Ascariasis - Through contaminated food and water.

Explanation:Ascariasis is caused by Ascaris lumbricoides. A large number of adult Ascaris worms infest a single host, they obstruct the intestinal passage and cause abdominal discomfort like colic pains. The patient may suffer from indigestion, diarrhoea and vomiting. The disease can be treated by administering antihelminthic drugs like oil of chenopodium, Alcopar, Bendex, Dewormis, Zental etc.