WEDNESDAY, Aug. 22, 2001 (HealthDayNews) -- In what health officials say is the first documented case of its kind, a pregnant woman from northeastern Ohio was infected by a rabies vaccine used in a wildlife bait program, the Centers for Disease Control and Prevention (CDC) reports.
The illness developed three days after the 28-year-old woman was bitten by her pet dog, which had been chomping on a chunk of rabies vaccine bait. The bait, scattered by public health officials to prevent the spread of rabies in wild animals, contained a genetically modified oral vaccine called vaccinia-rabies glycoprotein virus.
The woman experienced fever, swelling of the arm and inflamed red skin and was given antibiotics and had the infected wound surgically drained. She suffered no adverse effects, the researchers say, and there was also no effect on her unborn child.
The incident happened last September and the woman had been pulling the bait out of her dog's mouth when the animal bit her finger and grazed her arm, says Dr. Charles Rupprecht, chief of the CDC's rabies section and author of the case report that appears in the Aug. 23 issue of the New England Journal of Medicine.
"She washed her bitten finger very well, but where the dog grazed her arm, she probably did not pay as much attention," he says. "And that's where the virus impregnated the skin. And so we have the first documented infection with this recombinant virus."
Rupprecht says the dog must have punctured the packet of vaccine hidden within the bait.
"The vaccine is enclosed in something like a ketchup packet within the bait, which looks like a charcoal briquette. It uses a polymer, which binds together fish meal and fish oils that attract raccoons. Most carnivores, in fact, are attracted to the bait," he notes.
The genetically modified virus was developed in the 1980s as a way to orally inoculate raccoons and foxes against rabies. It was used successfully in Europe before it was field-tested in the United States in 1990.
The Food and Drug Administration approved the rabies vaccine bait in 1995, and since then planes have dropped tens of millions of these packets in wildlife areas throughout the eastern half of the United States.
"There are a number of firsts with this oral vaccine and bait," Rupprecht says. "It's the first vaccine to be used for an oral vaccination program against rabies in the United States, and it's the first bait ever used to control the disease in raccoons. It was the first wildlife vaccine ever used in the U.S., and it was the first release of a genetically modified organism in the world."
Dr. Michael Auslander, public health veterinarian for the state of Kentucky, says the case is an anomaly.
"We've had extensive experience with this bait, and this is the first known case of transmission from vaccinia," he notes. "Handling the bait has always been safe, and it's been going on for 10 years in Texas, which has the most experience."
Auslander says the bait is "used where there are naturally occurring epidemics of rabies in foxes and raccoons. These animals can pass rabies on to cattle and dogs, and that's what we are trying to avoid -- the spread of the disease from wildlife to domesticated animals or to people."
In 1999, there were 7,067 reported cases of rabies in animals in the United States, an 11 percent drop from 1998. Rabies in raccoons was virtually unheard of before the 1950s, but has spread since the 1970s. Last year, five Americans died of rabies; four of them came into contact with bats and the fifth was bitten by a dog while traveling in Africa.
The case study presents "sort of a mixed message," Rupprecht says. "It shows the relative safety of this vaccination approach, since this is the first case [of infection] we've been able to document in 10 years. And remember [the use of these baits has] been going on in Europe since 1986, where it helped to eliminate rabies in foxes in France.
"The mixed part of the message is that every year we've been putting out more and more doses in more geographic areas as part of a national plan," Rupprecht continues. "And we have data showing that the vaccine bait is controlling rabies." The report, for instance, says that no rabies cases were found among raccoons in 2000.
Rupprecht says that when public health officials scatter the bait, every effort is made to alert the public. "It's usually accompanied by a whole media campaign -- press, radio, letters to public health officials and veterinarians. But we've been doing it for 10 years, and the news starts to become old hat."
What To Do
"We don't want to become cavalier, and we want to remember the things we learned in childhood, such as washing all animal bites with soap and water," Rupprecht advises. "And contacting our primary care provider, if illness results."
For more on the oral rabies vaccine bait and control of the disease in wild animals, see the Centers for Disease Control and Prevention, which also has information on rabies. Another place to go is the New Jersey Department of Health and Senior Services.
