1 Table of Contents: “... Interactions of more than one Pathogenic Agent -- 12.3 Models of a Directly Communicated Disease or Parasite --...”

2 “... communicable diseases. It was a vaccine that en­ abled global eradication of the dreaded disease smallpo....”

3 “... communicable diseases. It was a vaccine~hat enabled global eradication of the dreaded disease smallpox. Mass...”