Sub-clinical neuromuscular dysfunction after envenoming by Merrem’s hump-nosed pit viper (Hypnale hypnale)

Does snake envenoming cause chronic kidney disease? A cohort study in rural Sri Lanka

BACKGROUND

There is limited information on the risk of chronic kidney disease (CKD) following snakebite and its relationship with chronic interstitial nephritis in agricultural communities (CINAC). We aimed to investigate CKD in patients with a confirmed snakebite in rural Sri Lanka.

METHODS

Patients prospectively recruited to the Anuradhapura snakebite cohort with authenticated bites were followed up. Two groups of patients were followed up: 199 patients in group I with a snakebite (August 2013-October 2014), reviewed after 4 years, and 168 patients in group II with a snakebite (May 2017-August 2018), reviewed after one year, with serum creatinine (estimated glomerular filtration rate [eGFR]) and urinary albumin to creatinine ratio (ACR).

RESULTS

There were 12/199 (6%) in group I and 9/168 (5%) in group II with AKI following snakebite; 3/12 in group I and 2/9 in group II had haemodialysis. On review after 1 and 4 years, no patient had CKD and all had an eGFR ≥60 mL/min/1.73m². Of 234 patients with a creatinine measured on discharge, 17/140 in group I and 11/94 in group II had a low eGFR (<60mL/min/1.73m²). In group I, 14/17 had a normal eGFR after four years, including 11/12 who had AKI following snakebite, and the 3/17 with a low eGFR on review had CKD or co-morbidities for CKD. In group II, 10/11 had a normal eGFR after one year, including all nine patients with AKI following snakebite, and the one patient with a low eGFR on review had CKD. Fifty patients (25%) in group I and 43 (26%) in group II had a high urinary ACR on review, all but two in each group had microalbuminuria. Multivariate logistic regression showed in group I that only comorbidities for CKD were associated with high urinary ACR, and in group II comorbidities for CKD, snakebite associated AKI and snake type were associated with high urinary ACR. All nine patients from both groups with a low eGFR (CKD stages 3-5) had CKD prior to the snakebite or treatment for hypertension or diabetes.

CONCLUSION

There was no significant association between snakebite-associated AKI and CKD in patients followed up from a snakebite cohort post-bite. Microalbuminuria was common in these patients but likely associated with hypertension, diabetes mellitus and CINAC in this rural farming population.

Long-term health effects perceived by snakebite patients in rural Sri Lanka: A cohort study

The acute effects of snakebite are often emphasized, with less information on long-term effects. We aimed to describe the long-term health effects perceived by patients followed up after confirmed snakebites. Two groups of snakebite patients (>18y) from the Anuradhapura snakebite cohort were reviewed: Group I had a snakebite during August 2013-October 2014 and was reviewed after 4 years, and group II had a snakebite during May 2017-August 2018, and was reviewed after one year. Patients were invited by telephone, by sending letters, or doing home visits, including 199 of 736 patients (27%) discharged alive from group I and 168 of 438 patients (38%) from group II, a total of 367 followed up. Health effects were categorised as musculoskeletal, impact on daily life, and medically unexplained. Health issues were attributed to snakebite in 107/199 patients (54%) from group I and 55/168 patients (33%) from group II, suggesting the proportion with health issues increases with time. Sixteen patients (all viperine bites) had permanent musculoskeletal problems, none with a significant functional disability affecting daily routine. 217/367 reported being more vigilant about snakes while working outdoors, but only 21/367 were using protective footwear at review. Of 275 farmers reviewed, only six (2%) had restricted farming activities due to fear of snakebite, and only one stopped farming. 104/199 (52%) of group I and 42/168 (25%) of group II attributed non-specific symptoms (fatigue, body aches, pain, visual impairment) and/or oral cavity-related symptoms (avulsed teeth, loose teeth, receding gums) to the snakebite, which cannot be explained medically. In multivariate logistic regression, farming, type of snake, antivenom administration, and time since snakebite were associated with medically unexplained symptoms. The latter suggests medically unexplained effects increased with time. Based on two groups of snakebite patients reviewed one and four years post-bite, we show that long-term musculoskeletal disabilities are uncommon and not severe in snakebite survivors in rural Sri Lanka. However, a large portion of patients complain of various non-specific general and oral symptoms, not explainable based on the known pathophysiology of snakebite. These perceived effects of snakebite were more common in patients with systemic envenoming, and were more frequent the longer the time post-bite.

Indian Polyvalent Antivenom Accelerates Recovery From Venom-Induced Consumption Coagulopathy (VICC) in Sri Lankan Russell’s Viper (Daboia russelii) Envenoming

Background

Venom-induced consumption coagulopathy (VICC) is an important clinical consequence of Russell’s viper (Daboia russelii) envenoming. There is limited evidence for antivenom effectiveness in resolving VICC. We aimed to compare the recovery of VICC in patients who received and did not receive antivenom following Russell’s viper envenoming.

Patients and Methods

This was a non-randomized observational study comparing patients with VICC from Russell’s viper envenoming given antivenom for systemic envenoming and those not given antivenom. Antivenom administration was decided by the treating physicians. We included 44 patients with confirmed Russell’s viper bites with one or more International Normalized Ratio (INR) value ≥ 1.5 (VICC). We compared five patients who did not receive antivenom with 39 patients who did receive antivenom. The primary outcome was the proportion of patients with an INR < 1.5 by 48 h post-bite.

