The main route to spread infection is primarily through direct contact between an infected person and another person. This occurs when infectious agents are transmitted via touching infected skin, mucous membranes, body fluids, or through respiratory droplets from coughing, sneezing, or talking. Indirect contact by touching contaminated objects or surfaces followed by touching the mouth, nose, or eyes also plays a significant role. Other important routes include:
- Airborne transmission , where pathogens travel as tiny particles or droplets suspended in the air and are inhaled by others (e.g., measles, tuberculosis).
- Faecal-oral transmission , where pathogens from feces contaminate food, water, or hands and enter the mouth (e.g., hepatitis A, cholera).
- Body fluids , such as blood and sexual secretions, that can transmit infections through cuts, sexual contact, or needle injuries (e.g., HIV, hepatitis B).
- Vectors , like mosquitoes or fleas, that transmit infections via bites.
Thus, infection spreads mainly by direct person-to-person contact and respiratory droplets, but also through indirect contact, contaminated food/water, bodily fluids, and vectors.