Epidemiology and clinical features of Hypnale nepa (hump-nosed pit viper) envenoming in Sri Lanka.

Sri Lanka homes 3 species of hump-nosed pit vipers including Hypnale Hypnale, H. zara and H. nepa from which, latter 2 are endemic to the country. Even though former 2 are the subject of several publications, no major clinical studies have been done regarding H. nepa bites. As these snakes confine only to central hills of the country, their bites are very rare. The objectives of this study were to describe epidemiological and clinical features of H. nepa bites. A prospective observational study was conducted for patients admitted with H. nepa bites to Teaching Hospital, Ratnapura, Sri Lanka for 5 years commencing from June 2015. Species identification was done using a standard key. There were 14 (3.6%) patients with H. nepa bites of which 9 (64%) were males and 5 (36%) were females. Their age ranged from 20 to 73 years (median 37.5). Seven bites (50%) occurred on lower limbs. Majority of bites (10; 71%) happened at daytime [0600-1759 h] in tea estates (8; 57%). Most patients (8; 57%) were admitted within 1-3 h from bite. Hospital stay was 2.5 days (IQR 2-3). Local envenoming was observed in all patients including local pain and swelling [mild (7; 50%), moderate (5; 36%), severe (2; 14%)], local bleeding (1; 7%) and lymphadenopathy (1; 7%). Nonspecific features were observed in 3 (21%). Systemic manifestations were found in 2 (14%) including microangiopathic haemolytic anaemia and sinus bradycardia. Two (14%) had myalgia. H. nepa bites frequently cause local envenoming. But, rarely systemic manifestations may occur.

Therapeutic Plasma Exchange for Venom-Induced Thrombotic Microangiopathy Following Hump-Nosed Pit Viper (Genus: Hypnale) Bites: A Prospective Observational Study.

INTRODUCTION: -Thrombotic microangiopathy (TMA), which is the triad of acute kidney injury (AKI), microangiopathic hemolytic anemia (MAHA), and thrombocytopenia, is a rare complication of snakebites, and in Sri Lanka, it is commonly seen with hump-nosed pit viper (HNPV) bites. METHODS: -We conducted a prospective observational study of patients with AKI caused by HNPV bites in Teaching Hospital, Ratnapura, Sri Lanka for 6 y, commencing in June 2015. Some patients with TMA underwent therapeutic plasma exchange (TPE) and some did not. These 2 groups were compared. Statistical analysis was carried out using Minitab 18.1. Data were presented as median (IQR). RESULTS: -There were 52 (8%) patients with TMA, of whom 21 (45%) were in the TPE group and 26 (55%) were in the non-TPE group. TPE improved time to platelet correction (4 d [IQR, 4-5 d] vs 7 d [IQR, 5-9 d]; P=0.009), time to MAHA correction (5 d [IQR, 3-4 d] vs 7 d [IQR, 6-9 d]; P=0.004), time to prothrombin time (PT)/international normalized ratio (INR) correction (1 d [IQR, 1-2 d] vs 3 d [IQR, 3-4 d]; P=0.003), and time to 20 min whole blood clotting test (WBCT20) correction (2 d [IQR, 1-2 d] vs 3 d [1QR 2-3 d]; P=0.020). Renal recovery was predicted by TPE (P=0.048) and highest creatinine level (P=0.001). There was no association between TPE and dialysis dependency at discharge (P=0.597), length of hospital stay (P=0.220), and the number of dialysis cycles prior to discharge (P=0.540). TPE did not improve the number of blood transfusions (5 packs [IQR, 3-8.5 packs] vs 4 packs [IQR, 0-9 packs]; P=0.290). CONCLUSIONS: -TPE is effective for TMA in the early correction of platelet counts, MAHA, PT/INR, and WBCT20 in HNPV bites.

Kounis Syndrome Following Hypnale zara (Hump-Nosed Pit Viper) Bite in Sri Lanka.

A 47-y-old man was bitten by a hump-nosed viper (Hypnale zara) and gradually developed retrosternal chest pain associated with ST segment elevation on electrocardiogram. He had normal troponin I levels and no evidence of coagulopathy. Initially, he was managed as having anterior ST elevation myocardial infarction with thrombolysis. Later, because troponin levels were normal, he was suggested to have the type I variant of Kounis syndrome (allergic coronary artery spasm). This was supported by high eosinophil counts in peripheral blood. He was successfully managed with supportive treatment and discharged 6 d after the snakebite. Cardiac complications are rarely reported after hump-nosed viper bites, and clinical reports of coronary vasospasm after snakebites are extremely rare in the literature. This is the first known report of Kounis syndrome after a hump-nosed viper bite.

Thrombotic Microangiopathy Following Hypnale zara (Hump-Nosed Pit Viper) Envenoming: The First Known Case Report from Sri Lanka.

A 65-y-old previously healthy farmer developed thrombotic microangiopathy (TMA) comprising the triad of acute kidney injury, microangiopathic haemolysis, and thrombocytopenia after a proven Hypnale zara (hump-nosed pit viper) bite. He developed coagulopathy, which was treated with fresh frozen plasma, and underwent 8 cycles of hemodialysis. He is being followed up in the nephrology clinic for acute kidney injury. TMA caused by Hypnale hypnale, the commonest species of genus Hypnale, has previously been reported, but this is the first known case of TMA following a bite by H zara, the endemic species in Sri Lanka.