|Year : 2013 | Volume
| Issue : 4 | Page : 148-153
Presentation and outcome of snake bite among children in Sokoto, North-Western Nigeria
Usman M Sani, Nma M Jiya, Paul K Ibitoye, Mohamad M Ahmad
Department of Paediatrics, Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria
|Date of Web Publication||21-Jan-2014|
Usman M Sani
Department of Paediatrics, Usmanu Danfodiyo University Teaching Hospital, Sokoto
Background: Snake bite with envenomation is a medical emergency. Children are at risk of severe manifestations due to small body mass. Unlike adult population, there is limited data on snake bite among children in Sokoto, North-Western Nigeria. We described the presentation and outcome of snake bite in children presenting to the Emergency Pediatric Unit of Usmanu Danfodiyo University Teaching Hospital, Sokoto. Materials and Methods: Case records of all children managed for snake bites from 1 st January 2003 to 31 st December 2012 were retrospectively reviewed. Demographic and other relevant information were retrieved and data analyzed using Microsoft Excel. Results: Out of 23,570 Pediatric admissions, 36 children had snake bites giving prevalence of 0.0015 (1.5/1000). Male: Female ratio was 1.6:1, with a mean (standard deviation) age of 9.6 ± 2.8 years (range = 1-14 years). Snakebites involved the lower limbs in 52.8%; and at home in 69.4%, and during the night in 58.3% of patients. The highest prevalence of bite was between April and July. Features of envenomation included local swelling (100%), prolonged clotting time (61.1%) and spontaneous hemorrhage (epistaxis and hematemesis) in 11.1%. One patient (2.8%) had seizure which may be incidental, though common causes such as hypoglycemia, malaria and meningitis were excluded by laboratory investigations. Polyvalent anti-snake venom was administered in 29 (80.6%) children, with adverse reaction observed in 13.8% (4/29) of the patients. Thirteen patients (36.1%) signed against medical advice while the remaining 23 (63.9%) were discharged home. Conclusion: Snake envenomation is associated with low morbidity and mortality in our study. Measures aimed at eliminating snake habitats around residential areas should be encouraged.
Keywords: Children, North-western Nigeria, snake bites, Sokoto
|How to cite this article:|
Sani UM, Jiya NM, Ibitoye PK, Ahmad MM. Presentation and outcome of snake bite among children in Sokoto, North-Western Nigeria. Sahel Med J 2013;16:148-53
|How to cite this URL:|
Sani UM, Jiya NM, Ibitoye PK, Ahmad MM. Presentation and outcome of snake bite among children in Sokoto, North-Western Nigeria. Sahel Med J [serial online] 2013 [cited 2020 Feb 20];16:148-53. Available from: http://www.smjonline.org/text.asp?2013/16/4/148/125557
| Introduction|| |
Snakes are ubiquitous creatures that vary in their morphologic characteristics and potential for envenomation. Some are non-venomous while others are known to cause severe envenomation.  Though various types of snakes have been described, those considered medically important in Nigeria and, to a large extent, West African sub-region include Echis carinatus (saw-scaled carpet viper), Naja nigricolis (spitting cobra) and Bitis arietans (Puff adder). ,, These species are responsible for most of mortality and morbidity associated with snake bites in the sub-region.  Their clinical manifestations depend on the biochemical characteristics of the injected venom, which represents modified saliva consisting of biologically active peptides.  Carpet viper is known for its severe local reaction and tendency for bleeding whereas cobras are famous for their neurotoxic symptoms. 
The exact burden of venomous snake bites is largely unknown, particularly in Africa where it is now categorized among the most neglected tropical health problems. ,, Data from available studies on the incidence of snake bites are highly variable and often conflicting. A recent global estimate, however, suggests that as high as 1,841,000 venomous snake bites and 94,000 snake-related deaths occur annually, with the greatest burden occurring in rural areas of Asia and Sub-Saharan Africa.  In Asia, as high as 15,400 to 57,600 deaths occur annually whereas; in Sub-Saharan Africa, the number of deaths varies between 3,500/annum and 32,100/annum. , These figures, though alarmingly high, still underestimate the actual burden of the problem in most developing countries as highlighted by Mohapatra et al. 
