MIGRATING birds may be spreading Lyme disease. Although they are known to
carry infected ticks, they were not previously suspected of having the disease
themselves.
Bj枚rn Olsen and his colleagues from Ume氓 University in Sweden infected
redwing thrushes with Borrelia burgdorferi, the bacterium that causes
the disease. They then fooled half the birds into thinking it was autumn by
reducing the number of hours of light, simulating the stress of migration (
Nature, vol 403, p 724).
Initially no bacteria were found in either group. But the stressed birds soon
started to show signs of infection. 鈥淢igration is enough to suppress the immune
system and reactivate the infection,鈥� says Olsen.
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