Scorpion venom neutralized

A drug used in Mexico proves effective in Arizona test

The Arizona bark scorpion may be small, but its sting delivers a neurotoxin that can kill or render critically ill a young child. A study in the May 14 New England Journal of Medicine finds that an antivenom drug commonly used in Mexico for such stings neutralizes the toxin, eliminates symptoms and reduces the need for sedation in children who have been stung.

Although only as long as a finger, the Arizona bark scorpion delivers a neurotoxin that can make a child critically ill. An antivenom used in Mexico has passed a U.S. test. APDIC/R. Wagner

More than 200 children in Arizona and a handful in New Mexico become critically ill from Arizona bark scorpion stings each year, but there is no U.S.–approved remedy for the stings. Children are rushed to intensive care units and sedated to prevent wild thrashing and choking, says pediatrician Leslie Boyer of the University of Arizona in Tucson. The victims are closely monitored until the neurotoxin’s effects fade, which takes 16 hours on average but can take several days. Some children require a mechanical ventilator to breathe.

Adults typically face painful but much milder symptoms from the sting of this scorpion, Centruroides sculpturatus.

During 2004 and 2005, Boyer and her colleagues randomly assigned 15 children showing up at Tucson hospitals with scorpion poisoning to receive either the Mexican antivenom and sedation as needed or a placebo infusion along with sedation. Both groups also received other care, such as breathing assistance if necessary. Doctors treating the patients didn’t know who was given antivenom and who wasn’t.

Eight of eight children receiving the antivenom showed no signs of scorpion venom in their blood after only one hour and recovered within four hours. Only one in seven children who received the placebo recovered in four hours, and that child was the oldest and heaviest of the group at 42 kilograms. The children not getting the antivenom also needed 65 times as much sedative drug as the others on average, Boyer says. None of the children died.

If approved, the antivenom could ease suffering and even prevent deaths among small children in rural areas that lack intensive care units, Boyer says. The team is now conducting an Arizona-wide study giving the antivenom to children who become seriously ill from such scorpion stings.

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