Snake bite envenomation in Riyadh province of Saudi Arabia over the period (2005–2010)

Abstract

The present investigation is a retrospective review of snake bites in Riyadh province over the period (2005–2010). A total of 1019 cases of bites admitted to the Ministry of Health medical centers in Riyadh province were analyzed on the basis of age, sex, time of bite and its site on the body, outcome of treatment, antiserum dose and type of snake. Bites occurred throughout the six years with the highest frequency in 2005 and least in 2006 where most of the bite cases were mild and all evolved to cure except four patients who died following the administration of antivenom during 24 h after snake bite. Most of the patients were males (81.7%) and the most attacked age was within the range of 11–30 years (51.5%). All the bites were mainly in the exposed limbs and the most frequently bitten anatomical regions were the lower limbs (427 cases, 41.9%), principally the feet. The study incriminates Cerastes cerastes gasperettii in most of the bites indicating it as the snake of medical importance in Riyadh province. Also, the study indicates low degree of threat in spite of high rate of snake bites as a result of the availability of the medical facilities and the antivenin use in medical centers in Riyadh province.

1. Introduction

Snake bite envenomation is a world problem that represents a threat to many countries including Saudi Arabia. It is estimated that globally at least 421,000 envenomation’s and 20,000 deaths occur each year due to snake bites (Kasturiratne et al., 2008). Each year there are over 8000 and 3000 poisonous bites in the U.S.A. and Australia respectively. Considerable studies on snake bites have been undertaken in several countries such as South-East Asia (Sawai et al.,1972), Nigeria (Pugh and Theakston, 1980; Paramonte, 2007), Papua New Guinea (Currie et al., 1991), South East of the Arabian Peninsula (Alkaabi et al., 2011), Central Iran (Dehghani et al., 2012, 2014a,b) Senegal (Trape et al., 2001), Brazil (Franco et al., 2001), India (Mohapatra et al., 2011), Nepal (Sharma et al., 2004), Malaysia (Chew et al., 2011) and Morocco (Arfaoui et al., 2009). Approximately 30% of the 3000 snakes across the globe are venomous and considered dangerous to humans (Hider et al., 1991). Fifty-one species of snakes have been recorded in Saudi Arabia, nine of these are venomous with four (Walterinnesia aegyptia, Atractaspis microlepidota, Cerastes cerastes gasperettii, and Echis coloratus) of which have been recorded in Riyadh province (Al-Sadoon, 1989; Gasperetti, 1988). The information concerning snake bites in Saudi Arabia is scarce and fragmentary (Kingston,1981; Tilbury et al., 1987; Al-Sadoon and Abdo, 1990; Al-Sadoon and Jarrar, 1994; Al-Mohareb and Al-Sadoon, 1994; Al-Durihim et al., 2010; Malik, 1995) with no reliable statistical studies on this issue and very little is known about the rate of snake bites in Riyadh province (Al-Sadoon and Jarrar, 1994). Snake bite envenomation leads to various clinical features, depending on the involved snake species. Hematological toxicity caused by family Viperidae (C. c. gasperettii and E. coloratus) can be manifested through bleeding that may develop into disseminated intravascular coagulopathy. The neurotoxicity caused by family Elapidae (W. aegyptia) and family Atractaspididae (A. microlepidota) may develop respiratory distress (Pantanowitz and Andrzejewski, 2006).

The present study is an attempt to evaluate the snake envenoming in Riyadh province over a six year period extending from 2005 to 2010.

2. Materials and methods

The incidence and frequency of snake bites in Riyadh province were reviewed for a 6-year period beginning from 2005. This study was based on 1019 cases of snake bites submitted to the emergency department at the hospitals and Medical centers of Riyadh province, Saudi Arabia. Data were extracted from the records of the Ministry of Health medical centers in Riyadh province and analyzed according to the following bases: age, sex, time of bite and submission (month and time of day), bite details including anatomic site, clinical finding at the site noted during hospitalization, laboratory results, presenting complaint, systemic symptoms, details of antivenom use including type and doses given, period of observation, outcome of each bite and snake species (if known) (Ministry of Health Riyadh, Saudi Arabia). Identification of the incriminated snakes was generally reported by patient report with assistance of Zoological photographs of Saudi Arabian venomous snakes which were available in some medical centers of Riyadh province. Data were analyzed by using ANOVA for each individual character.

