Table 2.
Examples of human and animal virus transmission patterns
| Infectious agent/disease | Mode of transmission | Portal of entry |
|---|---|---|
| Influenza virus/influenza | Contact/direct/indirect via droplets and droplet nuclei | Respiratory tract |
| Rhinoviruses/common cold | Contact/direct/indirect via droplets and droplet nuclei and fomites | Respiratory tract |
| Rubella virus/congenital rubella | Contact/direct/indirect via droplets and droplet nuclei | Respiratory tract |
| Vertical/congenital | Transplacental | |
| Rotaviruses/diarrhea | Contact/direct/indirect via fomites | Intestinal tract (oral) |
| Poliovirus/poliomyelitis | Contact/direct/indirect via fomites | Intestinal tract (oral) |
| Norovirus/diarrhea | Common vehicle/fecal contamination of water | Intestinal tract (oral) |
| Hepatitis A virus/hepatitis | Common vehicle/fecal contamination of food | Intestinal tract (oral) |
| Variant Creutzfeldt–Jakob disease prion/prion disease (spongiform encephalopathy) | Common vehicle/bovine spongiform encephalopathy prion contamination of beef or beef products | Intestinal tract (oral) |
| Herpes simplex virus/genital herpes | Contact/direct (sexual) | Genital tract |
| Human immunodeficiency virus 1/acquired immunodeficiency syndrome (AIDS) | Contact/direct (sexual), contact/direct (blood) | Genital tract, bloodstream, transplacental, at birth and via breast feeding |
| Vertical/congenital | ||
| Rabies virus/rabies | Zoonotic/contact/direct (saliva) | Skin (bite wound) |
| Russian spring summer encephalitis virus/encephalitis | Zoonotic/arthropod-borne | Skin (tick bite) |
| Dengue viruses/dengue | Zoonotic/arthropod-borne | Skin (mosquito bite) |
| Sin Nombre and related viruses | Zoonotic/contact/direct (rodent urine, saliva and feces) | Respiratory tract |
| Lassa virus | Zoonotic/contact/direct (rodent urine, saliva and feces) | Respiratory tract and intestinal tract (oral) |
| Ebola and Marburg viruses | Zoonotic/reservoir host unknown; secondary cases contact/direct/ nosocomial and iatrogenic | Index cases unknown, likely respiratory tract or skin and mucous membranes; secondary cases, contact and iatrogenic (injection) |
| Leukemia viruses/leukemias (proven only in animals) | Vertical/germ-line | Transmitted as genetic trait |