Birds can be long-distance lyme disease carriers
Date: 18-Feb-00
Country: UK
The birds can carry a latent form of the infectious disease that can be
reactivated when their immune system is weak. The illness can then be
passed on to ticks that infect humans, the researchers said in a letter
to the science journal Nature.
"Migratory birds are able to carry Lyme disease as a latent infection
for several months," said Bjorn Olsen of Umea University and Kalmar
County Hospital in Sweden.
Olsen and his colleagues said stress and fatigue caused by birds' long
flights can suppress their defences against the bacterium that causes
the illness.
Lyme disease mainly passes to humans from ticks on deer and dogs. Early
symptoms include a rash, fever, headache, lethargy and muscle pain. If
it is not treated early with antibiotics, it can develop into a chronic
condition with irreversible joint pain, severe arthritis, heart problems
and facial paralysis.
When the Swedish researchers simulated migration in the laboratory,
thrushes injected with the bacterium developed the disease and became
carriers.
"As thrushes and other birds often travel great distances during
migration, this reveals a new mechanism for facilitating the
long-distance spread of Lyme disease," the scientists added.
The illness was first identified in Old Lyme, Connecticut, in 1975. More
than 99,000 cases, most in North America, have been reported since it
was first recognised.