3. Results

3.1. Rate and distribution of bites

The total number of snake bites in Riyadh province over the period (2005–2010) was 1019 with an average of 169.8/year. As seen in Table 1, the highest rate (P < 0.05) of snake bites was in 2005 with 183 cases (17.90%) while 160 cases (15.70%) were recorded in 2006.

Table 1.

Rate and relative frequency of snake bites in Riyadh province over the period (2005–2010).

Years	Number of cases	Relative frequency (%)
2005	183	17.90
2006	160	15.70
2007	168	16.40
2008	172	16.80
2009	170	16.60
2010	166	16.20
Total	1019	100

3.2. Distribution of bites according to age

As seen in Table 2, ninety-eight bite cases (9.6%) were recorded with age category below 10 years. 13 bite cases were over 61 years old (1.2%) while most patients were males in their twenties (282.5 cases, 27.7%).

Table 2.

Distribution of snake bites according to age in Riyadh province over the period (2005–2010).

Years	<10 years	11–20 years	21–30 years	31–40 years	41–50 years	51–60 years	>61 years
2005	18.3	44.8	47	37.7	21.3	12.2	2
2006	15.2	37.7	41.7	31.5	18.4	12.5	3
2007	16.3	39.7	47.8	32.6	19.3	10.3	2
2008	16.3	39.5	52	33	19.4	10	2
2009	16.2	42	47	32.6	18.4	9.8	2
2010	16.2	39.7	47	32.6	18.3	10.2	2
Total	98.5	288.2	282.5	200	115.1	65	13
%	9.67	28.28	27.72	19.63	11.29	6.38	1.27

3.3. Distribution of bites according to sex

Male–female biting rate was 833 and 186 cases with a percentage of 81.70% and 18.20% respectively and males exceeded that of the females (P < 0.05) in all years of the study period. The highest rate of bites among males was recorded in 2005 (148 cases) while the lowest rate was recorded in 2006 (131 cases). The highest and lowest female rates were recorded in 2005 and 2006 (35 and 29 cases), respectively (Fig. 1).

Figure 1.

Distribution of snake bites according to sex in Riyadh province over the period (2005–2010).

3.4. Distribution of bites through the year

No snake bites were recorded in December, January and February in any year of the study period. Monthly incidence of bites showed peak incidence from March to November. The majority of the envenoming occurred during the hotter months of the year. The highest rate of snake bites was in August while the lowest rate was in March (P < 0.05). As it is seen in Fig. 2 and Table 5, March, April, October and November showed relatively low rate of snake bites while May through September account a high rate of snake bites.

Figure 2.

Distribution of snakebites through the year in Riyadh Province Over the period (2005–2010).

Table 5.

Rate and frequency of snake bites throughout the year in Riyadh province over the period (2005–2010).

Months	Number of cases	Relative frequency (%)
January	0	0.0
February	0	0.0
March	29.2	2.8
April	45.2	4.4
May	122.5	12.0
June	135	13.2
July	150	14.7
August	277	27.1
September	131	12.8
October	88.6	8.6
November	40.5	3.9
December	0	0

3.5. Time of bites

The highest rate of bite cases occurred at night during all the years. The nocturnal bites counted 505.9 cases (49.60%) and the diurnal ones were 284 cases (27.80%) while the undecided time cases counted 229 (22.49%). The analysis of the data showed that the highest nocturnal bites (P < 0.05) were recorded in 2005 (Fig. 3).

Figure 3.

Time of snake bites in Riyadh province over the period (2005–2010).

3.6. Bite site on the body

All bites occurred on the exposed areas of the limbs. The number of bites on the lower limbs was 427 cases (41.90%) and that on the upper limbs was 313 cases (30.70%). The bites on the lower extremities were 427 cases of which 230 (22.59%) were on the right foot and 197 (19.50%) on the left foot. No bites were recorded on the neck, head or rest of the body. The incidence of bites on different parts of the hand were as follows: Thumb 56.20 cases (6.30%), index finger 107 cases (10.50%), middle finger 59.10 cases (5.70%), and little finger 47.3 cases (4.60%) while no bites were recorded in the ring finger (Table 3).

Table 3.

Distribution of snake bites according to bite body site in Riyadh province over the period (2005–2010).

