chapter - 2 epidemiology introduction -...
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Chapter - 2
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EPIDEMIOLOGY
INTRODUCTION
Of the 3,000 or so snake species that exist in the world, about 600 are
venomous (Simpson and Norris., 2009). Venomous snakes—which exist on every
continent except Antarctica immobilize their prey by injecting venom (modified
saliva) that contains toxins into their prey's tissues through their specialized hollow
teeth called fangs. Snakes also use their venom for self defense and will bite people
who threaten, startle or provoke them. In India, majority of bites are caused by the
snakes belonging to the big four families; Viperidae (Saw scaled viper and Russell’s
viper) and Elapidae (krait and cobra) are particularly dangerous to people. The
potentially fatal effects of being “envenomed” by these snakes include widespread
bleeding, muscle paralysis, and tissue destruction around the bite site. Bites from
these snakes can also cause permanent disability. The best treatment for any snakebite
is to get the victim to a hospital as soon as possible where antivenoms can be given.
Since ancient times, snakes have been worshipped, feared, or loathed in South
Asia. Cobras appear in many tales and myths and are regarded as sacred by both
Hindus and Buddhists. Unfortunately, snakes remain a painful reality in the daily life
of millions of villagers in this region. Indeed, although antivenom is produced in
sufficient quantities by several public and private manufacturers, most snake bite
victims do not have access to quality care and in many countries, both morbidity and
mortality due to snake bites are high. The neglected status of snake bite envenoming
has recently been challenged (Simpson and Norris., 2009). But as outlined below,
apart from the production of antivenom, snake bite envenoming in South Asia shares
all the characteristics of a neglected tropical disease. This chapter in this thesis aims
at summarizing and discussing the epidemiology, clinical features, diagnosis, and
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treatment of snake bite in a South Indian hospital (Victoria Hospital, Bangalore,
Karnataka state).
Researchers estimate that worldwide at least 421,000 envenomings and
20,000 deaths from snakebite occur every year; the actual numbers they suggest could
be as high as 1.8 million envenomings and 94,000 deaths. Their estimates also
indicate that the highest burden of snakebite envenomings and death occurs in South
and Southeast Asia and in sub-Saharan Africa, and that India is the country with the
highest annual number of envenomings (90,000) and deaths (nearly 50,000)
(Kasturiratne et al., 2008).
An accurate measure of the global burden of snakebite envenoming remains
elusive despite several attempts to estimate it. Apart from a few countries, reliable
figures on incidence, morbidity and mortality are scarce (Chippaux et al., 1998).
South Asia is by far the most affected region. India has the highest number of deaths
due to snake bites in the world with 25,000–50,000 people dying per year according
to World Health Organization (WHO) direct estimates. In Pakistan, 40,000 bites are
reported annually, which result in up to 8,200 fatalities (Kasturiratne et al., 2008). In
Nepal, more than 20,000 cases of envenoming occur each year, with 1,000 recorded
deaths WHO (1987). In Sri Lanka, around 33,000 envenomed snake bite victims are
reported annually from government hospitals (Kasturiratne et al., 2008). A postal
survey conducted in 21 of the 65 administrative districts of Bangladesh estimated an
annual incidence of 4.3 per 100,000 population and a case fatality of 20% (Sarker et
al., 1999). However, existing epidemiological data remain fragmented and the true
impact of snake bites is very likely to be under estimated. Surveys in rural Sri Lanka
showed that hospital data record less than half of the deaths due to snakebite (De
Silva et al., 1981). In Nepal, a review of district hospital records showed that national
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figures under estimated the incidence of snake bite by one order of
magnitude (Sharma et al., 2003). Snake bite is an important occupational injury
affecting farmers, plantation workers, herders and fishermen. Open style habitation
and the practice of sleeping on the floor also expose people to bites from nocturnal
snakes. Bites are more frequent in young men, and generally occur on lower limbs.