In Nigeria, snake bites remain a common and serious problem especially in rural areas where access to prompt and effective treatment is limited. An earlier study on snake bites in the Savannah region of Northern Nigeria reported annual incidence of 497/100,000 and a mortality of 12.2%.  The tropical climate and the favorable environmental factors within this region are known to provide suitable habitat for snakes. In addition, the society is largely agrarian and the greater part of its population engaged in farming activities, livestock rearing, hunting and collection of firewood. These activities constitute occupational hazard for snake bites and are responsible for sustaining the high burden of the problem.
Children are at increased risk of snake bites due to their tendency to walk without protective foot wears while playing at homes or assisting in the farmlands. They are also more likely to develop signs of severe envenomation due to their relatively small body mass.  Some authors have shown a higher risk of adverse reactions to anti snake venom  and even increased mortality among children with snake envenomation compared to adults. , Hence, snake bite in children is a particularly serious medical emergency.
Though an earlier study on snake envenomation among adult patients from the study area had shown relatively favorable outcome (mortality rate of 2.7%);  there is little information on the epidemiology and outcome of snake bites among children in the study region. Since the outcome may differ between the two groups, it is necessary to document our experience regarding the pediatric age-group. The aim of this study was therefore to determine the presentation and outcome of snake bites among children admitted into the Emergency Pediatric Unit (EPU) of Usmanu Danfodiyo University Teaching Hospital (UDUTH), Sokoto.
| Materials and Methods|| |
This study was conducted at the Pediatric Department of UDUTH, Sokoto which is a tertiary hospital located in Sokoto, North-Western Nigeria. The Hospital serves as a referral center for other health care facilities within the region. The study was retrospective; covering a period of 10 years (1 st January 2003 to 31 st December 2012). All children managed for snake bites at the EPU of UDUTH during the study period were included. Their case records were retrieved from the hospital Medical record department. Demographic information such as age, gender and geographic location of the patients was extracted and entered into a predesigned study proforma data sheet. Other relevant clinical information obtained from the case records included place of bite, site of bite, features of envenomation, treatment given before and during hospitalization, use of polyvalent anti-snake venom (PASV), presence of adverse reaction to PASV, length of hospital stay and outcome after snake envenomation. Two patients whose case records could not be traced from the Medical Record Department were excluded from the study.
Data was entered into Microsoft Excel and analyzed. Nominal data was summarized using proportions and bar charts whereas means and frequency tables were used to illustrate quantitative data. Chi-square or where necessary, Fisher's Exact test was used to compare categorical variables. A P < 0.05 was considered statistically significant.
| Results|| |
Between January 1 st 2003 and December 31 st 2012, there were a total of 23,570 Pediatric admissions. Of this number, 36 children were admitted and managed for snake bites at the EPU of UDUTH, Sokoto given a prevalence rate of 0.0015 (1.5/1000). The demographic characteristics of the patients are shown in [Table 1]. Male: Female ratio was 1.6:1 and most of the children (63.9%) were from rural areas. Mean (standard deviation) age of the study cohort was 9.6 ± 2.8 years. [Table 2] shows the age and sex distribution of patients with 50% of the children aged between 11 and 15 years. Snake bites occurred at home in 25 (69.4%) patients and on the farmland in 11 (30.6%) patients. The prevalence of snake bites at home was higher in females than males 13/14 (92.9%) vs 12/22 (54.5%) whereas; bites that occurred on the farmland affected males more than females (10/22 vs 1/14). The difference is statistically significant (P = 0.03). Of the 25 victims bitten at home, the incident occurred while walking and/or playing around the house premises in 19 patients, during outdoor sleeping in 5 patients and inside a toilet in one patient. Bites outside the home environment occurred mostly as the victims were assisting their families on the farm or while collecting firewood. However, one child was bitten while picking a stone in the bush and another while exploring a rat hole.
|Table 1: Demographic characteristics of children admitted with snake bite|
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The study observed that bites occurred at night in21 (58.3%) patients and during the day time in 15 (41.7%) patients. Girls were bitten more at night than during the day (11 vs 3) whereas more boys were bitten during the day than at night (12 vs 10).This difference is however not significant (Fisher's Exact test PWW = 0.3). [Figure 1] shows the monthly distribution of snake bites in the study area. The highest prevalence of bites was observed between the months of April and July.
Nineteen (52.8%) and 16 (44.4%) patients had bites involving the lower and upper limbs respectively whereas one patient was bitten on the face while sleeping in the mother's room at night.
Snake type was identified only in 16 (44.4%) patients (carpet viper = 12 and cobra = 4), through verbal description from witnesses and/or patients' relatives.
