Amoebiosis is caused by Entamoeba histolytica. Infection occurs by ingesting cysts with food and drinks. These cysts are carried by flies from faeces of food and drinks.
(b) Malaria. Malaria is caued by Plasmodium sp. Malarial parasites are carried from the infected to the healthy person by the female Anopheles mosquito. The mosquito picks up the parasites alongwith the blood when it bites an infected person. when this mosquito bites healthy person, parasites migrate into his blood with the saliva, which the mosquito injects before sucking up blood to prevent its clotting.
(c) Ascariasis. Man gets infection by taking Ascaris eggs with food and water. Children become infected by ingesting soil.
(d) Pneumonia. It spreads by sputum of the patient. Pneumococci are inhaled and get lodged in the bronchioles.