1. Harvard University, Boston, MA 02115, USA.
2. Connecticut Agriculture Experiment Station, New Haven, CT 06504, USA.
3. North Carolina State University, Raleigh, NC 27695, USA.
4. University of California, Davis, CA 95616, USA.
5. University of Florida, Vero Beach, FL 32962, USA.
6. Yale University, New Haven, CT 06520, USA.
7. Cornell University, Ithaca, NY 14853, USA.
8. Illinois Natural History Survey, Champaign, IL 61820, USA.
9. Humboldt University, 10099 Berlin, Germany.
10. Centers for Disease Prevention and Control, Fort Collins, CO 80522, USA.
11. Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
12. Pasteur Institute, 75724 Paris Cedex 15, France.
13. Tulane University, New Orleans, LA 70118, USA.