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Reactions to Snake Venom Antisera: Study of pattern, severity and management at
General Hospital, Anuradhapura


The high rate of AVS reaction, (68%) observed in this study is similar to observation made in the past 5,6,7. Even though, a low rate of reaction are expected with monovalent antivenom, a recent study done at General Hospital, Anuradhapura using monovalent antivenom

(Polonga Tab) in Russell’s viper showed an adverse reaction rate of 34%(8).

This observation indicates that regardless of whether antivenom preparations are polyvalent or monovalent reactions can be expected, as long as animal sera are used in manufacturing antivenom. A recent study done in Colombia has shown a reduction of early antivenom reaction in Bothrops snake bite when using antivenom which was a production of whole IgG, produced by caprylic acid fractionation, in comparison to the conventional pepsin-digested method 9. So the management of reaction to antivenom is an integral part of management of snake envenoming in current practice.

This study shows that reactions to AVS treatment can not be predicted by a history of atopy in patients. Studies of prediction, prevention and mechanism of early anaphylactic antivenom reactions in victims of snake bite have been done in several countries including Nigeria and Thailand. Conventional cutaneous (intradermal) or conjunctival hypersensitivity testing was done before the administration of antivenom. However, this procedure failed to predict reactions to antivenom and it was concluded that conventional hypersensitivity tests had no predictive value for occurrence of hypersensitivity reactions and that


Table 3: Percentage of patients with the type of reaction

Percentage (n)






Cold clammy skin



65% (26)

57% (14)

55% (13)

24% (10)

24% (10)

21% (9)

5% (2)

5% (2)



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Table 2: The time of onset of the initial reaction after administration of AVS and the time duration of the reaction (minutes)

Onset time

(in minutes)

No. of Patients

Duration of reaction

(in minutes)

No. of patients







8 (19.5%)

13 (31.7%)

15 (36.5%)

5 (12%)

0 - 5

6 - 15

16 - 30

31 - 60


16 (30.9%)

9 (21.9%)

10 (24.5%)

5 (12.1%)

1 (2.4%)