Vaccine for deadly ant sting

People allergic to ant stings can be immunised against potentially fatal reactions, researchers have found.

The jack jumper ant is responsible for around 90% of severe reactions to ant venom in south-eastern Australia.

Researchers from the Royal Hobart Hospital in Hobart, Tasmania, found immunising people with venom, so they become desensitised to it, means they do not experience an allergic reaction if they are stung.

In contrast to normal immunisations, where a person's immune system is primed to produce antibodies against a substance, this treatment aims to tell the body not to react, so people will not have a severe reaction if they are stung.

Sixty-eight healthy people who were allergic to jack jumper ants, Myrmecia pilosula, were either given venom immunotherapy (Vit) - doses of the venom - or a dummy injection.

Jack jumper stings were given one week later in the resuscitation room of a hospital casualty department.

No severe reactions were seen among those given the Vit treatment.

In comparison, three-quarters of those given the placebo treatment had a severe reaction to the stings.

Disturbed

Researchers then switched the groups, so the placebo group was given Vit. Just one person in that group had a reaction, proving the therapy was effective, the researchers said.

However, they added that because the people receiving the therapy are, by definition, allergic to the venom, the treatment had to be given within a hospital setting in case they experienced a reaction.

Jack jumper ants are found in Perth, across south-eastern Australia and particularly in Tasmania.

They were given their name because of the way they move when they are disturbed.

Adrenaline is currently given as standard treatment for anybody who experiences a severe reaction.

Writing in the Lancet, the researchers led by Dr Simon Brown of the department of emergency medicine and pharmacy, said: "In our highly motivated, highly allergic, but otherwise healthy study population ... Vit was very effective in prevention of life-threatening sting anaphylaxis.

"Vit has some potential to prevent deaths and can result in striking improvements in the quality of life of affected individuals."

'Impressive evidence'

In an editorial in the Lancet, Dr David Warrell of the Nuffield department of clinical medicine, John Radcliffe Hospital, Oxford, UK, said: "This prophylaxis [Vit] can be recommended for susceptible patients in Australia.

"It will require a sustained supply of M pilosula and, perhaps, some other ant venoms."

"The demonstration by Brown and colleagues of such impressive evidence of the efficacy of immunotherapy with jack jumper ant venom now justifies more research investment in this area."