Differentiate primary, secondary, and tertiary levels of causes of diseases.

There are three levels of causes of diseases :

1. The primary level of cause: The primary level of cause occurs immediately as disease-causing organisms such as bacteria, and the virus infects the healthy person immediately.
2. Secondary level of cause: The secondary level of the cause of disease includes lack of nutrition in the diet.
3. The third level of cause: The third level of the cause of a disease is poverty as poor people live in an unclean environment which makes them more prone to contracting a disease.

Serial no.	Primary level	Secondary level	Third level
1.	Caused by the intake of contaminated food, with pathogens such as bacteria, viruses, and fungi	Caused due to a lack of nutrients in the diet	Caused by poverty and poor public health services.
2.	Everyone does not suffer equally from infectious agents.	Unhealthy persons are more prone to catching various diseases.	People living in unhealthy environments are more prone to them especially water-borne diseases.