European Journal of Cardiovascular Medicine

Snakes have always managed to grab human attention and have been an object of fear and veneration since historic civilizations. Snakes are found all over the world except in the Arctic, New Zealand, and Ireland, and are more commonly in temperate and tropical countries. Snakes are most likely to bite human beings when they feel threatened, startled, and provoked, and/or have no means of escape when cornered. Snakes are likely to approach residential areas when attracted by prey, such as mice and frogs. Snakebite is generally considered to be a rural problem and has been linked to environmental and occupational conditions. Snakebite is a common medical emergency and an occupational hazard, more so in Tropical India, where farming is a major source of employment. Over 2000 species of snakes are known worldwide, of which around 400 are venomous. These snakes belong to the families, Elapidae, Viperidae, Hydrophidae, and Colubridae. ⁽¹⁾ Viper bites are more common than other poisonous snakebites in human beings. Of the different varieties of vipers, Russell's viper (Vipera russelli) commonly inhabits the south Asian countries, and the Russell's viper's bite is regarded as an occupational hazard for the farming community.

The involvement of the predominantly young, healthy, and working population in rural areas which are compounded by poverty and the lack of access to health care services in these areas, signifies the social and economic impact of this problem. Most houses in the rural areas of India are made of mud and have many crevices where rodents flourish. Snakes have easy ingress to such houses and often enter them in search of food. Firewood and dried cow dung, stored in or near the house, provide ready shelter for snakes and rodents. ⁽²⁾ Morbidity and mortality from snakebite envenomation depends on the species of snake since the estimated fatal dose of venom varies among species. In India, almost two-thirds of the bites are attributed to the saw-scaled viper (as high as 95%in some areas such as Jammu), about a quarter to Russell's viper, and smaller proportions to cobras and kraits. Most snakebite studies in India deal with clinical and management aspects, and there are few epidemiological studies. (106) Contributing to this in developing nations, there is also deficiencies in the management of complications, transportation, hospital equipment, and public knowledge of appropriate first aid, which result in a mortality rate one hundredfold higher than in developed countries.The victims of snake bites are mainly of the rural population, who are bitten during field work and when sleeping outdoors.(108)

Venomous snakes prevalent in India belong to 3 families. ⁽³⁾ They are:

1.      Elapidae: includes Cobras and Krait – Neurotoxic. Renal involvement is less common in victims bitten by members of this family.

2.      Viperidae: Russell viper and saw scale viper – Vasculotoxic.

3.      Sea snake: Myotoxic.

Renal involvement has been associated with bites from last two families.

RR Singh, DharmendraUraiya, Anoop Kumar, Neeraj Tripathi in their study “Early demographic and clinical predictors of developing acute kidney injury in snake bite patients: A retrospective controlled study from an Indian tertiary care hospital in North Eastern Uttar Pradesh India” found that Of 138 patients who had venomous snake bites, 62 patients developed acute renal injury, putting the incidence of 44.92% for nephrotoxic bites. Renal toxicity due to snake bite occurred within 48 h to IO days of envenomation. Most of the patients (94%) developed symptoms and signs of acute renal failure within 48-72 h, while 6% of patients developed renal manifestations from 5 to 10 days after the snake bite. Most of the snake bite patients were males (84.05%). Patients who developed AKI were mostly older than those who did not develop AKI (34 ± 1.64 vs. 32 ± 1.62) (P < 0.05). In the  study, snake  bite patients  hailed predominantly from the rural population (97.87%). Furthermore, 59 out of 138  venomous  bite patients  (42.75%) took nonmedical treatment before coming to the health facility. Prolonged bite to ASV time had a significant relationship in developing AKI (P < 0.05). Among the clinical features there was an independent positive association of AKI with abdominal pain, tenderness and vomiting, cellulitis, myalgia, and black or brown urine (P < 0.05), as well as and bleeding tendencies, while neurological features had an inverse relation for the development of AKI. Hypotension on initial presentation did not show a positive association with AKI in the study. ⁽⁴⁾

