Saudi Journal for Health Sciences

: 2020  |  Volume : 9  |  Issue : 2  |  Page : 130--135

A retrospective study on snakebite and its outcome from a referral-cum-teaching hospital of Kolkata, India

Sisir Chakraborty1, Prithwijit Banerjee2, Rajdip Hazra3, Somnath Maity2, Swati Banerjee4, Niladri Sarkar5,  
1 Department of General Medicine, College of Medicine and Sagore Dutta Hospital, Kolkata, West Bengal, India
2 Department of Pharmacology, College of Medicine and Sagore Dutta Hospital, Kolkata, West Bengal, India
3 Department of Anaesthesiology, Coochbehar Government Medical College and Hospital, Coochbehar, West Bengal, India
4 Department of Statistics, Indian Institute of Social Welfare and Business Management, Kolkata, West Bengal, India
5 Department of Internal Medicine, Institute of Postgraduate Medical Education and Research, Kolkata, West Bengal, India

Correspondence Address:
Somnath Maity
Department of Pharmacology, College of Medicine and Sagore Dutta Hospital, 578 B.T. Road, Kamarhati, Kolkata - 700 058, West Bengal


Background: Snakebite-related fatality is among the highest in West Bengal and such patients display variety of clinical features. Precious time is also lost during the transport to health-care centers. Aim: The study was undertaken to find out the incidences and mortality associated with different snakebites and to compare the clinical features between the survivor and nonsurvivors. Materials and Methods: The data were derived from 286 indoor case records of snakebites from a referral hospital of Kolkata during January 2018 to September 2019. Patients' demographic details, exact bite history with subsequent management, clinical profile, and final outcome were compiled for analysis. Student's t-test and Fisher's exact test were performed to find out statistical significance. Results: The mean age of the patients was 28.44 ± 16.92 years and 69.23% were male. Overall, 67.13% of patients required hemodialysis and 13.63% ultimately died. Russell's viper caused the most number of bites (58.04%) and highest mortality (15.66%). Nonsurvivors had significantly higher levels of creatinine, urea, total count, total bilirubin, and prothrombin time and significantly low hemoglobin and platelet counts than that of the survivors. Bite-to-hospital time was also significantly prolonged among nonsurvivors (9.08 ± 9.68 h versus 4.64 ± 5.58 h; P = 0.0001). The highest (29.17%) mortality was observed among those who reported after 12 h of bite. Conclusion: Maximum snakebite-related mortalities were due to Russell's vipers in the current study. Patients with prolonged bite-to-hospital time were most vulnerable. Sepsis, coagulopathy, and acute kidney injury were significantly higher among the nonsurvivors.

How to cite this article:
Chakraborty S, Banerjee P, Hazra R, Maity S, Banerjee S, Sarkar N. A retrospective study on snakebite and its outcome from a referral-cum-teaching hospital of Kolkata, India.Saudi J Health Sci 2020;9:130-135

How to cite this URL:
Chakraborty S, Banerjee P, Hazra R, Maity S, Banerjee S, Sarkar N. A retrospective study on snakebite and its outcome from a referral-cum-teaching hospital of Kolkata, India. Saudi J Health Sci [serial online] 2020 [cited 2020 Oct 31 ];9:130-135
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Shockingly, India contributes to 50% of the estimated deaths due to venomous snakebites globally.[1] As many as 35,000–50,000 people succumb to snakebite every year in this country and experts still feel that the real number could be much higher thanks to gross underreporting of data.[2] West Bengal along with Uttar Pradesh, Andhra Pradesh, Bihar, Tamil Nadu, and Maharashtra exhibited the highest incidence of fatalities.[3] The incidence is even higher among rural areas because many of the snakebite victims loose precious time undergoing traditional and unscientific treatment before they actually reach hospital.[4]

Mainly four venomous land snakes pose public health problem in India. They are Elapidae, including cobra (Naja naja) and krait (Bungarus caeruleus) and Viperidae including Russell's viper (Daboia russelii) and saw-scaled viper (Echis carinatus).[5] Antisnake venom (ASV) remains the only specific treatment, and delay in ASV administration was associated with high incidence of complications and fatality in snakebite patients.[6],[7] Even in the referral center, the outcome of snakebite patients widely varies depending on the nature of bite and the time lost for the initiation of medical treatment. Furthermore, there was a lack of recent data from Kolkata regarding the snakebite-related outcome and bite-to-hospital time analysis. Therefore, the present study was conducted at a government referral-cum-teaching hospital in Kolkata to find out the incidences of various snakebites, their clinical manifestations, and mortality and to compare the clinical parameters between those who survived and those who did not.

