Cattle fever ticks were for the most part eliminated from the United States over 70 years ago. Now they are back and spreading well beyond the buffer zone established along the Texas-Mexico border designed to prevent their return. Techniques that succeeded in ridding the US of these dreaded ticks decades ago are no longer as effective at killing or even containing them.
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 south 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?
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.
African swine fever (ASF) is a deadly, contagious viral disease of pigs for which there is no vaccine or treatment. While primarily a scourge of sub-Saharan Africa, the disease’s recent spread into Russia and the European Union reminds us that ASF is not just a tropical disease.
Alarmingly for large swine-producing regions, from China to the EU and the United States, ASF’s behavior in the current Eastern European outbreak differs significantly from what was expected based on previous ASF outbreaks in Western Europe. These differences make expansion of the disease much more difficult to control, threatening huge economic losses to affected countries. Through October 2015, over 750,000 domestic pigs in Europe have died from or were culled to prevent the spread of the current ASF outbreak.