The incidence of snake bites is higher during the rainy season and during periods of
intense agricultural activity (Suleman et al., 1998). Snake bite incidence and mortality
also increase sharply during extreme weather events such as floods. During the 2007
monsoon flood disaster in Bangladesh, snake bite was the second most common
cause of death. After eclipsing mortality from diarrheal and respiratory diseases and
illustrating how important snake bite can be in this region compared to other health
problems.
MANAGEMENT OF SNAKE BITE VICTIMS AND RECOMMENDED
TREATMENT
Health workers in rural districts are usually poorly trained to manage snake
bite envenoming which is a complex emergency. A recent survey conducted in India
and Pakistan showed that many doctors were unable to recognize systemic signs of
envenoming (Simpson., 2008). Another study in northwest India revealed that most
snake bite victims presenting at primary health centres received inadequate doses of
antivenom and that out of 42 patients who required assisted ventilation only one was
incubated (Chauhan., 2005). Improving the knowledge at all levels of the health
system is a challenge of paramount importance and great urgency in South Asia.
Papua New Guinea, where snake bite management training programmes have been
implemented in both rural and urban hospitals, could serve as an inspiring model in
this regard.
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Antivenoms
Immunotherapy is the only specific treatment for snake bite envenoming.
Antivenoms are produced by fractionation of plasma obtained from immunized
animals, usually horses (Gutierrez. et al., 2007). They can be either monovalent or
polyvalent, depending on the number of species (single or multiple, respectively)
whose venoms are used for immunization. Although monovalent antivenom has often
been considered more efficacious, the production of polyvalent antivenom is
preferred in many countries as snake species identification is generally not possible
for the attending physician. Antivenoms have been available in South Asia for the
past 60 years and all existing products are manufactured by Indian companies.
Traditionally, the production has focused on four species believed to be responsible
for most deaths: N. naja, B. caeruleus, D. russelii, and E. carinatus. However, a
number of other species that contribute to morbidity and mortality in the region have
not been considered and envenoming by these species usually does not respond
adequately to existing antivenoms (Joseph et al., 2007). The success of antivenom
therapy depends on the ability of immunoglobulins to bind, extract and eliminate
toxins present in the body. While their efficacy in restoring haemostasis and
cardiovascular functions are well established, but the ability of antivenoms to prevent
tissue damage and to reverse neurotoxicity is more controversial (Theakston et al.,
1991). For instance, administration of antivenom to krait bite victims with established
respiratory paralysis does not reverse paralysis. This lack of clinical effectiveness
often contributes to the administration of excessive amounts of antivenom (Sharma N
et al., 2005). Moreover, treatment outcome can vary greatly with the geographical
area as the venom composition and antigenic properties of toxins can be highly
variable across the range of a given snake species (Shashidharamurthy et al., 2007).
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Indian antivenoms are produced using venoms from snakes captured in a tiny
geographic area of the State of Tamil Nadu and may therefore be less effective in
other regions (Simpson and Norris., 2007). For example, the efficacy of Indian
polyvalent antivenoms for the treatment of envenoming by Russell's viper in Sri
Lanka is controversial (Ariaratnam et al., 2001).
As a matter of fact, most of the antivenoms that are routinely used in South
Asia have never been subjected to independent preclinical testing and formal
evaluation in clinical trials. Their efficacy and safety profiles have not been properly
established and there is currently no evidence-based protocol for their administration
and dosage. Up to 80% of patients treated with Indian antivenoms present one or
more adverse effect(s) such as anaphylactoid or pyrogenic reactions, late serum
sickness (Seneviratne et al, 2000). While to our knowledge no fatal cases have been
reported in South Asia, severe drug reactions occur and are likely to be under-
reported. Adverse reactions can be efficiently managed by cheap, widely available
drugs (e.g. antihistaminics, corticoids, adrenalin), but their prophylactic use yielded
contradictory results (Gawarammana et al., 2004). The risk of severe adverse events
exists but must be balanced against the life-saving potential of this treatment.
Antivenoms may be supplied free of cost by some ministries of health but
their supply remains insufficient and irregular in several countries, leading to the
purchase of drugs by the patients relatives. One vial of antivenom of Indian
production costs around 490 rupees, thus, many cannot afford to purchase the average
10–15 vials needed to reverse envenoming .which is equivalent to several days of
salary for poor farmers (Bawaskar et al., 2008).
