Coagulopathy and extensive local swelling following Green pit viper (Trimeresurus trigonocephalus) envenoming in Sri Lanka

Effect of Agkistrodon halys antivenom in patients bit by green pit viper and the prognostic role of the disease - a retrospective cohort study

BACKGROUND AND AIMS

In Mainland China and Hong Kong, health authorities utilize Agkistrodon halys antivenom in the treatment of patients who sustained bites from green pit vipers. However, the treatment benefit of Agkistrodon halys antivenom among such patients is still controversial. The purpose of this study is to evaluate the coagulation parameters normalization time of Agkistrodon halys antivenom in patients who sustained green pit viper bites and explore independent risk factors of patient prognosis.

METHODS

Data were extracted from the Donghua Hospital Information System. Comparison of the two groups of patients - who used antivenom (GPUA) and who did not use antivenom (GPNUA) were performed using stratified analysis, univariate and multivariate ordered logistic regression models to evaluate the coagulation parameters normalization time. Univariate and multivariate ordered logistic regression models were used to explore independent risk factors of patient prognosis.

RESULTS

Between the GPUA and GPNUA groups, there is no significant difference in the coagulation parameters normalization time with the treatment of Agkistrodon halys antivenom. GPNUA consumed more cryoprecipitate and platelets and had a lower cost. The patient's severity of the bite, first coagulation profile, and dosages of fresh frozen plasma, platelet, and red cell suspension was found to be risk factors for the normalization time of coagulation parameters.

CONCLUSIONS

The therapeutic effect of Agkistrodon halys antivenom in green pit vipers bite patients is not quite satisfying. In addition, more attention should be paid to the first coagulation profile, blood clotting factors indices, platelet count (PLT), and hemoglobin when treating such patients.

Potential para-specific and geographical utility of Thai Green Pit Viper (Trimeresurus albolabris) Monovalent Antivenom: Neutralization of procoagulant and hemorrhagic activities of diverse Trimeresurus pit viper venoms

The Trimeresurus complex consists of diverse medically important venomous pit vipers that cause snakebite envenomation. Antivenoms, however, are in limited supply, and are specific to only two out of the many species across Asia. This study thus investigated the immunoreactivities of regional pit viper antivenoms toward selected Trimeresurus pit viper venoms, and examined the neutralization of their hemotoxic activities. Trimeresurus albolabris Monovalent Antivenom (TaMAV, Thailand) exhibited a higher immunoreactivity than Hemato Bivalent Antivenom (HBAV, raised against Trimeresurus stejnegeri and Protobothrops mucrosquamatus, Taiwan) and Gloydius brevicaudus Monovalent Antivenom (GbMAV, China), attributed to its monovalent nature and conserved antigens in the Trimeresurus pit viper venoms. The venoms showed moderate-to-strong in vitro procoagulant and in vivo hemorrhagic effects consistent with hemotoxic envenomation, except for the Sri Lankan Trimeresurus trigonocephalus venom which lacked hemorrhagic activity. TaMAV was able to differentially neutralize both in vitro and in vivo hemotoxic effects of the venoms, with the lowest efficacy shown against the procoagulant effect of T. trigonocephalus venom. The findings suggest that TaMAV is a potentially useful treatment for envenomation caused by hetero-specific Trimeresurus pit vipers, in particular those in Southeast Asia and East Asia. Clinical study is warranted to establish its spectrum of para-specific effectiveness, and dosages need be tailored to the different species in respective regions.

Identifying the snake: First scoping review on practices of communities and healthcare providers confronted with snakebite across the world

BACKGROUND

Snakebite envenoming is a major global health problem that kills or disables half a million people in the world's poorest countries. Biting snake identification is key to understanding snakebite eco-epidemiology and optimizing its clinical management. The role of snakebite victims and healthcare providers in biting snake identification has not been studied globally.

OBJECTIVE

This scoping review aims to identify and characterize the practices in biting snake identification across the globe.

METHODS

Epidemiological studies of snakebite in humans that provide information on biting snake identification were systematically searched in Web of Science and Pubmed from inception to 2nd February 2019. This search was further extended by snowball search, hand searching literature reviews, and using Google Scholar. Two independent reviewers screened publications and charted the data.

RESULTS

We analysed 150 publications reporting 33,827 snakebite cases across 35 countries. On average 70% of victims/bystanders spotted the snake responsible for the bite and 38% captured/killed it and brought it to the healthcare facility. This practice occurred in 30 countries with both fast-moving, active-foraging as well as more secretive snake species. Methods for identifying biting snakes included snake body examination, victim/bystander biting snake description, interpretation of clinical features, and laboratory tests. In nine publications, a picture of the biting snake was taken and examined by snake experts. Snakes were identified at the species/genus level in only 18,065/33,827 (53%) snakebite cases. 106 misidentifications led to inadequate victim management. The 8,885 biting snakes captured and identified were from 149 species including 71 (48%) non-venomous species.

