Please consider the graph below showing rates of infectious diseases in the United States from 1900...
Please consider the graph below showing rates of infectious diseases in the United States from 1900 to 2000. What important factors explain the downward trend over time? Which of these factors do you think had the greatest impact? Please explain. Copyright © The Meme Hll Comparis, ne. Permission required to protection or complex, 40 states have health departments 1000 Influenza pandemic 800 Rate 600 Last human-to-human transmission of plague First use 400 of penicillin First continuous Salk vaccine municipal use Introduced Passage of 200 of chlorine in water Vaccination Assistance Act in United States 0 1990 1920 1940 1960 1980 2000 Year