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Ancillary treatment
The management of envenomed snake bite is not limited to the administration
of antivenoms. In the case of neurotoxic envenoming, artificial ventilation and careful
airway management are crucial to avoid asphyxiation in patients with respiratory
paralysis. Cases of complete recovery from severe neuromuscular paralysis without
antivenom have been reported after prolonged artificial ventilation (Pochanugool et
al., 1998).
Anti cholinesterase drugs such as edrophonium can partly overcome blockade
by postsynaptic neurotoxins and have shown good efficacy in cobra bite
envenoming (Currie et al., 1988). A few cases of successful anti cholinesterase use
have also been reported in krait bite envenoming in India (Bawaskar, et al., 2004) but
there is currently no treatment to stop the destruction of nerve endings by presynaptic
krait toxins once this degeneration process has started.
Bacterial infections can develop at the bite site, especially if the wound has
been incised or tampered with nonsterile instruments, and may require antibiotic
treatment. However, there are currently no data supporting their systematic
use (Kularatne et al., 2005). A booster dose of tetanus toxoid should be administered
but only in the absence of coagulopathy. Necrosis on the bitten limb may require
surgery and skin grafts, particularly in the case of viper bites. If necrotic tissues are
not removed, secondary bacterial infections can occur. Tensed swelling, pale and cold
skin with severe pain may suggest increased intracompartmental pressure in the
affected limb. However, fasciotomy is rarely justified. In particular, it can be
disastrous when performed before coagulation has been restored. A clear proof of
significant compartment syndrome by measurement of substantially elevated
intracompartmental pressures is a prerequisite.
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Control and Prevention
In practice, strategies to control snake populations and to prevent snake bites
are nonexistent in South Asian countries. Many bites could be avoided by educating
the population at risk. Sleeping on a cot (rather than on the floor) and under bed nets
decreases the risk of nocturnal bites in Nepal (Chappuis et al., 2007). Rubbish termite
mounds and firewood which attract snakes can be removed from the vicinity of
human dwellings. Attempts can be made to prevent the proliferation of rodents in the
domestic and peridomestic area. Thatched roofs, mud and straw walls are favoured
hiding places for snakes and should be checked frequently. Many bites occur when
people walking barefoot or wearing only sandals accidentally step on a snake. Using a
torch/flashlight while walking on footpaths at night wearing boots and long trousers
during agricultural activities, could significantly reduce the incidence of bites. Many
areas where snake bite envenoming occurs are relatively inaccessible by road,
especially during the rainy season and transport to a health centre sometimes takes
more than 24 hours (Chauhan et al., 2005). In Nepal, a programme for rapid transport
of snake bite victims by motorcycle volunteers to a specialized treatment centre
significantly reduced the risk of fatal outcome.
Key Learning Points
• South Asia has the highest incidence and mortality rates of snake bite in the
world.
• Bites by venomous snakes in this region can cause local tissue damage,
neuroparalysis, systemic haemorrhages, generalized myotoxicity, acute renal
failure or complex combinations of these.
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• Recommended first aid measures include reassurance of the snake bite
victim, immobilization of the bitten limb and rapid transport to a competent
treatment centre.
• Antivenom is the only specific treatment for snake bite envenoming, but
existing products cover only a very limited number of medically significant
species.
Main Challenges
(1) Improving access
Access to care is hindered both by the remoteness of snake bite prone areas and by
the cost of snake bite management. A community survey in Nepal showed that snake
bite envenoming represents a substantial financial burden for rural households
(Sharma et al., 2004). Despite the mushrooming of well-equipped private clinics in
some rural areas of India, poor villagers rarely have access to mechanical ventilation
or dialysis.
(2) Improving clinical management
Simple and standardized protocols on snake bite management are needed. Despite the
publication of regional guiding principles (Warrell., 1999) national protocols are not
always consistent with each other (e.g., low initial dose of antivenom advised in
Nepal versus high initial dose in India and Bangladesh), are often not available in
peripheral health structures and are poorly explained to end users. Moreover,
manufacturer’s recommendations are often misleading (Simpson and Norris. 2007).
