FIG. 2.

The effect of an antimalarial vaccine on the mortality of canaries over a 3-year period. (A) Thirteen of 27 canaries put into an outside aviary in 1999 died of malaria (48% mortality). (B) Canaries were split randomly into two groups in 2000. One group was given a DNA vaccine, boosted, and mixed with unvaccinated canaries in an aviary at site A. The other group, housed at site B (∼1 km away), suffered a mortality rate similar to that seen at site A the year before. (C) Survivors of the exposure in 2000 from both locations were put into site A during the 2001 season. All the birds previously from cage B (in 2000) survived this second exposure, while the birds from cage A (in 2000) suffered the mortality rates indicated in the figure.