The [Table 3] shows the features of envenomation among the study patients. Pain and local swelling of varying severity were observed in all the patients (100%) whereas prolonged clotting time (>30 min) occurred in 22 (61.1%) patients. Four of the patients with prolonged clotting time also had spontaneous bleeding (epistaxis = 3, hematemesis = 1), warranting blood transfusion. One (2.7%) patient had episode of seizure which subsided within 24 h of admission. The results of random blood glucose, malaria microscopy and cerebrospinal fluid analysis for the patients were all normal.
|Table 3: Features of envenomation among children admitted with snake bites|
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Prior to hospital presentation, 19 (52.8%) patients had received various interventions from traditional healers including local incisions, use of herbal concoctions and prolonged application of tourniquet to the affected limb. On admission, all the patients were given various types of antibiotics including penicillin and metronidazole. They also had analgesic and tetanus prophylaxis. Anti-snake venom, though prescribed in all the patients, was procured and administered in 29 (80.6%) patients only. Four (13.8%) patients developed adverse reaction to the PASV in the form of pyrexia and rigors which warranted its discontinuation.
Three patients had severe complications including extensive necrosis of limb in one patient which was managed by skin grafting, abscess formation in one patient requiring incision and drainage, and severe progressive edema in another patient necessitating fasciotomy due to compartment syndrome. Two of these patients recovered satisfactorily after prolonged hospital stay >10 days. However, the patient who had limb necrosis lost one of his fingers despite skin grafting. Overall, 23 (63.9%) patients were discharged home, whereas the remaining 13 signed against medical advice and their outcome was unknown. Mean length of hospital stay was 5.2 ± 2.6 days (range = 1-16 days).
| Discussion|| |
Over the 10 year study period, only 36 children or approximately 1/1000 Pediatric admissions were admitted and managed for snake bites in our institution. This hospital prevalence of snake bites in children may not necessarily reflect the actual burden of the problem within the study area. This is because treatment for snake envenomation in our environment, like most parts of Africa, is often sought from traditional healers. ,, They enjoy a high level of patronage and remain the first level of contact for most victims.  In one study from Nigeria, the proportion of patients that sought hospital treatment after snake bites was as low as 8.5%.  High cost of hospital services including anti-snake venoms, inadequate access to health care facilities by victims from remote rural villages and death even before arrival to a health center may contribute to the low hospital burden. Hence, many cases of snake envenomation go unreported and the outcome remains unknown.
The epidemiology of snake bites among children in this study is similar to reports by other workers. ,, Snake bites are more common between April and July which is the period of intense farming activities as it coincides with the beginning of the rainy season. They also tend to occur at night when visibility is low. Majority of the victims were males, from rural areas and above the age of 10 years. The preponderance of teenage boys among children with snake bites may be attributed to the fact that boys are more likely to participate, along with adults, in occupational activities that predispose to snake bites such as farming, livestock rearing, hunting and collection of fire wood.  Their natural curiosity and risk taking behavior further increase their chances of coming in contact with snakes. On the other hand, girls within the study area frequently stay indoors for cultural and religious reasons, making them less vulnerable to snake bites especially on the farm compared to boys. The fact that many children were bitten within the house premises in our study highlights the need for control of environmental factors known to provide favorable habitat for snakes. These include tall grasses along pedestrian pathways, poor lightening conditions as well as rat holes and crevices within and around the house.  Children should also be encouraged to adopt personal protection measures such as use of foot wears while walking or playing even within the house premises.
The presenting features of envenomation among our patients included local swelling of variable severity, prolong clotting time with or without spontaneous hemorrhage and in one patient, transient seizure. Except for the latter, this pattern of presentation is similar to that of most other studies in Nigeria and Africa, , suggesting morphologic similarity of the snake species that inhabit the region. E. carinatus (saw-scaled carpet viper), N. nigricolis (spitting cobra) and B. arietans (Puff adder) are generally considered to be the most important venomous snake species in West African sub-region. ,,, It should be noted however that accurate determination of the offending snake species is not always reliable in many parts of Africa. This is because the mode of identification of the snakes is usually by verbal description from witnesses; and snakes, even when killed, are hardly brought to hospital along with its victim. These facts were further buttressed by the present study.
