An example of a virus transmitted mechanically is Equine Infectious
Anemia virus (a retrovirus/lentivirus). Transmission is from horse to
horse via a Tabanid fly. In this case, the biting of the fly is
irritating and the horse tries to brush it away. The fly then goes on
to the next horse, transmitting a bit of the blood of the first host in
the process. The virus does not replicate in the fly (see Fields
"Virology", Chapter 55, page 1579).
In addition, many arboviruses (such as LaCrosse encephalitis virus) can
be transmitted from one vertebrate host to another by mechanical means
during interrupted feeding. In this case, this is a minor pathway,
since these viruses replicate quite well in their arthropod hosts.
Martin Hewlett, Ph.D.
Department of Molecular and Cellular Biology
University of Arizona
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