Invading Fire Ants’ Sting Could Kill, Doctors Warn

The red fire ant invasion that has reached Southern California is more than just a nuisance. In some rare instances, the ant’s sting can cause severe allergic reaction or even death to those who already have been stung, experts say.

In the Southern states where the ant has long made its home, the insect “has become a significant health hazard and may be the No. 1 agent of insect stings,” according to the American College of Allergy, Asthma and Immunology in Chicago.

Allergists in Southern California said they’ve been made aware of the ant invasion and are preparing to treat any victims. About 100 fire ant mounds have been found in Southern California since Oct. 9.

“This is a new problem in Southern California, and doctors here are becoming aware of how to treat it,” said Dr. Donald Levy, an allergist in Orange. “Previously, it was a regional phenomenon that had not affected our region.”

The ants are believed to have been brought to the state on trees and shrubs imported by a nursery.

At least 40 people die in the United States annually in connection with insect stings, making the possibility of such deaths extremely rare, according to allergy specialists. It is estimated that half of the deaths are from fire ant stings, said Dr. Chester Stafford, a nationally recognized allergy expert at the Medical College of Georgia in Augusta.

As with other insect stings, the most severe cases occur only in people with an allergy to the insect’s venom who have previously been stung and sensitized, said medical experts.

In such repeat exposures, those allergic to ant venom may experience swelling of the larynx and tongue and, in the worst cases, dizziness, a drop in blood pressure and unconsciousness.

“Avoidance is the most important thing,” Levy said. “People should wear clothing over their legs and arms when they are potentially going to be in contact with ants. People don’t have to be worried about having a severe reaction the first time they are stung.”

The majority of fatalities have been recorded in Texas and Florida. Severe allergic reaction, not necessarily death, occurs in about 1 in 10,000 cases, according to Michael Merchant of Texas A&M; University.

More common than a severe reaction to the allergens is a swelling around the sting, which is caused by irritation from toxins in the venom, experts said. The fire ant, which is less than one-quarter inch long, is a particular hazard because of the high concentration of toxins in its venom and its pattern of repeat stings.

In the 13 Southern states where the ant is endemic, people are commonly stung in their homes.

The fire ant attacks by first biting its victim, then arching its body to inject venom with the stinger. The ant then stings repeatedly in a circular pattern around the initial bite while holding on with its mandibles, said Stafford.

Allergic reaction should be treated as a medical emergency, experts said.

Such reaction is characterized by extreme swelling at the sting site or elsewhere and can include facial flushing or swelling, generalized hives, swelling of the eyes or throat, wheezing or breathing difficulty.

About half of the deaths are due to swelling of the larynx, though other systemic reactions, including shock, can also be fatal, Stafford said. “Any throat constriction or change in voice or hoarseness is a serious sign,” he said.

People who develop a rash or hives after an initial sting should consider themselves possibly allergic and seek medical advice. “. . . That indicates someone could be susceptible to a more severe reaction next time,” Stafford said.

Those with known sensitivity to the venom should carry epinephrine or an emergency antivenin kit. In case of stings, the drug should be administered along with antihistamines while the victim seeks immediate attention from a physician, according to the American College of Asthma, Allergy and Immunology.

Allergists recommend immunotherapy for people who have a demonstrated sensitivity to the ant venom. It involves a series of injections to build up tolerance to the venom’s allergens. “Such treatment is 97% effective,” Stafford said.

Most victims are not allergic, however, and react to the toxin near the sting site. In these cases, there is an immediate, severe burning sensation, which is followed by redness and swelling around the sting area with intense itching that may last for hours, said Levy.

It should be treated with ice, a local steroid cream and oral antihistamines.

A pustule or whitehead develops within 24 hours and is the hallmark of fire ant stings, Levy said. Treatment is aimed at preventing secondary bacterial infection if the whitehead is scratched or broken.

Katherine Broman, a former Laguna Beach resident now living in Long Beach, was stung on several occasions while living in southern Florida.

The first time she was stung was at an outdoor concert. But when she was stung again six months later, after stepping on an anthill, she had trouble breathing.

“I looked down and I had ants all over,” she recalled. She was stung between 15 and 20 times, and within minutes she was covered with hives and had to be treated at an emergency room.

“Man, do they hurt,” Broman said.

Times staff writer Deborah Schoch contributed to this report.