Results

The antivenom group had higher peak serum venom concentrations [median (IQR) = 272 (96–1,076) ng/mL versus 21 (8–58) ng/mL] and more severe VICC compared to the no antivenom group. Twenty seven of 39 patients (69%) in the antivenom group had an INR < 1.5 at 48 h post-bite compared to none of the five patients (0%) in the no antivenom group (absolute difference: 69%; 95%CI: 13 to 83%; p = 0.006; Fisher’s exact test). The fibrinogen recovered in 32 of 39 patients (82%) in the antivenom group compared to one of five patients (20%) in the no antivenom group (absolute difference 62%; 95% CI: 28 to 95%; p = 0.001; Fisher’s exact test). Both INR and fibrinogen were significantly improved between 24 and 48 h post-bite in the antivenom group compared to the no antivenom group.

Conclusion

Antivenom accelerated the recovery of VICC in patients with Russell’s viper envenoming, compared to no recovery in a smaller group of patients with milder VICC not receiving antivenom. This supports the efficacy of antivenom in patients with VICC.

A comparative cross-reactivity and paraspecific neutralization study on Hypnale hypnale, Echis carinatus, and Daboia russelii monovalent and therapeutic polyvalent anti-venoms

Envenoming by the hump-nosed pit viper (Hypnale hypnale) raises concern as it inflicts significant debilitation and death in the Western Ghats of India and in the adjacent island nation of Sri Lanka. In India, its medical significance was realized only during 2007 due to its misidentification as Echis carinatus and sometimes as Daboia russelii. Of late, several case reports have underlined the ineptness of the existing polyvalent anti-venom therapy against H. hypnale envenoming. Currently, H. hypnale bite has remained dreadful in India due to the lack of neutralizing anti-venom therapy. Hence, this study was undertaken to establish a systematic comparative, biochemical, pathological, and immunological properties of Sri Lankan H. hypnale venom alongside Indian E. carinatus, and D. russelii venoms. All three venoms differed markedly in the extent of biochemical activities including proteolytic, deoxyribonuclease, L-amino acid oxidase, 5'-nucleotidase, hyaluronidase, and indirect hemolytic activities. The venoms also differed markedly in their pathological properties such as edema, hemorrhage, myotoxic, cardiotoxic, and coagulant activities. The venoms showed stark differences in their protein banding pattern. Strikingly, the affinity-purified rabbit monovalent anti-venoms prepared against H. hypnale, E. carinatus, and D. russelii venoms readily reacted and neutralized the biochemical and pathological properties of their respective venoms, but they insignificantly cross-reacted with, and thus failed to show paraspecific neutralization of any of the effects of the other two venoms, demonstrating the large degree of variations between these venoms. Further, the Indian therapeutic polyvalent anti-venoms from VINS Bioproducts, and Bharath Serums and Vaccines failed to protect H. hypnale venom-induced lethal effects in mice.

Clinico-epidemiology of Hypnale zara (hump-nosed pit viper) envenoming in Sri Lanka

BACKGROUND

Hump-nosed vipers of the genus Hypnale are the most common cause of venomous snakebites in Sri Lanka. The genus includes three species: Hypnale hypnale, Hypnale zara and Hypnale nepa. Of them, H. hypnale bites are the most common and are the subject of many publications. The epidemiology and clinical features of bites by the other two species have been less investigated.

METHODS

We conducted a prospective observational study of H. zara bites from January 2015 to June 2020 at the Teaching Hospital, Ratnapura, Sri Lanka. Data were collected for 5.5 years in the wet zone of the island, where the principal investigator did assessment of all patients and the data collection.

RESULTS

H. zara envenoming was confirmed through identification of dead or live snake specimens brought with the patients. Of the 480 patients with proven hump-nosed viper bites, H. zara bites accounted for 105 (22%), including dry bites (n=5 [5%]) and envenoming (n=100 [95%]), with gender distribution of 65 (62%) males and a mean age of 43.1 y. Most bites occurred on the lower limbs (n=71 [68%]) in the daytime (n=69 [66%]) in home gardens (n=45 [43%]). A total of 100 (95%) patients had local manifestations, including pain (n=100 [95%]), swelling (n=100 [95%]), bleeding (n=20 [19%]), bruising (n=11 [10%]), lymphadenopathy (n=10 [9%]), necrosis at the bite site (n=9 [9%]) and blistering (n=8 [8%]). Seven (6.7%) patients showed systemic effects, including acute kidney injury (n=2 [2%]), microangiopathic haemolysis (n=2 [2%]), sinus bradycardia (2 [2%]) and one (1%) each had coagulopathy, thrombotic microangiopathy, Kounis syndrome and ischaemic changes on electrocardiography. Eosinophilia was a significant haematological finding (n=26 [25%]) and 16 (15%) had leucocytosis and 15 (14%) had neutrophilia. Ninety six percent of patients (n=101) recovered. Antivenom is not available for hump-nosed viper bites in Sri Lanka and therefore patients were managed conservatively.

CONCLUSIONS

This study shows that H. zara bites mainly cause local envenoming and rarely systemic effects.