Mapping Deadly Venomous Ants

From the study, jack jumper (Myrmecia ludlowi) and the bulldog ant (Myrmecia gratiosa) (pictured), which are both endemic to Western Australia, were responsible for the majority of sting reactions.

Perth researchers have mapped and identified the four major ant groups responsible for anaphylaxis throughout Australia in a hope to develop a diagnostic venom-specific IgE (sIgE) testing kit. Western Professor Simon Brown and his team from the Australian Institute for Medical Research (WAIMR) also investigated venom immunotherapy (VIT) or desensitization relevant to the results of the venom-specific test.

Green head ants (Rhytidoponera metallica), along with species within the genus Myrmecia comprised of Jack jumper (JJA), bulldog and other Myrmecia.sp were shown to cause anaphylaxis.

Inadequate knowledge of the causative species by health professionals and the absence of diagnostic tests further complicate successful VIT because JJA is a “species complex,” comprising seven closely related species with almost identical morphology.

From the study, jack jumper (Myrmecia ludlowi) and the bulldog ant (Myrmecia gratiosa), which are both endemic to Western Australia, were responsible for the majority of Western Australian sting reactions.

Working with the Centre for Clinical Research in Emergency Medicine (CCREM) Professor Brown says “Results from these studies are needed to guide our diagnostic approach and then therapy. If we know it is a jack jumper ant (JJA), then we currently have VIT available.”

Professor Brown travelled around Australia collecting ants and extracting their venom.

“We developed approximately 12 ‘reference venom extracts.’ Then, taking blood from people, we tested it for antibodies to these reference venom extracts to determine the species responsible for severe allergic reactions. We could then ‘map’ responsible species across Australia.  This is a helpful guide for clinicians,” he says.

The VIT study used a randomized controlled trial comparing rapid treatment approaches over two to three weeks (three visits) versus the traditional ‘slow’ treatment approaches over two-three months (10 visits), as well as a comparison of the standard high dose of (100 mcg) versus a lower dose (50 mcg) for long term ‘maintenance’ injections (these are given every month for three to five years).

This study aims to assess changes in venom-specific immunoglobulin and cytokine responses during the time course of immunotherapy and how these correlate with clinical endpoints.

“These studies will better provide us with the ability to accurately diagnose venom-specific anaphylaxis throughout Australia — currently we can only do this in Tasmania for JJA.”

Professor Brown’s study has been published in The Medical Journal of Australia. He hopes the studies will better prepare clinicians in the diagnosis and treatment of ant venom stings, Australia-wide.