Mukhopadhyay P, R. Mishra, D. Mukherjee, R. Mishra, M. Kar in their study “Snakebite mediated acute kidney injury, prognostic predictors, oxidative and carbonyl stress: A prospective study” found that Two hundred and three snakebite patients (44.13%) developed AKI and 155 (33.70%) received HD during the period of April 2010  to  July  2011.  Most of the cases were from viper bite. There were 107 males and 48 females. The mean age was 36.2 ± 1.27 (range 4–74) years.  Pediatric (<18 years) population were 29 (18.7%) and elderly (>60) were 12 (7.7%). Most patients came from Midnapur district of West Bengal. The most common site of the bite was lower limb (88.7%). About 74.2% had received primary treatment in the form of tetanus toxoid and wound management. Oliguria and bleeding manifestation were the common presentation. Hypotension was found in 52 (33.5%) cases, cellulites and severe inflammation were found in 63.2% patients. Two patients had panhypopituitarism, 8.38% had regional lymphadenopathy. Mean creatinine was 4.56 ± 0.24 mg/ dl. About 42 (27.1%) had acute disseminated intravascular coagulation (DIC) as evidenced by thrombocytopenia and low plasma fibrinogen level. Isolated thrombocytopenia was found in 15 (9.68%) patients. Average 21.5 ± 1.94 vial (1 vial = 10 ml) ASV was used during treatment. Median number of HD was required 3 sessions. Mean hospital stay was 11 (range 2–34) days. Bite to HD initiation time was 3.2 days. The most common indication of HD was oliguria and rising creatinine. Forty‑six (29.7%) patient died during the hospital stay. Among expired patients 10 (34.48%) were <18 years. About 36 (78.2%) had cellulites and/or severe inflammation, 24 (52.2%) had hypotension or shock at initial presentation, bleeding manifestation was found in 37 (80.4%), and 22 (47.8%) had DIC (P < 0.05). Among variables subjected to univariate analysis  hypotension, DIC, bleeding manifestation, and cellulitis/ severe inflammation were found to predict the adverse outcome (i.e. death) of the SAKI patients underwent HD. Logistic regression analysis yields that cellulitis and severe inflammation (odds ratio [OR] =2.729, confidence interval [CI] =1.23–6.053, P = 0.012) and bleeding manifestation (OR = 2.78,  CI  = 1.22–6.053, P = 0.012) were confounding risk factor (Wald statistics, P > 0.05) for adverse outcome of SAKI patients whereas DIC (OR = 4.08, CI = 1.917–8.678, P < 0.001) and hypotension/shock (OR =  3.156,  CI  =  1.535–6.487, P = 0.001) at initial presentation came out as independent predictor of death (Wald statistics, P < 0.05). ⁽⁵⁾

Chugh K S, Pal Y et al in their article "Acute Renal Failure following Poisonous Snake bite" in AJKD, 1984 described their findings on 157 patients admitted at PGI,Chandigarh, India & found Bilateral Renal Cortical Necrosis(6%), Acute Tubular Lesion(15%) to be the major renal pathology. Mortality & sepsis was more in BRCN than ATL. They concluded that ARF in snakebite victims was multifactorial & a direct cytotoxic effect of the venom could be responsible for this effect. ⁽⁶⁾

This Descriptive, Observational, Cross-sectional, autopsy-based study was done after getting IEC Permission Vide Memo No.-BMC/I.E.C./547 dt 24/11/2022. All the dead bodies of snake bite cases that came for medicolegal autopsy at Burdwan Police Morgue after being screened through the following exclusion criteria :-

             I.          Decomposed bodies.

           II.          Any prior gross pathology in kidney.

         III.          Doubtful cases of snake bite.

Employment of the complete enumeration method made the sample size 51 (n= 51). The findings of the Naked Eye (gross) examination were noted and findings of histological are compared with those of normal tissue. Sample from the ward are taken by biopsy gun at the renal angle with the deceased in the prone position.

Socio-Demography related data were gathered from the Police Inquest.

After collection, data were analyzed by available statistical software.

TABLE 1: MONTH WISE DISTRIBUTION OF SNAKE BITE (n=51)

• Incidence of snake bite was maximum during rainy season in the month of June, July, August with August having the highest number of victims (12, approx 24%).
• Victims were lowest in winter during December, January & February; there was single victim during all those 3 months.

FIGURE 1: MONTH WISE DISTRIBUTION OF SNAKEBITE

TABLE 2 : SEX COMPOSITION OF VICTIMS ( n=51)

• Males are 69.4%, females are 30.6% in the study group.

.

