(a) Amoebiasis: By contaminated food and water containing cysts of Entamoeba histolytica.
(b) Malaria: Through the bite of infected female Anopheles mosquito.
(c) Ascariasis: By consuming food or water contaminated with eggs of Ascaris.
(d) Pneumonia: By inhaling droplets/aerosols from an infected person or using contaminated utensils.