 Materials and Methods

This was a retrospective study conducted at a government teaching-cum-tertiary care center of Kolkata. The data were derived from indoor case sheets of the admitted snakebite patients from January 2018 to September 2019 after obtaining requisite ethical approval from the institution. Initially, 403 case records were screened for the study. Many of these cases were referred from various peripheral health-care centers and lacked few vital data. Therefore, only 286 cases were finally considered in which the complete bite history and subsequent medical events were well documented, especially the time interval between the bite and first hospitalization, details of ASV administration, and other medical management and fatalities. The time difference in hours between the snakebite and first access to any health-care facility was termed as bite-to-hospital time. In many instances, the patients' relative or accompanying persons' statement was documented. During the hospital stay, many of the tests were repeated as a part of the treatment. In such circumstances, the peak value was considered for analysis. Identification of the snake species was done on the basis of the nature of fang marks, initial symptoms, and site of the bite. In many occasions, accompanying persons carried the corpse of the snake to the health-care center along with the victim. In two instances, the snake's picture was captured by the local people for later identification.

For statistical analysis, first, the relevant clinical as well as biochemical details, treatment course, and outcomes of all these patients during their hospital stay were tabulated in Microsoft Excel in a specially designed format. Continuously distributed variables were expressed in the form of mean with standard deviations. Student's t-test was performed to determine the significance of differences between the means of two independent samples. Fisher's exact test was used for the comparison of categorical variables. As per convention, P ≤ 0.05 was considered statistically significant. Computer-based statistical software was used for the analysis.


The basic details of the all 286 cases selected are shown in [Table 1]. The observation suggests that majority of the snakebites took place (61.88%) in rural areas. The mean bite-to-hospital time was found to be 5.13 ± 5.97 h. The average time spent in hospital was estimated as 6.44 ± 4.09 days. Overall, 39 (13.63%) deaths occurred as a direct consequence of the snakebites in the present study.{Table 1}

In the current observation, the incidence rates of different types of snakebites and consequent mortalities were also identified. The details of the same are depicted in [Table 2]. Russell's viper topped the list both in the categories of incidence of bite and resultant deaths.{Table 2}

[Table 3] demonstrates the range of symptoms exhibited by the snakebite patients once they reached the study center. Significant overlapping of clinical symptoms was evident in the study. However, cellulitis (67.83%) and vomiting (53.84%) appeared to be the most common in the list, whereas only 3 (1.04%) cases of convulsions were reported, making it the rarest symptoms of all.{Table 3}

The entire study population was subdivided into two categories based on the ultimate survival of these patients. Thirty-nine patients who died as a direct result of the snakebite were included in the nonsurvivor group, whereas the rest 247 patients fell in the survivor group. Comparison of various parameters of these two groups is displayed in [Table 4].{Table 4}

The mean age was found to be lower in the nonsurvivor category, which was statistically insignificant. Even though there were some numerical differences between the two groups in terms of male ratios, total vials of administered ASV, and total length of hospital stay, no statistical significance could be drawn. However, the proportion of rural patients was significantly higher in the nonsurvivor group (79.48% vs. 59.1%; P = 0.0201). Bite-to-hospital time expressed in hours was significantly lower in the survivor group comparatively (4.64 ± 0.58 vs. 9.08 ± 9.68; P = 0.0001). Peak serum creatinine, urea, total bilirubin, WBC count, and prothrombin time were significantly higher among the nonsurvivor category. Hemoglobin value and platelet count appeared higher in the survivor group, which was statistically significant as well. 153 (61.94%) patients required the support of hemodialysis once or more in the survivor category, whereas all 39 patients underwent during the observation period. This difference was statistically significant too.

In [Table 5], mortality due to delayed reporting of the snakebite cases to the health-care center is displayed. For this, the exact time gap between the bite and first contact with the health-care center was considered. A gradual increase in mortality rate with time delay was found during the analysis. The highest mortality of 29.17% was observed among those who reported after 12 h and more from the time of snakebite.{Table 5}


Snake–bite is still a public health problem in India. The present study was an attempt to describe the incidences of different snakebites and related mortalities and to compare the clinical picture between the survivors and nonsurvivors of the snakebite victims at a referral center in Kolkata for a period of 1 year and 10 months.

In [Table 6], incidences of various types of snakebites reported by the previous Indian authors were summarized with the current one. Depending on the study site, proportion of different snake species exhibited a wide variation. The nature of the culprit snake was established in as high as 93.36% of cases in the present observation.{Table 6}

In most of the studies including the present one, Russell's viper was responsible for maximum number of bites and the incidence varied from 0% to 95%. Likewise, cobras appeared to be the second highest biter species followed by kraits. However, there was a paucity of data regarding the species-specific mortality among those trials. Russell's viper caused most deaths (15.66%), followed by common kraits (13.15%) and cobra (12.69%) based on the current data.