In Nepal, the application of different protocols may play a role in the wide range
(3%–58%) of case-fatality rates reported from various hospitals (Sharma ,et al.,
2003).
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(3) Improving diagnostic and treatment tools
The lack of field-applicable diagnostic tools to identify snake species
contributes to poor case definitions, mismanagement of patients, and uncertainties
about snake bite epidemiology (Isbister., 2005). Snake bite victims in South Asia are
still reliant on old generations of antivenoms and several venomous species are not
covered by existing products (Simpson and Norris., 2007). The pharmacokinetic and
pharmacodynamic properties, efficacy and safety of most Indian antivenoms have
never been studied or compared. WHO has recently endorsed the strengthening of
antivenom production and efforts are being made to help Indian manufacturers to
improve the quality of existing products. However, the impact of this approach on the
cost of antivenom production needs to be carefully anticipated and closely monitored
(4) Improving knowledge
Improving the knowledge of both care-givers and rural communities is
crucial. Health workers in rural districts are usually poorly trained to deal with this
complex emergency. For example, many doctors in India and Pakistan appear to be
unaware of the criteria for antivenom administration (Simpson., 2008). Education of
rural communities on snake bite, avoidance of useless or dangerous first-aid measures
and the importance of rapid transport of victims to treatment centres should be widely
implemented (Sharma et al., 2004).
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SIGNIFICANCE OF THIS STUDY
Although snakebites occur throughout the world, venomous snakebites are
thought to pose a particularly important yet largely neglected threat to public health.
This is especially true in rural areas of tropical and subtropical countries where
snakebites are common, where there is limited access to health care and to
antivenoms. The true magnitude of the public-health threat posed by snakebites in
these countries (and elsewhere in the world) is unknown, which makes it hard for
public-health officials to optimize the diagnosis, prevention and treatment of
snakebites in their respective countries. The findings by Kasturiratne et al., 2008
indicate that snakebites cause considerable illness and death around the world.
Because of the careful methods used by the researchers, their global estimates of
snakebite and deaths are probably more accurate than previous estimates. However,
because the researchers had to make many assumptions in their calculations and
because there are so few reliable data on the numbers of snakebites and deaths from
the rural tropics, the true regional and global numbers of these events may differ
substantially from the estimates presented. In particular, the regional estimates for
eastern sub-Saharan Africa, a region where snakebites are very common and where
antivenoms are particularly hard to obtain, are likely to be inaccurate because they are
based on a single study. We therefore call for more studies on snakebite envenoming
and deaths to be done to provide the information needed to deal effectively with this
neglected public-health problem. A large number of victims survive with permanent
physical sequelae due to local tissue necrosis and no doubt about psychological
sequelae. Because most snakebite victims are young (Hansdak et al., 1998) the
economic impact of their disability is considerable. Despite the scale of its effects on
populations, snakebite has not received the attention it deserves from national and
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international health authorities, and may therefore be appropriately categorized as a
neglected tropical disease. Few reliable incidence data are available from the rural
tropics where snakebites occur most commonly; reliable data are mostly limited to a
few developed countries where bites are rare. Thus, the true global incidence of
snakebite envenoming, its impact and characteristics in different regions remain
largely unknown. However, information on the number of bites, envenomings deaths
and on the frequency of long-term sequelae due to snakebites are essential for
assessing the magnitude of the problem, drawing up guidelines for management,
planning health care resources, particularly antivenom and training medical staff to
treat snakebites. Recently no comprehensive global assessment has been made of
snakebite epidemiology. Swaroop and Grab's 1954 review was based mainly on
hospital admissions; such data from the rural tropics are fraught with inaccuracies.
