An Imperfect Storm: Why Lyme Disease Is Uncommon in the Southern United States

Ixodes tick. Primary bridging vectors for Lyme disease. Jerzy Gorecki

Ixodes tick, primary vectors for Lyme disease.     Jerzy Gorecki

Lyme disease is caused by Borrelia burgdorferi, a bacterium transmitted by ticks to a wide range of animal species (including people) in much of the world. The great majority of human Lyme disease cases in the United States occur in the Northeast and upper Midwest states. Yet, the impact of Lyme disease in the southern US remains minimal despite the abundant presence of the primary Ixodes tick vectors, numerous competent animal hosts, widespread suburban sprawl that brings people into frequent contact with ticks, and the documented presence of B. burgdorferi bacteria in the region. Why hasn’t the disease taken a stronger hold there?

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Migratory Birds as Spreaders of Emerging Diseases: Fact and Fiction

Storks on migration over Haifa, Israel. Some of these carried a particularly virulent form of West Nile Virus from Europe in 1998. David King

Storks on migration over Haifa, Israel. Several individuals of this species were found in this area carrying a particularly virulent form of West Nile Virus from Europe in 1998.        David King

Migratory birds move hundreds to thousands of kilometers twice a year, often spanning continents. As they share certain diseases with people, it is not surprising that birds are frequently blamed for transporting these diseases around the world. But while birds are undoubtedly implicated in the geographic expansion of some emerging diseases, the more interesting question is why it doesn’t happen more often, given the hundreds of millions of birds on the move.

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