Prevention of anaphylaxis with ant venom immunotherapy

Worldwide, eight genera of ants have been associated with sting allergy. Until recently only whole ant body extracts have been used for immunotherapy. The purpose of this review is to examine recent advances in the understanding of ant venom allergy and treatment using venom immunotherapy.

Public health problems due to severe ant sting anaphylaxis are not confined to the imported fire ant of North America. Pachycondyla sennaarensis (samsum ant), Pachycondyla chinensis, and Myrmecia pilosula (jack jumper ant) also appear to pose notable threats. The risk to humans from a particular species probably depends on complex interactions between likelihood of human contact, insect aggression, efficiency of the venom delivery apparatus, and venom allergenicity. The highest population prevalence of clinical ant sting allergy so far (3.0%) was reported from south-eastern Australia, due mainly to M. pilosula. Prospective follow-up of untreated people suggests that those older than 30 years with a history of severe reactions (respiratory compromise or hypotension) will benefit most from venom immunotherapy. Whereas the efficacy of ant whole body extract immunotherapy remains to be proven, ant venom immunotherapy has been demonstrated to reduce the risk of systemic reactions to M. pilosula from 72% to 3%. Although a simple method of venom extraction has been developed, small market size means that the treatment may never become widely available.

Ant venom immunotherapy is feasible and highly efficacious. However, the limited geographical distribution of each species presents a major challenge to making venom extracts available for clinical use.