For example, many snakebite victims in these areas are not hospitalized and seek
traditional treatments (Snow et al., 1994). Hospital mortality data are well known to
underestimate overall mortality due to snakebites and do not give any details of the
methodology used to calculate their estimates (Chippaux., 1998). Even data regarding
effective management of snake bitten victims are not available. For these reasons, re-
estimating the global burden of snakebite using scientifically rigorous and replicable
methodologies was necessary. In this study, we have made an attempt to report the
Epidemiology of snakebite cases admitted in a South Indian hospital (Victoria
Hospital, Bangalore, Karnataka state).
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METHODOLOGY
A retrospective study was carried out at Victoria hospital Bangalore, this
hospital is a referral government hospital in Karnataka, where patients come from the
district of Hassan, Mandya, Tumkur, Kolar and Hosur. The Average total patients
admission per year in this hospital was 20,000 during the study period. This is a
retrospective review of snake bite patients in Emergency Department of Victoria
hospital Bangalore (Jan 2002 to December 2011). The ethical permission to carry out
the study was from Bangalore medical college, Karnataka, India. The data was
obtained from medical records section of the hospital which uses ICD-10 ( ICD-10 is
the 10th revision of the International Statistical Classification of Diseases and Related
Health Problems (ICD), a medical classification list by the World Health
Organization system for classification of diseases. The relevant details were entered
in a form on which the site of bite and the type of treatment before referral was
recorded. Other details noted were the symptomology and in hospital treatment.
Neuroparalytic syndromes were identified mild to moderate if the patient had muscle
weakness and severe, if ptosis, ophthalmoplegia, drowsiness, dysarthria, dysphagia,
bulbar paralysis, flaccid paralysis of whole body, followed by respiratory failure,
hypoxia and convulsions. An observational time series study was carried out. The
presence of two definite puncture wounds with progressive swelling, tenderness with
persistent bleeding was taken as a poison bite and U- shaped multiple teeth marks was
taken as non-poisonous snake bite. Hemotoxic and neurotoxic signs and symptoms
were also noted. The results on categorical measurements are presented in Number
(%).Microsoft word and Excel has been used to generate graphs and tables.
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RESULTS
Incidence:
Cases of snake bite contributed to 1.53% of hospital admission during the
study period (Table 2.1 & Figure 1.0).
Age and Sex distribution:
More snake bite was observed in the productive age period of 15- 50 years
(Table 2.2 and Figure 1.1). Also out of 3254 snake bite cases 67.8% of the cases were
males (Table 2.3 and Figure 1.2), throughout the study period males were more prone
to snake bite compared to females every year (Table 2.4 and Figure 1.3).
Season:
More snake bite cases occurred during the months of May to October (during
rainy season) (Table 2.5 and Figure 1.4).
Site of bite and time of day:
Snake bites mostly occurred over the limbs 39% and it was observed 32% in
hands, 17% in arms. The other parts of the body included head - face (5%), trunk
(6%) and multiple sites (1%) Site of snake bites are significantly more associated
with Foot and Hand comprising 71.0% of patients. The incidence of snake bite was
observed with 2478 cases (78.1%) during day time and 99 cases (21.9%) were
observed during night time. (Table 2.6, 2.7 & Figure-1.5 & 1.6).
Occupational Incidence:
Snake bites were commonly seen among agricultural workers in the present
study with 2376 (73%). Also it was observed during walking 211 (6.49%), sleeping
390(12%), recreational activities 91 (2.8%), catching snakes 13 (0.4%) and in
unknown activities 173 (3.7%) (Table 2.8 & Figure 1.7).
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Regional Incidence:
Maximum snake bite incidence was observed in rural areas 2379 (73.1%) than
in urban areas 875 (26.9 %) (Table 2.9 & Figure 1.8).
Time from bite to presentation:
426 cases (13.1%) were admitted within one hour, 1132cases (34.8%) within
4hrs, 1607cases (49.4%) in between 4-24hrs, and 88cases (2.7%) above 24 hrs (Table
3.0 & Figure 1.9)
Incidence of death according to gender and age group:
Incidence of death is measured in male, female and overall is presented below.