CONCLUSION

Snakebite victims and healthcare providers can play a central role in biting snake identification and novel approaches (e.g. photographing the snake, crowdsourcing) could help increase biting snake taxonomy collection to better understand snake ecology and snakebite epidemiology and ultimately improve snakebite management.

Sri Lankan green pit viper (Trimeresurus trigonocephalus) bites in Deniyaya: A clinico-epidemiological study

Green pit viper (Trimeresurus trigonocephalus) is endemic to Sri Lanka and bites are reported from tropical rain forest and plantation areas. As scant data exists on clinico-epidemiological features of Sri Lankan green pit viper bite, objective of this study was to address this knowledge gap. A prospective observational study was conducted in Base Hospital Deniyaya from October 2013 to September 2015. Green pit viper as the offending snake was identified when the victims brought live or dead specimens. When the specimen was not available, green pit viper was identified by the victim pointing to preserved specimens and photographs of green pit viper and different similar appearing snakes. Clinical details were recorded during the hospital stay. Twenty four green pit viper bite patients (17-68 years) were studied. All cases were daytime bites despite green pit viper being a nocturnally active snake. Sixteen patients (67%) were bitten while they were working in tea plantation. Hands (42%), feet, (33%), forearms (8%), legs (8%), thighs (4%) and shoulders (4%) were the sites of bites. Thirteen (54%) had extensive limb swelling. Nine (38%) had local swelling and two had no swelling. Three (12.5%) developed haemorrhagic blisters. Four (17%) had regional lymphadenopathy. Two (8%) developed non clotting blood by the TWBCT. Green pit viper bites caused substantial morbidity. Risk factors included day time outdoor activities in bordering villages of tropical rain forests and occupation. Pain, extensive limb swelling and bite site swelling were prominent clinical features. However haemorrhagic blisters, regional lymphadenopathy and coagulopathy were reported. Nephrotoxicity and neurotoxicity were notably absent.

A confirmed bite by a Beautiful Pit Viper (Trimeresurus venustus) resulting in local symptoms

This case report describes the effect of an envenomation by the Beautiful Pit Viper Trimeresurus venustus (or Cryptelytrops venustus), which is a green pit viper native to Thailand and Malaysia. A previously healthy 60-year-old snake breeder with no relevant medical history was bitten by his adult T. venustus in the third finger of his right hand while taking it out of the feeding box. The bite was painful and swelling progressed to include his whole hand within an hour after the bite. He was treated symptomatically with pre-emptive antibiotics and analgesics, never developed any hematological disorders such as coagulopathy and bleeding or disseminated intravascular coagulation and was discharged 26 hours after the bite. The clinical course in our patient matched two other well-documented cases reported to our Poisons Centre, and one further case presented as a conference-poster. All patients recovered with symptomatic therapy and never required antivenom. Therefore, bites by T. venustus seem to present with less severe symptoms compared to other Trimeresurus species.

Epidemiology and clinical features of Green pit viper (Trimeresurus trigonocephalus) envenoming in Sri Lanka

Green pit viper is a venomous endemic snake in Sri Lanka. But little is known regarding its envenoming in the country. This study was carried out in order to find out epidemiology and clinical profile of its bites. A series of 17 patients with Sri Lankan Green pit viper (Trimeresurus trigonocephalus) bites was prospectively studied over 4 years. The mean age was 36 ½ years (range 12-61 years) and comprised 14 (82%) males. Except one case, all bites occurred during day time (0600 h-1800 h) due to inadvertent provocation. In 13 cases (76%) bite took place in estates (tea or cinnamon) and 8 patients (47%) were estate workers. The bitten sites were upper limbs in 11 cases (65%) and lower limbs in 6 cases (35%). Ten patients (59%) brought the offending snake to the hospital and one patient was asymptomatic. Sixteen (94%) developed local envenoming features- 16 (94%) local pain and swelling, 6 (35%) local bleeding and lymphadenopathy and blistering in 4 (24%) patients. Systemic envenoming developed in 4 (24%) patients including 3 (18%) with coagulopathy that was treated with fresh frozen plasma. One (6%) patient developed bradycardia. Sri Lankan Green pit viper bites commonly occurs in estates and causes local envenoming frequently and coagulopathy occasionally.