The death toll from pneumonia and other infectious diseases in the U.S. is much lower than it was 100 years ago, but new pathogens like the West Nile, dengue and Zika viruses pose challenges.
The death toll from pneumonia and other infectious diseases in the U.S. is much lower than it was 100 years ago, but new pathogens like the West Nile, dengue and Zika viruses pose challenges.