| Droplet spread | Influenza virus, Neisseria meningitidis, Respiratory syncytial virus (RSV), Streptococcus pyogenes, Bordetella pertussis |
| Faecal–oral | Salmonella spp., Norovirus, Shigella spp., Escherichia coli (ETEC/EHEC), Hepatitis A virus, Rotavirus |
| Invasion of intact skin | Leptospira spp., Schistosoma spp., Hookworm (via larvae), Strongyloides stercoralis |
| Invasion of breached skin | Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, Clostridium tetani |
| Sexual intercourse | HIV, Neisseria gonorrhoeae, Chlamydia trachomatis, Treponema pallidum (syphilis), Herpes simplex virus (HSV), Human papillomavirus (HPV) |