India: Snake bites are recognized by the WHO as a high priority neglected health issue

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Snakebite victims in India are getting the treatment they need quicker thanks to a public health campaign lead by a University of Reading researcher together with collaborators in India.

By working closely with a partnership of hospitals, doctors, schools and community groups, campaigners were able to provide life-saving advice and information to more than 3 million residents in rural Tamil Nadu, India, at a cost of only £25,000.

In the 12 months following the campaign, regional hospital TCR Multispeciality Hospital, Tamil Nadu saw the number of people seeking medical treatment for snakebites within the crucial first four hours increase from 60% to 95%, and most of these are aware of the campaign.

The results are outlined in a new paper published in PLOS Neglected Tropical Diseases published today (Thursday 31 December 2020). The scientist behind the campaign now hopes the success of their pilot could encourage funding for a nationwide campaign across rural India and elsewhere globally following the same model, potentially saving thousands of lives by breaking myths around snakes and snakebites, and encouraging people to seek prompt hospital treatment instead of practicing inappropriate first aid or ineffective traditional treatments.

Dr. Sakthi Vaiyapuri, Associate Professor in Cardiovascular & Venom Pharmacology at the University of Reading led the campaign and personally spent time in the rural regions of Tamil Nadu, India raising awareness about how to get prompt medical help for a snakebite.

Dr. Vaiyapuri said:

Snakebites are recognized by the WHO as a high priority neglected health issue, killing 140,000 people each year and leaving nearly half a million people permanently disabled, largely as a result of lack of sufficient public awareness about snakes and snakebites, and therefore delay in seeking prompt treatment.

“One of the major challenges in reducing the devastating effect that snakebites can have is ensuring that people in rural areas know that they need to get immediate medical help, especially in areas where people don’t automatically turn to healthcare in emergency situations.

We know that many people in rural communities believe that plant extracts from traditional healers are an effective treatment after a snakebite.

The Venomous Snakebites: rapid action saves lives campaign sought to promote a clear public message in harder to reach rural areas, with the simple message that seeking professional healthcare at the nearest hospital is best, and could save your life.

“We were delighted that the campaign was able to have a significant positive effect for the rural communities around Tamil Nadu that we worked with.

The four-hour window is extremely important for someone to get effective treatment after being bitten by a venomous snake. Timely access to healthcare will save lives.”

The Venomous Snakebites: rapid action saves lives campaign was set up to counter the continuing prevalence of deaths and serious disabilities caused by snakebites in rural populations of South India.

The public health campaign used a mixed media approach including print and online media, plus social media posts, which had combined reach of more than 2.8 million people. The team from the University of Reading and partners including Dr. C Soundararaj and Dr. Stephen Paul from TCR Multispeciality Hospital along with NGOs, journalists, snake rescuers and social activists in India also ran public engagement events in schools and rural communities which reached more than 200,000 people in person.

In a follow-up questionnaire, 85% of school children who took part in educational events were able to recall the key information about how to seek medical help after a snakebite even after one year—up from 10% before the campaign.

As well as public engagement, the team also ran a symposium for healthcare professionals based in rural areas of Tamil Nadu and accredited by the Tamil Nadu Medical Council.

The team strongly believes that a multifaceted communication education program similar to this study will enhance the public awareness about snakebites and thereby, prevent the snakebite-induced deaths and disabilities in rural areas of developing countries where snakebite is a major concern.


The World Health Organization (WHO) estimates that 81,000–138,000 people die each year from snakebites worldwide, and about three times that number survive and but are left with amputations and permanent disabilities (World Health Organization (WHO), 2019a).

Bites by venomous snakes can cause acute medical emergencies involving shock, paralysis, hemorrhage, acute kidney injury and severe local tissue destruction that can prove fatal or lead to permanent disability if left untreated. Most deaths and serious consequences from snakebite envenomation (exposure to venom toxins from the bite) are avoidable by timely access to safe and effective antivenoms (Gutiérrez et al., 2017).

Snakebite deaths and envenomation are largely neglected topics in global health. However, in 2017, the WHO included snakebite envenoming in the priority list of neglected tropical diseases (World Health Organization (WHO), 2019b) and launched in 2019 a strategy for prevention and control of snakebite, aiming to halve the numbers of deaths and cases of serious disability by 2030 as compared to 2015 baseline (World Health Organization (WHO), 2019c).

