Scientists have documented at least six attacks in nursing homes and as many other attacks in private residences, apartments and hotels over the last decade, said Robin Rockhold, a professor of toxicology and pharmacology at the University of Mississippi Medical School.
In addition to the attacks researchers documented in nursing homes — two each in Florida, Texas and Mississippi — fire ants have also attacked a resident in a state institution in Alabama. At least 4 nursing home residents have died within a week of a fire ant attack.
"In a sense, this is a wake-up call for the future," Rockhold said in a telephone interview last week before speaking at a national fire ant conference in Baton Rouge. "We need recognition of the potential for this problem."
Nursing home patients who were attacked by the ants had physical or mental ailments that kept them from moving away or shouting for help. The ants are fast-moving, covering about 6 inches of ground in 10 seconds. One nursing home resident was found covered with ants at 4 a.m.; there had been none four hours earlier, and a pest control inspector had not seen any the previous day, the researchers say.
Fire ants are about one-eighth to one-quarter inch long, but inflict a painful sting far out of proportion to their size. It's rare to be stung by a single fire ant. Large numbers will swarm onto the body and then sting almost simultaneously.
The stings show up first as small red welts which develop pinhead-sized pustules after 8 to 10 hours. They feel like fire at first, then turn to a severe itch.
About two percent of the population is allergic to fire ant stings, as with any other insect sting. But the documented deaths resulted not from allergic reactions, but complications the stings caused to victims' fragile conditions. For instance, a 90-year-old woman in a Texas nursing home died six days after a fire ant attack because of worsened congestive heart failure, according to a 1995 report by the researchers.
Fire ants are native to the South, but local ants have been crowded out by their South American counterparts, which have no natural enemies in the United States.
The South American fire ants arrived at Mobile, Ala., in the 1930s, probably in dirt used as ballast in ships. Over time, the ants spread throughout the Gulf states, and are now found as far north as the Carolinas, Kentucky, Arkansas and Oklahoma, and in spots in California and New Mexico.
Experts say they are likely to travel as far north as Virginia, Maryland and Delaware in the east and into Oregon and Nevada in the west. It is possible that they could get as far as Washington or Utah.
The University of Mississippi and Mississippi Department of Health medical entomologist Jerome Goddard recommended two years ago that health care facilities set up guidelines for dealing with fire ants.
The recommendations include keeping a log to let their pest control contractor know when and where ants and other pests have been seen, checking lawns once a week for fire ant mounds, and requiring the contractor to act within 24 hours if ants are found anywhere inside the facility.
Federal rules already require all nursing homes to have pest control contracts and to keep their facilities free of pests, said Jeff Smokler, spokesman for the American Health Care Association.
"Is seven attacks in 10 years a problem? Of course," he said. "One attack is a problem. One is too many.
"Unfortunately, fire ants move very quickly," Smokler said. "They are able to come through a small crack in the foundation in a very small time."