Lethal dose (LD50) of the big four snakes-a mini review

Abstract

to snake envenoming is the anti-snake venom serum (ASVS) that is acquired by hyperimmunization of animals. Raising antisera is a long and laborious task. So correct determination of LD 50 becomes need of hour for efficient production of ASVS. Several studies have been devised to study the LD 50 of big four snakes. The toxicity and lethality of the snake venom varies from species to species and even within the species depending upon geographical location, route of venom injection, age, size, locality, health, body temperature and even mood of the snake. Parveen et al. 5 determined the LD 50 of big four snakes as LD 50 of cobra (NajaNaja) about 6 to 7 μg/dose, Saw Scaled Viper (Echiscarinatus) 11 to 12 μg/dose, Russelviper (Viperarusselli) 5 to 6 μg/dose and Krait (Bungarescaeruleus) 4 to 5 μg/dose when injected intravenously (Figure 1). Figure 1 LD 50 of big four snakes estimated by Perveen et al. 5 Different researcher conducted studies to investigate the LD 50 of big four snakes at various institutes. And it is found to be varying in different geographical locations. This study presents the overview of the LD 50 as estimated by various researchers on mice. The LD 50 of Echiscarinatus (Saw-scaled viper) estimated by Parveen et al. 5 was 0.5655μg/g and by 6 was 22 μg/mouse of mice through intravenous route. LD 50 of Echiscarinatus multisquamatus which is found in Iran was calculated as 11.1 μg/mouse. 7 According to Australian online biodata of snake venom LD 50 of Echiscarinatus multisquamatus is 3.26 μg/g. 8 In case of Russell viper (Viperarusselii) the LD 50 was 0.3321 μg/g estimated by Parveen et al. 5 and 0.3 μg/g as calculated by Meier and Theakston (1986). Forkrait (Bungaruscaeruleus) LD 50 calculated by Perveen et al. 5 is 0.2828 μg/g for intravenous route. Engelmann and Obst et al. 9 obtained LD 50 value is 0.169μg/g and Mirajkar & More et al. 10 reported LD 50 of 0.16 μg/g. Australian Venom and Toxin database depicts the LD 50 value 0.169μg/g for Krait. 8 The LD 50 of cobra (Najanaja) estimated by Perveen et al. 5 was 0.2828 μg/g. Riaz & Zaman 11 estimated LD 50 of cobra about 1.2μg/g. The lethality of snake venom varies from species to species and even among the individuals of the same species. This is because of multiple factors such as ecological variables, biophysical environment, physical and physiological status, genetic variation (either adaptive or incidental) and various other molecular and ecological evolutionary factors. The influence of such factors in the controlled laboratory settings is although minimal but it cannot be completely eliminated. However, to minimize the variability comprehensive studies covering a range of factors needs to be conducted to determine snake venom lethality or potency.