Achieving this goal will require substantial progress in India, which is home to approximately half of global snakebite deaths. Snakebite deaths and disability remain a major public health challenge also for poor rural communities in many parts of Asia, Africa, Latin America and Oceania.

Direct estimation of 46,000 annual snakebite deaths in India in 2005 (Mohapatra et al., 2011) prompted a revision of the WHO’s global total, which had estimated about that number for the entire world. The 2005 Indian estimate relied upon analyses of about 123,000 verbal autopsy records from 2001 to 2003 in the Registrar General of India’s (RGI) Million Death Study (MDS), one of the largest nationally representative mortality surveys. Now the MDS has reported cause-specific mortality patterns on over 600,000 deaths from 2001 to 2014 for the whole of India.

Here, we report seasonal and temporal trends in snakebite mortality over the last two decades in India and its spatial distribution. We provide estimates of total snakebite deaths for the 20-year period 2000–2019 by age and sex. Our earlier report estimated a crude ratio of about one death to 20 envenomations. We now further quantify the levels of envenomations based on a systematic review of 88,000 snakebites in the published literature.

The literature also provides details on the specific causes, bite locations, and treatment of envenomations. Finally, enhanced surveillance including facility-based tracking will be central to the Government of India’s strategies to reduce snakebite deaths. Thus, we provide estimates on the degree to which snakebites and deaths are reported adequately in public facilities. Appendix 1—figure 1 shows the overall study design, data sources, input resources and outcomes.Go to:

Results

Trends in snakebite mortality and its geographic and temporal patterns

From 2001 to 2014, the MDS reported deaths with causes classified by physicians who examined verbal autopsy records collected from over 3.6 million households in three distinct nationally representative sampling frames (1993–2003; 2004–13; and 2014–23).

Two of 404 independent physicians coded each death to the International Classification of Diseases-10th revision (ICD-10), reconciling (anonymously) any coding differences with a senior physician adjudicating any persistent disagreements (Gomes et al., 2017Aleksandrowicz et al., 2014Menon et al., 2019).

Among 611,483 available records, 2833 deaths were assigned to snakebites (ICD-10 code X20). The two physicians agreed on the diagnosis 92% of the time. About 94% of snakebite deaths occurred in rural areas, and 77% occurred out of hospital (Appendix 1—table 1).

We applied the age- and sex-specific proportion of snakebite deaths to total deaths as estimated by the United Nations Population Division (UN) for India (United Nations, 2019) to estimate national death rates by age and sex, as well as absolute totals for each year (Table 1).

The UN totals are based on careful demographic review of census and other data sources. The fieldwork procedures of the Sample Registration System (SRS the underlying demographic survey on which the MDS is based) leads to some undercounts (of about 5–10%) of expected deaths (Gerland, 2014).

The SRS is representative at the state and rural/urban strata, and has a large, distributed sampling covering over 7000 small areas in the whole of the country (Registrar General of India, 2017). Hence, any missing deaths are generally randomly distributed across states, and not clustered in one state or one key sub-group, such as in rural areas (Dhingra et al., 2010Aleksandrowicz et al., 2014Menon et al., 2019). Thus, the proportion of snakebite deaths is not likely an underestimate. However, total snakebite deaths might be underestimated. The use of the UN death totals adjusts for these possible undercounts and provides a plausible national total for each year.

Table 1. – Snakebite deaths in the Million Death Study, age-standardized and age-specific mortality rates and risks in India from 2001-2014.

YearStudy deaths from snakebite/all causesStandardized death rate /100,000 (all ages) and age-specific rates /100,000*Snakebite mortality riskEstimated national deaths (000)
All ages0-1415-2930-69
2001199 /418265.35.43.65.90.40%55.0
2002183 /417405.25.23.55.80.39%55.3
2003179 /387985.15.03.45.80.38%55.8
2004190 /373805.04.63.55.70.38%55.6
2005244 /467554.94.83.46.40.40%60.8
2006214 /474715.34.73.26.70.40%62.7
2007225 /485365.34.53.06.40.39%61.0
2008215 /476735.14.22.85.90.36%57.4
2009183 /478734.73.92.65.30.33%53.8
2010200 /457194.33.92.65.00.32%52.4
2011185 /460994.24.02.75.10.33%54.9
2012227 /466354.34.32.85.40.36%59.2
2013214 /453314.64.43.05.80.38%62.3
2014175 /296474.74.23.05.90.37%61.2
2001-20142833 /6114834.84.53.15.80.37%807.5
Plausible range (Lower, Upper)§(4.4, 5.0)(4.1, 4.7)(2.8, 3.2)(5.3, 6.0)(0.34%, 0.38%)(738.2, 833.4)
* Death rates were standardized to the Indian population in census year 2001 to take into account minor changes in the age distribution over time.
 The probability of dying due to snakebite before reaching age 70 years in the hypothetical absence of other competing causes of death. This was calculated by summing the 5-yearly standardized death rates from ages 0 to 69 years.
 Total death estimates at all ages were calculated by applying the MDS sample weighted proportion of deaths from snakebites, using weighted 3-yearly moving average, to the United Nations Population Division death totals.
§ Plausible ranges: The inherent variation in these estimates is not from the underlying demographic estimates but in the determination of primary causes of death. Therefore, we used plausible ranges based on independent cause assignment by two physicians and subsequent agreement on ICD-10 codes (X20 or X29). The lower bound was based on immediate agreement of both physicians and upper bound based on either of two physicians coding snakebite deaths.

