When were antibiotics ______ ? (discovered)
About forty million people in the world _______ with HIV which causes AI DS. (are infected)
Malaria ___ by male mosquitoes. (is not transmitted)
How is flu _ on from person to person? (passed)
The plague in Florence _ by Boccaccio in Decameron. (was described)
Many infectious diseases _ by mice and rats. (are spread)
AIDS on by sneezing, coughing or touching. (is not passed)