Virology, Emerging Diseases & vaccines

Transmission of Viruses

Viral transmission is the process by which viruses spread between hosts. It includes spread to members of the same host species or spread to different species in the case of viruses that can cross species barriers. Transmissibility within human populations is a key determinant of epidemic potential. Many viruses that can infect humans are not capable of being transmitted by humans; most human transmissible viruses that emerge already have that capability at first human infection or acquire it relatively rapidly. Virus transmission to humans occurs via inhalation of aerosolized virus-contaminated rodent urine, saliva, and feces, rarely by rodent bites. Humans are usually considered as a dead-end host that does not transmit the virus further. For plant viruses, the pathways reviewed are vertical and horizontal transmission via pollen, and horizontal transmission by parasitic plants, natural root grafts, wind-mediated contact, chewing insects, and contaminated water or soil. For insect viruses, they are transmission by plants serving as passive “vectors,” arthropod vectors, and contamination of pollen and nectar.