Carpet viper is typically associated with local swelling and bleeding whereas cobras often lead to neuorotoxic symptoms. ,, The cause of seizure in one of the study patient is unknown. It may be incidental, though common causes of seizure such as hypoglycemia, meningitis and malaria were excluded by laboratory investigations. Occurrence of seizure due to cobra-induced neurotoxicity is unusual but may be a possibility. The spontaneous bleeding observed in some of the patients was most likely due to the hemotoxic venom of carpet viper, which acts as a systemic anticoagulant.  Though local swelling was mild to moderate in most of our patients, one patient had severe tissue edema of his limb, which warranted urgent fasciotomy. The mechanisms of tissue swelling may be related to the pressure effect of a tight fitting tourniquet or to the direct cytotoxic effect of the venom, which results in inflammation, fluid extravasations or hemorrhage within the soft-tissue.  In some patients, rapid progressive swelling with involvement of deep tissues may occur and this can compromise the vascular structures of a limb, causing compartment syndrome. This problem should be anticipated and identified early to prevent loss of a limb.
Despite its potential problems such as risk of secondary infection, prolongation of hospital stay and negative cosmetic effect,  fasciotomy still has a role in reducing the risk of gangrene in patients with compartment syndrome.  Like the present study, other workers had observed the occurrence of compartment syndrome in their patients and fasciotomy was done with good result. , Ideally, intra-compartmental pressure should be monitored and fasciotomy done when the measured pressure is >30 mm Hg of the mean arterial pressure. , Compartmental pressure was not measured in our patients and the decision for fasciotomy in one of the patients was based on clinical suspicion of compartment syndrome. Clinical features that may suggest this problem include marked increase in pain on limb stretching, onset of paraesthesia, feeling of hardness and absence of peripheral pulses. , However, clinical assessment is not always reliable as symptoms may be difficult to elicit in a child who cannot talk and peripheral pulses may be palpable when capillary blood flow is completely obstructed.  The decision for fasciotomy should therefore be guided not only by clinical assessment but, where possible, by direct measurement of intra-compartmental pressure.
PASV was prescribed in all the patients but was procured and administered in 80.6% of the patients. This may be related to the high cost of the PASV which limits universal access. The prevalence of an allergic reaction to the PASV was 13.8% among our study cohort. Other studies have reported prevalence ranging from 3% to as high as 50%. ,, This wide variation may be due to the differences in the type of antivenom used. Since the risk of allergic or anaphylactic reaction is always a possibility particularly in children, the use of PASV among children with snake bites should not be a mere routine. It should be given only when definite signs and symptoms of envenomation exist.
Besides PASV, all the patients had adjuvant treatment with analgesic, tetanus toxoid and antibiotics. In many parts of Africa, routine administration of antibiotics in patients with snake bites is a common practice.  However, there seems to be conflicting opinion regarding the role of antibiotics in snake bites. ,,,, Some authors discouraged the use of antibiotics in the acute phase as snake mouth has few microorganisms and the venom is considered to have antibacterial properties. ,, Yet, other workers noted that the oral flora of snakes is heavily colonized by bacteria  and that early bacterial infection was common among patients with snake bites;  hence the need for antibiotic cover especially against anaerobes. ,, The result of meta-analysis by Polly Terry showed no clear benefit of prophylactic antibiotics after venomous snake bites.  Nevertheless, antibiotics may be used in the presence of complications such as local tissue necrosis or abscesses and preferably after culture and sensitivity testing. 
In the present study, no mortality was recorded among the patients managed at our institution. Except for a patient who lost his finger, none of the patients had any long term complication or disability. Therefore, the outcome of snake bites among children in our study was good. Earlier studies from Zaria and Benin among children reported 3% and 0% mortality respectively , whereas a similar study among the adult population at UDUTH, Sokoto found a mortality rate of 2.7%.  Other hospital studies across the world have equally shown that snake bite is generally associated with low mortality. ,, This may be related to the well documented fact that only 5% of venomous snake bites are severe. 
Because this study was retrospective, we could not ascertain the outcome of patients that signed against medical advice and make a comparison between them and those who were managed at the hospital. Such comparison may be necessary since hospital mortality data may underestimate overall mortality due to snake bites.  Another limitation of this study is the fact that detail hematological profile of patients with suspected hemotoxicity was not documented. As such, some patients with subtle hematologic dysfunction may not be detected. Finally, the small number of patients may limit the strength of statistical analysis, making it difficult to generalize results. Hence, there is a need for a further prospective, large scale community-based study to ascertain the actual burden of snake bites among children in our region.
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[Table 1], [Table 2], [Table 3]