It is observed that, average incidence of death from 2002-2011 is 2.42%. There was
more mortality rate in females 39 (1.75%) than males 38 (3.87%). Incidence of death
is observed to be more in age group of 15 & above, as this age group is involved
more in agricultural activities and the female patients are more prone to death in their
productive age (Table 3.1, 3.2 & Figure 2.0, 2.1).
Systemic manifestations:
Neuroparalytic symptoms are more common presentation in major cases.
This is referred to Potosis, bulbar weakness, opthalmoplegia, Paresis, respiratory
distress and others. 72% cases showed neuroparalytic symptoms (Table 3.3& Figure
2.2). Hemorrhagic symptoms were also a common presentation in many cases. This
is referred to internal hemorrhage and hemorrhage from sites of bite other than the
local observed in 903 (27.75%) cases. This involves bleeding from bite site,
intravascular haemorrhage, Hematuria, Gastro intestinal bleeding, cutaneous bleed,
haemoptysis, and bleed per vaginum, lymphodenopathy, erythema and numbness at
bite site. (Table 3.4 & Figure 2.3).
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Table 2.1: Hospital based Incidence of Snake bite year wise.
Year of
observation
Total number of
patients
Number of patients
with snake bite
% of patients
with snake bite
2002 19086 339 1.744
2003 18404 233 1.222
2004 19019 208 1.072
2005 19126 361 1.892
2006 21100 284 1.355
2007 20720 289 1.394
2008 20032 274 1.377
2009 21282 340 1.625
2010 23796 463 1.975
2011 22972 463 2.015
Figure 1.0: Hospital based Incidence of Snake bite year wise.
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Table 2.2: Hospital based Incidence of Snake bite according to age
Age in
years Number of patients with snake bite %
0-4 34 1.00
5-9 54 2.00
10-14 150 4.00
15-19 318 10.00
20-29 908 28.00
30-39 710 22.00
40-49 555 17.00
50-59 301 9.00
60 & above 224 7.00
Total 3254 100.00
Figure 1.1: Hospital based Incidence of Snake bite according to age.
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Table 2.3: Hospital based Incidence of Snake bite according to gender
Gender Number of patients with snake bite %
Male 2209 67.89
Female 1045 32.11
Total 3254 100.00
Figure 1.2: Hospital based Incidence of Snake bite according to gender
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Table 2.4: Number of patients attended with snake bite year wise according to gender
Year
Total
Male Female Total
No % No % No %
2002 213 9.64 126 12.06 339 10.42
2003 161 7.29 72 6.89 233 7.16
2004 151 6.84 57 5.45 208 6.39
2005 215 9.73 146 13.97 361 11.09
2006 201 9.10 83 7.94 284 8.73
2007 186 8.42 103 9.86 289 8.88
2008 204 9.23 70 6.70 274 8.42
2009 250 11.32 90 8.61 340 10.45
2010 324 14.67 139 13.30 463 14.23
2011 304 13.76 159 15.22 463 14.23
Total 2209 100.0 1045 100.0 3254 100.0
Figure 1.3: Number of patients attends with snake bite year wise according to gender
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Table 2.5: Distribution of Snake bite patients according to season
Months
Total
Male Female Total
No % No % No %
January 111 5.02 37 3.54 148 4.55
February 125 5.66 44 4.21 169 5.19
March 140 6.34 50 4.78 190 5.84
April 182 8.24 64 6.12 246 7.56
May 218 9.87 119 11.39 337 10.36
June 236 10.68 116 11.10 352 10.82
July 202 9.14 103 9.86 305 9.37
August 226 10.23 125 11.9% 351 10.79
September 244 11.05 129 12.34 373 11.46
October 229 10.37 121 11.58 350 10.76
November 162 7.33 85 8.13 247 7.59
December 134 6.07 52 4.98 186 5.72
Total 2209 100.0 1045 100.0 3254 100.0
Figure 1.4: Distribution of Snake bite patients according to season
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Table 2.6: Site of Snake Bite
Site of Snake bite Number of patients %
Foot 1269 39.0
Hand 1041 32.0
Arms 553 17.0
Head- Face 118 5.0
Trunk 195 6.0
Multiple sites 32 1.0
Total patients 3254 100.0
Figure 1.5: Site of Snake Bite
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Table 2.7: Time of bite
Time of bite Number of patients %
Day - 6.00am to 6.00pm 2541 78.1
Night - 6.00pm to 6.00am 713 21.9
Total patients 3254 100.0