Years	Right foot	Left foot	Right arm	Left arm	Thumb	Index finger	Middle finger	Ring finger	Little finger
2005	40	36	35	24	9.2	21.3	10.3	–	7.2
2006	36	30	27	23	9	20.5	8.8	–	5.7
2007	38	32	27	25	10	20.6	9	–	6.4
2008	40	31	28	24	12	18	11	–	8
2009	35	34	30	20	13	17	10	–	11.4
2010	41	34	29	21	12	10	10	–	9

3.7. Treatment outcome

The number of deaths caused by snake bites in the current study was 4 out of the total of 1019, which makes 0.3%. Other bitten patients evolved to cure after being hospitalized. No cases were discharged against doctor advice.

3.8. Antiserum dose

Patients were given equine polyvalent ASV (The Antivenom and vaccine production center, National Guard Health Affairs, Riyadh, Saudi Arabia). Each vial contained 10 ml of purified immunoglobulin fractions against five types of snakes (Bitis aritanus, Cerastes cerastes, Echis carinatus, Echis coloratus and Naja haje). Most of the patients (606 cases) received less than 5 ml of antiserum dose while 203.5 patients received more than 5 ml. Antivenin was administered intravenously to patients (Table 4). 201.5 patients received undecided dose of Antivenom.

Table 4.

Distribution of snake bitten cases treated with antiserum dose in Riyadh province over the period (2005–2010).

Years	>5 ml dose	<5 ml dose	Undecided dose
2005	108	35.3	39.7
2006	95.7	34.8	29.5
2007	101.8	31.5	34.6
2008	101.9	35.6	34.5
2009	98.9	34.6	34.6
2010	98.8	31.6	36.6

3.9. Snake species

Most of the medical records of the bitten patients described the incriminated snake as the horned snake, C. c. gasperettii (86.90%). Few undecided venomous snake species were recorded.

4. Discussion

Venomous snakes are widely distributed in the Saudi Arabia and Arabian peninsula in general. Fifty-one species of snakes have been identified in Saudi Arabia, nine of these are venomous sea snakes and the remaining 42 species are terrestrial, of which 9 are venomous (Gasperetti, 1988; Al-Sadoon, 1989; Al-Sadoon and Al-Faraj, 1992). The results of the present study indicate that there were 1019 snake bites in Riyadh province during the period of six years extending between 2005 and 2010 with an average of 169.8 per year. The higher incidence of snake bites in this province could be explained by its large population. Also, the climate in this province, that varies from semiarid to arid, may play an important role in diverse fauna of venomous snakes and snake bites. The result of present investigation is in agreement with a previous study on the incidence of snake bites of the same province during the period 1986–1988 (Al-Sadoon and Jarrar, 1994). The present results are similar to those found in different regions of Saudi Arabia such as Asir and Hail which showed that snake bite is a medical problem (Al-Mohareb and Al-Sadoon,1994; Malik, 1995; Mahaba, 2000; Al-Durihim et al., 2010).

The low fatality rate (0.3%) was reported in spite of the high rate of snake bites in Riyadh province as shown by the present study and all victims were transferred to hospital within a reasonable time frame. This finding differs from other result that reported death following snake bites in Saudi Arabia. Death cases due to snake bite were reported in Riyadh city by previous work (Al-Sadoon and Jarrar, 1994; Al-Durihim et al., 2010) and in other areas of Saudi Arabia (Al-Sadoon and Abdo, 1990; Al-Mohareb and Al-Sadoon, 1994). These studies reported that mortality rate of snake bites in Riyadh city, Hail region and Al-baha was reported by previous studies as 2.3%, 4.8%, 2.9% and 1.2% respectively (Al-Sadoon and Jarrar, 1994; Al-Durihim et al., 2010; Mahaba, 2000; Al-Mohareb and Al-Sadoon, 1994). In other countries, the snake bite envenomation is considered as a real public health issue. The rate of snake bites has been reported as 8.5% in Philippines, 5.1% in Taiwan, 0.33% in Malaysia, 5.1% in Nigeria (Chapman, 1968: Sawai et al., 1972; Pugh and Theakston, 1980) and 5.6% in Morocco (Arfaoui et al., 2009). Twenty-six deaths were caused by snake bites during the period 1976–1999 in 42 villages of south-eastern Senegal (Trape et al., 2001). The low rate of death due to snake bites in Riyadh province as demonstrated in the present study and in comparison with previous reports indicates that this syndrome does not carry the degree of a real medical threat that has been reported in the past. This may be due to the excellent medical facilities and supportive care that developed in recent years in different regions of Saudi Arabia including Riyadh province. In addition, the present results indicate the success of the Saudi national strategy against snake bite envenomation as a consequence of the establishment of national records and moreover, manufacturing specific and poly antivenom targeting the spectrum of the local venomous snakes.

