Prevalence, severity, and natural history of jack jumper ant venom allergy in Tasmania.

BACKGROUND

The jack jumper ant (Myrmecia pilosula) is responsible for greater than 90% of Australian ant venom allergy. However, deaths have only been recorded in the island of Tasmania.

OBJECTIVES

We sought to determine the prevalence, clinical features, natural history, and predictors of severity of M pilosula sting allergy in Tasmania.

METHODS

We performed a random telephone survey supported by serum venom-specific IgE analysis, review of emergency department presentations, and follow-up of allergic volunteers.

RESULTS

M pilosula, honeybee (Apis mellifera), and yellow jacket wasp (Vespula germanica) sting allergy prevalences were 2.7%, 1.4%, and 0.6% compared with annual sting exposure rates of 12%, 7%, and 2%, respectively. Similarly, emergency department presentations with anaphylaxis to M pilosula were double those for honeybee. M pilosula allergy prevalence increased with age of 35 years or greater (odds ratio [OR], 2.4) and bee sting allergy (OR, 16.9). Patients 35 years of age or older had a greater risk of hypotensive reactions (OR, 2.9). Mueller reaction grades correlated well with adrenaline use. During follow-up, 79 (70%) of 113 jack jumper stings caused anaphylaxis. Prior worst reaction severity predicted the likelihood and severity of follow-up reactions; only 3 subjects had more severe reactions. Venom-specific IgE levels and other clinical features, including comorbidities, were not predictive of severity.

CONCLUSIONS

Sting allergy prevalence is determined by age and exposure rate. M pilosula sting exposure in Tasmania is excessive compared with that found in mainland Australia, and there is a high systemic reaction risk in allergic people on re-sting. Prior worst reaction severity (Mueller grade) and age predict reaction severity and might be used to guide management.