Figure 1.6: Time of bite
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Table 2.8: Incidence according to occupation
Occupation Number of patients %
Agricultural workers 2376 73.0
walking 211 6.49
Recreation activities 91 2.80
Catching snakes 13 0.4
sleeping 390 12.0
Others/Unknown 173 5.3
Total patients 3254 100.0
Figure 1.7: Incidence according to occupation
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Table 2.9: Incidence according to Region
Region Number of patients %
Rural 2379 73.1
Urban 875 26.9
Total patients 3254 100.0
Figure 1.8: Incidence according to Region
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Table 3.0: Time from bite to presentation
Time from bite to
presentation
Number of
patients %
< 1hr 426 13.1
-1-4 hr 1132 34.8
- 4-24 hr 1607 49.4
->24 hr 88 2.7
Total patients 3254 100.0
Figure 1.9: Time from bite to presentation
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Table 3.1: Incidence of death among the snake bite patients in male and female
Study period
Male Female Total
Total Number
of patients
Number of
patients death
% of death
Total Number
of patients
Number of
patients death
% of death
Total Number
of patients
Number of
patients death
% of death
2002 208 5 2.4 125 1 0.8 333 6 1.80
2003 157 4 2.5 68 4 5.9 225 8 3.6
2004 149 2 1.3 55 2 3.6 204 4 2.0
2005 211 4 1.9 141 5 3.5 352 9 2.6
2006 195 6 3.1 81 2 2.5 276 8 2.9
2007 183 3 1.6 96 7 7.3 279 10 3.6
2008 203 1 0.5 63 7 11.1 266 8 0.8
2009 248 2 0.8 88 2 2.3 336 4 3.3
2010 320 4 1.25 136 3 2.2 456 7 1.53
2011 297 7 2.35 153 6 3.9 450 13 2.88
Total 2171 38 1.77 1006 39 4.31 3177 77 2.42
Figure 2.0: Incidence of death among the snake bite patients in male and female
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Table 3.2: Incidence of death among the snake bite patients in different age group of
total study period
Age in years
Male Female Total
Total Number
of patients
Number of
patients death
% of death
Total Number
of patients
Number of
patients death
% of death
Total Number
of patients
Number of
patients death
% of death
0-4 20 0 0.0 14 0 0.0 34 0 0.0
5-9 24 0 0.0 30 0 0.0 54 0 0.0
10-14 90 0 0.0 60 0 0.0 150 0 0.0
15-19 217 4 1.95 92 5 5.43 309 9 2.9
20-29 641 9 1.56 242 16 6.61 883 25 2.83
30-39 467 12 2.87 227 4 1.76 694 16 2.30
40-49 371 5 1.55 172 7 4.06 543 12 2.20
50-59 204 2 1.11 92 3 3.26 296 5 1.68
60 &
above 137 6 4.91 77 4 5.19 214 10 4.67
Total 2171 38 1.93 1006 39 3.87 3177 77 2.42
Figure 2.1: Incidence of death among the snake bite patients in different age group of
total study period
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Table 3.3: Neuroparalytic symptoms
Neuroparalytic symptoms Number of patients %
Ptosis 1833 78.0
Bulbar weakness 1410 60.0
Opthalmoplegia 1034 44.0
pareisis 564 24.0
Loss of consciousness 352 15.0
Giddiness 235 10.0
Fever 188 8.0
Respiratory distress 1551 66.0
nausea and vomiting 255 11.0
headache 211 9.0
Total patients 2351 100.00
Figure 2.2: Neuroparalytic symptoms
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Table 3.4: Hemorrhagic Symptoms
Hemorrhagic Symptoms Number of patients %
Bleeding from bite site 379 42.0
Intravascular hemolysis 289 32.0
Hematuria 144 16.0
Gastro intestinal bleed 99 11.0
Cutaneous bleed 81 9.0
Haemoptysis 54 6.0
Bleed per vaginum 18 2.0
Lymphadenopathy 77 8.5
Erethema 134 14.9
Numbness at bite site 99 11.0
Total patients 903 100.00
Figure 2.3: Hemorrhagic Symptoms
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DISCUSSION
In India, the poisonous snakes belong to the elapid family (cobra and krait)
and viper family (Russell’s viper and Saw scaled viper). Envenomation attributes to
elapid bites causes paralysis of the occular, Bulbar, and Limbgirdmuscle. Viper bites
mainly causes bleeding from mucocutaneous sites, haemolysis, acute renal failure and
occasionally shock. Snake bite can be deadly if not treated quickly, it is considered as
a serious health hazard in many countries around the world specially tropical and
subtropical countries where there is limited access to health care and antivenom.
