IGHE and tetanus: Hypotheses include an IgE-mediated Type I hypersensitivity reaction in patients with prior exposure or sensitisation to antivenom components [7] or other animal-derived immunoglobulins (i.e. anti-tetanus and anti-rabies serotherapies), and a non-IgE-mediated activation of the complement system or heterophilic antibodies among patients without prior exposure [2,8].