Total snakebite deaths in India from 2001 to 2014 totaled about 808,000, with reasonably narrow uncertainty range of 738,000 to 833,000, based on both physicians immediately assigning snakebites or only one physician doing so. Some age-specific death rates fell, but as population growth averaged 1.1% annually, the application of annual age-specific rates to the UN death totals for that year showed that the overall number of snakebite deaths grew from about 55,000 in 2001 to about 61,000 in 2014. During the 2001–2014 MDS study period, the average age-standardized snakebite death rate (using the Indian census population of 2001 to take into account the minor change in age structure) was 4.8 per 100,000 population, falling annually by 0.8%.

Declines in the age-specific snakebite death rate were fastest for children aged 0–14 years (declining by about 1.6% annually), with slower declines in young adults aged 15–29 years (1.2% annually) and no declines among middle-aged adults (30–69 years).

Before 2010, snakebite death rates were higher in boys than girls but from 2010 to 2014, death rates in girls exceeded those for boys (Appendix 1—table 1). The age-specific risks translate to a probability of 0.37% (uncertainty range 0.34–0.38%) of dying from snakebite before age 70 years in the absence of competing mortality (Table 1). This suggests that the average risk of an Indian dying from snakebite prematurely before age 70 is approximately 1 in 250.

Because the risk of dying from snakebites has been stable from 2001 to 2014, we can make reasonably reliable forward projections from 2015 to 2019 and backward projections from 2001 to 2000 (Table 2). This reveals that 1.2 million snakebite deaths occurred over this 20-year period. Of these deaths, 602,000 occurred among males and 565,000 occurred among females.

With both sexes combined, about 543,000 (47%) occurred in middle-age (30–69 years), 325,000 (28%) among children below 15 years, 197,000 (17%) among adults aged 15–29 years, and 102,000 (9%) among those over age 70 years. Using the agreement of one or two physicians on the cause yielded generally narrow uncertainty estimates for each sex and age groups.

Table 2.

Estimated snakebite deaths in thousands by age and sex from 2000 to 2019 in India.

Age rangeMale (LL, UL)Female (LL, UL)Both (LL, UL)
0-14 years149 (134, 154)176 (160, 180)325 (294, 334)
15-29 years109 (102, 111)88 (82, 89)197 (184, 199)
30-69 years290 (269, 303)253 (232, 260)543 (501, 564)
70 years or above54 (45, 60)48 (44, 50)102 (89, 110)
All Ages602 (551, 626)565 (518, 578)1,167 (1068, 1204)
Total deaths for 2001-2014 MDS study period were 807,500 (Table 1). Deaths for 2000-2019 were calculated by extrapolating these annual deaths. The extrapolated annual deaths in thousands for outside the study period were 54.0 for 2000, 62.3 for 2015, 62.0 for 2016, 61.4 for 2017, 60.3 for 2018 and 59.8 for 2019.
Lower limit (LL) and Upper limit (UL) are lower and upper uncertainty bounds for estimates. The major uncertainty in our analyses, however, is not the demographic totals, but the cause of death classification. Hence, the lower bound was based on immediate agreement of both physicians on the ICD-10 code for snakebite and upper bound based on either of two physicians coding as snakebite death.

From 2001 to 2014, just under 70% of these snakebite deaths occurred in eight states with about 55% of the population: Bihar, Jharkhand, Madhya Pradesh, Odisha, Uttar Pradesh, Andhra Pradesh (which includes Telangana, a recently defined state), Rajasthan and Gujarat (Table 3).

