Virusses

In the cases which have been cited to prove the identity of the two virusses, it has been said that a diseased individual having had connection with several healthy persons, these latter would be variously affected; some would have chancres, some gonorrhœa, and others both together.

Source: wiktionary

In recent times the question of the origin of life is connected with the problem of the living or non-living character of the virusses.

Source: wiktionary

but it was only in recent years that it was discovered that certain organisms, namely virusses, are responsible for this degeneration. Leafroll is caused by a single virus, while most of the mosaic diseases are caused by one of the X, Y or A virusses.

Source: wiktionary

(a) infection by virusses, bacteria or parasites / […]

Source: wiktionary