Anaphylaxis to bull dog ant and jumper ant stings around Perth, Western Australia.

OBJECTIVE

To determine the main causative species, reaction characteristics and geographical locations of ant sting anaphylaxis around Perth, Western Australia (WA).

METHODS

Structured interviews were performed on a cohort of 10 patients referred to our Anaphylaxis Clinic who were allergic to ant venom, followed by field trips to collect ant specimens. A descriptive analysis of clinical data was performed.

RESULTS

Around Perth, Myrmecia gratiosa, a bull dog ant, was the only species of stinging ant found around the locations where reactions had occurred (eight patients). To the south-west of Perth, species implicated were another bull dog ant Myrmecia nigriscapa (one patient), and a jumper ant Myrmecia ludlowi (one patient). Twelve reactions were documented as mild (one), moderate (seven) and severe with hypotension (four). In three bull dog ant venom allergic patients, specific IgE was analysed, demonstrating substantial cross-reactivity with other bull dog ant species. Clinical patterns of reaction severity and response to repeated stings were consistent with known features of insect sting allergy.

CONCLUSIONS

A single species of bull dog ant, M. gratiosa, appears to be responsible for ant sting anaphylaxis around Perth. Further investigation is required for other regions of WA. The provision of effective immunotherapies for people allergic to native Australian ants might be simplified by the dominance of a limited number of ant species and IgE binding cross-reactivity between venoms, as was evident in this study.