Intranasal infection of Getah virus in experimental horses.

Aerosol transmission in equine Getah virus (GV) infection was examined by intranasal inoculation with 10(3.0) to 10(7.0) TCID50 of the MI-110 strain in 7 experimental horses. The establishment of intranasal infection of GV was confirmed in all these horses by detecting serum neutralizing antibody against the MI-110 strain. Horses inoculated with more than 10(4.0) TCID50 of the virus manifested mild pyrexia, eruptions, serous nasal discharge, lymphopenia or monocytosis. Viremia ranging from 10(1.0) to 10(3.5) TCID50/0.2 ml occurred in horses inoculated with 10(5.0) TCID50, or more. Virus recovery from the nasal cavity was observed only in horses inoculated with 10(7.0) TCID50, and the viral titers recorded were 10(3.0) TICD50/ml or less. From these results, it is assumed that GV disseminated from the nasal cavity of naturally infected horses, except for intranasal infection with a lot of the virus, is probably very low in titer. So it seems to be rare that GV in natural cycles is spread from horse to horse by aerosol transmission.