The presenting symptoms of the patients varied depending on whether the snake was hemotoxic or neurotoxic. Cellulitis and bleeding manifestation were commonly encountered with the former type, whereas peripheral neuroparalysis was most frequently reported with the later type during the current analysis. Similar observation was made by Halesha et al. in earlier research work.[8] The demographic features and some of the clinical parameters of snakebite patients documented by earlier observations were compared against the present one in [Table 7]. Except the study by Vikrant et al., male vulnerability to snakebite was evident unequivocally in all studies including the present one. This is simply because of the outdoor nature of their daily work, more so in rural settings. In the present study, majority (61.88%) of the snakebites were reported from rural areas where working in the field, sleeping on the floor, and walking barefoot were prevalent among large number of people.{Table 7}

Young adults displayed maximum susceptibility to snakebites in all previous clinical studies from India in the past one and half decade. In fact, the mean age was found to be least in the current observation among others. It suggests that the working young men are more prone to become snakebite victims.

Total duration of hospital stay in snakebite in this study was governed by the extent of envenomation, delay in initiating medical management, involvement of other systemic complications, and presence of comorbidities. In an earlier study, up to 46 days of hospitalization was reported.[17] However, the maximum was found to be 18 days in the current study. Patients who especially developed acute kidney injury (AKI) underwent repeated hemodialysis and thus required prolonged hospitalization. Associated comorbidities such as hypertension and diabetes mellitus often aggravated the situation. Interestingly, the total days spent on hospital were significantly lower among the nonsurvivors according to the present data. This can be justified by the fact that many patients from the nonsurvivors group expired within early treatment days.

Previous data also suggested that mortality went up as the percentage of patients requiring renal replacement therapy increased following snakebite and the present study too followed the similar trend. This is because of development of AKI, which is a strong predictor of in-hospital mortality among snakebite cases.[10],[18] Dharod et al. had earlier documented AKI as one of the major complications in areas where viper biters were predominant.[18]

The differences of various biochemical values between the survivors and nonsurvivors were compared in [Table 8] with the present analysis. Although statistical significance was absent in some of the earlier studies, serum urea and creatinine values were consistently higher among the nonsurvivors due to underlying renal injury associated with snake venom. The combined role of microangiopathic hemolytic anemia, disseminated intravascular coagulation, and direct nephrotoxicity of the snake venom was suggested by previous author in the pathogenesis of AKI following snakebite.[22] Phospholipase A2 present in the venom was blamed for some of those effects.[18] A raised total WBC count and reduced platelet count indicated inflammation and ongoing sepsis. Overall, platelet counts could be reduced thanks to the combination of consumptive coagulopathy and direct toxicity of the venom on platelets as documented by previous author.[18] Reduced mean hemoglobin values and elevated serum total bilirubin showed underlying hemolysis. Numerically higher incidences of bleeding manifestation were documented in all three authors though statistical significance was lacking unlike the present one which showed a significantly increased P-time among the patients died of snakebites.{Table 8}

In [Table 9], the association between time factor and mortality as well as development of AKI is tabulated based on the data from previously conducted clinical studies. Overall, there is sacrosanctity regarding the association of lesser bite-to-hospital time, an improved final mortality outcome in all studies. Sarkhel et al. and Ghosh et al. reported the least two snakebite-related mortalities in recent times owing to the narrow gap between snakebite and to hospital reporting.[14],[15]{Table 9}

Just like the present study data, bite-to-hospital time was significantly higher among the nonsurvivors of the snakebite patients in three previous literatures. As a matter of fact, the bite-to-hospital time was found to be the least in the present study. Consequently, the overall mortality of the present study stood much lower than that of Athappan et al. and Harshavardhan et al.[9],[10] The current analysis also revealed that 41.6% of patients reached hospital after 6 h of the bite. Halesha et al. found the same value quite similar as 38.8% earlier.[8]

In a similar fashion, bite-to-hospital time was consistently higher among the patients developed AKI following snakebite in three previous reports. The same parameter was however not evaluated in the current analysis. Thus, the above data strongly reiterates the importance of quick referral and transport of the patients to the near most health-care center to start medical management.

It is noteworthy that no statistically significant differences could be derived in terms of total ASV vials administered in both survivor and nonsurvivor categories in the previous reports of Athappan et al., Harshavardhan et al. and Mukhopadhyay et al.[10],[13] The findings of the current analysis was in concurrence with that.

Limitation of the study

The result from a single center-based retrospective study with relatively smaller sample size is often not applicable when it comes to larger population. This remained the most important limitation of the present study. Second, the identification of snake and documentation of the post bite events in a few cases were also done on the basis of history provided by patient or accompanying person and could not be verified. Another shortcoming of the study was the calculation of the exact bite-to-hospital time. The additional time lost to start the medical treatment after reporting to the hospital was not factored in during the present analysis.[24]


At the end of this retrospective institution-based study, the overall snakebite-related mortality was 13.63%, which was comparable to previous studies. Russell's viper was identified as the most frequent biter and was also responsible for the highest mortality. Patients from rural areas and with prolonged bite-to-hospital time were most vulnerable to die from snakebite. Sepsis, coagulopathy, and acute kidney injury were found to be significantly higher among the nonsurvivors. Community awareness regarding appropriate first aid, rapid transfer to health-care centers, and early initiation of ASV with proper supportive care hold to key to improve the mortality burden among the snakebite victims.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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