FIGURE 2: SEX COMPOSITION OF VICTIMS

TABLE 3 : AGE WISE DISTRIBUTION (n=51)

Maximum number of victims in the study group fall between the age range 41 to 50 years; there is only 2 victims each in the age range less than 10 & more than 70 years of age

FIGURE 3: AGE WISE DISTRIBUTION

TABLE 4 : ADDMISSION TO BURDWAN MEDICAL COLLEGE AND HOSPITAL FOR TREATMENT (n=51)

• Out of 51 cases, 30 patients were admitted in BMC&H, while 21 were brought from outside.

FIGURE 4: ADMISSION TO BURDWAN MEDICAL COLLEGE FOR TREATMENT

TABLE 5 : DISTRIBUTION ACCORDING TO TIME OF BITE(n=51)

• Highest number (20, 39.2%) of snakebite occurred between 6am to 12pm, most being between 6am to 6:30am, followed by those between 6pm to 12midnight (14, 27.5%).

Least incident (7, 13.7%) were in between midnight to 6am.

FIGURE 5: DISTRIBUTION ACCORDING TO TIME OF BITE

TABLE 6 : DISTRIBUTION ACCORDING TO SITE OF BITE (n=51)

• Highest number of bite were in the lower limb (41, 80.5.%), followed by upper limb (7, 13.7%) , (2, 3.9%) in the abdomen and lowest in the head-neck region (1, 1.9%)

FIGURE 6: DISTRIBUTION ACCORDING TO SITE OF BITE

TABLE 7 : DISTRIBUTION ACCORDING TO NATURE OF SNAKE (n=51)

• Out of 51 snakebite, 30 victims died due to vasculotoxic snake bite, while 21 victims died due to neurotoxic snake bite

FIGURE 7: DISTRIBUTION ACCORDING TO NATURE OF SNAKE

TABLE 17: DISTRIBUTION ACCORDING TO RESIDENTIAL AREA OF VICTIMS (n=51)

• Among 51 victims, maximum 11 victims are from  RAINA PS and 10 from   MONGALKOTE PS constituting about 21.6 % and 19.6% respectively.

FIGURE 15: DISTRIBUTION ACCORDING TO RESIDENTIAL AREA

The present descriptive, cross sectional, hospital and autopsy based study, conducted at Burdwan Medical College and Hospital  during September 2022 to January 2024  and included cases which fulfilled the selection criteria. Those with decomposed body or visible pathology in kidney were excluded from the study. Relevant statistical analysis was done using Chi square test and multivariate analysis, wherever applicable and p value less than 0.05 were considered to be statistically significant. During this period of 18 months, there were 51 cases of death due to snakebite, comprising 1.95% of all the autopsies done at BMCH Police morgue. The number of snakebite victims during 2020 and 2021 were 2.38% and 2.26%. In last 36 months, deaths due to snakebite accounted for 2.22% of all autopsies done at this centre. This relative percentage is somewhat less than those observed by Mohapatra and Warrel ⁽⁷⁾ in their study based in Andhra Pradesh (6.2%) or that in Burdwan district by Hati and Mandal ⁽⁸⁾ (10.1%). This apparent reduction is prevalence may be due to the fact that the present study was conducted at a tertiary level hospital, where the number of snakebite victims reporting for treatment has gradually reduced over the last few years, increase in number of new medical colleges from of districts and due to better treatment facilities, the mortality has also reduced to a great extent.

In the present study, the population comprises 29(57%) males and 22(43%) females with a sex ratio of 1.32:1 in the study group. Almost similar observations were made in studies conducted by Hati & Mandal ⁽⁸⁾ in Burdwan, Yogesh&Satish ⁽⁹⁾ (2014) in Bangalore, Kulkarni ML &Anees S ⁽¹⁰⁾ (1994) in Karnataka, Ganneru B &Sasidhar RB ⁽¹¹⁾ (2007) in Andhra Pradesh and Suchitra N et Al ⁽¹²⁾ (2008) in Kerala. This observation is not consistent with the findings recorded in the study conducted by Monterio NP et al ⁽¹³⁾ (2017) in Manipal, where female predominance was recorded with male to female ratio of 1:1.5. The probable reason for male predominance is males are more involved in outdoor activities compared to females.   

