An article by three UA researchers will be published in the May 14 edition of the New England Journal of Medicine.
Youngsters suffering severe nerve poisoning following a scorpion sting recover completely and quickly if a scorpion-specific antivenom is administered, according to a study conducted by University of Arizona researchers.
The research team published its findings in the May 14 issue of the New England Journal of Medicine.
The article, "Antivenom for Critically Ill Children with Neurotoxicity from a Scorpion Sting," recounts a study of 15 children conducted in Tucson in 2004 and 2005.
All of the children had been admitted to a pediatric intensive care unit following a scorpion sting and were experiencing abnormal eye movements, uncontrolled thrashing of limbs and respiratory distress – all symptoms of nerve poisoning caused by the venom of the bark scorpion.
Leslie Boyer is lead author on the article and principal investigator of the study. At the UA, Boyer serves as director of the Venom Immunochemistry, Pharmacology and Emergency Response, or VIPER, Institute at the UA College of Medicine.
In the study, eight of the children, most of whom were under 6 years old, received a scorpion antivenom that is commercially available in Mexico but is considered an investigational drug in the United States and is not approved for general use by the U.S. Food and Drug Administration. The seven other study participants received a placebo, which is a preparation containing no medication.
The symptoms of nerve poisoning were resolved in all of the children treated with the antivenom in less than four hours, and usually within two hours. The children who received the placebo continued to experience nerve poisoning for four hours or more and required large doses of sedative medication and extended hospitalization.
"This study told us that the dangerous effects of bark scorpion venom can be reversed quickly with the right antivenom," said Boyer, medical director of the Arizona Poison and Drug Information Center at the UA College of Pharmacy.
Arizona's bark scorpion and its Mexican "cousins" are the only North American scorpions with venom that can cause significant nerve poisoning in humans. Scorpions are very common throughout Mexico, and antivenom products have been manufactured and used there for decades.
Each year, about 8,000 scorpion stings occur in Arizona and about 200 result in serious nerve poisoning and require medical treatment.
Nearly all of these patients are young children, whose breathing may be impaired severely by the effects of the scorpion venom on the nerves controlling the respiratory system.
"One-hundred percent of the children who received it (the antivenom) got better very quickly, meaning that using this antivenom in the emergency room will make intensive care treatment unnecessary for most patients," Boyer said.
"This is particularly important in small Arizona towns without pediatric intensive care units. By avoiding helicopter trips and intensive care stays, we can save lives and keep treatment costs down at the same time," she added.
Before 2000, a project at Arizona State University produced a scorpion antivenom for use in the state. Supplies of that antivenom dwindled following the researcher's retirement, running out completely in 2004.
Without antivenom, treatment for nerve poisoning requires intensive supportive care, usually with heavy sedation and sometimes requiring a ventilator.
The UA-led study reported in the journal involved Anascorp, an antivenom made and supplied to the UA at no charge by the pharmaceutical company Instituto Bioclon, headquartered in Mexico City.
The study was funded by a grant from the Office of Orphan Products Development of the Federal Drug Administration. Beginning in 2004, additional funding from the state of Arizona has enabled 22 hospitals throughout the state to participate in the study and provide antivenom to their patients.
Andreas Theodorou, a professor of pediatrics and chief medical officer of University Medical Center in Tucson, was part of the study team and co-authored the study.
"This antivenom basically takes symptoms away in a very short time," Theodorou said. "What was a life-threatening disease that would put kids in the pediatric ICU has become, for most of them, an outpatient disease."
Other authors of the New England Journal of Medicine article are: Robert Berg, The Children's Hospital of Philadelphia, Department of Anesthesia and Critical Care Medicine; Joanne Mallie, the UA, VIPER Institute; Ariana Chávez-Méndez, Universidad Nacional Autónoma de México; Walter García-Ubbelohde, Instituto Bioclon SA de CV, Mexico City; Stephen Hardiman, Stephen Hardiman Statistics, New Jersey; and Alejandro Alagón, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Moralos.