The present investigation showed that the majority of snake bite victims in Riyadh province were males (81.70%). This finding is in agreement with previous results carried on snake bites in Saudi Arabia (Al-Sadoon and Jarrar,1994; Al-Durihim et al., 2010; Mahaba, 2000; Al-Mohareb and Al-Sadoon, 1994) and with other studies in different countries such as Brazil where 89.5% of the patients were males (Franco et al., 2001); southeast of Arabian peninsula where the majority (87%) were male farmers (Al-Kaabi et al., 2011); Morocco where 53% were males (Arfaoui et al., 2009) and the snake bite patients were males (96%) in Isfahan province, Iran (Dehghani et al., 2014a,b). Snake bites in males outnumbered females in the present investigation. This may reflect the fact that women in Riyadh province as other districts of Saudi Arabia in contrary to men spend most of their times indoors with their families whereas males are involved in farming activities or young camper or Bedouins’ who spend most of their life in the desert.

The present result demonstrated that young adults and adolescents (51.5%) are more affected by snake bites. The high rate of snake bites among victims younger than 30 years may be explained on the basis where this age category is associated with most outdoor activities.

According to the data from this study, no snake bites were reported in the winter months (December through February). This may be due to the fact that snakes hibernate and become totally inactive due to lowered ambient temperatures. The highest incidence of snake bites was more frequent during the summer months (May through September) with a maximum frequency in August. This result corroborates some studies in other regions of Saudi Arabia (Al-Sadoon and Jarrar,1994; Al-Kaabi et al., 2011) and in Morocco (Arfaoui et al., 2009) but differs from other studies (Tchoua et al., 2002; Paula Neto et al., 2005; Pacheco and Zortéa, 2008) in which snake bites were reported between November and April.

Most bites in this study occurred during night time. The large number of cases (506) at night may be explained by the fact that most of the venomous snakes in Saudi Arabia are nocturnal. This finding is similar to that previously reported by Al-Sadoon and Jarrar (1994).

The results of the present study showed that the most common bite intensity is in the lower limbs, with the upper limbs next suggestive of the lack of protective footwear among victims. This finding is similar to other finding (Franco et al., 2001; Al-Sadoon and Jarrar,1994 Al-Kaabi et al., 2011) and may be explained on the basis that the exposed limbs are usually used in most manual activities and moving or entering the snake retreats.

The present study points to C. c. gasperettii as the species of medical importance in Riyadh province. The implicated horned viper was identified in 886.5 cases (86.9%). A previous study identified C. cerastes, E. coloratus and A. microlepidota as the cause of the snake bites in Riyadh city (Al-Durihim et al., 2010; Kingston, 1981; Al-Sadoon and Abdo, 1990; AL-Sadoon and Jarrar, 1994). C. c. gasperettii has an hemotoxic venom and is also one of the most common species in human bites throughout the Middle East. Other deadly snake species have been reported in other regions of Saudi Arabia such as Naja haje arabicus, E. coloratus and W. aegyptia (Tilbury et al.1987; Al-Mohareb and Al-Sadoon, 1994; Malik, 1995). In other countries, snake bites are incriminated by Naja nigricollis (in Nigeria), the saw-scaled viper Echis ocellatus (in Senegal) (Pugh and Theakston, 1980; Trape et al., 2001) and Bitis arietans, Naja h. legionis, Coluber hippocrepis, and Vipera mauritanica (in Morocco) (Arfaoui et al., 2009).

Main symptoms of C. c. gasperettii envenomation were local pain, shock, swelling, edema and tenderness in most of the patients. This finding is in agreement with other results (Al-Durihim et al., 2010; Al-Kaabi et al., 2011; Al-Mohareb and Al-Sadoon, 1994).

In conclusion, from this study, we found that among those identified snakes, the most common venomous snake bite was of the horned viper, C. c. gasperettii. These bites result in envenomation needing antivenom administration but with no serious clinical complication. Although the rate of snake bite is high in Al-Riyadh province most of the bitten patients recovered. This does not imply a real medical threat. This may be due to the excellent medical facilities and having the antivenom available in the health centers in recent years in different regions of Saudi Arabia. It is very important to educate the native people to increase awareness about the possibility of venomous snakes and the risk of snake bites is greater during the hot months of the year. General awareness for those who intend to hike or camp in areas known to be inhabited by venomous snakes is important. Education of the emergency medical staff for identification of venomous snakes is an essential step in the treatment.