The mean age of subjects was 44.62 years with a range of 54 years. The highest age is 73 years & the lowest is 08 years. A maximum number of the subjects were aged 41 to 50 years. Overall this had the highest (12, 23.5%) number of people among all age groups. Similar findings were observed by Satish et al ⁽⁹⁾  (2008), Bhardwaj and Sokhey ⁽¹⁴⁾ (1998), Hansdak et all ⁽¹⁵⁾ (1998), and Inamdar et al ⁽¹⁶⁾ (2010). This age group, in both sexes, is ambulant, and mostly involved in outdoor activities -- hence the higher incidence of snake bite in this group.

Snakebite, like all other insect bites, has a definite seasonal variation, varying widely in temperate & tropical climates. In this study, as seen from Table 1, the incidence of snakebite was maximum during the rainy season in the months of June, July & August; with August having the highest number of victims (12, 23.6%). Victims were lowest in winter during December, January & February months. This finding is similar to that of Hansdak et al ⁽¹⁵⁾ (1998), Lahori et al ⁽¹⁷⁾ (1981). During the rainy season, rainwater floods their burrows and snakes then try to take shelter near human dwellings, which increases the chances of snakes feeling threatened or startled or provoked by human beings, and biting them in defense. Also, the humid climate is a favorable habitat for poisonous snakes, thus increasing the mortality.

Table 5 reveals that the highest number (20, 39.2%) of snakebites occurred between 6 am to 12 noon with most happening between 6 am to 6:30 am, followed by those between 6 pm and 12 midnight (14, 27.5%). Thus, snakebites commonly occur during the dark hours of the day. Similar diurnal variation was observed in the studies by Bawaskar HS et al ⁽²⁾ (2008) in rural Maharashtra, and Monterio NP et al ⁽¹³⁾  (2010) in Manipal. Least incidents occurred in between 12 midnight to 6 am as humans were less active at that time & interaction with snakes was a low possibility.

In Table 6, the site of snakebite was described, which shows that in (41, 80.5%) cases, the snakebite was in the lower limbs, upper limbs in (7, 13.7%), and abdomen in (2, 3.9 %)  cases. This was similar to the findings of Yogesh et al ⁽⁹⁾ (2014), A similar observation was reported in a study which was done by Viramani et al ⁽¹⁸⁾ (1987), Banerjee et al ⁽¹⁹⁾ (1978). When farmworkers are in the fields, cutting grass, etc., their lower limbs, hands, and fingers are closest to ground level. Consequently, snakebites are more common on the lower and upper extremities. Also, people accidentally step on snakes while walking, thus snakebite is more common in the lower limbs. The bite on the abdomen may be attributed to the fact that they were bitten while they were sleeping on the ground.

In Table 4, we see that out of all victims, (30, 58.8%) were admitted to BMC&H, while the other (21, 41.2%) were admitted to other health facilities including PHC, BPHC, and Private Hospital with Nursing Homes.  Most of the victims were treated at a primary center before referral.

In Table 7, we find that (30, 58.8%) of victims died after a vasculotoxic snakebite, whereas the rest (21, 41.2%) were due to a neurotoxic bite. This is because most of the victims after a vasculogenic bite required further treatment after the development of AKI and were referred to a tertiary center for the same.

The small sample size is the major limitations of the study. The entire work was done on fatal cases of venomous snakebites brought to a tertiary hospital morgue for the purpose of medicolegal autopsy over a span of twelve months. In this periods, by purposive sampling technique, only fifty one subjects could be taken. They varied in various socio demographic factors, thus making the statistical analysis results more complicated. Though statistical significant result were achieved, they could not be generalized to the population as a whole, mainly because of the small sample size in the study. This limitation can be overcome by choosing a longer time period, or by performing the study in several centres simultaneously.

Funding

This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

Acknowledgment

We are sincerely thankful and grateful from core of our heart to Dr. Soma Ghosh, Associate Professor, Department Of Pathology, Budwan Medical College and Prof (Dr.) Sanchita Das Kundu, Professor and Head of the Department, FMT of Raigunj Medical College, WB to act as the orchestra master of our study

Conflict Of Interest

The authors declare that there is no conflict of interest. This research work is a part of the dissertation of the First Author, submitted at the West Bengal University of health sciences in compliance with partial fulfilment of eligibility for the MD Examination for the year 2024.

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