Majority of snake bite cases were in the age group of 15 to 50 years. Males
dominated females in the study, which is consistent with the study done by (Brunda
and Shashidhar., 2007). As per the study by Punde., 2005 majority people affected by
snake bites were farmers and maximum were bitten by poisonous snakes during
monsoon which is consistent with the present study. Majority of snake bites occur in
rainy season, this may be attributed to the flooding of rainwater in the dwelling places
of snakes, thus causing the dislodgement, consequently human population becomes
accidental victims to the snake bite. Further, the situation is aggravated by the
propinquity of rodents near the human habitants thus increasing the risk of snake bite.
The predominance of male victims suggests a special risk of outdoor activity.
However, in our present investigation females death was more when compared to
males, this is due to poor knowledge about snake bite and poor management of
snakebite. As per the study done by Eric et al., 2002 males were the maximum
victims and the body area commonly bitten was the lower limb which is consistent
with the present study but the peak age of victims who got affected were mostly the
youth who were in their age range of 20-40 years. Victoria hospital being a teaching
hospital has got all the facilities for management of snake bite. But still high mortality
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may be due to the delay in arriving of the envenomated patients at Victoria hospital,
which may be because of the long distance, as majority of the cases came from
around 50 km and secondly initial treatment seeking behavior from traditional healers
and local practitioners. As the chance of getting complication following snake bite
increases with passage of time. This might be responsible for the observed mortality
among our study subject despite best treatment available. Other important factor for
mortality is failure in identifying the snake species responsible for bite, and as result
administration of polyvalent anti snake venom is necessary. Administration of
polyvalent anti snake venom leads to secondary complications such as
hypersensitivity. And people who have got first dose of anti snake venom may need
booster doses, during this time patient needs extra medical care such as ventilators
and other which cannot be afforded by poor people. To overcome all these afore said
limitations identification of snake species responsible for bite is necessary. Snake
identification is difficult as we do not have snake venom detection kit.
In the present study, highest number of bites was seen in the period from June
to November during the rainy season. The mortality rate observed among the
admitted cases of snake bites in the present study was 2.42% this is quite a high
number. The management and outcome of the patients was regularly monitored,
antibiotics were prescribed to two third of Patients; (Mainly for Prophylaxis) tetanus
toxoid and analgesics were routinely given when needed. For majority of cases, 1 – 8
vials of Anti snake venom was given and for the remaining cases antivenom was with
held in the absence of systemic envenomation
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Snake bite mainly afflicts the rural men of developing countries. Availability
of antivenom at primary health care centers and rapid transportation facilities may
change the morbidity associated with snake bite. There is an urgent need to educate
the rural population about the hazards and treatment of snake bites, also randomized
controlled trails are needed to investigate the side effects caused by antivenom
treatment. Knowing that polyvalent antivenom induces secondary complications; only
possible way to bring down this is to administer monovalent antisnake venom, which
can be done upon bitten species identification. There is an urgent need for the
development of venom detection kit so that specific anti venom can be raised and
administered according to the specificity of the snake venom. Majority of the cases
pertaining to this study showed neuroparalytic symptoms which are characteristic of
elapid bites. Based on this, we have selected Naja naja venom to develop specific
diagnostic kit against it.