Indirect transmission occurs through flies, food and fluid, etc. Infectious agents are transmitted through water and food including vegetable, fruits, milk, milk products, ice, blood serum, plasma, etc. Their transmission is vehicle-borne. Some examples are as follows:
| Hepatitis A virus | Multiplies in water |
| Diarrhoea, typhoid fever, polio, cholera | Transmitted by water and food |
| Hepatitis B, malaria, syphilis, chagas disease. | Transmitted by vectors |