Explanation:
(a)

Disease	Causative Organism	Vector	Control
Cholera	Vibrio Cholerae	Housefly/Cockroach	Good sanitation/good personal hygiene/ any other method of good sanitation/inoculation/vaccination
Trypanosomiaasis/Sleeping sickness	Trypanasome	Tsetsefly/Glossina	Destroying habitat of vector/clearing the vegetation, killing vector/ eradicate flies.
Malaria	Plasmodium sp	Penale anopheles mosquito	Proper sanitation/using spraying recommended insecticide/fumigation, clearing of bushes/drainages of breeding sites/sleeping under nets.
Ringworm	Tinea Sp/Fungi/Microsponium	None	Good personal hygiene, avoid contact with infected persons/material, use of drugs/griseofluvin

(b) Biological Basis of Preserving Foods by;
(i) Salting; Removes water/moisture from food by osmosis therefore prevents micro-organisms from growing on food by dehydrating and killing them.
(ii) Irradation; Involves the exposure of food to high energy gamma rays/x-rays radiation to destroy enzymes that cause spoilage, delay ripening of fruits, sprouting of vegetables therefore allowing long storage periods.
(iii) Smoking; Reduces the water content of food thereby creating unfavourable conditions for microbial growth and survival also called curing. Smoking contains phenols/carbon that kills microbes on the surface of food.