In these high-burden states, the age-standardized death rate was about six per 100,000. Snakebite death rates generally rose over time in most high-burden states, particularly in Bihar, but fell in Andhra Pradesh. The remaining lower-burden states began the study period with age-standardized death rates of about 3.7, which fell over time. 

Figure 1 shows the absolute risk of dying from snakebite using data from 7400 small areas (the small sampling units used in the RGI’s Sample Registration System for the MDS) from 2004 to 2013. The absolute risks were calculated applying spatially smoothed predictive relative risks from a spatial Poisson model to the overall national risk before age 70 years (of about 0.4%, Table 1) after adjusting for any differences in rural/urban status, female illiteracy levels, temperature, and altitude of local areas. We observed greater than 0.6% (1 in 167) mortality risk before age 70 years in the highest risk sub-areas of Andhra Pradesh, Odisha, Bihar, Uttar Pradesh, Madhya Pradesh, Chhattisgarh, and Rajasthan. About 260 million people lived in these areas in 2015, including about 4 million people living in hot spots that had a 1% or greater risk of death from snakebite. Appendix 3 provides statistical details and credible intervals of these risk estimates.

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Figure 1.
Spatial distribution of snakebite mortality risk in India for 2004-13.Note: About 0.33% of the Indian population lived in areas with an absolute risk of 1% or greater of dying from snakebite before age 70 years, and 21% lived in areas with absolute risk of 0.6% or higher. Population estimates used the Gridded Population of the World version 4 for year 2015 (Center for International Earth Science Information Network – CIESIN – Columbia University, 2015). Further details of statistical method and stochastic uncertainties of spatial mortality risk pertaining to these estimates are explained in Appendix 3.

Table 3.

Snakebite death rates by state in India for 2001-2014.

Study deaths in MDSAnnual average standardized death rate /100,000Estimated deaths for 2001-14 (000)
State2001-20042005-20092010-2014Trend
Higher burden states17265.96.16.2An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf1.jpg557.4
Andhra Pradesh2718.57.35.6An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf2.jpg82.9
Bihar3215.67.68.9An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf3.jpg101.9
Odisha1917.57.25.9An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf4.jpg40.3
Madhya Pradesh1956.77.76.0An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf5.jpg67.8
Uttar Pradesh3225.25.96.0An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf6.jpg153.6
Rajasthan1924.96.75.0An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf7.jpg52.1
Gujarat1764.14.85.1An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf8.jpg38.8
Jharkhand584.92.07.1An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf9.jpg20.1
Lower burden states11073.73.12.1An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf10.jpg249.9
Chhattisgarh426.06.52.5An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf11.jpg16.8
Jammu & Kashmir645.37.00.9An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf12.jpg7.0
Tamil Nadu1766.13.43.0An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf13.jpg42.1
Karnataka1375.63.32.9An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf14.jpg33.0
Maharashtra1474.23.72.6An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf15.jpg56.0
West Bengal1884.13.32.9An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf16.jpg42.7
Punjab672.93.14.0An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf17.jpg14.5
Haryana452.93.31.8An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf18.jpg9.5
Assam272.80.72.1An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf19.jpg7.3
Northeastern states372.30.90.7An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf20.jpg2.4
Kerala431.81.30.5An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf21.jpg6.5
All other states1344.33.93.2An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf22.jpg12.2
All India28335.14.94.5An external file that holds a picture, illustration, etc.
Object name is elife-54076-inf23.jpg807.5
States are in descending order of annual average death rates for the study period of 2001-2014. We included only the states with populations over 10 million. Andhra Pradesh included Telangana. The Northeastern states include Arunachal Pradesh‚ Manipur‚ Meghalaya‚ Mizoram‚ Nagaland‚ Sikkim and Tripura.

Half of all snakebite deaths occurred during the southwest monsoon seasons from June to September. Seasonality was similar in each of the study years (Appendix 1—figure 2) and was similar in higher-burden and lower-burden states (data not shown). We used a Poisson time series model for snakebite deaths from 2001 to 2014 to predict the average daily snakebite mortality in India. The peak (294 deaths per day) was in mid-July and the trough (78 deaths per day) was in mid-February (Figure 2A). We also aggregated the deaths from 2001 to 2013 by every 100 m of altitude above sea level (Figure 2B). The crude death rates in areas below 400 m were about three times those in areas at about 1000 m. Over 80% of snakebite deaths occurred below 400 m and 50% occurred below 200 m.

