Antivenoms in Snake Envenoming: Are they Safe? Deshpande Rushikesh Prabhakar1*, Motghare Vijay Motiram2 and Bhamare

Snake antivenoms are the only definitive management of snake envenoming. Parenteral administration of antivenom mitigates the toxic effects due to snake venom components. However, these benefits come with additional risk of antivenom reactions. The morbidity and mortality of antivenom reactions largely go unnoticed due to lack of awareness and many times these are wrongly attributed to effects of snake venoms. Depending upon the duration between antivenom administration and onset of clinical manifestations, World Health Organization (WHO) has classified these reactions into three types; namely i) early anaphylactic reactions: occur within 10-180 minutes after antivenom infusion, ii) pyrogenic (endotoxic) reactions: develop within 1-2 hours after initiation of treatment, and iii) late reactions: usually develop 1-12 (mean 7) days after treatment. The conjunctival or skin hypersensitivity tests are not only unreliable but can also be sensitizing to antivenom reactions, and hence, not recommended by WHO. The majority of early anaphylactic reactions are non-IgE mediated owing to anticomplementary activity of antivenom and few reactions are attributed to IgE mediated release of anaphylotoxins namely histamines, leukotriens etc. Contamination of antivenom with endotoxins during manufacturing process leads to development of pyrogenic reactions. Late antivenom reactions are the result of production of IgM or IgG antibodies in patients towards antivenom proteins, which ultimately cause formation of immune complexes. The deposition of these immune complexes throughout body leads to manifestations of late reactions. There should be a vigilant approach towards prediction and prevention of antivenom reactions for a better quality of health care.