OptiMisTick
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Note: at first I thought they meant into the food of *patients* - that was scary.
Researchers Propose Introducing Vaccines into Food of Lyme Disease Carriers
Source: Chicago Tribune Publication date: 2004-12-28 Arrival time: 2004-12-27
Dec. 28--Bubonic plague, monkey pox, SARS and West Nile virus all have one thing in common: animals provided the link that brought these diseases into the human world.
Now a new study on Lyme disease suggests a way such maladies might be stymied before they ever reach people: take the vaccinations straight to the animal kingdom.
"There is more than one way to try to reduce Lyme disease risk besides relying just on developing vaccines for humans," said Michigan State University disease ecologist Jean Tsao. "We also should try ways to intervene in nature because we can potentially help more people by reducing the risk at its source."
Tsao and others caution that the research is a long way from reaching a practical application, but they propose that vaccines could be incorporated into food sources targeting important carriers of the disease--in this case mice and other forest critters.
The study, which researchers say is the fruit of an emerging field blending ecology and medicine, appears in the Dec. 28 edition of the Proceedings of the National Academy of Sciences.
It demonstrates scientists' increasing focus on going out into the wild to understand how diseases reach the human population, and how, perhaps, that link can be broken, said J. Timothy Wootton, an associate professor of ecology and evolution at the University of Chicago, who helped design the study.
"It's worth thinking about things other than just looking in a laboratory for solutions and causes of disease, in other words, a plural approach," he said.
Lyme disease, which affects the skin, nervous system, heart and joints, is not particularly common in Illinois, but Chicago's outdoor playground, Wisconsin, is one of the national hotbeds.
The disease is caused by bacteria that incubate and multiply in the bodies of forest animals, such as mice. Black-legged ticks, also known as deer ticks, are "vectors" that pick up the disease when they bite the mice. They deliver it to humans if they bite them later on.
From 1998 to 2001, Tsao and other researchers trapped and anesthetized almost 1,000 white-footed mice in a dozen southern Connecticut forests. The woods there are a high-risk area for Lyme disease and they're chock full of ticks.
The blood-sucking bugs were feasting on mice--one mouse had as many 60 stuck to just one ear. "As a tick researcher, I felt really spoiled there," Tsao said with a laugh.
Using a needle, the researchers gave the mice a shot of vaccine, tagged them, re-hydrated them with an apple slice and sent them back into the forest. The mice developed immunity to the Lyme bacteria, making them "dead end hosts," Tsao said. When an infected tick fed on an immunized mouse, the mouse's antibodies killed the bacterium inside the tick--leaving it unthreatening to humans.
After immunizing about 55 percent of the forests' mouse population, researchers found an overall 16 percent reduction in the prevalence of infected nymphs--young ticks no bigger than a pinhead that feed on mice, and also are responsible for roughly nine out of 10 human infections.
If all the mice in the forest had been vaccinated, the percentage of infected nymph ticks would have dropped 27 percent, they extrapolated. That showed the researchers that vaccinating mice could be a way to suppress the disease, but it also exposed the important role other host animals, such as chipmunks, shrews and robins, also play in spreading Lyme.
Contrary to public belief, deer do not play as direct a role in the transfer of Lyme disease to humans, though they are crucial to the tick life cycle.
Deer are the insect's preferred host animal when they reach the adult stage and need a big bloody meal before mating and manufacturing eggs.
The researchers aren't suggesting that someone give shots to every mouse, chipmunk and shrew in the forest. But they say there are more logical ways to potentially vaccinate large numbers of animals--either as food pellets or in bait boxes targeted to certain species, as has been done to successfully curb rabies.
"When integrated with other protective measures, this strategy could have significant implications, not only for preventing Lyme disease, but for preventing other vector-borne diseases as well, including plague and West Nile virus," said Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases.
"It's intriguing," said Phil Pellitteri, an entomologist who specializes in Lyme disease at the University of Wisconsin-Madison. "To me the ultimate feasibility comes down to a cost issue, but the science behind it sounds pretty interesting."
The vaccination concept is still in such an early stage that researchers can't estimate what it would eventually cost a park district, for example, to use such a technique to ward off Lyme disease.
In 2002, there were 23,763 cases of Lyme disease reported in the United States, up from 9,908 a decade earlier. Most of the high-risk areas in the country are in the Northeast, but the disease also is highly prevalent in Wisconsin. In 2002, Wisconsin was 6th most of any state with 1,090 cases, according to the U.S. Centers for Disease Control.
The vast majority of cases come from the western two-thirds of the state. The ticks that carry the disease prefer thick brushes and woodland, so the most susceptible people are hunters, hikers and other outdoor sports lovers.
(c) 2004, Chicago Tribune. Distributed by Knight Ridder/Tribune Business News. For information on republishing this content, contact us at (800) 661-2511 (U.S.), (213) 237-4914 (worldwide), fax (213) 237-6515, or e-mail [email protected].
[ 01-24-2011, 06:39 AM: Message edited by: OptiMisTick ]
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