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Object name is elife-54076-fig2.jpg
Figure 2.
Predicted daily snakebite deaths from analysis of seasonality observed in 2001-2014 (Panel A) and snakebite crude death rates by altitude in meters in 2004-2013 (Panel B).Notes: The daily snakebite totals are a composite of all study years from 2001 to 2014. The crude death rates by elevation use the RGI’s Sample Registration System population as denominators, and hence are generally lower than the overall rates we apply to the whole of India (using the United Nations death totals, which has the benefit of taking into account undercounts in the SRS data [Menon et al., 2019]). However, the relationship of crude death rates with elevation is unaffected by this procedure.

Snakebite and mortality surveillance

The Government of India relies on reporting via public hospitals to track snakebites and deaths (Government of India, 2015). We examined the total bites and deaths available from 2003 to 2015 in Government hospitals and compared these deaths to the MDS in-hospital deaths (Table 4). Over this 13-year period, the MDS estimated about 154,000 snakebite deaths in public and private hospitals, and the Government reported 15,500 deaths in hospitals, meaning that the routine reporting system captured only 10% of the expected hospital-based deaths. The most complete reporting was in Karnataka which captured 26% of expected hospital snakebite deaths.

Table 4.

Government hospital reports of snakebites and deaths, compared to MDS death totals by state for 2003-2015.

Government reporting*MDS estimates
StateNo. of bites (000)No. of deaths (000)% died in hospitalTotal no. of deaths (000)No. died in hospital (000)% Government coverage
(1)(2)(3)(4)(5)(6)=(4)*(5)(7)=(3)/(6)
Higher burden states530.06.919%539.694.67%
 Andhra Pradesh251.31.416%74.111.612%
 Bihar20.90.116%105.417.01%
 Odisha76.21.829%36.910.917%
 Madhya Pradesh28.31.122%64.414.18%
 Uttar Pradesh27.80.613%150.720.23%
 Rajasthan71.31.016%49.67.813%
 Gujarat45.70.827%38.610.57%
 Jharkhand8.50.112%20.02.56%
Percentage to national41%45%71%61%
Lower burden states772.28.628%219.859.614%
 Chhattisgarh16.70.317%14.32.413%
 Jammu & Kashmir18.40.026%5.91.52%
 Tamil Nadu106.60.528%36.010.05%
 Karnataka89.21.621%28.16.026%
 Maharashtra178.71.225%49.012.510%
 West Bengal208.93.441%38.915.922%
 Punjab9.10.210%14.21.413%
 Haryana14.30.116%8.51.311%
 Assam3.60.132%6.62.13%
 Northeastern states11.10.125%1.80.411%
 Kerala37.90.227%5.23.56%
 All other states77.80.824%11.12.732%
Percentage to national59%55%29%39%
India1302.215.522%759.4154.210%
* Government statistics are as published by the Ministry of Health and Family Welfare, Government of India (Government of India, 2015).
 Higher burden states are those where the snakebite death rate at all ages is above 5/100,000 deaths for the entire study period of 2001-14 as listed in Table 3. In cases of number less than 100 deaths, they are listed as 0.0 in thousands.

Snakebite prevalence and envenomation

Among the 87,590 snakebites reported in the literature, there were 3329 reported deaths (Appendix 2—table 1). We fitted death and bite data from each study to an ordinary least square regression to calculate a case-fatality rate, after removing the extreme outliers. We estimated a crude case-fatality rate of 3.2% for in-hospital cases.

Based on mostly cautious assumptions about the ratio of in-hospital to out-of-hospital prevalence of snakebites (Appendix 1—table 2), we estimate the total number of snakebites to range from 1.11 to 1.77 million in 2015. Based on 44 hospital studies where 70% of patients sought treatment, were diagnosed with systemic envenomation, and received antivenom, we estimate that the annual number of envenomations is about 0.77 to 1.24 million with the remainder being ‘dry bites’ or bites by non-venomous species (0.33 to 0.53 million).

reference link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7340498/


More information: Stephen Paul Samuel et al. Venomous snakebites: Rapid action saves lives—A multifaceted community education programme increases awareness about snakes and snakebites among the rural population of Tamil Nadu, India, PLOS Neglected Tropical Diseases (2020). DOI: 10.1371/journal.pntd.0008911

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