| Most plants primarily infected by PVT remain symptomless, but plants of potato cv. |
| They are either symptomless or may cause disturbances such as halos around lights especially at night, blurring of vision or photophobia. |
| An individual infected with it may remain symptomless for several years and then relapse. |
| Infection by this strain may be symptomless or produce mosaic symptoms, both mild and severe. |
| Pre-eclampsia is symptomless in its early stages and at present detectable only by regular checks on the mother's blood pressure and urine. |
| However, the symptomless nature of the infection makes necessary to test individual mother plants. |
