaca bites.

Envenomation by Micrurus coral snakes in the Brazilian Amazon region: report of two cases

Two cases of proven coral snake bites were reported in Belém, Pará State, Brazil. The first case was a severe one caused by Micrurus surinamensis. The patient required mechanical ventilation due to acute respiratory failure. The second case showed just mild signs of envenomation caused by Micrurus filiformis. Both patients received specific Micrurus antivenom and were discharged without further complications. Coral snake bites are scarcely reported in the Amazon region and there is a broad spectrum of clinical manifestations, varying from extremely mild to those which may rapidly lead to death if the patient is not treated as soon as possible.

Epidemiologic and clinical survey of victims of centipede stings admitted to Hospital Vital Brazil (São Paulo, Brazil).

We retrospectively analyzed 98 proven cases of centipede stings admitted to Hospital Vital Brazil, Butantan Institute, São Paulo, Brazil, between 1990 and 2007. Most stings occurred at the metropolitan area of São Paulo city (n=94, 95.9%), in the domiciles of patients (n=67, 68.4%), and during the warm-rainy season (n=60, 61.2%). The mean age of the victims was 32.0+/-18.8-years-old. Cryptops and Otostigmus genera were responsible for most cases. Around 86% of the patients sought medical care within 6h after the sting. Both lower (56.1 %) and upper limbs (41.8 %) were most frequently bitten, especially the feet and hands (89.8%). The most frequent local clinical manifestations were pain (94.9%), erythema (44.9%) and edema (21.4%), and the latter was mainly observed in patients bitten by Otostigmus spp. Supportive treatment was used in only 28.6% of the patients, namely administration of local anesthesia (9.2%) and systemic analgesia (13.3%). No sequels or complications were observed in patients, and the prognostic was benign.