Vaccinating Mice Could Reduce Lyme Disease
Date: 15-Dec-04
Country: USA
The study is one of the first to show that immunizing a wild animal that carries a disease might serve to protect humans, the National Institute of Allergy and Infectious Diseases said.
"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 NIAID head Dr. Anthony Fauci.
Lyme disease is caused when people are bitten by a tick carrying the Borrelia burgdorferi bacteria.
It affected 23,000 Americans in 2002 and causes a characteristic "bull's-eye" rash, fatigue, chills and fever, headache, muscle aches and joint pain. Untreated, it can lead to more severe symptoms and arthritis.
It passes from mice and other small rodents to people via black-footed ticks. Often deer are involved.
It would be necessary to develop a vaccine that could be given orally, probably in mouse bait, the researchers report in this week's issue of the Proceedings of the National Academy of Sciences.
For their study, the team at Yale University and elsewhere caught 1,000 white-footed mice, drew their blood, examined the ticks in their fur and then vaccinated half of them.
When an infected tick nymph feeds on an immunized mouse, the mouse's immune system kills the bacteria inside the nymph.
After vaccinating the mice, the researchers found 55 percent fewer tick nymphs were infected.
But they also found that mice are not the only carriers.
"We've learned we shouldn't naively ignore other hosts -- shrews, chipmunks, robins, and maybe others," said Jean Tsao, now at Michigan State University, who worked on the study.
"The targeted vaccination of wildlife carriers could offer more far-reaching protection against vector-borne diseases than vaccinating humans," added Dr. Alan Barbour at the University of California, Irvine, who helped lead the study.
"When the vaccine is targeted to humans, only those who experienced a satisfactory immune response to the vaccine are protected; however, when the vaccine is targeted to wildlife carriers, the risk of infection is lowered for everyone in the community."
